Chapter 6 Cretaceous carbonate biostratigraphy and environments in Honduras

Chapter 6

Cretaceous Carbonate B iostratigraphy and Environments in Honduras

ROBERT W. SCOTT and R.C. FINCH

A carbonate platform developed on the Chortfs block beginning in the Berriasian-Aptian and ending in the Albian. This platform is represented in Honduras by carbonate strata of the Yojoa Group, mainly the Atima Formation. We report new stratigraphic and paleontological data from exposures of this carbonate package and superjacent Upper Cretaceous strata in easternmost Honduras. In addition, new paleontological data from west-central Honduras are presented confirming previous interpretations there. In west-central Honduras, carbonate deposition of the Atima Formation was interrupted in the Aptian by an influx of non-marine, terrigenous sediments of the 'Mochito shale', and terminated at the beginning of the Cenomanian by coarse redbed strata of the lower Valle de Angeles Group. The exact nature of the Atima/Valle de Angeles contact in west-central Honduras is not known, but may be gradational. In the Montafias de Col6n area in eastern Honduras, no equivalent of the 'Mochito shale' has yet been identified, and late Albian deposition of the Atima was ended by an influx of fine-grained, shallow marine, terrigenous sediments of the Cenomanian 'Krausirpi beds'. Although the Krausirpi beds are only known locally, we include them in the Yojoa Group as an informal member. After deposition of the Krausirpi beds, local subaerial exposure and erosion occurred prior to deposition of the redbeds of the lower Valle de Angeles Group. In west-central Honduras, carbonate platform deposition was resumed during the Cenomanian represented by the Jaitique Formation and by the slightly younger and lithologically distinct Esqufas Formation just east of the outcrop area of the Jaitique. These limestone units conveniently divide the Valle de Angeles Group into lower and upper redbed sections. No equivalent limestone unit has been found in the Montafias de Col6n area. Instead, deposition of continental redbeds began here in the Cenomanian and continued into latest Cretaceous, as indicated by radiometrically dated volcanic flow units within the redbeds. The Jaitique Formation consists of a lower thick-bedded limestone member overlain by a thin shaly limestone member in the area south and west of Lake Yojoa. In central Honduras the Esqufas Formation consists of interbedded limestone, marl and shale. The remainder of Cretaceous deposition was fluvial clastic sediments and volcanic rocks which belong to the upper Valle de Angeles Group. New paleontologic data from limestone of the Atima Formation, shale of the Krausirpi beds, limestone conglomerate in the Valle de Angeles Group, and from the Jaitique Formation confirm the ages and depositional environments. The Atima ranges from Barremian-Aptian to late Albian based on ten foraminiferal taxa, one caprinid rudist and three calcareous algae. The Krausirpi beds are Albian-Cenomanian based on nine palynomorph taxa and two planktic foraminifers. The Jaitique is middle to late Cenomanian with the benthic foraminifer Biconcava, which is reported for the first time in the Caribbean Province. A Cenomanian dasyclad, Dissocladella undulata, was recovered in a limestone clast in the Valle de Angles Group suggesting the possibility that Cenomanian as well as older limestone units were eroded during the Late Cretaceous. The Atima records at least two shoaling upward depositional cycles, and the Jaitique was deposited in an open shelf environment that became restricted near the end of deposition.

INTRODUCTION

Cretaceous marine and non-marine strata cover much of the Chortfs block of northern Central America, and represent Early to mid-Cretaceous carbonate platform sedimentation buried by Late Cretaceous terrigenous redbeds. Honduras comprises most of

the Chortfs block, and published detailed stratigraphic and paleontologic data were, until recently, restricted mainly to the western and central portions of the republic. The geology of easternmost Honduras, however, was known from reconnaissance work by Mills et al. (1967), Mills and Hugh (1974), and Weiland et al. (1992). The first detailed strati-

Caribbean Basins. Sedimentary Basins of the World, 4 edited by E Mann (Series Editor: K.J. Hsti), pp. 151-165. 9 1999 Elsevier Science B.V., Amsterdam. All rights reserved.

152

R.W. SCOTT and R.C. FINCH

graphic data from this part of the Chortfs block has recently been provided by Rogers (1994, 1995) and Mills and Barton (1996). Mills and Barton (1996) used these Cretaceous carbonate strata in southeastern Honduras to define the Col6n platform. The geology and tectonic history of the Chortfs block has been summarized by Azema et al. (1985), Donnelly et al. (1990), Finch and Dengo (1990), and Gordon and Muehlberger (1994). The Chortfs block, which today forms the northwest comer of the Caribbean plate, is bounded on the southwest by the Middle America Trench subduction zone and on the north by the Cayman transform and its continental extension in the Motagua-Chixoy-Polochfc fault zones. To the south the Chortfs block is thought to be separated from the Chorotega block of the Caribbean plate by the Santa Elena fault-Hess escarpment. The eastern limit is undefined, but the Nicaraguan rise is generally included as a submarine extension of the Chortfs block (e.g., Pindell and Barrett, 1990). Prior to its Late Cretaceous suturing against the Maya block (Donnelly et al., 1990), the Chortfs was independent of the Maya, as indicated by differences in basement rocks (Gordon, 1989a,b; Gordon and Gose, 1989; Donnelly et al., 1990) and paleomagnetic data (Gose, 1985a,b; Gordon and Gose, 1989). Gose's paleomagnetic data also strongly imply that prior to its emplacement adjacent to the Maya block, Chortfs was not part of the Caribbean plate of today (Gose and Finch, 1992). Since mid-Cretaceous time the Chortfs block has rotated counterclockwise into

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its present position. Consensus is growing, based on paleomagnetic data, lithologic similarities between Chortfs and the Guerrero block of Mexico, and plate reconstructions, that Chortfs formerly lay along the present southwest coast of Mexico (e.g, Anderson and Schmidt, 1983; Dengo, 1985; Gose, 1985a; Fourcade and Michaud, 1987; Pindell and Barrett, 1990; Burkart, 1994). As a consequence of its location west of Mexico during the Early Cretaceous, the new paleontological data reported here have biogeographic significance. The biota of the Chortfs block is very similar to that of the Caribbean Province. The primary purpose of this paper is to report new paleontological results from samples collected in easternmost Honduras by R.C. Finch and T.J. Weiland in a traverse across the Montafias de Col6n fold belt, and along the Rio Patuca and Rio Wampfi, and to place these results in the context of stratigraphic interpretations made by Rogers (1994, 1995). This report provides new data from a region lying some 200 km east of most of the previously studied areas of the Honduran Cretaceous. A secondary purpose is to describe other collections yielding new paleontological data from the region south and west of Lake Yojoa in west-central Honduras (Fig. 1). In 1984 Amoco Production Co. sponsored a field party to eastern Honduras to investigate and sample outcrops in the Montafias de Col6n-Rio Wampfi area near the border with Nicaragua (Fig. 1). This area consists of three distinct physiographic elements: (1)

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CRETACEOUS CARBONATE BIOSTRATIGRAPHY AND ENVIRONMENTS IN HONDURAS [

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a northeast-trending belt of folded and faulted limestone mountains (the Montafias de Col6n), flanked on the northwest by (2) a low terrain of clastic strata flooring the broad northeast-trending valley of the Rio Patuca, flanked, in turn, to the northwest by (3) a mountainous mixed metamorphic/sedimentary terrain drained by the Rio Wamp6, a southeast-flowing tributary to the Patuca (Fig. 2). Paleontological results were obtained from a measured section representing a thin interval of the uppermost part of the Atima Formation exposed at Tirisne Cliffs and from other locations along the Sutawala Valley cutting across the Montafias de Col6n (Fig. 2). Additional collections were made along the Rios Patuca and Wamp6. Paleontological results from the present study demonstrate that Chortfs mid-Cretaceous carbonate strata were part of the same biogeographic province as coeval carbonate rocks of the Caribbean Province in Jamaica, northern Mexico and the Gulf of Mexico. Previous paleontological data from west-central Honduras (Mills et al., 1967; Lozej, 1976) suggested such a relationship. Likewise, outcrops of Atima Formation limestone reported by Emmet et al. (1992) in central Honduras (some 50 km north-northeast of Tegucigalpa in the Agalteca quadrangle, 4 in Fig. 1) contain late Aptian to middle Albian planktic foraminifers, colomiellids, and calcispheres. These forereef basinal fossils also demonstrate biogeographic similarities and exchange with coeval carbonate environments in Guatemala, Jamaica, Mexico and southern United States.

STRATIGRAPHY

Lithostratigraphy The Cretaceous stratigraphic terminology of Honduras (Fig. 3) was revised by Finch (1981) and summarized by Donnelly et al. (1990). The mid-Cretaceous platform carbonates are widely exposed across Honduras and have been designated the Yojoa Group (Mills et al., 1967), consisting of the locally developed Cantarranas Formation overlain by the widespread Atima Formation (see Gose and Finch, 1992, fig. 4, and Donnelly et al., 1990, fig. 7, for stratigraphic columns in west-central Honduras). The Cantarranas Formation (Carpenter, 1954) is a shaly limestone of variable lithology ranging in thickness from 30 to 190 m. The unit is dated as Valanginian-Hauterivian by ammonites (Gordon and Young, 1993) and represents a shelf lagoon. Outside of its type area near Talanga northeast of Tegucigalpa, the Cantarranas has been found to be of limited value as a map unit at the 1:50,000 scale used for geologic quadrangle mapping in Honduras, but has been mapped by Gordon (1990). We did not recognize the Cantarranas in the Rio Wampfi-Montafias de Col6n area, nor did Rogers (1994, 1995), although Mills et al. (1967) reported Cantarranas exposed on a tributary to the Wampfi. The Atima Formation, named by Mills (1959), is a widely recognized map unit consisting primarily of thick-bedded micritic limestone ranging in thickness from 90 to 1400 m (Finch, 1981). In the area of the

154

R.W. SCOTT and R.C. FINCH t...= rE o t.-

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"Mochito Shale"

Honduras Group sandstone, shale & metasedimentary rocks above basement rocks ,m O N O

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Fig. 3. Generalized, composited stratigraphic section of Mesozoic strata in eastern and western Honduras showing distribution of key samples listed in Tables 1 and 2. Krausirpi beds found only in the eastern region and the Jaitique Formationonly in the western region. Mochito Mine west of Lake Yojoa (Fig. 1) the Atima is divided into informal lower and upper intervals separated by about 100 m of green and gray mudstone with limestone interbeds and some red shale. In the Mochito area Lozej (1976) dated the lower limestone of the Atima as upper Barremian through Aptian by "possible 'early' Orbitolina" sp. and by Tintinnopsella cf. carpathica (Murgeanu and Filipescu), which in the Gulf Coast ranges from Berriasian through Barremian. A rudistid facies is present about 210 m below the top of the lower limestone. The upper Atima was dated as latest Aptian through upper Albian (Lozej, 1976) by the presence of orbitolinids, Cuneolina, Coskinolina/Dictyoconus, and Dicyclina. An interval between the orbitolinid facies contains the offshore shelf protozoan Colomiella recta Bonet, which ranges from Barremian through lower Albian in the Gulf Coast (Bonet, 1956). Rudistid facies are developed about 150 m below the top of the upper limestone. The shale and mudstone interval within the Atima Formation has been informally designated the "Mochito shale", and comprises a mappable unit at the

Mochito Mine near E1 Mochito (Fig. 1) and in the area north and west of the mine (Finch, 1973, 1985). This shale was described by Lozej (1976) as "of 'red bed' affinity (somewhat similar lithologically to the overlying and underlying formations)...". He reported conformable boundaries with the lower and upper Atima limestones "marked by green and/or red mottled mudrock interbeds". The transitional beds at the top of the lower Atima contain ostracodes and the base of the upper limestone contains charophytes, gastropods and ostracodes (Lozej, 1976). He concluded that the Mochito was late Aptian by its position between the Barremian-lower Aptian lower Atima limestone and the Albian upper Atima limestone. At three widely separated exposures in central Honduras, Gallo and Van Wagoner (1978) described sections 130 to 150 m thick of predominantly clastic strata within the Atima, which they correlated with the Mochito shale. In the Agalteca quadrangle (4 in Fig. 1), Emmet (1983a,b) also subdivided the Atima into upper and lower intervals separated by a shaly unit. It is not known if Emmet's un-named shale correlates with the Mochito shale, but it is

CRETACEOUS CARBONATE BIOSTRATIGRAPHY AND ENVIRONMENTS IN HONDURAS possible to infer that at least one major shale break in carbonate deposition is relatively widespread in the Atima Formation of central Honduras. This shale interval represents a regressive depositional phase, which contrasts with a widespread transgressive marine shale break between mid-Cretaceous carbonates in northern Mexico and the U.S. Gulf Coast (Scott et al., 1988). In the Montafias de Col6n area no Mochito shale-equivalent has been identified (Rogers, 1995). For the present study, the upper Atima Formation was sampled in the Montafias de Col6n in a traverse along the Rfo Sutawala that drains a prominent valley transecting the folded and faulted limestone mountains approximately perpendicular to stratigraphic and structural strike (Fig. 2). Along this traverse the strata dip southeastward 20 to 65 degrees and strike generally northeast-southwest. Brownish-gray limestone is found near the confluence of the Rfo Sutawala with the Rfo Patuca, in the Sutawala channel. Several kilometers upstream, and about 100 m higher topographically, a section of 54.8 m of the upper part of the Atima was measured and sampled bed by bed at the Tirisne Cliffs exposure, which is 4.5 km east of the junction of Sutwala with Rfo Patuca directly south of the Sutawala Valley trail in the Confluencia Rfos Patuca y Wamp6 quadrangle (Fig. 1, quadr. 1; 16PGM253530; Fig. 2, Table 1). Farther up the Sutawala valley from this measured section, shaly strata of the 'Krausirpi beds' are exposed, apparently in sedimentary contact overlying the upper Atima (Rogers, 1994, 1995). Additional collections were made northeast of Rfo Wamp6 in the Krausirpi and Wampusirpi quadrangles (Fig. 1, quadr. 2, 3). The base of the Yojoa Group is not exposed in the Montafias de Col6n. However, wherever the basal contact can be seen, the limestone overlies siliciclastic strata now generally assigned to the Honduras Group (Ritchie and Finch, 1985; Finch and Ritchie, 1990; Donnelly et al., 1990). The Honduras Group includes: (1) strata mapped as E1 Plan Formation near Tegucigalpa (Carpenter, 1954), (2) unnamed siliciclastic beds (Simonson, 1977, 1981), 3) strata formerly mapped on the Chortfs block as Todos Santos Formation (Finch, 1985; Ritchie and Finch, 1985; Emmet et al., 1992; Rogers, 1995), and (4) a thick succession of dark marine shale, marine and non-marine sandstone and conglomerate designated the Agua Frfa Formation in eastern and southeastern Honduras. The Agua Frfa Formation was named by Ritchie and Finch (1985) after a long section exposed near Danlf, which was first described by Roberts and Irving (1957). Agua Frfa strata have been widely mapped in eastern Honduras (Kozuch, 1989, 1991; Gordon, 1992; Finch and Ritchie, 1990; Weiland

155

et al., 1992; Rogers, 1994, 1995; Mills and Barton, 1996). Ammonites from marine portions of the Agua Frfa indicate a Middle Jurassic age (Ritchie and Finch, 1985; Gordon and Young, 1993). The Honduras Group underlies Lower to middle Cretaceous carbonates of the Yojoa Group with no detected unconformity or in fault contact. If there is no hiatus in deposition between the two groups, then deposition of the upper Honduras strata continued into the Early Cretaceous. However, in several areas, including the Rfo Wamp6 area, strata of the Agua Frfa have undergone a weak dynamic metamorphism (Kozuch, 1989; Gordon, 1990; Rogers, 1994, 1995) that did not affect the Yojoa Group limestone, leaving open the possibility that a significant hiatus occurred between deposition of the Honduras Group and the Yojoa Group. At the present time we do not know if Honduras Group deposition continued into the Early Cretaceous. In west-central Honduras carbonate strata of the Atima Formation are overlain, apparently gradationally, by red terrigenous clastic strata of the Valle de Angeles Group, named by Carpenter (1954) for exposures between Tegucigalpa and San Juancito (Fig. 1). In the area west and south of Lake Yojoa (Fig. 1) the Valle de Angeles redbeds are divided into lower and upper intervals by the presence of a prominent limestone unit, the Jaitique Formation (Finch, 1981). Somewhat to the east of Lake Yojoa and north of Tegucigalpa, the Esqufas Formation (Home et al., 1974) divides the Valle de Angeles. The Jaitique Formation includes two units, an unnamed cliff-forming limestone member, overlain by a thin section of distinctive petroliferous limestone designated the Guare Member (Finch, 1981). The lower member is about 100-150 m thick, comprised of thick-bedded shelfal limestone, well-dated paleontologically as Cenomanian. No unconformity was seen in the field at the base of the Jaitique, and paleomagnetic data suggest that the contact between the basal Jaitique and the underlying redbeds of the lower Valle de Angeles Group is conformable (W.A. Gose, in Finch, 1981). The Guare is about 10 m thick, consisting of thin- to medium-bedded, flaggy weathering, oil-stained, laminated, dark-gray to black limestone with black shale interbeds. The Guare is in turn overlain by laminated gypsum that grades upwards into fine-grained red clastic strata of the upper Valle de Angeles Group (Finch, 1981). Farther east, in central Honduras near the village Esqufas (Fig. 1) marly and argillaceous limestone of the Esqufas Formation (Weaver, 1942; Atwood, 1972; Home et al., 1974; Finch, 1981) divides the redbeds. Like the Jaitique Formation, the Esqufas apparently is in conformable contact with the enclosing redbeds (Home et al., 1974). The age of the unit is not well defined, paleontologically,

156

R.W. S C O T T and R.C. F I N C H

Table 1 Age-diagnostic taxa in samples from the Tirisne Cliffs measured section, Honduras, along cliffs directly south of the Sutawala valley trail and about 5 km east-southeast of the Rfo Patuca Field No.: Cum. thickn. (m):

Barkerina barkerensis Cuneolina walteri Globigerina delrioensis Globigerina planispira? Globochaeta alpina Lenticulina sp. Heterohelix globulosa Nezzazata simplex Nodosaria sp. Praeg lob igerina delrioensis Pseudocyclammina hebergi Radiolaria Sponge spicules

Micritosphaera ovalis Pithonella ovalis Pithonella sphaerica Saccomma sp.

T1 0-1.5

T2 3.6

T3 3.9

T4 4.5

T5 5.4

T6 6.3

T7 7.9

T8 8.9

T9 9.5

T10 10.0

R

R?

Tll 10.6

Barkerina barkerensis Cuneolina walteri Globigerina delrioensis Globigerina planispira? Globochaeta alpina Lenticulina sp. Heterohelix globulosa Nezzazata simplex Nodosaria sp. Praeglobigerina delrioensis Pseudocyclammina hebergi Radiolaria Sponge spicules

Micritosphaera ovalis Pithonella ovalis Pithonella sphaerica Polystrata alba Saccomma sp.

T13 T14 1 6 . 1 17.8

R? R? R?

R

R

R

R?

R?

R R

R

F

R

R R?

R

Oc

F

R F

F

R?

R? R?

F

F

R

R

T20 29.1

R

R

R R F

R

R

R

R

R

R

F

R R

R R R

F

R

R

R A

R

Oc

Oc

R R

R

R

R R

T26 44.8

Indet. calc. algae Indet. caprinids Field No." Cum. thickn. (m)"

T12 13.4

T15 20.6

R

T16 22.0

T17 22.4

T18 24.3

T19 27.8

R

R?

R? R?

T22 33.4

R?

R R

T23 35.7

T24 39.9

T25 41.8

R?

R?

R?

R

R

R

T21 31.8

R

R

R

R

T28 52.1

T29 54.8

R

R

F

R

R

R

R

R R?

R

T27 50.0

R

F

R

R F F

F

Oc

R?

R?

R

R

R

R

R R

R

R

R

R

R

R? R

R

Indet. calc. algae Indet. caprinids Indet. radiolitids?

R R

R?

R

R Oc

9

Long. 84~ lat. 14o 56 ! 35 I! N. Collected by T. Weiland, measured from lowest bed exposed at west edge of cliff face. Relative abundance scheme: R = rare, F = few, Oc = occasional, A -- abundant.

but a Cenomanian-Turonian age is suggested, and its paleopole position indicates that the Esqufas is somewhat younger than the well-dated Cenomanian Jaitique Formation (Gose and Finch, 1992) Although the Jaitique and Esqufas formations differ in lithology and somewhat in age, where present, each conveniently divides the thick Valle de Angeles Group into upper and lower redbed intervals, and provide some constraint on the age of the lower redbeds. The lower Valle de Angeles redbeds lie above the paleontologically well-dated upper Atima

Formation of mainly Albian age, and below the Jaitique of Cenomanian age or the Esqufas of upper Cenomanian or Turonian age. The age of the lower Valle de Angeles redbeds are, therefore constrained to upper Albian to Lower Cenomanian. Thus, in western and central Honduras, Yojoa carbonate deposition appears to have ceased toward the close of the Albian and to have been superseded by redbed clastic deposition by early Cenomanian time. In west-central Honduras the upper contact of the Valle de Angeles Group is an angular unconformity,

CRETACEOUS CARBONATE BIOSTRATIGRAPHY AND ENVIRONMENTS IN HONDURAS with the redbeds overlain by middle Tertiary volcanic rocks of the Matagalpa Formation or by the Miocene-Pliocene Padre Miguel Group (Williams and McBirney, 1969; Everett, 1970; Finch, 1972, 1981; Emmet, 1983b). It is not known if redbed sedimentation continued into the early Tertiary. Neither the Jaitique nor the Esqufas Formation has been found within the Valle de Angeles Group in the Rfo Wampfi-R/o Patuca area (Weiland et al., 1992; Rogers, 1994, 1995). Instead, in the Montafias de Col6n region of easternmost Honduras, the upper Albian Atima Formation is overlain apparently conformably by non-red, olive tan shale and silty, shallow marine strata. These strata were designated the 'Krausirpi beds' by Rogers (1994, 1995), who reported the unit to include gray and tan shale, arkosic sandstone, graywacke, and minor conglomerate. Rare wood fragments were observed in clastic beds. However, the shale and sandstone beds are calcareous, and thin limestone beds occur within the unit. In thin section one sample is a silty planktic foram lime mudstone. A sample collected from the Krausirpi beds by Finch and Weiland contained a latest Albian to Early Cenomanian biota. At the village of Krausirpi (Fig. 2), Rogers found an erosional surface developed on top of the Krausirpi beds with the Valle de Angeles redbeds overlying them in a slightly angular unconformity. Where the Krausirpi beds are missing, Valle de Angeles redbeds directly and unconformably overlie the Atima (Rogers, 1995). South of Cerro Wampfi (Fig. 2) karstic features are developed at the top of the Atima (Rogers, 1995). Rogers suspects that the Atima was subaerially exposed prior to deposition of the Valle de Angeles in this region (R.D. Rogers, pers. commun., 1996). Thus, in the Montafias de Col6n region, marine deposition continued into the Cenomanian, and deposition of the Valle de Angeles did not commence until latest Cretaceous. Although Rogers (1995) noted that it is "possible that the Krausirpi beds are a local unit of the Yojoa Group", he concluded that they "should not be correlated with other mapped units in Honduras". However, we feel that, in spite of their local nature, it is appropriate to include the Krausirpi beds in the Yojoa Group as an informal member because of their marine character, the absence of redbeds, their conformable contact with the Atima, and their unconformable contact with the Valle de Angeles. Within the Valle de Angeles Group throughout Honduras, conglomerates of various compositions form a significant portion of the unit. In west-central Honduras the lower Valle de Angeles section is more conglomeratic than the upper, with quartz pebble conglomerate beds being prominent ledge-formers in outcrop. However, the most distinctive conglomerate units consist of limestone pebble- to boulder-con-

157

glomerate, with the clasts embedded within a redbed matrix. These limestone conglomerates, commonly designated the Ilama Formation (Mills et al., 1967; Southernwood, 1986; Mills and Barton, 1996) are found throughout Honduras. Available paleontological evidence indicates that the limestone clasts were derived from the Atima Formation and the conglomerates certainly indicate widespread erosion of Yojoa Group carbonates during Valle de Angeles time. However, there is no good evidence that limestone conglomerate production was coeval across Honduras, or that the various conglomerate exposures should all be assigned to one formation. Indeed, Southernwood's stratigraphic correlation chart (Southernwood, 1986, plate 4) indicates a wide variety of stratigraphic positions for the conglomerates of the 'Ilama Formation', as would be expected for such coarse, fluvial deposits, which possibly were deposited as alluvial fans shed from fault blocks. 'Ilama-type' limestone conglomerate deposits occur in the valley of the Rio Patuca, along the northwest flank of the Montafias de Col6n, within redbeds assigned to the Valle de Angeles Group (Rogers, 1994, 1995; Mills and Barton, 1996). Limestone clasts in these conglomerates sampled by Finch and Weiland yielded Cretaceous microfossils and megafossils that suggest that most clasts were derived from the Atima Formation. A single sample contains a dasyclad alga known only in Cenomanian rocks elsewhere in the Tethys suggesting that Cenomanian limestone was a local source in the Montafias de Col6n, although no in-situ outcrops are mapped. The Krausirpi beds contain local limestone beds that may be of Cenomanian age and could have been a source. Rogers (1994, 1995) has demonstrated that the volcanic units dated by Weiland et al. (1992; K Ar dates from unaltered plagioclase separations) at 80-70 Ma are interbedded with the Valle de Angeles redbeds. Thus, the Valle de Angeles redbed sedimentation continued at least into the latest Cretaceous in easternmost Honduras, but at present there is, as in west-central Honduras, no evidence to show that redbed deposition continued as late as Tertiary time.

Biostratigraphy The Atima Formation in the Montafias de Col6n region is as young as upper Albian. The age of the 55-m-thick section of the uppermost Atima Formation at Tirisne Cliffs section is upper Albian based on the co-occurrence of Cuneolina walteri Cushman and Applin (Fig. 4A-C), Pseudocyclammina hedbergi Maync (Fig. 4D,E), and Praeglobotruncana delrioensis (Plummer). The first two species occur in middle and upper Albian carbonates in northwestern Mexico (Scott and Gonzales-Leon, 1991) and elsewhere in the Gulf Coast (Conkin and Conkin,

158

R.W. SCOTT and R.C. FINCH

CRETACEOUS CARBONATE BIOSTRATIGRAPHY AND ENVIRONMENTS IN HONDURAS 1958). The third species, a planktic foraminifer, ranges from late Albian to late Cenomanian (Bolli et al., 1985). Samples from the limestone section in the Rfo Sutawala stratigraphically below the Tirisne Cliffs section yield Pseudonummoloculina [Nummoloculina] heimi (Bonet) (Fig. 4F), which ranges through Albian and lower Cenomanian rocks in the Gulf Coast region (Scott and Gonzales-Leon, 1991). The genetic reassignment of this species was made by Hottinger et al. (1989) because the apertural structure differs from the Neogene genus Nummoloculina. From west-central Honduras we can demonstrate the presence of the key benthic foraminifer Orbitolina (Mesorbitolina) subconcava Leymerie (Fig. 5D,E) in the Atima Formation in several places, which probably was the more advanced type reported by Lozej (1976). This species ranges from the late Aptian to the late Albian and is reported in lower Albian strata of Texas and Mexico (Schroeder and Neumann, 1985). This species occurs in the uppermost Atima a few meters below its contact with the Valle de Angeles Formation southwest of Lake Yojoa (in the Montafia de Santa B~irbara, Table 2). This suggests that the upper Atima is not younger than upper Albian. The species also occurs in a limestone clast within a conglomerate in the Valle de Angeles along the Rfo Patuca (Fig. 2). Other benthic foraminifers support the lower to upper Albian age of the upper Atima limestone. Coskinolinoides sp. cf. C. texanus Keijzer is found southwest and west of E1 Mochito near Lake Yojoa (in the San Pedro Zacapa and the Santa Bfirbara quadrangles, Table 2). This species occurs in the middle to lower-upper Albian Fredericksburg Group in central Texas and unnamed species of this genus range up into the upper Albian part of the Washita Group (Coogan, 1977). Praechrysalidina infracretacea Luperto Sinni, which we found in the Atima with Orbitolina texana (Roemer) and Cuneolina walteri southwest of Lake Yojoa (in the Santa Bfirbara quadrangle), is a Hauterivian-Albian species in the Middle East (Banner et al., 1991). Another Albian taxon in the upper Atima in this area is Coskinolinella sp., which is well illustrated by Schroeder and Neumann (1985). Outcrop grab samples from the Olancho district (Fig. 1, in the area indicated by the name Olancho) collected by M.B. Gordon (pers. commun.,

159

1990) contain key taxa of rudists and foraminifers that confirm the age of the Atima to range from Barremian-lower Aptian to upper Albian. Poorly preserved rudist specimens from a caprinid packstone in the upper 50 m of the Atima Formation are close to either Kimbleia sp. (late Albian), or Caprinula sp. (Albian-Turonian) (Table 2). Other samples of the Atima contain the Barremian-early Aptian foraminifer Choffatella decipiens Schlumberger with Pseudocyclammina hedbergi, the bivalve Chondrodonta sp., and the alga Lithocodium aggregatum Elliott. All of these taxa are common in theGulf of Mexico part of the Caribbean Province. The post-Atima Krausirpi beds exposed in the bottom of Rfo Sutawala are represented by two samples. One yielded late Albian-early Cenomanian palynomorphs identified by R.W. Aurisano (written commun., 1985): Reticulisporitesjardinus, Xenascus ceratioides, Dinopterygium sp., Diconodinium sp., Oligosphaeridium sp., Classopollis sp., Coronifera sp., Scriniodinium sp., Trichodinium sp., and tricolpate pollen. A thin section of a second sample contains Globigerinoides cushmani and Heterohelix globulosa, which together indicate a latest Albian to early Cenomanian age for the Krausirpi beds, showing that shallow marine sedimentation continued into the Cenomanian in the eastern part of the Chortfs block. Limestone conglomerate in the Valle de Angeles Group exposed along the Rfo Patuca in the Krausirpi and Wampusirpi quadrangles also contains late Albian fossils (Table 2). Important taxa are Orbitolina subconcava, Cuneolina walteri, Pseudonummoloculina [Nummoloculina] heimi, Pseudocyclammina hedbergi, Favusella [Globigerina] washitensis (Carsey), and Globigerinoides cushmani, the caprinid Mexicaprina sp., and calcareous algae, Polystrata alba (Pfender) and Parachaetetes texana Johnson (Fig. 5A). Evidently these cobbles were eroded from the Atima Formation At Boca Wampfi a conglomerate with a reddish brown sandy matrix and cobbles of red siltstone and well rounded, light-gray limestone was identified in the Valle de Angeles Group, although the limestone cobbles are lighter colored than most of the Atima Formation and they contain miliolids, textulariids, and bivalves. A limestone clast from this conglomerate yields the calcareous dasyclad alga, Dissocladella undulata (Raineri) (Fig. 4G), which is

Fig. 4. (A-G) Photomicrographs of key fossils found in the Atima Formation in eastern Honduras and the Jaitique Limestone in central Honduras. (A-C) Cuneolina walteri Cushman and Applin (1947); (A) proloculus, sample A-4, 75 x; (B) transverse section, sample A-4, 75• (C) longitudinal section, sample T-29, 47x. (D-E) Pseudocyclammina hedbergi Maync (1953); (D) axial view, sample T-7, 30x; (E) longitudinal view, sample T-7, 30x. (F) Pseudonummoloculina [Nummoloculina] heimi (Bonet, 1956), emend. Conkin and Conkin (1958), generic reassignment by Hottinger et al. (1989), sample A-4, 75x. This specimen has flatter chambers than is typical of P. heimi. (G) Dissocladella undulata (Raineri, 1922; Pia, 1936), sample A-11, Valle de Angeles Group, 55x. (H) Biconcava n. sp., Jaitique Limestone, sample FTC-3, 60•

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R.W. SCOTT and R.C. FINCH

CRETACEOUS CARBONATE BIOSTRATIGRAPHY AND ENVIRONMENTS IN HONDURAS

161

Table 2 Location and description of key samples collected in Honduras by R.C. Finch during several field seasons (locations given using the Universal Transverse Mercator Grid system)

Krausirpi quadrangle P-1 Valle de Angeles Gp. at 16PGM257617, Krautara on Rfo Patuca; cobble conglomerate of light-gray limestone and lesser amounts of volcaniclastics, quartz, and quartzite of silicified siltstone in a matrix of reddish sandstone. Fossils in limestone clasts: Orbitolina subconcava, Nummoloculina heimi, Cuneolina walteri, Pseudocyclammina hedbergi, Parachatetes texana, Lithocodium aggregatum. P-2 Valle de Angeles Gp. at 16PGM346681, Pimienta on Rfo Patuca; 'Ilama' limestone conglomerate as above. Fossils in limestone clasts: Mexicaprina sp., Lithocodium aggregatum. Wampusirpi quadrangle P-4 Valle de Angeles Gp. at 16PGM523723, Walpatanta on Rfo Patuca; 'Ilama' limestone conglomerate as above. Fossils in limestone clasts: Globigerina delrioensis, Favusella washitensis, Globigerellinoides cushmani, Parachaetetes texana, Polystrata alba, Lithocodium aggregatum. Confluencia Rfos Patuca y Wampft quadrangle A series Atima Fm. collected by core; all are limestone except A-9 which is shale of the Krausirpi beds and A-11 which is conglomerate in Valle de Angeles Gp.; A-l: 16PGM221544; A-2: 16PGM221543; A-3: 16PGM223540; A-4: 16PGM234539; A-6: 16PGM227540; A-7: 16PGM231542; A-8: 16PGM247533; A-9: 16PGM262529; A-10: 16PGM279520; A-11: 16PGMI74547. T series Atima Fm. collected in measured section at Tirisne Cliffs by T. Weiland; T-1 (base) through T-29 (top) at 16PGM253530, 84054, 19"W, 14~ HA-locality in Rfo Sutawala estimated at 16PGM289512. Santa B6rbara quadr. (west side of Lake Yojoa in Fig. 1) FSB-3 Uppermost Atima Fm. no more than a few tens of meters below contact with Valle de Angeles Fm. at 16PCM711409. Orbitolina subconcava. FSB-4 Uppermost Atima Fm., no more than a few tens of meters below contact with Valle de Angeles Fm. in a quarry near 16PCM844433. Coskinolinella sp. FSB-46 Upper Atima Fm., very probably the upper part on top of Montafia Santa B~irbara near 16PCM788454. Coskinolinella texanus, Praechrysalidina infracretacea. FSB-47 Upper Atima Fm., probably the upper part, from near 16PCM828419 in the Mochito graben. Coskinolinella texanus. FSB-100 Atima Fm., low on the southwest flank of Montafia Santa B~irbara at about 16PCM717535 apparently above the 'Mochito shale'. Orbitoliina texana, Praechrysalidina infracretacea. FM-21 Upper Atima Fm., possibly lower part from inside the Mochito Mine at level 1350, cross-cut 9444E. Praechrysalidina infracretacea (16PCM9394230). FM-33 Upper Atima Fm., lower part near contact with 'Mochito shale' inside Mochito Mine at level 850, cross-cut 992. Colomiella coahuilensis (16PCM939423). Taulab# quadr. (southeast of Lake Yojoa in Fig. 1) FTC-3 Uppermost part of lower, unnamed member of Jaitique Fm. directly below basal contact of Guare Mbr. at 16PCM998218 near Carrizal-La Mision. See fig. 4 in Finch (1981) for stratigraphic position. Specimens of Biconcava n. sp. in thin section. San Pedro Zacapa quadr. (southwest of Lake Yojoa in Fig. 1) FZ-28, 32 Uppermost Atima Fm. near 16PCM870343; FZ-32 is approximately 50 m above FZ-28. Coskinolinella texanus.

characteristic of the C e n o m a n i a n in the Tethys (Bassoullet et al., 1978). This is the first report of this species in the C a r i b b e a n P r o v i n c e . This l i m e s t o n e clast m a y have b e e n d e r i v e d f r o m one of the C e n o m a n i a n l i m e s t o n e units within the Valle de A n g e l e s , or f r o m a l i m e s t o n e b e d within the K r a u s i r pi beds. If this is the case, it is the first t e n u o u s e v i d e n c e that C e n o m a n i a n l i m e s t o n e d e p o s i t i o n m a y h a v e e x t e n d e d this far east. To date, no l i m e s t o n e unit has b e e n m a p p e d within the Valle de A n g e l e s r e d b e d s in the W a m p d - P a t u c a r e g i o n ( W e i l a n d et al., 1992; R o g e r s , 1995).

T h e rudist M e x i c a p r i n a sp. is r e p o r t e d f r o m H o n duras for the first time. This g e n u s is charact eri s tic of u p p e r A l b i a n rocks in M e x i c o and the U.S. T h e s p e c i m e n was f o u n d in a c o n g l o m e r a t e within the Valle de A n g e l e s G r o u p and is c o m p l e t e l y recrystallized so that internal structures are not visible (Fig. 5F). This s p e c i m e n has the distinctive ridges at the corners similar to M e x i c a p r i n a sp. illustrated by C o o g a n (1977, pl. 17, figs. 8), w h i c h is f r o m the E1 A b r a F o r m a t i o n at Taninul quarry in M e x i c o . T h e H o n d u r a n s p e c i m e n , h o w e v e r , is a b o u t 10 m m across and the M e x i c a n s p e c i m e n is a b o u t 23 m m

Fig. 5. Photomicrographs of fossils from limestone clasts in conglomerates of the Valle des Angeles Group (A, D, E, F) in eastern Honduras and the Jaitique Limestone (B, C) in west-central Honduras. (A) Parachaetetes texana Johnson, sample P-4, 55• (B, C) Biconcava n. sp, sample FTC-3, sagittal and axial sections, 151 x. (D, E) Orbitolina (Mesorbitolina) subconcava Leymerie, sample P-1, 47 x. (F) Mexicaprina sp., sample P-2, transverse section, 7.4 x.

162 in longest diameter. A similar species, Mexicaprina minuta Coogan, is 8 to 11 mm across, but it does not have the large ridges. The Honduran specimen may be a new species of this very specialized genus. Coogan (1973) described the genus from the E1Abra Formation and from the Stuart City Formation in the subsurface of Texas (Coogan, 1977, pl. 17, fig. 5). The age of the Stuart City is middle to lowerupper Albian by its foraminifers and rudists (Scott, 1990). The age of the E1 Abra is less clear; Coogan (1973, 1977) placed it in the Cenomanian based on the radiolitid rudists, Pecten roemeri and Parkeria sphaerica, and the absence of characteristic Albian taxa. The age of the oldest radiolitids is indefinite; Pecten roemeri is found in lower Cenomanian rocks of north Texas, and Parkeria sphaerica is originally known from the uppermost Albian beds in England and its Cenomanian attribution comes from its occurrence in the E1 Abra (Dieni and Turn~ek, 1979). Recently, Mexicaprina minuta and Mexicaprina cornuta have been found with the late Albian rudists Kimbleia and Caprinuloidea in northern Mexico (Alba and L6pez-Casillas, 1993). Therefore, the age significance of Mexicaprina spp. is late Albian. The Jaitique Formation has yielded specimens of the foraminifera Biconcava n. sp. (Fig. 4H, Fig. 5B,C), which is reported from the Caribbean Province for the first time. The sample was collected southeast of Lake Yojoa in the Taulab6 area from the uppermost part of the lower, unnamed member directly below basal contact of Guare Member (fig. 4 in Finch, 1981). These specimens possess the major features of the genus as defined by Hamoui and Saint-Marc (1970): the planispiral test is slightly involute and expands gradually; the proloculus is simple, globular; chamber cross-section is lunate but the periphery of these specimens is more convex than in the genotype, Biconcava bentori Hamoui and Saint-Marc (1970). The wall of both species is microgranular calcite. The aperture appears to be a simple pore in the septal face (Fig. 5B, thirdlast septa in final whorl). B. bentori ranges through the middle and upper Cenomanian in its type area of Lebanon and Israel, but similar specimens have been reported in upper Albian and Senonian strata (Schroeder and Neumann, 1985), so the range of the genus is yet to be defined precisely.

PALEOENVIRoNMENTS

The upper Atima Formation exposed near the mouth of the Rfo Sutawala records a transgressive succession. The beds dip southeast and the samples were collected from outcrops in the valley floor. Top: rudist-peloid packstone; rudist packstone-wackestone; quartz-peloid packstone; echi-

R.W. SCOTT and R.C. FINCH noid wackestone with pycnodont oysters; red shale with plant debris (probably not Atima); silty peloidostracode packstone. Farther upstream in the Sutawala Valley, at Tirisne Cliffs, 55 m of upper Atima Formation were measured and closely sampled. This section records a shoaling upwards facies succession (Fig. 6). Two major microfacies were collected: a lower peloidforam-spicule wackestone/packstone and an upper peloid-foram-bivalve wackestone/grainstone. These facies indicate an environmental change from the middle shelf to the inner shelf. Overall, taxonomic diversity decreases slightly near the top of the section where carbonate sands were more common. The upwards shoaling is indicated by the decrease in number of planktic taxa, the decrease in sponge spicules, and the replacement of Lenticulina sp. and Nodosaria sp. by shallow-water benthic foraminifers. Bottom waters were well oxygenated and water energy increased up-section where grainstone is more common. The post-Atima Krausirpi beds are poorly exposed. This unit represents an influx of terrigenous sediments into a shallow marine environment terminating the Atima carbonate platform. Bottom waters may have been poorly oxygenated. The depositional environment may have been prodeltaic (Rogers, 1994, 1995). The limestone conglomerates within the Valle de Angeles Group along the Rfo Patuca in the Krausirpi and Wampusirpi quadrangles were deposited in non-marine to nearshore environments. The limestone clasts were derived mainly from the Atima Formation, which was deposited in a shallowwater, moderate- to high-energy environment with rudists. The common facies are rudist packstone, intraclast-peloid grainstone and rudist-peloid grainstone. Some clasts represent quiet water lagoonal or shelf environments with foram wackestone. One clast contains radiolarian-planktic foram wackestone in contact with peloid grainstone turbidite. So the cobbles represent a suite of environments ranging from the shelf margin to the slope. A major shift in depositional regime from carbonate shelf to terrigenous shelf, possibly prodeltaic, in eastern Honduras is recorded by the termination of Atima deposition by an influx of terrigenous sediments of the lower Cenomanian Krausirpi beds. Water depths were up to approximately 50 m to accommodate the planktic foraminifers and dinoflagellates. Deposition of the Krausirpi beds was followed by a period of exposure, during which an erosional unconformity developed that cut out part of the Krausirpi beds and, locally, exposed the top of the Atima Formation. This exposure event on the eastern part of the Chortfs block may correspond with one of several middle Cenomanian sequence boundaries

CRETACEOUS CARBONATE BIOSTRATIGRAPHY AND ENVIRONMENTS IN HONDURAS M 55

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Fig. 6. Paleoenvironmental interpretation of the Atima Formation at the Tirisne Cliffs section, Sutwala valley, Rio Wampd, Honduras. Relative abundance ranges from absent (0), to rare, few, occasional, common, and abundant (A). (Haq et al., 1988); the unconformity at the lowermiddle Cenomanian boundary is widespread in the U.S. Gulf Coast and Arabian shelf and platform sections (Scott et al., 1988). Deposition of redbeds of the Valle de Angeles Group buried this exposure surface, which, locally, overlies karstic Atima (Rogers, 1995). In west-central Honduras a similar, but gradual environmental shift deposited conglomeratic redbeds with Atima limestone clasts prior to deposition of the Jaitique and Esqufas formations. However, in the area south and west of Lake Yojoa some occurrences of limestone conglomerate containing abundant light-gray limestone clasts that do not look like typical Atima limestone were mapped by Finch (1972, 1985) as within the upper Valle de Angeles. So a second, younger local erosional event may be recorded in this area.

SUMMARY New collections from Cretaceous carbonate strata in eastern Honduras yield taxa new to the area that confirm the upper Albian age of the upper part of the Atima Formation. Some of these taxa have been reported to the generic level, but not illustrated nor identified to species: Cuneolina walteri (Fig. 4A-C), Pseudocyclammina hedbergi (Fig. 4D,E), and Pseudonummoloculina [Nummoloculina] heimi. Some have never before been re-

ported in Honduras: Mexicaprina sp., Kimbleia sp. (late Albian), or Caprinula sp. (Albian-Turonian), and Praeglobotruncana delrioensis. The presence of Choffatella decipiens with Pseudocyclammina hedbergi on the western margin of the Montafias de Col6n indicates that the lowermost part of the Atima crops out there. In west-central Honduras the upper Aptian to upper Albian Orbitolina subconcava is documented for the first time, as is Coskinolinoides sp. cf.

C. texanus, Orbitolina texana, Cuneolina walteri, Coskinolinella, and Coskinolinella sp. The Atima Formation in eastern Honduras is overlain conformably by a marine shale, the Krausirpi beds (Rogers, 1994, 1995), that contain late Albian to early Cenomanian dinoflagellates and planktic foraminifers. The limestone conglomerates in the Valle de Angeles Group were derived mainly from the Atima; however, some may have been derived from a Cenomanian limestone unit, as suggested by the presence of the dasyclad alga Dissocladella undulata, which is reported here from the Caribbean Province for the first time. Accepting the placement of Chortfs near the Guerrero block on the Pacific side of Mexico during the mid-Jurassic (Anderson and Schmidt, 1983; Dengo, 1985; Pindell and Barrett, 1990), the biota reported here confirm that by Aptian and Albian time, the Chortfs block had moved into biogeographic connection with the fauna of the Caribbean

164

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P r o v i n c e . A n e a s t w a r d c o m p o n e n t o f t r a n s l a t i o n is i m p l i e d , likely s o u t h e a s t w a r d a l o n g a structure like the A c a p u l c o - G u a t e m a l a

megashear of Anderson

and S c h m i d t (1983).

REFERENCES

Alba, J.A. and L6pez-Casillas, 1993. Mid-Cretaceous rudists (Bivalvia-Hippuritacea) from Durango, north-central Mexico. Proc. 3rd Int. Conf. Rudists, UNAM, Inst. de Geologfa, pp. 2-3. Anderson, T.H. and Schmidt, V.A., 1983. The evolution of Middle America and the Gulf of Mexico-Caribbean Sea region during Mesozoic time. Geol. Soc. Am. Bull. 94: 941-966. Atwood, M.G., 1972. Geology of the Minas de Oro Quadrangle, Honduras, Central America. Unpubl. M.A. thesis, Wesleyan University, Middletown, CT, 88 p. Azema, J., Biju-Duval, B., Bizon, J.J, Carfantan, J.C., Masclr, A.J. and Tardy, M., 1985. Le Honduras (Am6rique centrale nucl6aire) et le bloc d'Oaxaxa (Sud du Mexique): deux ensembles comparables du continent Nord-Am6ricain s6par6s par le jeu d6crochant s6estre des failles du syst~me Polochic-Motagua. Symp. Geodynamique des Caribes, Paris, 5-8 Fevrier 1985. Editions Technipp, Paris, pp. 427-438. Banner, ET., Simmons, M.D. and J.E. Whittaker, 1991. The Mesozoic Chrysalidinidae (Foraminifera, Textulariacea) of the Middle East: the Redmond (Aramco) taxa and their relatives. Bull. Br. Mus. Nat. Hist. (Geol.), 47: 101-152. Bassoullet, J.P., Bernier, P., Conrad, M.A., Deloffre, R. and Jaffrezo, M., 1978. Les algues dasycladales du Jurassique et du Cr6tac6. Geobios, M6m. Sp6c., 2, 330 pp., 40 pl. Bolli, H.M., Saunders, J.B. and Perch-Nielsen, K., 1985. Plankton Stratigraphy. Cambridge Univ. Press, London, 1032 pp. Bonet, E, 1956. Zonifacaci6n microfaunistica de las calizas cret~icicas del este de M6xico. Asoc. Mex. Ge61. Petrol. Bol., 8: 389-488. Burkart, Burke, 1994. Northern Central America. In: S.K. Donvan and T.A. Jackson (Editors), Caribbean Geology: An Introduction. U.W.I. Publisher's Association, Kingston, Jamaica, pp. 265-284. Carpenter, R.H., 1954. Geology and ore deposits of the Rosario mining district and the San Juancito Mountains, Honduras, Central America. Geol. Soc. Am. Bull., 65: 23-38. Conkin, J.E. and Conkin, B.M., 1958. Revision of the genus Nummoloculina and emendation of Nummoloculina heimi Bonet. Micropaleontology, 4: 149-150. Coogan, A.H., 1973. Nuevos rudistas del Albian y Cenomaniano de Mexic6 y del sur de Texas. Rev. Inst. Mex. Pet. 5:51-82. Coogan, A.H., 1977. Early and middle Cretaceous Hippuritacea (rudists) of the Gulf Coast. In: D.G. Bebout and R.G. Loucks (Editors), Cretaceous Carbonates of Texas and Mexico. Bur. Econ. Geol., Univ. Texas Austin, Rept. Invest., 89: 32-70. Cushman, J.A. and Applin, E.R., 1947. Two new species of Lower Cretaceous foraminifera from Florida. Cushman Lab. Foraminiferal Res. Contrib., 23: 29-30. Dengo, G., 1985. Mid America: tectonic setting for the Pacific margin from southern Mexico to northwestern Colombia. In: A.E.M. Nairn and EG. Stehli (Editors), The Ocean Basins and Margins. Plenum Press, New York, 7, pp. 123-180. Dieni, I. and Turngek, D., 1979. Parkeria sphaerica Carter, 1877 (Hydrozoan) in the Vraconian (Lower Cretaceous) of Orosei (Sardinia). Boll. Soc. Paleontol. Ital., 18: 200-206. Donnelly, T.W., Horne, G.S., Finch, R.C. and L6pez-Ramos, E., 1990. Northern Central America: The Maya and Chortfs blocks. In: G. Dengo and J.E. Case (Editors), The Caribbean

Region. The Geology of North America, Vol. H, Geological Society of America, pp. 37-76. Emmet, P.A., 1983a. Mapa geol6gico de Honduras, cuadningulo de Agalteca, escala 1:50.000. Tegucigalpa, D.C., Instituto Geognifico Nacional, 1 sheet. Emmet, P.A., 1983b. Geology of the Agalteca Quadrangle, Honduras, Central America. Unpubl. MS thesis, University of Texas at Austin, 210 pp. Emmet, P.A., White, R.J. and Curry, R.P., 1992. Measured stratigraphic sections, biostratigraphy and sequence stratigraphy of Mesozoic strata in the Agalteca Quadrangle, Honduras. Geological Society of America, South-Central Section, Abstracts with Programs, p. 10. Everett, J.R., 1970, Geology of the Comayagua quadrangle, Honduras, Central America. Unpubl. PhD. dissertation, University of Texas at Austin, 152 pp. Finch, R.C., 1972. Geology of the San Pedro Zacapa Quadrangle, Honduras, Central America. Unpubl. PhD. dissertation, University of Texas at Austin, 238 pp. Finch, R.C., 1973. Mochito number 1 exploration 1973. Unpubl. report, Rosario Resources Corp., E1 Mochito, Honduras, 28 PP. Finch, R.C., 1981. Mesozoic stratigraphy of central Honduras. Am. Assoc. Pet. Geol., Bull., 65: 1320-1333. Finch, R.C., 1985. Mapa Geol6gico de Honduras, Cuadningulo de Santa B~irbara, escala 1" 50.000. Instituto Geognifico Nacional, Tegucigalpa, D.C., Honduras, 1 sheet. Finch, R.C. and Dengo, G., 1990, NOAM-CARIB plate boundary in Guatemala: a Cretaceous suture zone reactivated as a Neogene transform fault. Geological Society of America Annual Meeting, Field Trip No. 17 Guidebook, 46 pp. Finch, R.C. and Ritchie, A.W., 1990. Mapa Geol6gico de Honduras, Cuadr~ingulo de Danlf, escala 1:50.000. Instituto Geognifico Nacional, Tegucigalpa, D.C., Honduras, 1 sheet. Fourcade, E. and Michaud, E, 1987. L'ouverture de l'Atlantique et son influence sur les peuplements des grands foraminif~res de plates-formes p6ri-oc6aniques au M6sozoique. Geodin. Acta (Paris), 1 (4/5): 247-262. Gallo, J. and Van Wagoner, J.C., 1978. Stratigraphy and facies analysis of Honduras. Exxon Production Research Co., unpubl, special report. Gordon, M.B., 1989a. The Chortfs block is a continental, pre-Mesozoic terrane. In: D.K. Lame and G. Draper (Editors), Transactions of the 12th Caribbean Geological Conference, St. Croix, U.S.V.I. Miami Geological Society, pp. 505-512. Gordon, M.B., 1989b. Mesozoic igneous rocks on the Chortfs block: implications for Caribbean reconstructions (abstr.). Eos, 70: 1342. Gordon, M.B., 1990. Strike-slip faulting and basin formation at the Guayape fault-Valle de Catacamas intersection, Honduras, Central America. Ph.D. dissertation, University of Texas at Austin, 260 pp. Gordon, M.B., 1992. Northern Central America: The Chortfs block. In: G.E.G. Westermann (Editor), Jurassic of the Circum-Pacific Region. World and Regional Geology 3, Cambridge University Press, New York, pp. 93-121. Gordon, M.B. and Gose, W.A., 1989. The Chortfs block: a raft of Mesozoic sediments and Cenozoic volcanics on a solid foundation. Geol. Soc. Am. Abstr. Prog., 21: 12. Gordon, M.B. and Muehlberger, W.R., 1994. Rotation of the Chortfs block causes dextral slip on the Guayape fault. Tectonics, 13: 858-872. Gordon, M.B. and Young, K., 1993. Bathonian and Valanginian fossils from Honduras. In: S. Elmi, C. Mangold and Y. Alm6ras (Editors), 3~me Symposum International: C6phalopodes Actuels et Fossiles, Symposium F. Roman. G6obios, M6m. Sp6c., 15: 175-179.

CRETACEOUS C A R B O N A T E B I O S T R A T I G R A P H Y AND E N V I R O N M E N T S IN H O N D U R A S Gose, W.A., 1985a. Paleomagnetic results from Honduras and their bearing on Caribbean tectonics: Tectonics, 4: 565-585. Gose, W.A., 1985b. Caribbean tectonics from a paleomagnetic perspective. In: EG. Stehli and D. Webb (Editors), The Great American Biotic Interchange. Plenum Press, New York, pp. 285-301. Gose, W.A. and Finch, R.C., 1987. Magnetostratigraphic studies of Cretaceous rocks in Central America. Actas Fac. Ciencias Tierra U.A.N.L. Linares, E1 Cret~icico de M6xico y Am6rica Central, Resumenes, 2, pp. 233-241. Gose, W.A. and Finch, R.C., 1992. Stratigraphic implications of palaeomagnetic data from Honoduras. Geophys. J. Int., 108: 855-864. Hamoui, M. and Saint-Marc, E, 1970. Microfaunes et microfacies du C6nomanien du Proche-Orient. Bull. Cen. Rech. Pau-SNPA, Pau, 4 (2): 257-352. Haq, B.U., Hardenbol, J. and Vail, ER., 1988. Mesozoic and Cenozoic chronostratigrapy and cycles of sea-level change. Soc. Econ. Paleontol. Mineral. Spec. Publ., 42: 71-108. Horne, G.S., Atwood, M.G. and King, A.E, 1974. Stratigraphy, sedimentology and paleoenvironment of Esqufas Formation in Honduras. Am. Assoc. Pet. Geol., Bull., 58: 176-188. Hottinger, L., Drobne, K. and Caus, E., 1989. Late Cretaceous, larger, complex miliolids (Foraminifera) endemic in the Pyrenean faunal province. Facies, 21 : 99-134. Kozuch, M.J., 1989. Mapa Geol6gico de Honduras, Cuadr~ingulo de San Francisco de Becerra, escala 1:50.000. Instituto Geogr~fico Nacional, Tegucigalpa, D.C., 1 sheet. Kozuch, M.J., 1991. Mapa Geol6gico de Honduras, Segunda Edici6n, escala 1:50.000. Instituto Geogr~ifico Nacional, Tegucigalpa, D.C., 3 sheets. Lozej, G.E, 1976. Stratigraphy and petrography of the Mochito limestone, central Honduras (preliminary report). Unpubl. report, Rosario Resources Corp., E1 Mochito, 22 pp. Maync, W., 1953. Pseudocyclammina hedbergi n. sp. from the Urgo-Aptian and Albian of Venezuela. Cushman Found. Foraminiferal Res. Contrib., 4:101. Mills, R.A., 1959. Habr~ petr61eo en Honduras?. Pet. Interam., 17 (5): 39-44. Mills, R.A. and Barton, R., 1996. Geology of the Ahuas area in the Mosquitia Basin of Honduras: preliminary report. Am. Assoc. Pet. Geol., Bull., 80:1627-1640. Mills, R.A. and Hugh, K.E., 1974. Reconnaissance geologic map of Mosquitia region, Honduras and Nicaragua Caribbean coast. Am. Assoc. Pet. Geol., Bull, 58: 189-207. Mills, R.A., Hugh, K.E., Feray, D.E. and Swolfs, H.C., 1967. Mesozoic stratigraphy of Honduras. Am. Assoc. Pet. Geol., Bull., 51:1711-1786. Pia, J., 1936. Calcareous green algae from the Upper Cretaceous

165

of Tripoli (North Africa). J. Paleontol., 10: 3-13. Pindell, J.J. and Barrett, S.E, 1990. Geological evolution of the Caribbean region; a plate tectonic reconstruction. In: G. Dengo and J.E. Case (Editors), The Caribbean Region. The Geology of North America, Vol. H, Geological Society of America, pp. 405-432. Raineri, R., 1922. Alghi sifonee fossili della Libia. Soc. Ital. Sci. Nat., Milano, Atti, 61: 72. Ritchie, A.W. and Finch, R.C., 1985. Widespread Jurassic strata on the Chortfs block of the Caribbean plate. Geol. Soc. Am., Abstr. Prog., 17:700-701. Roberts, R.J. and Irving, E.M., 1957. Mineral deposits of Central America. U.S. Geol. Surv. Bull., 1034, 205 pp. Rogers, R.D., 1994. Preliminary stratigraphy and structure along the Rfo Patuca and Rfo Wampd, La Mosquitia, Honduras. Geol. Soc. Am., Abstr. Prog., 26 (7): A-247. Rogers, R.D., 1995. Geology along the Rfo Patuca and Rfo Wamp6, La Mosquitia, Honduras. Open-file report, Instituto Geogr~ifico Nacional, Tegucigalpa, D.C., 21 pp. Schroeder, R. and Neumann, M., 1985. Les grands foraminif~res du Cr6tac6 moyen de la r6gion M6diterran6nne. Geobios, M6m. Sp6c., 7, 161 pp., 68 pl. Scott, R.W., 1990. Models and stratigraphy of Mid-Cretaceous reef communities, Gulf of Mexico. Soc. Econ. Paleontol. Mineral., Concepts Sedimentol. Paleontol., Vol. 2, 102 pp. Scott, R.W. and Gonzales-Leon, C., 1991. Paleontology and biostratigraphy of Cretaceous rocks, Lampazos area, Sonora, Mexico. Geol. Soc. Am., Spec. Pap., 254:51-67. Scott, R.W., Frost, S.H. and Shaffer, B.L., 1988. Early Cretaceous sea level curves, Gulf Coast and southeastern Arabia. Soc. Econ. Paleontol. Mineral., Special Publ., 42: 275-284. Simonson, B.M., 1977. Geology of the E1 Porvenir quadrangle, Honduras, Central America. Open-file report, Instituto Geogr~fico Nacional, Tegucigalpa, D.C., 84 pp. Simonson, B.M., 1981. Mapa geol6gico de Honduras, cuadrangle de E1 Porvenir, escala 1:50.000. Instituto Geogr~fico Nacional, Tegucigalpa, D.C., 1 sheet. Southernwood, R., 1986. Late Cretaceous limestone clast conglomerates of Honduras. Unpubl. MS thesis, University of Texas at Dallas, 299 pp. Weaver, C.E., 1942. A general summary of the Mesozoic of South America and Central America. Proc. 8th Am. Sci. Congr., Geol. Sci., 4:179-180. Weiland, T.J., Suayah, I.B. and Finch, R.C., 1992. Petrologic, stratigraphic and tectonic significance of Mesozoic volcanic rocks in the Rfo Wampd area, Eastern Honduras. J. S. Am. Earth Sci., 6: 309-325. Williams, H. and McBirney, A.R., 1969. Volcanic history of Honduras. Univ. Calif. Publ. Geol. Sci., 85, 101 pp.