Provenance and geochronological insights into Late Cretaceous-Cenozoic foreland basin development in the Subandean Zone and Oriente Basin of Ecuador

CHAPTER

Provenance and geochronological insights into Late CretaceousCenozoic foreland basin development in the Subandean Zone and Oriente Basin of Ecuador

9

E. Gabriela Gutiérrez⁎, Brian K. Horton⁎,†, Cristian Vallejo‡, Lily J. Jackson⁎,†, Sarah W.M. George⁎ Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, United States* Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, United States† Departamento de Geología, Facultad de Ingeniería en Geología y Petróleos, Escuela Politécnica Nacional, Quito, Ecuador‡

1 ­Introduction The western margin of South America experienced multiple tectonic regimes throughout Phanerozoic time. Mesozoic-Cenozoic evolution of the northern Andes departs from the rest of the Andean margin on account of its tectonic interactions with accreted oceanic terranes such as the Caribbean Large Igneous province (CLIP; Kerr et al., 2002; Vallejo et al., 2006). The northern Andes exhibit relatively low-magnitude crustal shortening and are highly influenced by the reactivation of inherited fault systems and inversion of pre-Andean sedimentary basins (Cooper et al., 1995; Mora et al., 2009; Baby et al., 2013; Horton, 2018). Similar to other segments of the Andes, retroarc shortening and flexural subsidence are fundamental to construction of the orogenic system, but the onset and advance of the fold-thrust belt and foreland basin are not fully understood. In Ecuador (Fig. 1), exhumation of the narrow Andean orogen and subsidence of the Oriente Basin have been addressed by previous studies that variably emphasize diverse structural, thermochronological, and stratigraphic records (e.g., Tschopp, 1953; Dashwood and Abbotts, 1990; Balkwill et al., 1995; Jaillard and Soler, 1996; Christophoul et al., 2002; Ruiz, 2002; Pratt et al., 2005; Spikings et al., 2005, 2010, 2015; Ruiz et  al., 2007; Martin-Gombojav and Winkler, 2008; Baby et  al., 2013). Integrated

Andean Tectonics. https://doi.org/10.1016/B978-0-12-816009-1.00011-3 © 2019 Elsevier Inc. All rights reserved.

237

238

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

FIG. 1 Regional map and schematic cross section of the Ecuadorian Andes showing tectonic provinces, geologic units, major faults, and sample locations (modified from Ruiz et al., 2007; Chew et al., 2007; Ramos, 2010). Inset map (upper right) shows South American cratonic provinces.

sedimentologic and geochronologic approaches offer opportunities to explore temporal changes in ­mountain building, tectonic regime, and basin evolution, as expressed in the development of sediment source regions, depositional systems, and basin accommodation space. In Ecuador, the MesozoicCenozoic depositional history of the Oriente Basin involved detrital input from the Amazonian craton, Andean magmatic arc, and Andean fold-thrust belt.

2 ­ Geologic framework

239

We present new detrital zircon U-Pb results for Cretaceous-Cenozoic fill of the Subandean Zone and Oriente foreland basin of Ecuador to identify sediment source regions and their evolution. We seek to pinpoint the onset of Andean crustal shortening and thrust-belt advance as well as patterns of sediment delivery from the craton and magmatic arc of northern South America. These efforts are designed to enhance temporal constraints on the evolution of source regions, thus improving the basin-scale stratigraphic framework, paleogeography, and sediment dispersal patterns.

2 ­Geologic framework A west–east transect across the northern Andean margin includes the magmatic arc, retroarc foldthrust belt, foreland basin, and distal craton. The Ecuadorian Andes (Fig.  1) are delineated by two north-trending ranges (Western and Eastern Cordilleras) with an adjacent forearc basin, hinterland basin (Interandean Valley), and retroarc foreland basin (Oriente Basin) (Tschopp, 1953; Dashwood and Abbotts, 1990; Baby et al., 2004; Horton, 2012, 2018). The Western Cordillera broadly defines the Cenozoic magmatic arc and includes accreted Mesozoic basement of oceanic affinity and volcanic arc, volcaniclastic, and sedimentary units (Lebras et al., 1987; Reynaud et al., 1999; Hughes and Pilatasig, 2002; Kerr et al., 2002; Mamberti et al., 2003; Vallejo et al., 2006, n.d.). The Eastern Cordillera (or Cordillera Real) defines the elevated segment of the retroarc fold-thrust belt and consists principally of poorly understood Paleozoic metasedimentary basement (Litherland et al., 1994; Chew et al., 2008; Mišković et al., 2009; Horton et al., 2010; George et al., n.d.) overprinted by Mesozoic magmatic and low- to high-grade metamorphic rocks (Aspden and Litherland, 1992; Pratt et al., 2005; Spikings et al., 2015). Andean basement also crops out in the forearc within the east-trending Amotape-Tahuin block (Fig. 1), a piece of the Eastern Cordillera that was detached and rotated during oblique Cretaceous– Eocene deformation (Mourier et al., 1988; Litherland et al., 1994; Spikings et al., 2005; Kennan and Pindell, 2009). The Subandean Zone represents the frontal fold-thrust belt, a transitional region between the Eastern Cordillera and Oriente foreland basin. This zone includes thin- and thick-skinned structures capped by wedge-top deposits of the proximal foreland basin (Balkwill et al., 1995; Ruiz et al., 2007; Baby et al., 2013). The Subandean to Oriente transition is critical to understanding sediment provenance and foreland basin evolution as the advancing fold-thrust belt progressively incorporated new source regions into the growing orogenic wedge. The Oriente Basin of Ecuador (Fig.  1) is an active retroarc foreland basin that developed as a result of flexural subsidence induced by Andean crustal thickening. The basin is contiguous with the Putumayo Basin of southern Colombia and Santiago-Marañón Basin of northern Peru; it stores the products of Andean denudation and the gradual incorporation of new source regions during foldthrust encroachment (Ruiz et al., 2007; Martin-Gombojav and Winkler, 2008; McGroder et al., 2015; Wolaver et al., 2015). The Oriente Basin contains ~4.5 km of principally clastic deposits (Fig. 2). The Cretaceous-Cenozoic succession overlies basaltic to rhyolitic lava flows and pyroclastic deposits of the Misahualli Formation in the west and tuffaceous and nonmarine clastic deposits of the Chapiza Formation farther east (Romeuf et al., 1995). This up to ~600-m-thick volcaniclastic section is unconformably overlain by the Lower Cretaceous Hollín Formation comprising ~150 m of fluvial to marine tidal deposits of quartz sandstone and sporadic coal layers representing the onset of long-term marine conditions (Tschopp, 1953; Dashwood and Abbotts, 1990; Baby et al., 2004). The conformably overlying Upper Cretaceous Napo Group includes a ~600-m-thick transgressive sequence of

240

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

FIG. 2 Generalized stratigraphic column and simplified geologic map of the study area in the Subandean Zone and Oriente Basin showing major stratigraphic units and the location of detrital zircon U-Pb samples (circles), including levels that yielded maximum depositional age constraints (stars) (modified from Balkwill et al., 1995; digitalized map from Litherland et al., 1993).

shallow-marine sandstone, limestone, and organic-rich shale. An unconformity separates the marine Napo Group from the overlying nonmarine Maastrichtian-Paleocene Tena Formation, which is composed of ~750 m of fluvial red siltstone intercalated with silty sandstone (Tschopp, 1953; Dashwood and Abbotts, 1990; Toro Álava and Jaillard, 2005). This sharp change in deposition suggests different basin conditions and sediment sources for the Tena Formation, likely marking a transition to foreland basin conditions (Jaillard and Soler, 1996; Baby et al., 2004; Ruiz et al., 2007; Toro Álava and Jaillard, 2005; Martin-Gombojav and Winkler, 2008; Horton, 2018). Capping the Tena Formation in either transitional or unconformable contact is the Paleocene-Eocene Tiyuyacu Formation, a ~200–800-m-thick

3 ­ Depositional systems

241

coarse-grained unit distinguished by complex thickness variations and internal unconformities (Christophoul et al., 2002; Baby et al., 2013). The Tiyuyacu Formation recorded fluvial channel-belt and possibly alluvial-fan deposition during eastward migration of thrusting. Shallow marine deposits of the Oligocene Orteguaza Formation conformably overlie the Tiyuyacu Formation and reach only 250 m (Christophoul et al., 2002; Roddaz et al., 2011), representing a period of limited sediment accumulation. Increased sedimentation was recorded by the Oligocene-lowermost Miocene Chalcana Formation, which corresponds to fluvial channel and floodplain deposits up to 450 m thick (Burgos et al., 2005; Roddaz et al., 2011). Miocene deposits include the Arajuno Formation, an eastern marine equivalent (Curaray Formation), and the partially coeval Chambira Formation. The Arajuno Formation is a ~1000–1500-mthick unit containing sandy and gravelly fluvial channel deposits intercalated with rooted floodplain deposits (Christophoul et al., 2002; Burgos et al., 2005; Roddaz et al., 2011). The Pliocene-Quaternary Mesa and Mera Formations compose <200 m of thick gravel terraces representing proximal deposition by the Pastaza fluvial megafan (Bès de Berc et al., 2005). The distal eastern margin of the foreland basin is flanked by Precambrian basement of the Amazonian craton, which consist of westward-younging Proterozoic orogenic (mobile) belts accreted to a common Paleoproterozoic-Archean nucleus. These tectonic provinces include the Maroni-Itacaiunas, VentuariTapajos, Rio Negro-Juruena, Rondonian-San Ignacio, and Sunsás-Aguapeí belts (Geraldes et al., 2001; Cordani and Teixeira, 2007; Ramos, 2010; Teixeira et al., 2010). Farther west, younger basement of principally Neoproterozoic-early Paleozoic age (probable equivalents of the Brasiliano, Pampean, and Famatinian orogenic systems) may reside beneath the Andean foreland and Andean orogen (Chew et al., 2007, 2008; Mišković et al., 2009).

3 ­Depositional systems The Cretaceous-Cenozoic sedimentary succession of the Oriente Basin (Figs. 1 and 2) attains a thickness of ~4.5 km in most regions. Although exposure is limited, four separate stratigraphic sections were measured to characterize key Cenozoic units, including the Tiyuyacu, Chalcana, and Arajuno Formations, which are most representative of foreland basin development (Figs. 3 and 4). Facies associations were recognized using varied classification schemes (Miall, 1978, 1985; Perez and Horton, 2014; Calle et al., 2018), which enabled the interpretation of depositional processes and environments.

3.1 ­Eocene Tiyuyacu Formation: Gravelly braided river The Tiyuyacu Formation contains 3–12 m thick, poorly cross-stratified conglomerates (Gt) interbedded with 0.3–1.5-m-thick sandstones (Figs. 3A and 4A). Amalgamated conglomerate beds are laterally extensive for tens of meters and contain lenticular channel geometries 1–3 m deep by 5–12 m wide. The conglomerates show poor sorting of pebble to cobble clasts in a coarse sandstone matrix, with local inverse grading. Clast-supported conglomeratic beds transition upsection to gravelly sandstones. Imbricated clasts in lower intervals indicate transport to the southeast. Clast compositions include white vein quartz, tan quartzose sandstone, and red and brown chert.

242

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

FIG. 3 Representative measured stratigraphic sections of Cenozoic fill in the Oriente Basin: (A) Paleocene-Eocene Tiyuyacu Formation, gravelly braided river to alluvial fan deposits (Puyo-Tena road); (B) Oligocene Chalcana Formation, silty sand-dominated river (Misahualli airport road); (C) Miocene Arajuno Formation, sanddominated meandering to braided river (El Capricho and Santa Clara mines).

3 ­ Depositional systems

243

FIG. 4 Outcrop photographs for representative measured stratigraphic sections (Fig. 3). (A) Paleocene-Eocene Tiyuyacu Formation (Puyo-Tena road); (B) Oligocene Chalcana Formation (Misahualli airport road); (C) Miocene Arajuno Formation (El Capricho mine).

Beds of fine- to very coarse-grained sandstone are thinner (tens of centimeters) and show normal grading with horizontal (Sh), planar (Sp), and trough cross stratification (St) (Figs. 3A and 4A). Whereas horizontally stratified sandstones (Sh) coarsen upward and grade into conglomeratic beds, planar (Sp) and trough cross-stratified (St) sandstones have sharp erosive bed boundaries with local pebble-lag deposits. Upward fining packages are typically overlain by 2–4-m-thick silty sandstone beds and mud plug (Fl) facies that fill channel scours. The thin-bedded (cm-scale) silty sandstones show horizontal (Sh), cross lamination (Sl), and normal grading. The Tiyuyacu Formation is representative of coarse-grained braided fluvial systems. Lenticular cross-stratified conglomerates and interbedded sandstones are interpreted as gravel bars and minor sandy bars deposited during water floods. The clast-supported conglomeratic framework suggests deposition by flows of high water discharge and sediment concentration, with clast imbrication consistent with downstream accretion of gravel bars. Upsection decreases in clast content and size are likely associated with lower flow velocities and lateral bar migration (Miall, 1985). Upward grading of amalgamated conglomerates to sandstones and occasional mudstones may suggest lateral accretion within a fluvial system, with possible overlapping sandy transversal (St) and longitudinal (Sh) bars

244

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

followed by abandonment (Hein and Walker, 1977; Germanoski and Schumm, 1993). Thin stratified sandstones and laminated siltstones are interpreted as intermittent episodes of sandy lateral bar accretion followed by reduced flow velocities and late-stage deposition of sand and silt. Capping siltstones are interpreted as overbank deposits or abandoned channel plug deposits after lateral migration or avulsion of the active channel (Williams and Rust, 1969). In summary, upward fining conglomerate and sandstone deposits (Gt, St, Sh) suggest gravel bar formation in a high-energy environment. Accompanying sand bar deposits (Sh, St) with lateral accretion geometries reveal traction currents in gravel-bed braided rivers. Such multistory sand bodies of a braided river channel belt may be part of a shifting fluvial system in a distributive megafan depositional environment (Horton and DeCelles, 2001). Sporadic floodplain deposition (Sl, Fl) is symptomatic of lateral migration or avulsion due to continuous shifting and abandonment of distributary channel systems (Miall, 1985; Rust, 1978).

3.2 ­Oligocene-lowermost Miocene Chalcana Formation: Silty sand-dominated meandering river The Chalcana Formation consists of horizontally laminated mudstones (Fl) and 3–5-m-thick tabular sandstone beds consisting of very fine- to medium-grained beds of structureless (Sm), trough cross-stratified (St), and horizontally stratified (Sh) sandstones (Figs. 3B and 4B). The sandstones are mostly arranged into upward fining packages, but inversely graded sandstones are also present. All sandstone beds are laterally extensive (tens to hundreds of meters) and show sharp erosive contacts with underlying and overlying silty sandstone, siltstone, and shale beds. The finer-grained beds exhibit internal horizontal lamination (Fl), with occurrences of roots and plant remnants (Fr), and calcareous nodules (P). Laterally extensive intervals (tens of meters) of horizontally laminated siltstone (Fl) beds are arranged into 0.3 to 2 m upward fining, thick packages capped by laminated clay-rich shale beds (Fl). Internal bed boundaries between siltstone and shaley beds are gradational, whereas the basal and upper contacts of the upward-fining packages are bounded by sharp nonerosive surfaces. The uppermost Chalcana Formation consists of 3–5-m-thick upward fining packages of very fineto coarse-grained, trough cross-stratified sandstones facies. These packages include multistory stacked sandstones representing highly lenticular 1 m deep by 3–7-m-wide channels with sharp concave-­ upward basal erosive surfaces. Coarse- to very coarse-grained sandstone lag deposits commonly overlie the erosive surfaces. Fine- and coarse-grained Chalcana deposits are interpreted as relatively distal meandering fluvial systems with reduced sediment supply. Thin-bedded, laterally persistent mudstones and sandstones are indicative of unconfined deposition from suspension. Upward-coarsening and fining trends may reveal progradation and abandonment during crevasse splay deposition. Laminated mudstones are arranged into upward fining packages, consistent with deposition by suspension settling during late-stage flooding episodes. These floodplain deposits are characterized by calcareous nodules and plant remnants, suggesting intervening phases of pedogenesis. Together the facies represent overbank deposition of sandy crevasse splays and silt from suspension fallout during waning-flood conditions. These intermittent episodes allowed soil generation between successive flooding events. In contrast, trough cross-stratified sandstone beds of the uppermost

4 ­ Sediment source regions

245

Chalcana Formation represent multistory channel-fill deposits comprising transverse bar deposits. Collective observations for the Chalcana Formation suggest dominantly suspended load conditions in a meandering river system with a limited supply of coarse-grained sediment. In upper levels, however, thick-stratified sandstones suggest a shift to amalgamated stacked channels in a braided river system.

3.3 ­Miocene Arajuno Formation: Meandering to sand-dominated braided river The Arajuno Formation contains sandstone and subordinate mudstone deposits (Figs.  3C and 4C). Laterally extensive (hundreds of meters) sheets of very fine- to medium-grained sandstones are arranged into 1–3-m-thick upward-fining packages that exhibit low-angle inclined surfaces and trough cross stratification (St). Paleocurrent data indicate transport to the southeast. The upper levels of these packages are defined by ripple cross-stratified (Sr) horizons with occasional desiccation cracks. Sharp upper contacts are commonly overlain by preserved remnants of wood and plant matter, including coal layers. Sandstones packages are capped by 8–10-m-thick intervals of laminated siltstone and shale, with selective preservation of plant and roots remnants. Fine-grained deposits consist of 5–8-m-thick packages of laterally persistent (hundreds of meters) shale and siltstone beds with intercalated thin sandstones. The shales contain roots and other plant and woody debris. The sandstone beds exhibit planar cross stratification (Sp) and horizontal stratification (Sh), with ripples toward the top (Sr). Upward-fining trends are common, and expressed by increased proportions of clay-rich shale relative to siltstone. Deposits of the Arajuno Formation are interpreted as sand-dominated fluvial systems with relatively high sediment supply. Sand deposition in fluvial channels contrasted with principally mud deposition in overbank floodplain areas. Trough cross-stratified sandstones, low-angle inclined surfaces, and capping finer deposits are consistent with deposition by lateral accretion and various stages of bar development within braided fluvial systems. Laterally extensive shale and siltstone beds with plant and woody debris are consistent with deposition in floodplain settings. An upsection coarsening and thickening of beds within the upper Arajuno Formation suggest evolution from a suspended-load meandering river to a mixed-load sand-dominated river. A lack of lateral accretion deposits in the upper levels suggests relatively lower sinuosity fluvial channels characterized by avulsion rather than systematic lateral channel migration. These trends are suggestive of progressively higher transport energy and/or sediment supply.

4 ­Sediment source regions The Oriente Basin received sediment from eastern cratonic sources and western Andean sources (Fig. 5). In the east, cratonic basement sources include the Amazonian, Maroni-Itacaiunas, VentuariTapajós, Rio Negro-Juruena, Rondonian-San Ignacio, and Sunsás provinces. In the west, Andean sources include the magmatic arc, fold-thrust belt, and limited basement occurrences. Accurately determining the presence and geographic distribution of sediment sources through time provides a spatial–temporal framework in which to interpret detrital age distributions and evaluate relative contributions from diverse sources.

246 Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

FIG. 5 Regional geologic column of Ecuador showing rock units (potential sediment sources) across the major tectonic provinces and a simplified stratigraphic framework for the Oriente foreland basin. The Western Cordillera includes Cretaceous-Cenozoic igneous sources from a continental magmatic arc and accreted oceanic terranes. The Eastern Cordillera consists of igneous and metasedimentary sources (including Andean basement) of Proterozoic to Mesozoic age. The color scheme for rock units is based on geologic age. Data compiled from Baldock (1982), Hughes and Bermudez (1997), Litherland et al. (1994), and multiple additional sources (listed at left).

4 ­ Sediment source regions

247

4.1 ­Cratonic source regions South American basement provinces (Figs. 1 and 5) represent successively younger accretionary belts along the western margin of a common Amazonian nucleus (Tassinari and Macambira, 1999; Geraldes et  al., 2001, 2015; Cordani and Teixeira, 2007; Cordani et  al., 2009; Teixeira et  al., 2010, 2011; Bettencourt et al., 2010; Ramos, 2010). (1) The Amazonian craton (3200–2600 Ma) comprises a nucleus of Archean igneous and metamorphic rocks with adjacent northwest-trending accretionary belts presenting the following age relationships. (2) The Maroni-Itacaiunas (2250–2150 Ma) and VentuariTapajós (2150–1800 Ma) provinces correspond to calc-alkaline magmatic rocks, granulite complexes, granite-greenstone belts, and intraoceanic magmatic arcs with juvenile isotopic signatures. (3) The Rio Negro-Juruena province (1800–1550 Ma) comprises granites and gneisses affected by amphibolite and granulite facies metamorphism. (4) The Rondonian-San Ignacio belt (1550–1300 Ma) shows a metamorphic belt consisting of granite-gneiss-migmatitic terranes and amphibolitic to granulitic rocks. (5) The Sunsás-Aguapeí province (1300–900 Ma) is a Grenville-age orogenic zone composed of granitic and low-to-medium grade metamorphic rocks. (6) Farther west, Sunsás-Aguapeí and NeoproteroicPaleozoic basement is potentially buried beneath Cenozoic basin fill of the northern Andean foreland (Cordani et al., 2005; Chew et al., 2008, 2011; Cardona et al., 2009; Mišković et al., 2009).

4.2 ­Andean source regions Andean sources include Mesozoic-Cenozoic cover strata, igneous rocks, and limited Paleozoic metasedimentary basement (Figs. 1 and 5). (1) The Paleozoic metasedimentary rocks (schists and slates) that form the mechanical basement of the Ecuadorian Andes exhibit multiple detrital age groups, including a dominant late Neoproterozoic (650–550 Ma) population and subordinate Sunsás (1300–900 Ma), Famatinian (550–450 Ma), and middle-late Paleozoic (450–250 Ma) signatures (Pratt et al., 2005; Chew et al., 2007, 2008, 2011; Cardona et al., 2009; Mišković et al., 2009; Horton et al., 2010; Villagómez et al., 2011; Mejía et al., 2012; Anderson et al., 2016; George et al., n.d.). (2) Triassic (250–200 Ma) magmatic rocks and associated metamorphic products define segments of the Eastern Cordillera and Amotape-Tahuin Block in Ecuador (Tres Lagunas granite, Sabanilla, and Agoyan units) (Noble et al., 1997; Cochrane, 2013; Cochrane et al., 2014; Spikings et al., 2015). (3) Jurassic (200–145 Ma) igneous rocks in the Eastern Cordillera and Oriente Basin include volcanic (Misahualli and Chapiza Formations) and plutonic rocks (Rosa Florida, Zamora, Abitagua, and Azafran granitic batholiths) (Romeuf et al., 1995; Chiaradia, 2009; Cochrane, 2013; Cochrane et al., 2014; Spikings et al., 2015). (4) Cretaceous (145–65 Ma) sources include: (a) Early Cretaceous (145–100 Ma) volcanic and metamorphic rocks (Alao-Paute, Upano, and Raspas unit), granodioritic intrusions (Azafran and Chingual batholiths), and mafic igneous rocks (Peltetec unit); and (b) Late Cretaceous (100–66 Ma) sources linked to subductionrelated arc magmatism, back-arc alkaline magmatism (Pimampiro, Magtayan, Curiplaya, and Tangula plutons) (Aspden and Litherland, 1992; Barragan et  al., 2005; Palacios et  al., 2008; Schütte, 2009; Vallejo et al., 2006; Valarezo et al., 2017), and possible age equivalents in Colombia (Antioquia and Cordoba batholiths) (Villagómez et  al., 2011). Additional Late Cretaceous sources include accreted oceanic rocks of the forearc and Western Cordillera, considered part of the Caribbean Large Igneous province (CLIP) (Lebras et al., 1987; Luzieux, 2005;Vallejo et al., 2006, 2009) (5) Paleocene-Eocene (66–34 Ma) sources include magmatic arc intrusive rocks (Tangula, Pimampiro, San Lucas, Rio Blanco, El Tingo, Amaluza plutons) and related volcanic deposits (Silante, Chinchin, Loma Blanca, Macuchi Formations) (Kennerley, 1980; Herbert and Pichler, 1983; Aspden et  al., 1992; Bineli Betsi, 2007,

248

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

2017; Vallejo et al., 2006, 2009; Vallejo et al., 2016; Schütte et al., 2010). (6) Oligocene (34–23 Ma) sources include extensive ignimbrite deposits (Saraguro Group, Loma Blanca, and San Juan de Lachas Formations) and associated plutons (Telimbela, Balsapamba, Las Guardias, and Portachuela batholiths) (Barberi et al., 1988;; Dunkley and Gaibor, 1997; McCourt et al., 1997; Boland et al., 1998; Bineli Betsi, 2007; Bineli Betsi et al., 2017; Vallejo et al., 2006; Schütte et al., 2010). (7) Miocene-Quaternary (<23 Ma) sources are linked to broadening of arc magmatism (including the Apuela, Corazon, El Mozo, Chaucha, Molleturo, and Junin plutons) and volcanism (Saraguro and younger volcaniclastic deposits such as the Biblian, Santa Isabel, Mangan, Pisayambo, Cojitambo, Zumbagua, Quisamcocha, and Tarqui Formations) (Barberi et al., 1988; Lavenu et al., 1992; Vallejo et al., 2006; Bineli Betsi, 2007; Bineli Betsi et al., 2017; Schütte et al., 2010).

5 ­Zircon U-Pb geochronology A total of 17 samples (14 medium-to coarse-grained sandstones, 2 conglomerate clasts, 1 schist) were collected from outcrops of Mesozoic-Cenozoic formations within the Subandean to Oriente foreland basin (Figs. 2 and 5; Appendix A in the online version at https://doi.org/10.1016/B978-0-12-8160091.00011-3). Following established procedures (Gehrels et al., 2006), zircon grains were isolated through rock crushing, separation by water, magnetic, and heavy liquid methods, and final hand picking and placement into epoxy mounts 20 μm thick (Chisholm et al., 2014). Zircon U-Pb geochronological analyses were conducted by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) at the Arizona LaserChron Center (Gehrels et al., 2006, 2008; Gehrels and Pecha, 2014). Zircon grains were ablated with a beam diameter of 20 μm using a Photon Machine Analyte G2 excimer laser equipped with a Helex sample ablation cell. The laser was set at a wavelength of 193 nm, a repetition rate of 8 Hz, and a fluence of ~5 J/cm2. Ablated material was carried in helium to the plasma source of an Element2 HR ICMPS for simultaneous analyses of U-Th-Pb isotopic ratios. For age calibration, measurements were compared to a primary age standard, Sri Lanka zircon (563.5 ± 2.3 Ma; Gehrels et  al., 2008), and secondary standards FC-1 (206Pb/238U age of 1099.5 ± 0.5 Ma and 206Pb/207U age of 1099 ± 0.6 Ma; Paces and Miller, 1993), and R33 (206Pb/238U age of 419.3 ± 0.4 Ma; Black et al., 2004). Uncertainties for 206Pb/238U and 206Pb/207Pb ages are 1%–2% (1σ error). Reported ages for zircons younger than 1000 Ma are 206Pb/238U ages and for zircons older than 1000 Ma are 206Pb/207Pb ages. Individual analyses with >20% discordance, >5% reverse discordance, or 10% internal uncertainty were filtered and discarded from further consideration.

5.1 ­Detrital zircon provenance analyses Detrital zircons serve as key provenance tracers in which diagnostic detrital age populations can be matched to distinct source regions. A total of 17 samples were analyzed (Figs. 6 and 7; Appendix B in the online version at https://doi.org/10.1016/B978-0-12-816009-1.00011-3): a single sample of Triassic metasedimentary rock and 16 samples from sedimentary rocks spanning 6 different timeframes: (1) Early Cretaceous (Hollín Formation); (2) Late Cretaceous (Napo Group, Tena Formation); (3) Paleocene-Eocene (Tiyuyacu Formation); (4) Oligocene (Chalcana Formation);

5 ­ Zircon U-Pb geochronology

249

(5) Miocene (Arajuno Formation); and (6) Pliocene-Quaternary (Mesa/Mera Formation). For each sample, U-Pb ages were obtained for 90–134 individual zircon grains. Age results and associated uncertainties are presented in age probability plots, facilitating identification of major age groups and graphical comparison of age distributions among different samples. Our interpretations assign significance to age peaks defined by at least three zircon grains with individual ages that overlap at the 2σ level. In addition, maximum depositional ages of several host stratigraphic units were constrained by determining the youngest U-Pb ages defined by at least three individual zircon grains (Dickinson and Gehrels, 2009). Finally, multidimensional scaling (MDS) plots are used to assess the similarity of detrital zircon age distributions, where spatial proximity within an MDS plot reflects their statistical similarity (Vermeesch, 2013; Satkoski et al., 2013; Horton et al., 2015; Sundell and Saylor, 2017). In addition, stress values obtained from Shepard plots are also provided as a measure of goodness of fit between samples, with a value of 0 defining a perfect fit and 0.2 a poor fit.

FIG. 6 Composite probability density plot showing detrital zircon U-Pb geochronological results for 14 CretaceousQuaternary sandstone samples of the Oriente Basin. Diagnostic age populations are representative of detrital contributions from four principal tectonic provinces: (1) Western Cordillera magmatic arc (<100 Ma); (2) Eastern Cordillera metasedimentary basement (650–250 Ma), Triassic intrusions (250–200 Ma), and limited Cretaceous igneous rocks (145–66 Ma); (3) Subandean Zone basin fill (recycled cratonic signatures from Cretaceous strata); and (4) crystalline basement of the South American craton (>900 Ma).

250

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

FIG. 7 See figure caption on opposite page.

5 ­ Zircon U-Pb geochronology

251

5.1.1 ­Triassic-Jurassic metasedimentary rocks

Zircon U-Pb age results from a pelitic schist of the Triassic-Jurassic Agoyan unit in the axial Eastern Cordillera (near Baños; Sauer, 1965) show a dominant Triassic age group (>75% of ages; Fig. 8A; sample ECGG21). This signature is consistent with derivation from widespread extension-related Triassic granites (e.g., Tres Lagunas, Sabanilla granites) (Ruiz, 2002; Ruiz et  al., 2007; Martin-Gombojav and Winkler, 2008; Cochrane et al., 2014; Spikings et al., 2015). The youngest age population coincides closely with previously reported ages (Martin-Gombojav and Winkler, 2008), yielding an Early Jurassic weighted mean age of 194.8 ± 4.4 Ma (Appendices B and C in the online version at https:// doi.org/10.1016/B978-0-12-816009-1.00011-3), suggesting syndepositional volcanic input. A secondary age population (<15%) of 450–250 Ma grains suggests partial derivation from Andean Paleozoic metasedimentary basement. The results indicate that Triassic-Lower Jurassic metasedimentary rocks of the Eastern Cordillera were supplied by proximal magmatic and limited Andean basement sources (Figs.  6 and 8A). This configuration raises the possibility of a western continuation of Triassic-Early Jurassic extensional sub-basins of the Oriente and Santiago basin provinces of Ecuador and northern Peru (Baby et  al., 2004). Similar but younger extensional sub-basins in back-arc settings have been reported along strike in Colombia (Cooper et al., 1995; Kammer and Sánchez, 2006; Mora et al., 2009; Horton et al., 2010; Wolaver et al., 2015).

5.1.2 ­Cretaceous Hollín and Napo Formations

U-Pb results for the Aptian-Albian Hollín Formation show the dominant influence of cratonic sources east of the basin. A quartz sandstone from basal Hollín fluvial deposits directly above a regional unconformity (Fig.  7; sample ECGG18) yields prevailing age groups (~65% of ages) of 1550–1300 Ma (Rodonian-San Ignacio) and 1300–900 Ma (Sunsás) from the westernmost cratonic provinces. Secondary cratonic sources (~25%) include older eastern provinces such as Rio Negro-Juruena (1800–1550 Ma) and Ventuari-Tapajós (2150–1800 Ma). Minor Neoproterozoic-early Paleozoic populations suggest limited input from Andean metasedimentary basement. Our U-Pb age results confirm previous interpretations for the Hollín Formation (Baby et al., 2004; Ruiz et al., 2004, 2007; Martin-Gombojav and Winkler, 2008; Vallejo et al., 2017) and underscore derivation from cratonic sources. Detrital zircon U-Pb ages for the Albian-Cenomanian Napo Group are compiled from past studies spanning the Oriente Basin (Fig. 7; Martin-Gombojav and Winkler, 2008; Vallejo et al., 2017). These published results for 8 samples show input principally from eastern cratonic sources, FIG. 7, CONT'D Probability density plots showing detrital zircon U-Pb geochronological results for 14 Cretaceous-Quaternary sandstone samples arranged in stratigraphic order (Appendices A and B in the online version at https://doi. org/10.1016/B978-0-12-816009-1.00011-3). Maximum depositional age (MDA) values are shown for samples with young age populations (Appendix C). Precambrian cratonic sources (>900 Ma) in the east are the major contributor to Cretaceous deposits (Hollín Formation, Napo Group). A latest Cretaceous reversal in sedimentary polarity is marked by initial contributions from Andean sources (<650 Ma) in the west (Tena Formation). Paleocene-Eocene (Tiyuyacu Formation), Oligocene-Miocene (Chalcana Formation, Arajuno Formation), and Quaternary (Mesa/Mera Formation) samples show dominant contributions from the Cretaceous magmatic arc (<100 Ma), Triassic intrusions (250–100 Ma), and late Neoproterozoic-Paleozoic metasedimentary basement (650–250 Ma) of the Eastern Cordillera and Western Cordillera.

252

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

FIG. 8 Detrital zircon U-Pb geochronological results for a Triassic metasedimentary rock and two quartzose sandstone clasts of an Eocene conglomerate. (A) Probability density plot for the Agoyan unit showing a characteristic Triassic age signature for Triassic metasedimentary units of the Eastern Cordillera. (B) Multidimensional scaling (MDS) plot of the entire set of samples showing the statistical similarity (as displayed by sample proximity within the plot) for two quartzose sandstone cobble clasts of the Paleocene-Eocene Tiyuyacu Formation with the sandstone of the Lower Cretaceous Hollín Formation. For these three samples, a Shephard plot with a stress value close to zero (1.2e−16) indicates an excellent statistical similarity, demonstrating a shared provenance and common origin.

5 ­ Zircon U-Pb geochronology

253

with dominant 1800–1550 (Rondonian-San Ignacio) and 1550–1300 (Rodonian-San Ignacio) age groups and subordinate 1800–2150 (Ventuari-Tapajós) and 1300–900 Ma (Sunsás) signals. Relative to the Hollín Formation, the progressive increase in older, eastern cratonic sources likely reflects eastward basin expansion during regional thermal subsidence (e.g., Horton et al., 2010). For westernmost exposures of the Napo Group, an important albeit minor component of Proterozoic to Triassic ages indicates partial derivation from Andean sources. Although local Ecuadorian sources cannot be ruled out, we suggest that the Andean signature is likely related to Late Cretaceous sources in northern Peru (such as the Marañón basement complex and its detrital products), with northward axial flow in the united Marañón and Oriente basins (e.g., Pindell and Tabbutt, 1995; Jaillard et al., 2000).

5.1.3 ­Upper Cretaceous Tena Formation

Results for the Maastrichtian-Paleocene Tena Formation reveal a provenance reversal that accompanied a change from marine to nonmarine deposition. Red fluvial Tena sandstones and siltstones unconformably overlie the marine Napo Group (Baby et al., 2004; Jaillard and Soler, 1996), and represent shortening, reactivation of inherited extensional faults, and basin inversion (Tschopp, 1953; Baby et al., 2004; Balkwill et al., 1995), possibly linked to collision of the Caribbean Large Igneous province at ~73 Ma (Reynaud et al., 1999; Vallejo et al., 2006, 2009). A basal Tena sandstone (Figs. 2 and 7; sample ECGG19) shows a major U-Pb age concentration (75% of ages) at 1550–1300 Ma (Rondonian-San Ignacio) and subsidiary peaks (<25%) at 1800–1550 Ma (Rio Negro Juruena) and 1300–900 Ma (Sunsás). Despite these cratonic signatures, the Tena Formation shows no derivation from the easternmost cratonic Ventuari-Tapajós province, and more importantly, records two latest Cretaceous ages (81.2 and 70.9 Ma) from Andean magmatic sources. An upper Tena sample (Figs.  2 and 7; sample ECGG17) shows dominant age groups (~45%) representative of the cratonic Rondonian-San Ignacio province (1550–1300 Ma) and latest Cretaceous Andean magmatic arc (90–68 Ma). Remaining age reflects other cratonic provinces (2150–900 Ma) and Neoproterozoic-Paleozoic Andean basement (650–250 Ma). The three youngest U-Pb ages within Tena samples yield a weighted mean age of 68.6 ± 3.5 Ma (Figs. 2 and 8C; sample ECGG17–19). This latest Cretaceous age is consistent with previous estimates from Maastrichtian planktonic foraminifers and ammonites (Jaillard et  al., 2005) and overlaps within error of a single Paleocene age (63 ± 3 Ma) from a detrital zircon fission-track analysis (Ruiz, 2002). U-Pb results for the Tena Formation record a reversal in sedimentary polarity involving a switch from cratonic to Andean sources during initial regional shortening (Horton, 2018). Increased contributions from the magmatic arc and enhanced unroofing of Andean basement coeval with accretion of an oceanic terrane (Reynaud et al., 1999; Hughes and Pilatasig, 2002; Kerr et al., 2002; Ruiz et al., 2004; Spikings et  al., 2005, 2010, 2015; Vallejo et  al., 2006, 2009; Kennan and Pindell, 2009; Chiaradia, 2009) are in accord with paleocurrent data, heavy mineral assemblages, and a shift to nonmarine sedimentation (Tschopp, 1953; Dashwood and Abbotts, 1990; Christophoul et al., 2002; Ruiz, 2002; Ruiz et  al., 2007; Jaillard et  al., 2005; Martin-Gombojav and Winkler, 2008). Latest Cretaceous igneous rocks are preserved locally in the Western Cordillera to westernmost Eastern Cordillera of Ecuador (94–73 Ma Pimampiro and 86–68 Ma Magtayan plutons; 92 ± 1.6 Ma Curiplaya and Tangula batholiths; Aspden et al., 1992; Palacios et al., 2008; Schütte, 2009; Cochrane, 2013; Valarezo et al., 2017) and Colombia (95–75 Ma Antioquia and Cordoba batholiths; Villagómez et  al., 2011). Documented

254

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

exhumation of 7–9 km (Ruiz et al., 2007; Spikings et al., 2010; Spikings and Simpson, 2014) suggests that the magmatic arc was deeply eroded, consistent with Late Cretaceous age signatures in forearc sediments to the west (Valarezo et al., 2017; Vallejo et al., 2017; Witt et al., 2017). Finally, the large proportion of cratonic detritus is considered the product of initial recycling (cannibalization) of thick Cretaceous basin fill (Napo and Hollín Formations) that originally covered much of the present-day Eastern Cordillera and Subandean Zone (e.g., Horton et al., 2010, 2015).

5.1.4 ­Paleocene-Eocene Tiyuyacu Formation

The Paleocene-Eocene Tiyuyacu Formation caps the Tena Formation in regional unconformity and contains intraformational unconformities possibly related to fold-thrust deformation during coarsegrained sedimentation in the foreland basin (Valdez Pardo, 1997; Christophoul et  al., 2002; Baby et al., 2004). Detrital zircon U-Pb results for three Tiyuyacu sandstones (Fig. 7; samples ECGG15, ECGG20, ECGG13) show greatly enhanced Andean contributions at the expense of eastern cratonic sources. The sharp appearance of multiple Andean signatures (~75% of ages) is expressed in a 250– 200 Ma age signal representative of Triassic granitic rocks and the joint appearance of 650–450 Ma (late Neoproterozoic-early Paleozoic) and 1300–900 (Sunsás) age groups representative of Paleozoic metasedimentary basement sources. These trends are further accompanied by the disappearance of Late Cretaceous magmatic age signatures and extreme reduction to disappearance of pre-1300 Ma cratonic signatures. U-Pb results for two clasts of quartzose sandstone from Tiyuyacu cobble conglomerates (Fig. 8B; samples ECGG16A, ECGG16B) help pinpoint specific source units and demonstrate recycling of Cretaceous basin fill. For each sandstone clast, the age distributions show a prevailing 1300–900 Ma (Sunsás) age population (30%–45% of analyzed grains) with subordinate smaller populations from all other cratonic provinces (2150–900 Ma) and Neoproterozoic-Paleozoic Andean basement (650– 250 Ma), and Late Jurassic-Early Cretaceous magmatic arc. Both samples bear a remarkable similarity to the Cretaceous Hollín Formation in terms of comparable U-Pb age distributions and diagnostic age peaks. Multidimensional scaling (MDS) plots (Fig. 8B) demonstrate this statistical similarity, which supports the interpretation of these clasts as craton-derived sandstones of the Hollín Formation that were recycled from early Andean source areas west of the basin. The MDS comparison also highlights the sharp contrast between the craton-derived Hollín Formation and age distributions for younger foreland basin fill derived exclusively from western Andean sources. The appearance and upsection increase in western sediment sources can be related to advance of the fold-thrust belt, structural disruption of the westernmost basin margin, and recycling of older (Cretaceous) basin fill (e.g., Christophoul et al., 2002; Horton et al., 2010). Exhumation of Andean sources, including enhanced input from Paleozoic metasedimentary basement rocks, is consistent with thermochronological evidence for enhanced exhumation during Eocene shortening (Spikings et  al., 2010; Spikings and Simpson, 2014). The clear identification of Hollín sandstone clasts within the Tiyuyacu Formation requires large-scale recycling of craton-derived material in the westernmost Cretaceous basin that was uplifted by fold-thrust deformation in the Eastern Cordillera. Moreover, the upsection disappearance of Cretaceous magmatic arc (90–68 Ma) signatures suggests that a considerable topographic barrier, possibly composed of durable basement rocks, may have isolated the subduction-related magmatic arc from the developing foreland basin. In summary, U-Pb results for Tiyuyacu sandstones and conglomerate clasts indicate derivation from Andean sources, with systematic exhumation of deeper geologic units and progressive recycling (cannibalization) of westernmost basin fill caused by growth and advance of the fold-thrust belt during crustal shortening.

5 ­ Zircon U-Pb geochronology

255

5.1.5 ­Oligocene-lowermost Miocene Chalcana Formation

Fluvial deposits of the Chalcana Formation help characterize a finer-grained Oligocene interval (including the marine Orteguaza Formation not sampled in this study) commonly associated with tectonic quiescence (Christophoul et  al., 2002; Horton, 2018). Detrital zircon U-Pb ages for three samples (Fig. 7; samples ECGG14, ECGG27, ECGG01) indicate Andean sources west of the basin, with a clear Triassic (250–200 Ma) signal (>22% of ages), subordinate Neoproterozoic-Paleozoic (650–250 Ma) and Sunsás (1300–900 Ma) signatures, and magmatic arc signals marked by the reappearance of Late Cretaceous (90–68 Ma) ages and the first appearance of robust Cenozoic (65–25 Ma) ages. Maximum depositional ages are constrained by the youngest populations from the lower and upper samples, which yield weighted mean ages of 29.6 ± 1.3 Ma and 22.8 ± 0.8, respectively (Appendices B and C in the online version at https://doi.org/10.1016/B978-0-12-816009-1.00011-3). These ages show that the Chalcana Formation spans the Oligocene to earliest Miocene, consistent with palynological analyses (Zambrano et al., 1999). U-Pb results for the Chalcana Formation show continued derivation from the Andean fold-thrust belt and the return of an Andean magmatic arc signature. The presence of Cenozoic ages may be related to enhanced Oligocene-earliest Miocene magmatism (including the extensive and voluminous Saraguro Formation; Steinmann et al., 1999; Hungerbühler et al., 2002; Schütte et al., 2010). In addition, diminished Andean uplift may have allowed for elimination of an Eastern Cordillera topographic barrier in the Ecuadorian Andes and westward expansion of the regional drainage system feeding the foreland basin (Ruiz, 2002; Roddaz et al., 2011).

5.1.6 ­Miocene Arajuno Formation

U-Pb results for braided fluvial sandstones of the Arajuno Formation help define Miocene provenance during the main phase of Andean surface uplift and exhumation, partially coeval with collision of the Carnegie Ridge. The Arajuno Formation shows a gradational lower contact with the Chalcana Formation and it is partially coeval with the Chambira Formation to the west and Curaray Formation to the east (Burgos, 2006; Roddaz et al., 2011). Detrital zircon U-Pb age spectra for all four samples (Fig. 7; samples ECGG07, ECGG09, ECGG06, ECGG05) reveal a dominant contribution from Andean sources, with a prevailing age group (up to 35% of ages) that corresponds to Triassic granites (250– 200 Ma), with subordinate Precambrian and Cretaceous-Cenozoic age groups. However, a pronounced upsection shift is revealed in which the Precambrian cratonic and Cretaceous magmatic arc signatures present in lower Arajuno samples disappear from upper Arajuno samples. Maximum depositional age constraints for the upper three Arajuno samples (Fig. 8C) yield weighted mean ages of 17.6 ± 0.8, 14.6 ± 4.2, and 13.3 ± 0.4 (Appendices B and C in the online version at https:// doi.org/10.1016/B978-0-12-816009-1.00011-3). These ages are slightly younger than palynological estimates (22–16 Ma; Burgos, 2006 and references therein) and apatite and zircon fission track results (~22–21 Ma; Ruiz, 2002), suggesting early and middle Miocene ages for the lower and upper Arajuno levels, respectively. U-Pb age distributions for the Miocene Arajuno Formation show provenance transitions consistent with exhumation of new structural zones within the Andean fold-thrust belt. We interpret an initial increase in cratonic age signatures relative to the underlying Chalcana Formation to represent eastward encroachment of Miocene shortening and recycling of Cretaceous-Paleocene basin fill rich in cratonic detritus. Upsection, the near disappearance of Precambrian cratonic and Cretaceous magmatic arc signatures coupled with increased Andean populations may be the combined product of (1) erosional removal of the westernmost Cretaceous-Paleocene basin fill, (2) the

256

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

establishment of a hinterland drainage barrier that prevented delivery of Cretaceous arc detritus, and (3) the main phase of erosional exhumation of Triassic granites within the fold-thrust belt. Not only do these patterns coincide with rapid Miocene exhumation (Spikings et al., 2000, 2001, 2010; Spikings and Simpson, 2014), but also the presence of syndepositional (<25 Ma) zircons is consistent with eastward inboard advance of Miocene magmatism into hinterland segments of the fold-thrust belt.

5.1.7 ­Pliocene-Quaternary Mesa/Mera Formation

A single coarse-grained sample of Pliocene-Quaternary basin fill represents the Mesa/Mera Formation along the modern Subandean deformation front. These deposits unconformably overlie OligoceneMiocene basin fill and form terraces affected by faulting (Mesa Formation) and younger alluvial fan deposits (Mera Formation). Despite the low zircon yield, U-Pb age spectra for 35 grains reveal principally Andean sources (Fig. 7; sample ECGG12). The dominant Triassic signatures (250–200 Ma) are complemented by subordinate ages associated with the Jurassic-Early Cretaceous magmatic arc, including the Abitagua granite, Azafran granite, and volcanic deposits of the Misahualli Formation. Age populations from more-western Andean sources (such as the Late Cretaceous and Oligocene-Miocene arcs) were not recorded, suggesting preferential input from proximal sources in the eastern frontal segment of the Andean fold-thrust belt, possibly implying renewal of a topographic barrier within the Eastern Cordillera potentially in close proximity to the present-day hinterland drainage divide. However, the limited number of available zircons suggests that some age groups could be underrepresented within the small set of analyzed grains.

6 ­Discussion 6.1 ­Early Cretaceous development of postextensional sag basin Detrital zircon U-Pb ages for Cretaceous strata of the Oriente basin complement previous studies (Ruiz, 2002; Martin-Gombojav and Winkler, 2008; Vallejo et al., 2017) and show clastic input from eastern cratonic sources during deposition of the Aptian-Albian Hollín Formation (150 m) and AlbianCenomanian Napo Group (200–600 m) (Figs. 7 and 9A). Subsidence analyses indicate slow rates of Cretaceous accumulation (9 m/Myr) (Thomas et  al., 1995; Horton, 2018), consistent with regional thermal subsidence in a postextensional sag basin prior to construction of the Ecuadorian Andes (Fig. 9A).

6.2 ­Late Cretaceous onset of shortening, flexure, and foreland basin sedimentation A latest Cretaceous depositional shift from the shale-rich shallow-marine Napo Group to coarsegrained nonmarine Tena Formation coincided with a reversal in sedimentary polarity (Horton, 2018) driven by early Andean uplift (Figs. 7 and 9B). This provenance switch is defined by the appearance of Andean basement and magmatic arc signatures in the form of U-Pb age distributions (Fig. 7; this study) and heavy mineral assemblages linked to the Eastern Cordillera (Ruiz, 2002; Martin-Gombojav and Winkler, 2008). These shifts are further accompanied by several-fold increases in the rates of exhumation and subsidence at 75–60 Ma (Thomas et al., 1995; Ruiz et al., 2004, 2007; Spikings et al., 2005, 2010, 2015; Spikings and Simpson, 2014).

6 ­ Discussion

257

Andes Exhumation

Eastern EC

SL

Rapid foredeep Flexural subsidence

Arajuno-ChambiraCurara Fms. (Miocene)

Hinterland Basin South American Craton

(E) Arc migration Eastern EC

SL

Seaway

Chalcana Fm. (Oligocene)

South American Craton

(D)

p

Eastern EC

SL

imal For ox ed Pr niba e liza e n Ca tio n

Foredeep Flexural subsidence

(C)

Tiyuyacu Fm. (Paleocene-Eocene)

South American Craton

Late Cretaceous Igneous Complex 89.8-68 ma

Exhumation

SL

Initial foredeep Flexural subsidence

?

(B)

Tena Fm. (Late Cretaceous)

South American Craton

Thermal subsidence

Hollin Fm. - Napo Gp. (Early Cretaceous)

SL

(A) FIG. 9 See figure caption on next page.

Alao Arc?

South American Craton

258

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

Maastrichtian-Paleocene deposits of the Tena Formation represent the establishment of a flexural foreland basin due to shortening and crustal loading in the Eastern Cordillera (Fig. 9B). Although deep exhumation resulted in nearly complete erosional removal of Late Cretaceous igneous rocks from the Western Cordillera and westernmost Eastern Cordillera, the presence of comparable age peaks in both the foreland basin (Martin-Gombojav and Winkler, 2008; Horton et al., 2010; Vallejo et al., 2017; this study) and forearc basin (Villagómez et al., 2011; Valarezo et al., 2017; Witt et al., 2017) demonstrates the existence of a Late Cretaceous magmatic arc of continental affinities. Detrital products of this magmatism further allow the calculation of depositional ages for the coeval Tena Formation (Fig. 7 and Appendix C in the online version at https://doi.org/10.1016/B978-0-12-816009-1.00011-3).

6.3 ­Paleocene-Eocene shortening and thrust belt advance The Paleocene-Eocene Tiyuyacu Formation recorded coarse-grained fluvial deposition during early growth of the fold-thrust belt and continued flexural subsidence in the Oriente basin (Fig. 9C). U-Pb ages suggest unroofing of deeper levels of Andean source units and recycling of older basin fill (Fig. 8B). Contributions from Triassic granites and Andean basement sources are coupled with a conspicuous absence of Late Cretaceous signatures expected from westernmost Andean segments (Fig. 7). These ages point to contributions from an Eastern Cordillera fold-thrust belt that may have formed a topographic barrier and exerted a significant flexural load. This interpretation is consistent with continued rapid subsidence and considerable exhumation from 56 to 46 Ma (Ruiz, 2002; Christophoul et al., 2002; Ruiz, 2002; Spikings and Simpson, 2014; Spikings et al., 2005, 2010). Moreover, the appearance of clasts of the Hollín Formation within the Tiyuyacu Formation reveals the structural incorporation and cannibalization of Cretaceous preforeland basin deposits during eastward encroachment of the fold-thrust belt (Figs. 9C and 8B). Advance of the locus of shortening may be further reflected in reported but poorly understood unconformities at basal and intermediate levels of the Tiyuyacu Formation (Christophoul et al., 2002). These features may represent growth structures within a wedge-top depozone or large-scale isostatic rebound related to phases of flexural loading. FIG. 9, CONT'D Schematic cross sections of the Ecuadorian margin at 0°–2°S emphasizing the evolution of sediment source regions during Cretaceous-Cenozoic basin development in the Subandean Zone and Oriente Basin, showing dominant source regions (red arrows), exhumation or subsidence (wide black arrows), and advance or retreat of the subducting slab and magmatic arc (open arrows). (A) Cretaceous postextensional thermal subsidence (Hollín Formation, Napo Group): sag basin fed by eastern cratonic sources. (B) Late Cretaceous onset of shortening, flexure, and foreland basin sedimentation (Tena Formation), with reversal in sedimentary polarity driven by early Andean uplift and eastward delivery of sediment from Andean basement and magmatic arc sources. (C) Paleocene-Eocene shortening, thrust belt advance, and continued flexural subsidence (Tiyuyacu Formation), with structural disruption and large-scale recycling of westernmost basin fill. (D) Oligocene diminished shortening, hinterland magmatic flareup (e.g., Saraguro Formation), and continued contributions from Andean sources during diminished foreland accumulation (Chalcana Formation). (E) Miocene– Quaternary main phase of Andean shortening and rapid flexural subsidence in the Oriente foreland basin (Arajuno Formation, Mesa/Mera Formation), with detrital contributions from Andean basement and intrusive rocks, as well as syndepositional magmatic sources during broadening and/or eastward advance of arc magmatism in the Western and Eastern Cordilleras.

6 ­ Discussion

259

6.4 ­Oligocene diminished shortening and magmatic flareup Oligocene deposition of the finer-grained Chalcana and Orteguaza Formations reflected continued erosional unroofing of Andean sources during a potential change in the pace of mountain building (Fig. 9D). U-Pb ages for the Chalcana Formation reveal not only a dominant detrital input from Andean sources to the west, but also the reappearance of a Late Cretaceous magmatic arc (90–68 Ma) and initial appearance of a syndepositional Cenozoic age population (25–65 Ma) (Fig. 7). This record suggests integration of western Andean sources, possibly due to erosion of a former topographic barrier and headward (westward) expansion of drainage networks during a phase of diminished mountain building (Fig. 9D), as reflected in thermochronological records (Ruiz, 2002; Spikings and Simpson, 2014; Spikings et al., 2015). This proposal is consistent with a roughly late Eocene-early Oligocene period of reduced accumulation rates, notably for the Orteguaza Formation, followed thereafter by renewed high rates of sedimentation from the late Oligocene onward (Horton, 2018). Important Oligocene magmatic activity is evidenced by widespread ignimbrites of the Saraguro Group across much of the Eastern Cordillera of Ecuador, possibly reflecting a magmatic flareup related to changes in plate dynamics (Schütte et al., 2010). Accordingly, the Chalcana Formation contains syndepositional zircon grains that yielded maximum depositional ages that span the Oligocene to earliest Miocene (Appendix C in the online version at https://doi.org/10.1016/B978-0-12-816009-1.00011-3), consistent with palynological analyses (Zambrano et al., 1999; Ruiz, 2002).

6.5 ­Miocene-Quaternary main phase of Andean shortening The Miocene Arajuno and Pliocene-Quaternary Mesa/Mera Formations yield detrital zircon U-Pb age signatures that show the progressive introduction of eastern Andean sources at the expense of older magmatic arc and cratonic sources (Fig. 7) during growth and advance of the fold-thrust belt (Fig. 9E). Relative to the underlying Oligocene Chalcana Formation, the Neogene reappearance of Precambrian age signatures can be linked to eastward deformation advance into the Eastern Cordillera/Subandean Zone and attendant recycling of Cretaceous-Paleocene basin fill rich in cratonic detritus. Thereafter, the nearly complete disappearance of both Cretaceous magmatic arc (Western Cordillera) signatures and recycled Precambrian cratonic detritus (Eastern Cordillera) is accompanied by a pronounced increase in Andean populations, notably from Triassic igneous rocks that occupy the hinterland of the Andean fold-thrust belt (Fig. 7). The U-Pb results suggest wholesale exhumation of the westernmost Oriente Basin and establishment of a hinterland drainage barrier during Andean uplift focused in the Eastern Cordillera (Fig. 9E). These trends correlate with increased exhumation starting at 15 Ma (Spikings et al., 2010; Spikings and Simpson, 2014) along with a significant increase in sediment accumulation rates (Horton, 2018). In addition, middle to late Miocene broadening and/or eastward advance of arc magmatism in the Western and Eastern Cordilleras (Schütte et al., 2010) may help account for the renewed appearance of syndepositional age signatures within the proximal Oriente foreland basin (Fig. 7, Fig. 9E). Collectively, the changes in provenance, exhumation, and subsidence can be linked to eastward advance of the Andean fold-thrust belt in Ecuador, with the probable establishment of a hinterland drainage barrier that blocked Cretaceous arc detritus, intensified exhumation of Triassic granites in the frontal foldthrust belt, and accelerated accumulation in the proximal foredeep. A latest Cenozoic eastward inboard advance of magmatism may reflect the effects of subduction of the Carnegie ridge, and late-stage partitioning of the proximal foreland by basement-involved uplifts (Napo uplift, Cutucu uplift) (Fig. 9).

260

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

7 ­Conclusions New detrital zircon U-Pb ages from Cretaceous-Cenozoic clastic sedimentary fill of the Subandean Zone and Oriente Basin of Ecuador provide insights into sediment provenance and dispersal patterns during Cretaceous thermal subsidence, latest Cretaceous-Paleocene shortening and initial development of the Andes, and Cenozoic growth and advance of the fold-thrust belt. Contributing source regions are clearly identified by diagnostic age populations representative of magmatic arc rocks, igneous and metamorphic rocks, recycled sedimentary deposits, and Precambrian crystalline basement of the Western Cordillera, Eastern Cordillera, Subandean Zone, and eastern cratonic regions of the Amazonian shield. Detrital zircon U-Pb geochronologic results show a wholesale switch from eastern cratonic sediment sources (Hollín Formation and Napo Group) to early Andean sources (Tena Formation) that can be assigned to a Maastrichtian onset of shortening, flexural subsidence, and shift from marine to nonmarine deposition in the Ecuador segment of the northern Andes. Continued growth and advance of the fold-thrust belt in Ecuador was recorded by changing provenance signatures recorded in Cenozoic fill of the contemporaneous Oriente foreland basin (Tiyuyacu, Chalcana, Arajuno, and Mesa/Mera Formations). Progressive exhumation of deeper levels of Andean basement, large-scale recycling (cannibalization) of the westernmost Oriente deposits, and possible establishment and erosional elimination of hinterland topographic barriers can be inferred from the appearance, disappearance, and relative contributions of diagnostic source regions.

­Acknowledgments This research was supported by National Science Foundation grant EAR-1338694, National Geographic Society grant 9909-16, and a graduate fellowship from SENESCYT (Secretaria de Educación Superior, Ciencia, Tecnología e Innovación), Ecuador. We appreciate research discussions with Amanda Calle, Tomas Capaldi, Alfredo Buitron, Marco Rivadeneira, Anne Valdez, Fritz Palacios, Felipe Naranjo, Chelsea Mackaman-Lofland, Kelly Thompson, Doug Barber and Cullen D. Kortyna. Jhonatan Enriquez assisted in the field. The manuscript was improved by reviews from Wilfried Winkler and Richard Spikings.

­Appendix: Supplementary material Supplementary material related to this chapter can be found on the accompanying CD or online at https://doi.org/10.1016/B978-0-12-816009-1.00011-3.

­References Anderson, V.J., Horton, B.K., Saylor, J.E., Mora, A., Tesón, E., Breecker, D.O., Ketcham, R.A., 2016. Andean topographic growth and basement uplift in southern Colombia: implications for the evolution of the Magdalena, Orinoco, and Amazon river systems. Geosphere 12, 1235–1256. Aspden, J.A., Litherland, M., 1992. The geology and Mesozoic collisional history of the Cordillera Real, Ecuador. Tectonophysics 205, 187–204. Aspden, J.A., Harrison, S.H., Rundle, C.C., 1992. New geochronological control for the tectono-magmatic evolution of the metamorphic basement Cordillera Real and El Oro Province of Ecuador. J. S. Am. Earth Sci. 6, 77–96.

­References

261

Baby, P., Rivadeneira, M., Barragan, R., 2004. La Cuenca Oriente: Geologia y Petróleo, 1ra Edición, 295. Quito, Ecuador: Convenio IFEA-IRD-Petroecuador. Baby, P., Rivadeneira, M., Barragán, R., Christophoul, F., 2013. Thick-skinned tectonics in the Oriente foreland basin of Ecuador. In: Nemčok, M., Mora, A.R., Cosgrove, J.W. (Eds.), Thick-Skin-Dominated Orogens: From Initial Inversion to Full Accretion. vol. 377. Geological Society, London, pp. 59–76. Special Publications. Baldock, J.W., 1982. Geología del Ecuador: Boletín de Explicación del Mapa geológico de la Républica del Ecuador. Dirección General de Geología y Minas, Quito, Ecuador. 70 p. Balkwill, H.R., Rodrigue, G., Paredes, F.I., Almeida, J.P., 1995. Northern part of Oriente Basin, Ecuador: reflection seismic expression of structures. In: Tankard, A.J., Suarez, S.R., Welsink, H.J. (Eds.), Petroleum Basins of South America. vol. 62. AAPG Memoirs, pp. 559–571. Barberi, F., Coltelli, M., Ferrara, G., Innocenti, F., Navarro, J.M., Santacroce, R., 1988. Plio-quaternary volcanism in Ecuador. Geol. Mag. 125, 1. https://doi.org/10.1017/S0016756800009328. Barragan, R., Baby, P., Duncan, R., 2005. Cretaceous alkaline intra-plate magmatism in the Ecuadorian Oriente Basin: Geochemical, geochronological and tectonic evidence. Earth Planet. Sci. Lett. 236, 670–690. https:// doi.org/10.1016/j.epsl.2005.03.016. Bès de Berc, S., Soula, J.C., Baby, P., Souris, M., Christophoul, F., Rosero, J., 2005. Geomorphic evidence of active deformation and uplift in a modern continental wedge-top–foredeep transition: example of the eastern Ecuadorian Andes. Tectonophysics 399, 351–380. https://doi.org/10.1016/j.tecto.2004.12.030. Bettencourt, J.S., Leite, W.B., Ruiz, A.S., Matos, R., Payolla, B.L., Tosdal, R.M., 2010. The Rondonian-San Ignacio Province in the SW Amazonian craton: an overview. J. S. Am. Earth Sci. 29, 28–46. https://doi.org/10.1016/j. jsames.2009.08.006. Bineli Betsi, T., 2007. The Low-Sulfidation Au-Ag Deposit of Rio Blanco (Ecuador): Geology, Mineralogy, Geochronology and Isotope Geochemistry. MSc. thesis, University of Geneva. 93 pp. Bineli Betsi, T., Ponce, M., Chiaradia, M., Ulianov, A., Camacho, A., 2017. Insights into the genesis of the epithermal Au-Ag mineralization at Rio Blanco in the cordillera occidental of southwestern Ecuador: constraints from U-Pb and Ar/Ar geochronology. J. S. Am. Earth Sci. 80, 353–374. https://doi.org/10.1016/j. jsames.2017.10.004. Black, L., Kamo, S., Allen, C., Davis, D., Aleinikoff, J., Valley, J., Mundil, R., Campbell, I., Korsch, R., Williams, I., Foudoulis, C., 2004. Improved 206Pb/238U microprobegeochronology by the monitoring of a traceelement-related matrix effect; SHRIMP, 8 ID–TIMS, ELA–ICP–MS and oxygen isotope documentation for a series of zircon standards. Chem. Geol. 205, 115–140. Boland, M.P., McCourt, W.J., Beate, B., 1998. Mapa geologico de la Cordillera Occidental del Ecuador entre 0°-1° N, 1 : 200,000. Burgos, J.D.Z., 2006. Genese et progradation d’un cône alluvial au front d’une chaîne active: exemple des Andes équatoriennes au Néogène. Université Paul Sabatier, Toulouse 3, Toulouse, p. 373. Burgos, J.D.Z., Christophoul, F., Baby, P., Antoine, P.-O., Soula, J.C., Good, D., Rivadeneira, M., 2005. Dynamic evolution of Oligocene-Neogene sedimentary series in a retro-foreland basin setting: Oriente Basin, Ecuador. In: 6th International Symposium on Andean Geodynamics (ISAG 2005, Barcelona), Extended Abstracts. pp. 127–130. Calle, A.Z., Horton, B.K., Limachi, r., Stockli, D.F., Uzeda-Orellana, G., Anderson, R.B., Long, S.P., 2018. Cenozoic provenance and depositional record of the sub-Andean foreland basin during growth of the central Andean fold-thrust belt, southern Bolivia. In: Zamora, G., McClay, K.R., Ramos, V.A. (Eds.), Petroleum basins and hydrocarbon potential of the Andes of Peru and Bolivia: AAPG Memoir 117, p. 483–530. Cardona, A., Cordani, U.G., Ruiz, J., Valencia, V.A., Armstrong, R., Chew, D., Nutman, A., Sanchez, A.W., 2009. U-Pb zircon geochronology and Nd isotopic signatures of the pre-Mesozoic metamorphic basement of the eastern Peruvian Andes: growth and provenance of a late Neoproterozoic to carboniferous accretionary Orogen on the northwest margin of Gondwana. J. Geol. 117, 285–305. https://doi.org/10.1086/597472. Chew, D.M., Schaltegger, U., Košler, J., Whitehouse, M.J., Gutjahr, M., Spikings, R.A., Miškovic, A., 2007. U-Pb geochronologic evidence for the evolution of the Gondwanan margin of the north-Central Andes. Geol. Soc. Am. Bull. 119, 697–711.

262

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

Chew, D., Magna, T., Kirkland, C., Miskovic, A., Cardona, A., Spikings, R., Schaltegger, U., 2008. Detrital zircon fingerprint of the Proto-Andes: evidence for a Neoproterozoic active margin? Precambrian Res. 167, 186–200. https://doi.org/10.1016/j.precamres.2008.08.002. Chew, D.M., Cardona, A., Mišković, A., 2011. Tectonic evolution of western Amazonia from the assembly of Rodinia to its break-up. Int. Geol. Rev. 53, 1280–1296. https://doi.org/10.1080/00206814.2010.527630. Chiaradia, M., 2009. Adakite-like magmas from fractional crystallization and melting-assimilation of mafic lower crust (Eocene Macuchi arc, Western Cordillera, Ecuador). Chem. Geol. 265, 468–487. https://doi. org/10.1016/j.chemgeo.2009.05.014. Chisholm, E.I., Sircombe, K.S., DiBugnara, D.L., 2014. Handbook of Geochronology Mineral Separation Laboratory techniques. Geoscience Australia, Record 2014/46. http://dx.doi.org/10.11636/Record.2014.046. Christophoul, F., Baby, P., Dávila, C., 2002. Stratigraphic responses to a major tectonic event in a foreland basin: the Ecuadorian Oriente Basin from Eocene to Oligocene times. Tectonophysics 345, 281–298. Cochrane, R., 2013. U-Pb Thermochronology, Geochronology and Geochemistry of NW South America: Rift to Drift Transition, Active Margin Dynamics and Implications for the Volume Balance of Continents. University of Geneva. Cochrane, R., Spikings, R., Gerdes, A., Ulianov, A., Mora, A., Villagómez, D., Putlitz, B., Chiaradia, M., 2014. Permo-Triassic anatexis, continental rifting and the disassembly of western Pangaea. Lithos 190–191, 383– 402. https://doi.org/10.1016/j.lithos.2013.12.020. Cooper, M.A., Addison, F.T., Alvarez, R., Coral, M., Graham, R.H., Hayward, A.B., Howe, S., Martinez, J., Naar, J., Peñas, R., Pulham, A.J., Taborda, A., 1995. Basin development and tectonic history of the Llanos basin, Eastern Cordillera, and Middle Magdalena Valley, Colombia. AAPG Bull. 79, 1421–1443. Cordani, U.G., Teixeira, W., 2007. Proterozoic accretionary belts in the Amazonian Craton. In: Geological Society of America Memoirs. Geological Society of America, pp. 297–320. https://doi.org/10.1130/2007.1200(14). Cordani, U.G., Cardona, A., Jimenez, D.M., Liu, D., Nutman, A.P., 2005. Geochronology of Proterozoic basement inliers in the Colombian Andes: tectonic history of remnants of a fragmented Grenville belt. Geol. Soc. Lond. Spec. Publ. 246, 329–346. https://doi.org/10.1144/GSL.SP.2005.246.01.13. Cordani, U.G., Teixeira, W., D’Agrella-Filho, M.S., Trindade, R.I., 2009. The position of the Amazonian craton in supercontinents. Gondwana Res. 15, 396–407. https://doi.org/10.1016/j.gr.2008.12.005. Dashwood, M.F., Abbotts, I.L., 1990. Aspects of the petroleum geology of the Oriente Basin. Ecuador Geol. Soc. Lond. Spec. Publ. 50, 89–117. Dickinson, W.R., Gehrels, G.E., 2009. Use of U–Pb ages of detrital zircons to infer maximum depositional ages of strata: a test against a Colorado Plateau Mesozoic database. Earth Planet. Sci. Lett. 288, 115–125. https://doi. org/10.1016/j.epsl.2009.09.013. Dunkley, P.N., Gaibor, A., 1997. Mapa geologico de la Cordillera Occidental del Ecuador entre 2°-3° S. escale 1/200.000. CODIGEM-Min. Energ. Min.-BGS publs., Quito. Gehrels, G., Pecha, M., 2014. Detrital zircon U-Pb geochronology and Hf isotope geochemistry of Paleozoic and Triassic passive margin strata of western North America. Geosphere 10 (1), 49–65. Gehrels, G., Valencia, V., Pullen, A., 2006. Detrital zircon geochronology by laser-ablation multicollector ICPMS at the Arizona LaserChron Center. Paleontol. Soc. Pap. 12, 67–76. Gehrels, G.E., Valencia, V., Ruiz, J., 2008. Enhanced precision, accuracy, efficiency, and spatial resolution of U-Pb ages by laser ablation–multicollector–inductively coupled plasma–mass spectrometry. Geochem. Geophys. Geosyst. 9, Q03017https://doi.org/10.1029/2007GC001805. George, S.W.M., Horton, B.K., Jackson, L.J., Moreno, F., Garzione, C., Carlotto, V., 2019. Sediment provenance variations during contrasting Mesozoic-early Cenozoic tectonic regimes of the northern Peruvian Andes and Santiago-Marañón foreland basin, this volume (Chapter 10), https://doi.org/10.1016/B978-0-12-816009-1.00012-5. Geraldes, M.C., Van Schmus, W.R., Condie, K.C., Bell, S., Teixeira, W., Babinski, M., 2001. Proterozoic geologic evolution of the SW part of the Amazonian Craton in Mato Grosso state, Brazil. Precambrian Res. 111, 91– 128. https://doi.org/10.1016/S0301-9268(01)00158-9.

­References

263

Geraldes, M.C., Tavares, A.D., Santos, A.C.D., 2015. An overview of the Amazonian craton evolution: insights for paleocontinental reconstruction. Int. J. Geosci. 06, 1060–1076. https://doi.org/10.4236/ijg.2015.69084. Germanoski, D., Schumm, S.A., 1993. Changes in Braided River morphology resulting from aggradation and degradation. J. Geol. 101, 451–466. https://doi.org/10.1086/648239. Hein, F.J., Walker, R.G., 1977. Bar evolution and development of stratification in the gravelly, braided, Kicking Horse River, British Columbia. Can. J. Earth Sci. 14, 562–570. https://doi.org/10.1139/e77-058. Herbert, H.J., Pichler, H., 1983. K-Ar ages of rocks from the eastern cordillera of Ecuador. Z. Dtsch. Geol. Ges. 134, 483–493. Horton, B.K., 2012. Cenozoic evolution of hinterland basins in the Andes and Tibet. In: Busby, C., Azor, A. (Eds.), Tectonics of Sedimentary Basins: Recent Advances. Wiley-Blackwell, Oxford, pp. 427–444. Horton, B.K., 2018. Sedimentary record of Andean mountain building. Earth Sci. Rev. 178, 279–309. https://doi. org/10.1016/j.earscirev.2017.11.025. Horton, B.K., DeCelles, P.G., 2001. Modern and ancient fluvial megafans in the foreland basin system of the Central Andes, southern Bolivia: implications for drainage network evolution in fold-thrust belts. Basin Res. 21, 43–63. Horton, B.K., Saylor, J.E., Nie, J., Mora, A., Parra, M., Reyes-Harker, A., Stockli, D.F., 2010. Linking sedimentation in the northern Andes to basement configuration, Mesozoic extension, and Cenozoic shortening: evidence from detrital zircon U-Pb ages, Eastern Cordillera, Colombia. Geol. Soc. Am. Bull. 122, 1423–1442. Horton, B.K., Anderson, V.J., Caballero, V., Saylor, J.E., Nie, J., Parra, M., Mora, A., 2015. Application of detrital zircon U-Pb geochronology to surface and subsurface correlations of provenance, paleodrainage, and tectonics of the middle Magdalena Valley basin of Colombia. Geosphere 11, 1790–1811. https://doi.org/10.1130/GES01251.1. Hughes, R., Bermudez, R., 1997. Geology of the Cordillera Occidental of Ecuador between 0°00’and 1° 00’S. Proyecto de desarollo minero y control ambiental, programa de información cartográfica y geológica. Report Number 4, CODIGEM–British Geological Survey, Quito, Ecuador. 75 p. Hughes, R.A., Pilatasig, L.F., 2002. Cretaceous and tertiary terrane accretion in the Cordillera occidental of the Andes of Ecuador. Tectonophysics 345, 29–48. Hungerbühler, D., Steinmann, M., Winkler, W., Seward, D., Egüez, A., Peterson, D.E., Helg, U., Hammer, C., 2002. Neogene stratigraphy and Andean geodynamics of southern Ecuador. Earth Sci. Rev. 57, 75–124. Jaillard, E., Soler, P., 1996. Cretaceous to early Paleogene tectonic evolution of the northern Central Andes (0– 18°S) and its relations to geodynamics. Tectonophysics 259, 41–53. Jaillard, E., Hérail, G., Montfret, T., Diáz-Martinez, E., Baby, P., Lavenu, A., Dumon, J.F., 2000. Tectonic evolution of the Andes of Ecuador, Peru, Bolivia and northernmost Chile. In: Cordani, U.G., Milani, E.J., Thomaz Filho, A.M., Campos, D.A. (Eds.), Tectonic evolution of South America, 31st International Geological Congress, Rio de Janeiro, pp. 481–559. Jaillard, E., Bengtson, P., Dhondt, A.V., 2005. Late Cretaceous marine transgressions in Ecuador and northern Peru: A refined stratigraphic framework. J. South Am. Earth Sci. 19, 307–323. https://doi.org/10.1016/j. jsames.2005.01.006. Kammer, A., Sánchez, J., 2006. Early Jurassic rift structures associated with the Soapaga and Boyacá faults of the Eastern Cordillera, Colombia: sedimentological inferences and regional implications. J. S. Am. Earth Sci. 21, 412–422. https://doi.org/10.1016/j.jsames.2006.07.006. Kennan, L., Pindell, J.L., 2009. Dextral shear, terrane accretion and basin formation in the northern Andes: best explained by interaction with a Pacific-derived Caribbean plate? Geol. Soc. Lond. Spec. Publ. 328, 487–531. https://doi.org/10.1144/SP328.20. Kennerley, J.B., 1980. Outline of the Geology of Ecuador. vol. 55. Institute of Geological Sciences: Overseas Geology and Mineral Resources, p. 17. Kerr, A.C., Aspden, J.A., Tarney, J., PILATASIG, L.F., 2002. The nature and provenance of accreted oceanic terranes in western Ecuador: geochemical and tectonic constraints. J. Geol. Soc. Lond. 159, 577–594.

264

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

Lavenu, A., Noblet, C., Bonhomme, M.G., Egüez, A., Dugas, F., Vivier, G., 1992. New K Ar age dates of Neogene and quaternary volcanic rocks from the Ecuadorian Andes: implications for the relationship between sedimentation, volcanism, and tectonics. J. S. Am. Earth Sci. 5, 309–320. https://doi.org/10.1016/0895-9811(92)90028-W. Lebras, M., MéGard, F., Dupuy, C., Dostal, J., 1987. Geochemistry and tectonic setting of pre-collision Cretaceous and Paleogene volcanic rocks of Ecuador. Geol. Soc. Am. Bull. 99, 569. https://doi. org/10.1130/0016-7606(1987)99<569:GATSOP>2.0.CO. Litherland, M., Aspden, J.A., Jemielita, R.A., 1994. The Metamorphic Belts of Ecuador. Overseas Memoir 11. British Geological Survey, Nottingham, p. 147. Litherland, M., Zamora, A., Eguez, A., Aspden, J., Baez, N., Beate, B., Benitez, S., Jaillard, E., Van Thournout, F., 1993. Mapa geológico de la República del Ecuador. Br. Geol. Surv. escala 1: 1,000,000. Mamberti, M., Lapierre, H., Bosch, D., Jaillard, E., Ethien, R., Hernandez, J., Polvé, M., 2003. Accreted fragments of the late cretaceous Caribbean–Colombian plateau in Ecuador. Lithos 66, 173–199. Martin-Gombojav, N., Winkler, W., 2008. Recycling of Proterozoic crust in the Andean Amazon foreland of Ecuador: implications for orogenic development of the northern Andes: multiple recycling of Proterozoic crust in the northern Andes. Terra Nova 20, 22–31. https://doi.org/10.1111/j.1365-3121.2007.00782.x. McCourt, W.J., Duque, P., Pilatasig, L.F., Villagomez, R., 1997. Mapa geológico de la Cordillera Occidental del Ecuador entre 1° - 2° S., escala 1/200.000. CODIGEM-Min. Energ. Min.-BGS publs., Quito. McGroder, M.F., Lease, R.O., Pearson, D.M., 2015. Along-strike variation in structural styles and hydrocarbon occurrences, Subandean fold-and-thrust belt and inner foreland, Colombia to Argentina. In: DeCelles, P.G., Ducea, M.N., Carrapa, B., Kapp, P.A. (Eds.), Geodynamics of a Cordilleran Orogenic System: The Central Andes of Argentina and Northern Chile. vol. 212. Geological Society of America Memoir, pp. 79–114. Mejía, M.I.A., García, G.Z., Martens, U., 2012. Caracterización Petrográfica, Geoquímica Y Edad De La Sienita Nefelínica De San José Del Guaviare. Bol. Geol. 34 (1). Miall, A.D., 1978. Lithofacies types and vertical profile models in braided river deposits: a summary. In: Miall, A.D. (Ed.), Fluvial Sedimentology, Vol. 5. Canadian Society of Petroleum Geologists, Calgary, p. 859. Miall, A.D., 1985. Architectural-element analysis: a new method of facies analysis applied to fluvial deposits. Earth Sci. Rev. 22, 261–308. https://doi.org/10.1016/0012-8252(85)90001-7. Mišković, A., Spikings, R.A., Chew, D.M., Košler, J., Ulianov, A., Schaltegger, U., 2009. Tectonomagmatic evolution of Western Amazonia: geochemical characterization and zircon U-Pb geochronologic constraints from the Peruvian Eastern Cordilleran granitoids. Geol. Soc. Am. Bull. 121, 1298–1324. Mora, A., Gaona, T., Kley, J., Montoya, D., Parra, M., Quiroz, L.I., Reyes, G., Strecker, M., 2009. The role of inherited extensional fault segmentation and linkage in contractional orogenesis: a reconstruction of Lower Cretaceous inverted rift basin in the Eastern Cordillera of Colombia. Basin Res. 21, 111–137. https://doi. org/10.1111/j.1365-2117.2008.00367.x. Mourier, T., Laj, C., Mégard, F., Roperch, P., Mitouard, P., Medrano, A.F., 1988. An accreted continental terrane in northwestern Peru. Earth Planet. Sci. Lett. 88, 182–192. Noble, S.R., Aspden, J.A., Jemielita, R., 1997. Northern Andean crustal evolution: new U-Pb geochronological constraints from Ecuador. Geol. Soc. Am. Bull. 109, 789–798. Paces, J.B., Miller, J.D., 1993. Precise U-Pb ages of Duluth Complex and related mafic intrusions, northeastern Minnesota: geochronological insights to physical, petrogenetic, paleomagnetic, and tectonomagmatic processes associated with the 1.1 Ga midcontinent rift system. J. Geophys. Res. 98, 13997–14013. Palacios, O., Pilatasig, L., Sanchez, J., Gordon, D., Shaw, R., Feininger, T., 2008. Mapa geologico binacional region sur del Ecuador y norte del Peru. Ingeomin 1 (500). Perez, N.D., Horton, B.K., 2014. Oligocene-miocene deformational and depositional history of the andean hinterland basin in the Northern Altiplano Plateau, Southern Peru. Tectonics 33, 1819–1847. https://doi. org/10.1002/2014TC003647. Pindell, J.L., Tabbutt, K.D., 1995. Mesozoic-Cenozoic Andean paleogeography and regional controls on hydrocarbon systems. In: Tankard, A.J., Soruco, R.S., Welsink, H.J. (Eds.), Petroleum Basins of South America. AAPG Memoir, Vol. 62. American Association of Petroleum Geologists, pp. 101–128.

­References

265

Pratt, W.T., Duque, P., Ponce, M., 2005. An autochthonous geological model for the eastern Andes of Ecuador. Tectonophysics 399, 251–278. https://doi.org/10.1016/j.tecto.2004.12.025. Ramos, V.A., 2010. The Grenville-age basement of the Andes. J. S. Am. Earth Sci. 29, 77–91. https://doi. org/10.1016/j.jsames.2009.09.004. Reynaud, C., Jaillard, É., Lapierre, H., Mamberti, M., Mascle, G.H., 1999. Oceanic plateau and island arcs of southwestern Ecuador: their place in the geodynamic evolution of northwestern South America. Tectonophysics 307, 235–254. Roddaz, M., Hermoza, W., Mora, A., Baby, P., Parra, M., Christophoul, F., Brusset, S., Espurt, N., 2011. Cenozoic sedimentary evolution of the Amazonian Foreland Basin system. In: Hoorn, C., Wesselingh, F.P. (Eds.), Amazonia: Landscape and Species Evolution. Wiley-Blackwell Publishing Ltd., Oxford, pp. 61–88. https:// doi.org/10.1002/9781444306408. Romeuf, N., Aguirre, L., Soler, P., Féraud, G., Jaillard, E., Ruffet, G., 1995. Middle Jurassic volcanism in the Northern and Central Andes. Rev. Geol. Chile 22, 245–259. https://doi.org/10.5027/andgeoV22n2-a08. Ruiz, G.M.H., 2002. Exhumation of the northern sub-Andean zone of Ecuador and its source regions: a combined thermochronological and heavy mineral approach. ETH Zurich. https://doi.org/10.3929/ethz-a-004489528. Ruiz, G.M.H., Seward, D., Winkler, W., 2004. Detrital thermochronology—a new perspective on hinterland tectonics, an example from the Andean Amazon Basin, Ecuador. Basin Res. 16, 413–430. https://doi. org/10.1111/j.1365-2117.2004.00239.x. Ruiz, G.M.H., Seward, D., Winkler, W., 2007. Chapter 36 Evolution of the Amazon basin in ecuador with special reference to hinterland tectonics: data from zircon fission-track and heavy mineral analysis. Dev. Sedimentol. 58, 907–934. https://doi.org/10.1016/S0070-4571(07)58036-2. Rust, B.R., 1978. Depositional models for braided alluvium. In: Miall, A.D. (Ed.), Fluvial sedimentation. Can. Soc. Petrol. Geol. Mem. 5. pp. 605–626. Satkoski, A.M., Wilkinson, B.H., Hietpas, J., Samson, S.D., 2013. Likeness among detrital zircon populations—an approach to the comparison of age frequency data in time and space. Geol. Soc. Am. Bull. 125, 1783–1799. https://doi.org/10.1130/B30888.1. Sauer, W., 1965. Geología del Ecuador. Ministerio de Educación, Quito, Ecuador, p. 583. Schütte, P., 2009. Geochronology, Geochemistry, and Isotopic Composition (Sr, Nd, Pb) of Tertiary Porphyry Systems in Ecuador (PhD Thesis). University of Geneva. Schütte, P., Chiaradia, M., Beate, B., 2010. Geodynamic controls on Tertiary arc magmatism in Ecuador: Constraints from U–Pb zircon geochronology of Oligocene–Miocene intrusions and regional age distribution trends. Tectonophysics 489, 159–176. https://doi.org/10.1016/j.tecto.2010.04.015. Spikings, R., Simpson, G., 2014. Rock uplift and exhumation of continental margins by the collision, accretion, and subduction of buoyant and topographically prominent oceanic crust. Tectonics 33, 635–655. https://doi. org/10.1002/2013TC003425. Spikings, R.A., Seward, D., Winkler, W., Ruiz, G.M., 2000. Low-temperature thermochronology of the northern Cordillera Real, Ecuador: Tectonic insights from zircon and apatite fission track analysis. Tectonics 19, 649– 668. https://doi.org/10.1029/2000TC900010. Spikings, R., Winkler, W., Seward, D., Handler, R., 2001. Along-strike variations in the thermal and tectonic response of the continental Ecuadorian Andes to the collision with heterogeneous oceanic crust. Earth Planet. Sci. Lett. 186, 57–73. https://doi.org/10.1016/S0012-821X(01)00225-4. Spikings, R.A., Winkler, W., Hughes, R.A., Handler, R., 2005. Thermochronology of allochthonous terranes in Ecuador: unravelling the accretionary and post-accretionary history of the northern Andes. Tectonophysics 399, 195–220. https://doi.org/10.1016/j.tecto.2004.12.023. Spikings, R.A., Crowhurst, P.V., Winkler, W., Villagomez, D., 2010. Syn- and post-accretionary cooling history of the Ecuadorian Andes constrained by their in-situ and detrital thermochronometric record. J. S. Am. Earth Sci. 30, 121–133. https://doi.org/10.1016/j.jsames.2010.04.002. Spikings, R., Cochrane, R., Villagomez, D., Van der Lelij, R., Vallejo, C., Winkler, W., Beate, B., 2015. The geological history of northwestern South America: from Pangaea to the early collision of the Caribbean large Igneous Province (290–75Ma). Gondwana Res. 27, 95–139. https://doi.org/10.1016/j.gr.2014.06.004.

266

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

Steinmann, M., Hungerbühler, D., Seward, D., Winkler, W., 1999. Neogene tectonic evolution and exhumation of the southern Ecuadorian Andes: a combined stratigraphy and fission-track approach. Tectonophysics 307, 255–276. Sundell, K.E., Saylor, J.E., 2017. Unmixing detrital geochronology age distributions. Geochem. Geophys. Geosyst. 18, https://doi.org/10.1002/2016GC006774. Tassinari, C.C.G., Macambira, M.J.B., 1999. Geochronological provinces of the Amazonian Craton. Episodes 22, 174–182. Teixeira, W., Geraldes, M.C., Matos, R., Ruiz, A.S., Saes, G., Vargas-Mattos, G., 2010. A review of the tectonic evolution of the Sunsás belt, SW Amazonian Craton. J. S. Am. Earth Sci. 29, 47–60. https://doi.org/10.1016/j. jsames.2009.09.007. Teixeira, W., Geraldes, M.C., D’Agrella-Filho, M.S., Santos, J.O.S., Sant’Ana Barros, M.A., Ruiz, A.S., Corrêa da Costa, P.C., 2011. Mesoproterozoic juvenile mafic–ultramafic magmatism in the SW Amazonian Craton (Rio Negro-Juruena province): SHRIMP U–Pb geochronology and Nd–Sr constraints of the Figueira Branca Suite. J. S. Am. Earth Sci. 32, 309–323. https://doi.org/10.1016/j. jsames.2011.04.011. Thomas, G., Lavenu, A., Berrones, G., 1995. Subsidence evolution of the northern part of the Ecuadorian Oriente Basin (Upper Cretaceous to Present). C. R. Acad Sci II 320, 617–624. Toro Álava, J., Jaillard, E., 2005. Provenance of the Upper Cretaceous to upper Eocene clastic sediments of the Western Cordillera of Ecuador: geodynamic implications. Tectonophysics 399, 279–292. https://doi. org/10.1016/j.tecto.2004.12.026. Tschopp, H.J., 1953. Oil explorations in the Oriente of Ecuador, 1938-1950. AAPG Bull. 37, 2303–2347. Valarezo, M., Horton, B.K., Winkler, W., Spikings, R., Esteban, J., Jackson, L.J., 2017. Sedimentology and provenance analysis of the alamor lancones basin, southern ecuador: a late cretaceous pre-accretional forearc basin. In: GSA Annual Meeting in Seattle, WA, United States. https://doi.org/10.1130/ abs/2017am-304108. Valdez Pardo, A.M., 1997. Reinterpretacion sedimentologica, estratigrafica de la Formacion Tiyuyacu y su relacion con la tectonica del Terciario inferior. Tesis de grado, Universidad Central del Ecuador 141, 5 annexes. Vallejo, C., Spikings, R.A., Luzieux, L., Winkler, W., Chew, D., Page, L., 2006. The early interaction between the Caribbean plateau and the NW south American plate: caribbean plateau-south American plate collision. Terra Nova 18, 264–269. https://doi.org/10.1111/j.1365-3121.2006.00688.x. Vallejo, C., Winkler, W., Spikings, R.A., Luzieux, L., Heller, F., Bussy, F., 2009. Mode and timing of terrane accretion in the forearc of the Andes in Ecuador. Geol. Soc. Am. Mem. 204, 197–216. https://doi. org/10.1130/2009.1204(09). Vallejo, C., Soria, F., Tornos, F., Naranjo, G., Rosero, B., Salazar, F., Cochrane, R., 2016. Geology of El Domo deposit in Central Ecuador: a VMS formed on top of an accreted margin. Mineral. Deposita 51, 389–409. https://doi.org/10.1007/s00126-015-0616-x. Vallejo, C., Tapia, D., Gaibor, J., Steel, R., Cardenas, M., Winkler, W., Valdez, A., Esteban, J., Figuera, M., Leal, J., Cuenca, D., 2017. Geology of the Campanian M1 sandstone oil reservoir of eastern Ecuador: a delta system sourced from the Amazon Craton. Mar. Pet. Geol. 86, 1207–1223. https://doi.org/10.1016/j.marpetgeo.2017.07.022. Vallejo, C., Spikings, R.A., Horton, B.K., Luzieuz, L., Romero, C., Winkler, W., and Thomsen, T., 2019. Late Cretaceous to Miocene stratigraphy and provenance of the coastal forearc and Western Cordillera of Ecuador: evidence for accretion of a single oceanic plateau fragment, this volume (Chapter 8), https://doi.org/10.1016/B978-0-12-816009-1.00010-1. Vermeesch, P., 2013. Multi-sample comparison of detrital age distributions. Chem. Geol. 341, 140–146. https:// doi.org/10.1016/j.chemgeo.2013.01.010. Villagómez, D., Spikings, R., Magna, T., Kammer, A., Winkler, W., Beltrán, A., 2011. Geochronology, geochemistry and tectonic evolution of the Western and Central cordilleras of Colombia. Lithos 125, 875–896. https://doi. org/10.1016/j.lithos.2011.05.003. Williams, P.F., Rust, B.R., 1969. The sedimentology of a braided river. J. Sediment. Petrol. 39, 649–679. https:// doi.org/10.1306/74D71CF3-2B21-11D7-8648000102C1865D.

­Further reading

267

Witt, C., Rivadeneira, M., Poujol, M., Barba, D., Beida, D., Beseme, G., Montenegro, G., 2017. Tracking ancient magmatism and Cenozoic topographic growth within the Northern Andes forearc: constraints from detrital U-Pb zircon ages. Dengue Bull. 129, 415–428. Wolaver, B.D., Coogan, J.C., Horton, B.K., Suarez Bermudez, L., Sun, A.Y., Wawrzyniec, T.F., Zhang, T., Shanahan, T.M., Dunlap, D.B., Costley, R.A., de la Rocha, L., 2015. Structural and hydrogeologic evolution of the Putumayo Basin and adjacent fold-thrust belt, Colombia. Am. Assoc. Pet. Geol. Bull. 99, 1893–1927. Zambrano, I., Ordóñez, M., Jiménéz, N., 1999. Micropaleontología de 63 muestras de afloramientos de la Cuenca Oriental Ecuatoriana. Informe técnico No. 016-PPG-99, Labogeo, Petroproducción, Distrito Guayaquil.

­Further reading Burkley, L.A., 1976. Geochronology of the Central Venezuelan Andes (Ph.D. thesis). Case Western Reserve University, Cleveland. 150 p. Cardona, A., Cordani, U., Ruiz, J., Valencia, V., Nutman, A., Sanchez, A., 2006. U/Pb detrital zircon geochronology and Nd isotopes from Paleozoic metasedimentary rocks of the Maranon complex: insights on the proto-Andean tectonic evolution of the Eastern Peruvian Andes. In: Fifth South American Symposium on Isotope Geology, Punta del Este, Uruguay, April 24–25, pp. 208–211. Cobbing, E.J., 1982. The segmented coastal batholith of Peru: its relationship to volcanicity and metallogenesis. Earth Sci. Rev. 18, 241–251. DeCelles, P.G., Giles, K.A., 1996. Foreland basin systems. Basin Res. 8, 105–123. Gaibor, J., Hochuli, J.P.A., Winkler, W., Toro, J., 2008. Hydrocarbon source potential of the Santiago formation, Oriente Basin, SE of Ecuador. J. S. Am. Earth Sci. 25, 145–156. https://doi.org/10.1016/j.jsames.2007.07.002. Heller, P.L., Angevine, C.L., Winslow, N.S., Paola, C., 1988. Two-phase stratigraphic model of foreland-basin sequences. Geology 16, 501–504. Ingersoll, R., 2012. Tectonics of sedimentary basins, with revised nomenclature. In: Busby, C., Azor, A. (Eds.), Tectonics of Sedimentary Basins: Recent Advances. Wiley-Blackwell, Oxford, pp. 1–43. Jacay, J., Sempere, T., 2005. Emplacement levels of the Coastal Batholith in Central Peru. In: 6th International Symposium on Andean Geodynamics (ISAG2005, Barcelona), Extended Abstracts. pp. 397–399. Jagger, L.J., McClay, K.R., 2018. Analogue modelling of inverted domino-style basement fault systems. Basin Res. 30, 363–381. https://doi.org/10.1111/bre.12224. Jaillard, E., Ordoñez, M., Suárez, J., Toro, J., Iza, D., Lugo, W., 2004. Stratigraphy of the late cretaceous–Paleogene deposits of the cordillera occidental of Central Ecuador: geodynamic implications. J. S. Am. Earth Sci. 17, 49–58. https://doi.org/10.1016/j.jsames.2004.05.003. Jaillard, E., Bengtson, P., Ordoñez, M., Vaca, W., Dhondt, A., Suárez, J., Toro, J., 2008. Sedimentary record of terminal cretaceous accretions in Ecuador: the Yunguilla Group in the Cuenca area. J. S. Am. Earth Sci. 25, 133–144. https://doi.org/10.1016/j.jsames.2007.08.002. Lawton, T.F., Hunt, G.J., Gehrels, G.E., 2010. Detrital zircon record of thrust belt unroofing in lower cretaceous synorogenic conglomerates, Central Utah. Geology 38, 463–466. Litherland, M., Annells, R.N., Appleton, J.D., Berrange, J.P., Bloomfield, K., Burton, C.C.J., Darbyshire, D.P.F., Fletcher, C.J.N., Hawkins, M.P., Klinck, B.A., Llanos, A., Mitchell, W.I., O’Conner, E.A., Pitfield, P.E.J., Power, G., Webb, B.C., 1986. The Geology and Mineral Resources of the Bolivian Precambrian Shield. British Geological Survey, Overseas Memoir. HMSO, London. 153 p. Litherland, M., Fortey, N.J., Beddoe-Stephens, B., 1992. Newly discovered Jurassic skarnfields in the Ecuadorian Andes. J. S. Am. Earth Sci. 6, 67–75.

268

Chapter 9  Late Cretaceous-Cenozoic development of the Oriente Basin

Quenardelle, S.M., Ramos, V.A., 1999. Ordovician western Sierras Pampeanas magmatic belt: record of Precordillera accretion in Argentina. Special Paper 336. In: Laurentia-Gondwana Connections Before Pangea. Geological Society of America, pp. 63–86. https://doi.org/10.1130/0-8137-2336-1.63. Sylvester, P.J., 1998. Post-collisional strongly peraluminous granites. Lithos 45, 29–44. https://doi.org/10.1016/ S0024-4937(98)00024-3. Van der Lelij, R., Spikings, R., Ulianov, A., Chiaradia, M., Mora, A., 2016. Palaeozoic to Early Jurassic history of the northwestern corner of Gondwana, and implications for the evolution of the Iapetus, Rheic and Pacific Oceans. Gondwana Res. 31, 271–294. https://doi.org/10.1016/j.gr.2015.01.011. Van Thournout, F., 1991. Stratigraphy, Magmatism and Tectonism in the Ecuadorian Northwestern Cordillera: Metallogenic and Geodynamic Implications (PhD thesis). Katholieke Universiteit Leuven. 150 pp. Vásquez, M., Altenberger, U., Romer, R.L., Sudo, M., Moreno-Murillo, J.M., 2010. Magmatic evolution of the Andean Eastern Cordillera of Colombia during the Cretaceous: influence of previous tectonic processes. J. S. Am. Earth Sci. 29, 171–186. https://doi.org/10.1016/j.jsames.2009.02.003. Villagómez, D., Spikings, R., 2013. Thermochronology and tectonics of the Central and Western Cordilleras of Colombia: early cretaceous–tertiary evolution of the northern Andes. Lithos 160–161, 228–249. https://doi. org/10.1016/j.lithos.2012.12.008.