The regional record of Albian oceanic anoxic events at the Apulian Platform Margin (Gargano Promontory, southern Italy)

Revue de micropal´eontologie 50 (2007) 239–251

Original article

The regional record of Albian oceanic anoxic events at the Apulian Platform Margin (Gargano Promontory, southern Italy) L’enregistrement r´egional des e´ v´enements anoxiques de l’Albien sur la marge de la plate-forme apulienne (Promontoire de Gargano, Italie m´eridionale) Valeria Luciani a,∗ , Miriam Cobianchi b , Stefano Fabbri a a

Dipartimento di Scienze della Terra, Universit`a degli Studi di Ferrara, Polo Scientifico Tecnologico, Via Saragat 1, 44100 Ferrara, Italy b Dipartimento di Scienze della Terra, Universit` a degli Studi di Pavia, Via Ferrata 1, 2700 Pavia, Italy

Abstract The Gargano Promontory, located on the eastern margin of the Apulia Platform, represents a distinctive Tethyan area where the transition from carbonate platform to adjacent basin is exposed on land. The Albian stratigraphic record, represented by shallow-water, slope and deep-water deposits, provides a good opportunity to investigate the regional response to oceanic anoxic events (OAEs) in different depositional settings by using an integrated, high-resolution micropalaeontological (planktonic foraminifers and calcareous nannofossils) approach. Results show that organic matter preservation is confined to the more distal areas (Marne a Fucoidi Formation), and consists of black shale intervals from the middle and late Albian (Ticinella primula/Prediscosphaera columnata Zones; upper Ticinella praeticinensis Subzone/R. achlyostaurion Zone, respectively). Integrated biostratigraphic data correlate the intervals of black shale deposition to the Urbino and Amadeus levels, previously identified and named in the Umbria-Marche Basin. These black shales record the effects of OAEs 1b and 1c. The biotic changes in the pelagic Albian succession of the Apulian Platform Margin provide evidence for episodes of eutrophication that correlate to the deposition of these black shales. Genetic models for the two episodes of organic matter preservation are proposed, taking into account both global and local controlling factors. © 2006 Elsevier Masson SAS. All rights reserved. R´esum´e Le promontoire de Gargano, situ´e sur la marge orientale de la plate-forme apulienne, repr´esente une r´egion privil´egi´ee, o`u la transition entre plate-forme carbonat´ee et ses bassins adjacents est expos´ee sur terre. L’enregistrement stratigraphique de l’Albien, repr´esent´e au sein de d´epˆots peu profonds ou de talus ou de bassin profond, offre une tr`es bonne occasion pour e´ tudier la r´eponse r´egionale aux e´ v´enements d’anoxie oc´eanique dans des contextes de d´epˆot diff´erents, en utilisant une approche micropal´eontologique (foraminif`eres planctoniques et nannofossiles calcaires) int´egr´ee et de haute r´esolution. Les r´esultats montrent que la pr´eservation de la mati`ere organique est confin´ee aux endroits les plus distaux (Formation des Marnes a` Fucoidi) et constitu´es d’intervalles d’argillites noires enregistr´ees dans la partie de l’Albien moyen et sup´erieur (Zones a` Ticinella primula–Prediscosphaera columnata ; partie sup´erieure des sous-zones Ticinella praeticinensis–R. achlyostaurion, respectivement). Les donn´ees biostratigraphiques int´egr´ees corr`elent les intervalles de d´epˆot d’argillites noires aux niveaux Amadeus et Urbino, d´etermin´es auparavant et nomm´es dans le bassin d’Ombrie-Marches. Ces argillites noires enregistrent les effets des e´ v´enements anoxiques 1b et 1c. Les changements biotiques dans la s´erie p´elagique albienne de la marge de la plate-forme apulienne fournissent des preuves pour des e´ pisodes d’eutrophisation qui se corr`elent avec le d´epˆot des argillites noires. Des mod`eles g´en´etiques sont avanc´es pour les deux e´ pisodes de pr´eservation de mati`ere organique en tenant aussi bien compte des facteurs globaux que locaux. © 2006 Elsevier Masson SAS. All rights reserved. Keywords: Albian; Oceanic anoxic events; Apulian platform; Southern Italy; Planktonic foraminifera; Calcareous nannofossils ´ enements d’anoxie oc´eanique ; Plate-forme apulienne ; Italie m´eridionale ; Foraminif`eres planctoniques ; Nannofossiles calcaires Mots cl´es : Albien ; Ev´

∗

Corresponding author. E-mail address: [email protected] (V. Luciani).

0035-1598/$ – see front matter © 2006 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.revmic.2006.06.001

240

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

1. Introduction The mid-Cretaceous is characterised by global palaeoceanographic and palaeobiological events. An increase in ocean crust-production, together with the formation of large igneous provinces, are considered the origin of a “greenhouse climate” through input of huge amounts of carbon dioxide to the atmosphere (e.g. Larson, 1991; Tarduno et al., 1991; Jones and Jenkyns, 2001). Warm temperatures and regional increases in primary productivity induced dysoxic and anoxic conditions on the seafloor, promoting several distinct episodes of organiccarbon (Corg ) accumulation (oceanic anoxic events, OAEs; e.g. Schlanger and Jenkyns, 1976; Jenkyns, 1980; De Graciansky et al., 1984; Arthur et al., 1990). The origin of OAEs is still debated, although they are classically interpreted using two main models: (1) The stagnant ocean model of Bralower and Thierstein (1984) (e.g. Br´eh´eret, 1994; Erbacher et al., 1996), which is based on high sea levels and changes in thermohaline circulation resulting in decreased oxygen concentrations and expansion of the oxygen minimum zone; or (2). The productivity model, which is based on increased surface water primary productivity (e.g. Weissert et al., 1985; Erba, 1994; Follmi, 1995; Jenkyns, 1999). Palaeoceanographic changes associated with OAEs are also closely

linked to microfossil evolution (e.g. Erbacher and Thurow, 1997; Bischoff and Mutterlose, 1998; Mutterlose, 1998; Leckie et al., 2002). Although recent analyses have used combined biostratigraphic, sedimentologic and geochemical methods, the role of climate, productivity, and palaeoceanographic change during Albian OAEs is still poorly constrained, as is their regional versus global extent. Three main OAEs are recognised in the Albian: early Albian OAE1b, early late Albian OAE1c and latest Albian OAE1d. Early Albian OAE1b (e.g. Br´eh´eret, 1988; Bralower et al., 1993; Erbacher et al., 1999; Herrle, 2002) falls within the nannofossil Prediscosphaera columnata Zone and the foraminifer Hedbergella planispira Zone (e.g. Strasser et al., 2001; Herrle, 2002; Herrle et al., 2003). Anoxic conditions during this event probably lasted ∼46 kyr (Erbacher et al., 2001), and resulted in several carbon burial episodes, each designated with a regional name. Originally described from southeastern France (Niveau Paquier, Vocontian Trough; Br´eh´eret, 1985), OAE1b also occurs in Germany and Austria, and is now recognised throughout the Tethyan region and the Atlantic Ocean, including deepsea sites (Br´eh´eret, 1997; Bralower et al., 1993; Leckie et al., 2002; Jenkyns, 2003). Early late Albian OAE1c spans the entire Biticinella breggiensis Zone (Bralower et al., 1993). It has been

Fig. 1. a. Location of the Gargano Promontory. b. Palaeogeographic position of the Gargano Promontory in southern Italy during the Jurassic–Cretaceous showing the Gargano Promontory divided between the Apulia Platform in the southwest and the Ionian Basin in the northeast. Shallow-water carbonate-platform facies are indicated by brick ornament; deeper-water facies by grey shading (modified from Zappaterra, 1990). c. Simplified geologic map and location of the studied sections (modified from Cobianchi et al., 1997). The location of Coppa della Nuvola section is also indicated. This section, cited in the text, was analysed by Luciani et al. (2004) and includes the carbon and oxygen isotope curves of the studied interval. Fig. 1. a. R´epartition g´eographique du promontoire de Gargano. b. Position pal´eog´eographique du promontoire de Gargano de l’Italie m´eridionale durant le JurassiqueCr´etac´e. Ceci est partag´e en deux entre la plate-forme d’Apulie dans le sud-ouest et le bassin Ionien dans le nord-est. Les faci`es peu profonds de plateforme carbonat´ee sont indiqu´es par le motif en brique; les faci`es d’eau-profonde par un motif en gris (modifi´e d’apr`es Zappaterra, 1990). c. Carte g´eologique simplifi´ee et localisation des coupes e´ tudi´ees (modifi´e d’apr`es Cobianchi et al., 1997). La localisation de la coupe Coppa Della Nuvola est aussi indiqu´ee. L’ e´ tude de cette coupe, analys´ee par Luciani et al. (2004) et cit´ee dans le texte, comprend les diagraphies des isotopes du carbone et oxig`ene pour l’intervalle examin´e.

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

identified in both the Tethyan region (e.g. Coccioni et al., 1990; Erba, 1988; Coccioni and Galeotti, 1993; Cobianchi et al., 1997) and the Saxony Basin in northern Europe (Fenner, 2001). This event includes deposit of Corg -rich layers within bedded cycles that are clearly controlled by orbital parameters (Galeotti et al., 2003). Erbacher et al. (1996); Erbacher and Thurow (1997) reported that terrestrial organic matter (type III kerogen) dominates in black shales related to OAE1c. Latest Albian OAE1d, which falls within the nannofossil Eiffellithus turriseiffelii Zone and the foraminifer Rotalipora apenninica Zone, is named the “Breistroffer interval” in south-eastern France (Br´eh´eret, 1988), and was recently recognised as another interval of Corg burial for the Cretaceous. The Urbino and Amadeus levels are the regional names assigned to the Albian black shales recognised in the Marne a Fucoidi Formation of the Umbria-Marche Basin (Coccioni, 2001; Coccioni et al., 1987, 1989, 1990). The Urbino Level seems to be part of the sedimentary expression of OAE1b, while the Amadeus level partially records OAE1c (Coccioni et al., 1990; Coccioni and Galeotti, 1993). According to Bralower et al. (1993), OAE1c spans the entire B. breggiensis Zone; however, the Amadeus level includes only a portion of this zone (i.e. the upper part of the Ticinella praeticinensis Subzone). During the last decade, equivalents of these black shales have been recognised in other Italian regions. Cobianchi et al.

241

(1997) found the Urbino and Amadeus levels in the Gargano Promontory (Fig. 1), located on the eastern margin of the Apulia Platform (Fig. 1b). The Albian interval is represented by shallow-water, slope and deep-water deposits, thus offering an opportunity to investigate palaeoenvironmental changes related to Albian episodes of Corg accumulation in different depositional settings. The purpose of this paper is to (i) Present results on one new section (Coppa della Guardia) and revise data for two others (Ischitella, Vico del Gargano). (ii) Synthesise available data for Albian black shales of the Gargano Promontory and (iii) Outline a genetic model that highlights both local and supraregional/global control on deposition of the Albian black shales. 2. Geological and stratigraphic setting of the Gargano Promontory The Gargano Promontory consists of a Mesozoic carbonate succession belonging to the Apulian Platform in the southwest and to the Ionian Basin in the northeast (Zappaterra, 1990; Fig. 1b). The current lithostratigraphic terminology of the Cretaceous basin-and-slope units in this area varies according to different authors (e.g. Luperto Sinni and Masse, 1987; Coccioni and Luperto Sinni, 1989; Luciani, 1993; Luciani and Cobianchi, 1994; Luperto Sinni and Borgomano, 1994; Neri and

Fig. 2. Stratigraphic framework and nomenclature of the second order depositional sequences and formations (according to Bosellini et al., 1999) for the Albian interval investigated here, plotted against the system tracts and planktonic foraminifer and calcareous nannofossil biostratigraphy. Fig. 2. Contexte stratigraphique et nomenclature des s´equences de d´epˆot de deuxi`eme ordre et des formations rencontr´ees dans l’intervalle temporel de cette e´ tude (d’apr`es Bosellini et al., 1999), plac´ees par rapport aux unit´es de s´equences stratigraphiques et aux zones des foraminif`eres planctoniques et des nannofossiles calcaires.

242

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

Luciani, 1994; Cobianchi et al., 1997, 1999; Luciani et al., 2001; Graziano, 2000). The stratigraphic framework adopted here follows Bosellini et al. (1993, 1999) and Cobianchi et al. (1997). Fig. 2 shows this stratigraphic framework and nomenclature for second order depositional sequences and formations. During the Late Jurassic-Early Cretaceous, the Apulia Platform was a productive carbonate platform, with its rim colonised by bioconstructors and its inner area characterised by typical peritidal environments. The external margin zone extends eastward to the slope and basin. Albian shallow-water deposits are rare and crop out only locally (Bosellini et al., 1993, 2000). An Albian–Cenomanian inner-platform succession crops out in southern Gargano and consists of mudstone-wackestone with peloidal packstone–grainstone intercalations containing orbitolinids of late Albian age (Masseria Quadrone Formation, Fig. 2; Merla et al., 1969; Luperto Sinni, 1996). The late Aptian–Albian Apulia Platform margin is represented by bioconstructed limestones (Monte degli Angeli 2 Formation). Only the upper Aptian portion of this platform is preserved (rudists, Ellipsactinia and stromatoporoids), whereas the Albian portion occurs only as platform-derived breccias (rudists, corals,

spongae and Nerinea) in the slope and base-of-slope deposits (Mattinata 2 Formation, Fig. 2; Luciani and Cobianchi, 1994; Bosellini et al., 2000). During the latest Albian–Cenomanian, huge megabreccia bodies (Monte S. Angelo Formation, Fig. 2) were deposited along the slope and base-of-slope belt, coeval with the general emergence and karst development of the southern Apennine carbonate platforms. The Cretaceous pelagic succession across these areas consists of three superimposed stratigraphic units, that correspond in part to the classic basinal Cretaceous succession recognised in the Umbria-Marche Basin, central Italy. These units are the Maiolica (Valanginian–early Aptian), Marne a Fucoidi (early Aptian–late Albian), and Scaglia (late Albian–Coniacian). Near the margin of the platform, the Mattinata Formation, rich in gravity-displaced deposits, laterally replaces the Maiolica (Bernoulli, 1972; Bosellini et al., 1993; Luciani and Cobianchi, 1994; Cobianchi et al., 1997; Graziano, 2000). The Albian portion of the pelagic succession shows marllimestone couplets typical of the Marne a Fucoidi, the deposition of which was probably controlled by orbital (Milankovitch) parameters. In the sections close to the Apulia Platform margin, the

Fig. 3. Stratigraphic correlation of the main calcareous nannofossil (solid line) and planktonic foraminifer (dashed line) biostratigraphic events in the Albian succession of the Gargano Promontory, which contains episodes of organic matter preservation correlatable with the Urbino and Amadeus Levels of the Umbria-Marche Basin. Biostratigraphic schemes are according to Caron, 1985; Sliter, 1989, 1992; Robaszynski and Caron, 1995 (planktonic foraminifers); Thierstein, 1971, 1973, 1976; Erba, 1992 (calcareous nannofossils). Fig. 3. Corr´elation stratigraphique des principaux e´ v´enements biostratigraphiques des nannofossiles calcaires et des foraminif`eres planctoniques (lignes en tirets) de la s´erie albienne du promontoire de Gargano contenant des e´ pisodes de pr´eservation de mati`ere organique corr´elables avec les e´ quivalents des niveaux Urbino et Amadeus. Les sch´emas biostratigraphiques utilis´es sont d’apr`es Caron, 1985; Sliter, 1989, 1992; Robaszynski et Caron, 1995 (foraminif`eres planctoniques) et Thierstein, 1971, 1973, 1976; Erba, 1992 (nannofossiles calcaires).

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

deposition of the Cenomanian Monte Sant’Angelo Megabreccia produced a wide erosional hiatus spanning the entire Upper Albian interval. The Upper Albian transition between the Marne a Fucoidi and superimposed Scaglia Formations is preserved in the more distal sections where resedimented deposits are rare or absent (Luciani et al., 2004). 3. Material and methods The new section from Coppa della Guardia is 44 m thick. It is located about 1 km south of Vico del Gargano (Fig. 1c) along the road connecting Pizzo di Crepacore to Coppa della Guardia. The lithology consists of cyclically arranged couplets of bioturbated grey marlstones and locally silicified off-white marly limestones with chert nodules referable to the Marne a Fucoidi Formation. Slumps and turbiditic intervals occur sporadically. A 90-cm laminated black-shale interval crops out in the lower middle part of the section (Figs. 3 and 4). A total of 28 samples from the Coppa della Guardia section were analysed for foraminifers and calcareous nannofossils, following standard laboratory techniques. Foraminifer procedure consisted of disaggregation of marly samples and black shales in Desogen (a surface-tension-active chemical product of the Ciba Geigy Company), followed by washing through a 38-␮m sieve to avoid the loss of very small specimens. Limestones and cherty limestones were analysed in thin section. Thin sections from marly-limestone samples were also studied to directly relate radiolarian and total foraminifer abundances to the standard percent diagrams for visual estimation in sedimentary rocks given by Baccelle and Bosellini (1965). These diagrams allow

243

to evaluate the percentage of various type of grains (in our case radiolarians and foraminifers) with respect to the matrix. Drawing the diagrams these authors have considered the real grain shapes, conveniently standardised and the psychological effects due to chromatic differences between the grains and the matrix. Both the scarcity of washed residues and the dominance of radiolarians in some samples prevented continuous quantitative analysis of foraminifer assemblages. The same methods have been applied for the other stratigraphic sections (Cobianchi et al., 1997). Smear-slides from samples of all the rock-types (marly limestone, marl, calcareous shale and black shale) were prepared for calcareous nannofossil analyses. Quantitative and semiquantitative estimates of calcareous nannofossil species abundance were carried out using a polarising light microscope at a magnification of 1250×. Two sets of data were produced for the studied samples. The first includes raw counts of 300 specimens per sample (Coppa della Guardia section), while the second includes counts of nannofossil species per field of view (FOV) (Ischitella, Vico del Gargano sections) for 300 FOVs in a random traverse. The relative abundance of the species is expressed as follows: A (abundant) > 1 specimen/FOV; C (common) = 1 specimen/1–10 FOVs; F (few) = 1 specimen/11–30 FOVs; R (rare) = 1 specimen/30 FOVs. The data are plotted as abundance curves to detect peaks of the dominate taxa in the assemblages. Biostratigraphy is according to standard lowlatitude zonal schemes (e.g. Caron, 1985; Sliter, 1989, 1992; Robaszynski and Caron, 1995, for planktonic foraminifers; Thierstein, 1971, 1973, 1976; Erba, 1992, for calcareous nannofossils).

Fig. 4. Detail of the Coppa della Guardia section stratigraphic column showing the interval containing the Urbino Level equivalent plotted against the calcareous nannofossil and planktonic foraminifer biostratigraphy. Curves are shown for calcareous nannofossil, radiolarian and planktonic foraminifer abundances (abundances for the last two estimated in thin section by comparison with the standard percent diagrams of Baccelle and Bosellini, 1965) as well as the abundance of selected calcareous nannofossils and planktonic foraminifers. For the lithological symbols see Fig. 3. Fig. 4. D´etail de la stratigraphie de la coupe de Coppa della Guardia indiquant l’intervalle qui contient l’´equivalent du Niveau Urbino. La biostratigraphie des nannofossiles calcaires et des foraminif`eres planctoniques est plac´ee en face des courbes d’abondance des Radiolaires et des foraminif`eres planctoniques (estim´ees en lame mince par comparaison avec les diagrammes standards de Baccelle et Bosellini, 1965) ainsi que des courbes d’abondance de certains taxa s´electionn´es de nannofossiles calcaires. Pour la lecture des symboles lithologiques voir la Fig. 3.

244

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

4. Results In this paragraph we present results from the new section at Coppa della Guardia and revised semi-quantitative analyses of calcareous nannofossils and foraminifers from two sections (Ischitella and Vico del Gargano) studied previously by Cobianchi et al. (1997) in order to highlight palaeoceanographic and palaeoecological conditions related to deposition of Albian black shales in the Gargano area. 4.1. Coppa della Guardia Integrated planktonic foraminifer and calcareous nannofossil biostratigraphy from Coppa della Guardia indicate the whole section is early Aptian–late Albian in age (Cobianchi and Luciani, unpublished data) (Fig. 3). The planktonic foraminifer and calcareous nannofossil range charts are available upon request. Fig. 4 illustrates the Albian interval of the section that contains a 90 cm-thick black shale horizon characterised by cyclic alternations of marls and black shales. This interval is referred to the Ticinella primula (planktonic foraminifer) and P. columnata (calcareous nannofossil) Zones. Biostratigraphic data indicate this black shale interval corresponds to the Urbino Level equivalent. Planktonic foraminifers are almost completely absent within the Urbino Level, whereas radiolarians are very abundant (Fig. 4). Only scattered hedbergellids (Hedbergella delrioensis, H. planispira), Ticinella roberti and T. primula were observed. An impoverished benthonic fauna also occurs within the black shales. The calcareous nannofossil assemblage is dominated by two species: Watznaueria barnesae and Lithraphidites

carniolensis. The inverse correlation between the abundance of Zeugrhabdotus spp. and Nannoconus spp. is notable throughout the interval. Zeugrhabdotus spp. increase in abundance in the upper portion of the black shale horizon, whereas nannoconids are rare or absent within the black shale, but well represented above it. 4.2. Ischitella section The interval corresponding to the Amadeus Level equivalent in the Ischitella section contains black shale horizon completely barren of planktonic foraminifers alternating with layers rich in radiolarians. In some cases the latter also contain an impoverished planktonic foraminifer fauna mainly represented by hedbergellids (H. planispira and H. delrioensis), and more rarely by globigerinelloidids, T. praeticinensis, T. primula, and B. breggiensis. An impoverished benthonic fauna occurs within the black shales (Fig. 5). Nannoconids occur only in the lower portion of the Amadeus Level equivalent. The high abundance of the calcareous nannofossil W. barnesae, a diagenesis resistant taxa (Roth and Bowdler, 1981; Roth, 1984, 1986; Roth and Krumbach, 1986; Erba, 1992), may suggest a certain degree of diagenetic modification of the primary assemblage composition (Fig. 5). 4.3. Vico del Gargano section Planktonic foraminifers are absent within the horizons richest in organic matter in the Urbino and Amadeus level equivalents at Vico del Gargano. In contrast, radiolarians are very abundant, particularly at the base of the Urbino

Fig. 5. Semiquantitive estimates of changes in abundance of selected calcareous nannofossil taxa, expressed per FOV, across the Amadeus Level equivalent of the Ischitella section (after Luciani et al. in 1997). For each smear-slide, 300 FOVs were observed in random traverses. The relative abundance of the species is expressed as follows: A (abundant) > 1 specimen/FOV; C (common) = 1 specimen/1–10 FOVs; F (few) = 1 specimen/11–30 FOVs; R (rare) = 1 specimen/30 FOVs. Radiolarian and planktonic foraminifer abundances are estimated by comparison with the standard percent diagrams of Baccelle and Bosellini (1965). The main foraminifer events are also indicated. For lithological symbols see Fig. 3. Fig. 5. Estimation semi-quantitative de l’abondance de certains taxa s´electionn´es de nannofossiles calcaires, exprim´es par champs visuel (CV), a` travers l’´equivalent du niveau Amadeus de la coupe de Ischitella (d’apr`es Luciani et al. en 1997). Pour chaque frottis, 300 champs visuels ont e´ t´e observ´es selon des traverses faites au hasard. L’abondance relative des esp`eces est exprim´ee comme suit: A (abondant) > 1 individu par CV; C (commun) = 1 individu par 1–10 CV; F (peu abondant) = 1 individu par 11–30 CV; R (rare) = 1 individu par 30 CV. Les courbes d’abondance des Radiolaires et des foraminif`eres planctoniques sont estim´ees a` partir des lames minces par comparaison avec les diagrammes standards de Baccelle et Bosellini (1965). Les principaux e´ v´enements des foraminif`eres planctoniques sont e´ galement indiqu´es. Pour l’explication des symboles lithologiques voir la Fig. 3.

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

245

Fig. 6. Semiquantitive estimates of changes in abundance of selected calcareous nannofossil taxa, expressed per FOV, across the Urbino and Amadeus Level equivalents of Vico del Gargano section (after Luciani et al., 1997). For each smear-slide, 300 FOVs were observed in random traverses. The relative abundance of the species is expressed as follows: A (abundant) > 1 specimen/FOV; C (common) = 1 specimen/1–10 FOVs; F (few) = 1 specimen/11–30 FOVs; R (rare) = 1 specimen/30 FOVs. Radiolarian and planktonic foraminifer abundances are estimated by comparison with the standard percent diagrams of Baccelle and Bosellini (1965). The main foraminifer events are also indicated. For lithological symbols see Fig. 3. Fig. 6. Estimation semi-quantitative de l’abondance de certains taxa s´electionn´es de nannofossiles calcaires, exprim´es par champs visuel (CV), a` travers les e´ quivalents des niveaux Urbino et Amadeus de la coupe de Vico del Gargano (d’apr`es Luciani et al. en 1997). Pour chaque frottis, 300 champs visuels ont e´ t´e observ´es selon des traverses faites au hasard. L’abondance relative des esp`eces est exprim´ee comme suit: A (abondant) > 1 individu par CV; C (commun) = 1 individu par 1–10 CV; F (peu abondant) = 1 individu par 11–30 CV; R (rare) = 1 individu par 30 CV. Les courbes d’abondance des Radiolaires et des foraminif`eres planctoniques sont estim´ees a` partir des lames minces par comparaison avec les diagrammes standards de Baccelle et Bosellini (1965). Les principaux e´ v´enements des foraminif`eres planctoniques sont e´ galement indiqu´es. Pour l’explication des symboles lithologiques voir la Fig. 3.

Level (Fig. 6). Hedbergellids (mainly H. planispira), rare globigerinelloidids (G. ultramicrus, G. bentonensis) and T. primula occur in the intervals correlating to the Urbino and Amadeus Level equivalents. Biticinella subbreggiensis is found only in the Amadeus Level equivalent. An impoverished benthonic fauna occurs within the black shales from both the Urbino and Amadaeus Level equivalents. Calcareous nannofossils occur discontinuously. They are common and diverse in the interval immediately below the base of the Urbino Level equivalent black shale, on the contrary their abundance drops sharply to zero both at the base and top of this carbon-rich horizon. Nannoconids are absent throughout the interval, as is Rhagodiscus asper. The abundances of Biscutum constans and Zeugrhabdotus erectus peak in the upper portion of the black shale. In the Amadeus Level equivalent of this section, W. barnesae dominates the nannofossil assemblages (Fig. 6). R. asper is absent or poorly represented, as is L. carniolensis, whereas nannoconids are always absent. Only a small peak of Zeugrhabdotus spp. occurs in this interval.

5. The sedimentary and biotic record of Albian OAEs in Gargano Some of the Gargano Promontory Albian pelagic sections record episodes of Corg preservation. The Vico del Gargano and Coppa della Guardia sections contain a black shale which falls within the nannofossil P. columnata and foraminifer T. primula Zones and correlates to the Urbino Level of the Umbria-Marche Basin (Coccioni and Galeotti, 1991). The Ischitella and Vico del Gargano sections also contain another black shale referable to the upper Albian Amadeus Level on the basis of its foraminiferal and nannofossil content (nannofossil R. achlyostaurion Zone and foraminifer T. praeticinensis Subzone). As discussed above, these black horizons record the regional effects of OAEs 1b and 1c, respectively. It must be noted that, according to the terminology of Arthur et al. (1990), OAE1c spans the entire B. breggiensis Zone, whereas the Amadeus level from the UmbriaMarche Basin (Coccioni and Galeotti, 1993; Galeotti, 1998; Galeotti et al., 2003), as well as the Amadeus level equivalent from the Gargano Promontory are confined to the upper part of the T. praeticinensis Subzone.

246

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

In the Vico del Gargano section, the Urbino Level equivalent consists of three couplets suggesting a possible duration of 60 kyr for this event, attributing 20 kyr (precession cycle) for each couplet. At ODP Site 1049 in western subtropical Atlantic, Erbacher et al. (2001) calculate a duration of 210 kyr for the entire OAE1b interval, according to the estimated sedimentation rate. The record of the Amadeus Level equivalent in the Ischitella section includes 20 couplets, indicating a length of ∼400 kyr, the same duration evaluated for the Amadeus Level in the Umbria-Marche Basin (Galeotti et al., 2003). Black shales are not present in some of the Albian successions examined from the Apulia Platform margin. In the Val Carbonara section (Luciani and Cobianchi, 1994), which represents the Cretaceous slope connecting the Apulia Platform to the Ionian Basin, the absence of Albian black shales may be related to frequent resedimentation episodes during a highstand phase. Emplacement of gravity deposits may have removed anoxic sediments or favoured vertical mixing of the water-mass and, hence, an aerobic sea bottom. In the Ischitella section some covered tracts occur in the stratigraphic interval corresponding to the Urbino Level (Cobianchi et al., 1997). In the Coppa della Nuvola section (Fig. 1), analysed for both microfossils and stable isotopes (Luciani et al., 2004), the Urbino Level equivalent probably coincides with a covered tract, whereas the absence of the Amadeus Level equivalent may be related to a short hiatus or local lack of preservation of organic matter. Even if carbon-rich levels do not occur, it is likely that the lower Albian (T. primula/P. columnata Zones) and upper Albian (T. praeticinensis Subzone-R. subticinensis Zone/R. achlyostaurion Zone) isotope events record the pattern of global carbon burial related to OAEs1b and 1c. The carbon and oxygen isotope curves record two marked synchronous negative shifts probably preceding the anoxic events. A marked increase in radiolarian abundance is recorded in the Coppa della Nuvola section below the intervals corresponding to the Urbino and Amadeus Levels (Luciani et al., 2004). The uppermost Albian Pialli Level (OAE1d), described from the Umbria-Marche Basin by Coccioni (2001), is always absent in the Gargano region, both in sections close to the Apulia platform margin and more distal ones. The absence of the Pialli black shale is probably due to erosion or condensation. The micropalaeontological analyses of the Urbino and Amadeus levels of the Gargano Promontory region highlight the results summarised below. Calcareous nannofossils from the Urbino Level equivalents are rare and poorly diversified throughout the black shale interval, and they are completely absent at both its base and top. Nannoconids experienced a crisis that appears similar to the Aptian “nannoconid crisis” preceding the Selli Event (Erba, 1994). Nannoconids are interpreted as deep-dwellers indicating oligotrophic conditions (Erba, 1994; Herrle et al., 2003). Moreover, the warm and mesotrophic nannofloral indices (R. asper and L. carniolensis; Roth and Krumbach, 1986; Mutterlose, 1989, 1996; Erba et al., 1992) show a sharp abundance decrease in the black shale. On the contrary, the cooler water and eutrophic taxa (Zeugrhabdotus spp., Discorhabdus rotatorius and B. constans; Roth, 1981, 1983, 1986; Roth and Bowdler, 1981; Roth

and Krumbach, 1986; Premoli Silva et al., 1989; Coccioni et al., 1992; Erba, 1992; Herrle et al., 2003) increase in abundance upwards through that interval (Figs. 4 and 6). Planktonic foraminifers are absent in the organic-rich layers of the Urbino Level and poorly represented in the lighter laminated intervals. In the latter, the assemblages include opportunistic taxa, mainly small hedbergellids (e.g. Premoli Silva and Sliter, 1999). Among them, the species H. planispira, which constitutes a conspicuous component of this group, is also considered tolerant of low salinity conditions (Keller and Pardo, 2004). Radiolarians, by comparison with modern plankton, are considered to be indicators of eutrophic conditions during the Cretaceous (e.g. Hallock, 1987; Roth and Krumbach, 1986; Jarvis et al., 1988; Robaszynsky et al., 1990, 1994). They are more abundant than foraminifers throughout the black shale interval, and display two peaks in abundance, one at the base and one at the top of the Urbino Level (Figs. 4 and 6). Within the Amadeus Level, the calcareous nannofossil assemblages are dominated by W. barnesae, considered a tolerant, opportunistic taxon (Mutterlose, 1996; Negri et al., 2003; Lees et al., 2004) and a dissolution/diagenesis indicator (Roth and Bowdler, 1981; Roth, 1984, 1986; Roth and Krumbach, 1986; Erba et al., 1992). The relative abundances of calcareous nannofossil mesotrophic versus eutrophic indices is out of phase, and the latter group dominates the upper part of the interval. Nannoconids experienced a further crisis during this interval, as they are totally absent in the black shale. Planktonic foraminifers are rare, but not completely absent in the Amadeus Level black shales. Small opportunistic hedbergellids dominate the assemblages. Rare specimens of T. primula, and very rare T. praeticinensis and B. breggiensis also occur. Members of these genera are generally considered specialised, and are usually regarded as intermediate- or deeper-dwelling forms than the smaller hedbergellids (e.g. Leckie, 1987, 1989; Hart, 1999; Premoli Silva and Sliter, 1999). T. primula is considered more tolerant of palaeoenvironmental changes than T. praeticinensis or T. roberti and may be also related to upwelling areas (Premoli Silva and Sliter, 1999). On the other hand, recent isotopic data from Albian–Cenomanian planktonic foraminifers indicate T. primula and B. breggiensis lived in near-surface waters (Norris and Wilson, 1998, 1999; Wilson and Norris, 2001; Leckie et al., 2002). Radiolarians are abundant throughout the Amadeus Level and show a record similar to that described for the Urbino Level. A marked increase in radiolarian abundance is also recorded in the Coppa della Nuvola section below the intervals corresponding to the Urbino and Amadeus Levels (Luciani et al., 2004). Recent studies have shown the relationship between elongated chambered foraminifers (e.g. leupoldinids, schackoinids, “Muricohedbergella” simplex) and OAEs, which has been used to interpret their ecological/palaeoceanographic significance (e.g. Coccioni et al., 2006 and reference therein). These forms become consistent components of the assemblage during OAEs (particularly OAE1a and OAE2), and thus are interpreted as being adapted to low oxygen levels in the upper water col-

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

247

Fig. 7. Summary of the main regional and supraregional/global features recorded across OAEs 1b and 1c in the Gargano Promontory, plotted against the planktonic foraminifer and calcareous nannofossil biostratigraphy, the regional system tracts and the main changes in the general geodynamic-climatic context. See text for discussion. Fig. 7. Sch´ema r´ecapitulatif des principaux aspects r´egionaux et suprar´egionaux/globaux enregistr´es a` travers les OAE1b et OAE1c du Promontoire de Gargano, plac´es dans le cadre biostratigraphique des foraminif`eres planctoniques et des nannofossiles calcaires, le cadre s´equentiel r´egional et les principaux changements du contexte g´eodynamique et climatique g´en´eral. Voir texte pour discussion.

umn. Their true ecological significance is actually poorly known, although it appears that the interplay of several factors was responsible for this morphological adaptation (Coccioni et al., 2006). The Albian anoxic events record the lowest abundance of elongated chambered forms (Coccioni et al., 2006). The general low abundance and diversity of this group during Albian OAEs has been related to a minor environmental perturbation for these events compared to OAE1a and OAE2, which record the highest numbers of species and/or abundances of these peculiar planktonic foraminifera (Coccioni et al., 2006). In the Gargano Promontory elongated chambered forms were not present within the black shales but only below and/or above them in low percentages even if greater than those recorded from other Tethyan areas (see Fig. 8 in Coccioni et al., 2006). Some evidence indicates that eutrophication of surface waters, coupled with other factors (low oxygen, temperature, salinity, nutrients, type of food, trace elements), may have favoured the proliferation of these forms (Coccioni et al., 2006). The relative greater abundance of elongated chambered forms across the Albian OAEs at Gargano, together with other evidence discussed below, could support local eutrophy for the investigated area. 6. Palaeoclimatic, palaeoceanographic and palaeoecologic aspects of Albian OAEs from the Apulian Platform Margin The data collected from the Gargano Promontory indicate a marked perturbation of the biotic signal during both the Urbino

and Amadeus Level anoxic events (Fig. 7). The calcareous plankton is less abundant and diversified compared to intervals of background pelagic carbonate sedimentation (Maiolica facies). The specialised, oligotrophic nannoconids are absent. Planktonic foraminifers present within the black shale intervals are generally opportunistic, eutrophic forms, particularly within the Urbino Level equivalent. Additional indications of increased eutrophy across these intervals are the radiolarian-abundance peak and increase in calcareous nannofossil eutrophic indices. The latter become particularly abundant at the top of both black shale episodes. The occurrence of an impoverished benthonic fauna within the black shales suggests dysaerobic conditions at the seafloor. Dysaerobic conditions rather that complete anoxia have also been recorded in the Urbino and Amadeus Levels of the Umbria-Marche Basin (Coccioni and Galeotti, 1993; Galeotti, 1998). In the Coppa della Nuvola section, the carbon and oxygen isotope curves record two marked synchronous negative shifts probably preceding the anoxic events (Luciani et al., 2004). This record has been interpreted, as analogous to similar records across OAE1a and the Paleocene/Eocene boundary (see Jenkyns, 2003 for a review), which document dissociation of gas hydrates in the world ocean and the near-instantaneous oxidation of the released methane to carbon dioxide, with subsequent rapid global warming (Luciani et al., 2004) (Fig. 7). How can we interpret the biotic and isotopic signals recorded in the Albian black shales of the Gargano Promontory? In other words, which paleoecological and paleoceanographic scenarios can produce a similar record?

248

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

The biotic record from Gargano Promontory suggests increased primary productivity. Weissert et al. (1998) postulated increased primary productivity related to enhanced hydrological cycling favoured by intensified greenhouse conditions for OAE1b. According to Herrle (2002); Herrle et al. (2003), the cyclicity recorded in OAE1b correlates with productivity cycles linked to precessional variations of monsoonal circulation in a supposed ice-free Earth. In contrast, according to other authors (Erbacher et al., 2001; Wilson and Norris, 2001) the hydrological cycling primarily caused increased thermohaline stratification and preservation of organic carbon at the seafloor, particularly in semi-restricted basins of the western Tethys and North Atlantic. The Albian margin of the Apulia platform at Gargano Promontory, even if it was part of a narrow basin (Ionian Basin, Fig. 1b), does not record biotic evidence of marked water column stratification. Therefore, increased surface water fertility is the more plausible origin of the Urbino Level equivalent. Erbacher et al. (1996) interpreted OAE1c as a “detritic” OAE coinciding with regression, hence the organic matter would be essentially of terrestrial origin. In the Gargano Promontory we do not have data on the nature of the organic matter; however, we have general regional biotic and isotopic records similar to that of OAE1b, suggesting conditions for the Amadeus Level event at Gargano Promontory may have been similar. The presence of rare large, possibly more specialised deeper-dwelling planktonic foraminifers (T. praeticinensis and B. breggiensis) (e.g. Leckie, 1987, 1989; Hart, 1999; Premoli Silva and Sliter, 1999), as well as the opportunistic, surface-dwelling, low salinity tolerant species H. planispira (Keller and Pardo, 2004), in some of the organic-rich layers in the middle upper part of the Ischitella section could suggest water-mass stratification favouring the preservation of organic matter. Alternatively, if we interpret B. breggiensis and T. primula as surface dwellers (Norris and Wilson, 1998, 1999; Wilson and Norris, 2001; Leckie et al., 2002) and the latter as a possible upwelling indicator (Premoli Silva and Sliter, 1999), the signal indicates perturbed eutrophic conditions. The absence of the relatively specialised oligotrophic deeper-dwelling nannoconids and the increased radiolarian abundance may support the latter speculation. Galeotti et al. (2003) analysed the cyclic nature of the Amadeus Level in the Umbria-Marche Basin, and concluded that continental runoff and water-mass stratification played a major role in shaping the organic carbon-rich facies, whereas eutrophic conditions prevailed during deposition of carbonaterich beds. Although we did not conduct detailed analysis of each couplet in the black shales of Gargano Promontory, our data show an evolution of environmental conditions from the base to the top of the interval. The eutrophic and cooler calcareous nannofossil indices, and the radiolarians in some cases, show a peak in the upper part of both the Urbino and Amadeus Level black shales. This concurs with the oxygen-isotope record, which indicates a cooling trend in these same intervals following a marked warming (Luciani et al., 2004). This cooling episode may have caused a moderate intensification of vertical mixing, which may have accelerated nutrient recycling and consequent eutrophy.

General enhanced primary productivity in the Albian oceans could be related to mechanisms similar to those proposed for OAEs 1a and 2. It is noteworthy that ocean crust-production was also very active during the Albian. Strontium-isotope ratios from marine carbonates show minor radiogenic values for the entire Lower Cretaceous below OAE1b (Bralower et al., 1997; Jones and Jenkyns, 2001). Changes to the strontium isotope system are interpreted as dominated by hydrothermal flux related to increased rates of seafloor spreading that accompanied the formation of submarine large igneous provinces during both the early Albian (Kerguelen-Elan Bank) and late Albian (Central Kerguelen) (Bralower et al., 1997; Leckie et al., 2002; Jenkyns, 2003). During OAE1c the 87 Sr/86 Sr curve moves towards more positive values that are comparable to those recorded for the Selli Event (Bralower et al., 1997; Leckie et al., 2002). The volcanic activity may have increased input of hydrothermal biolimiting elements favouring global nutrification analogous to OAE1a (Erba and Tremolada, 2004; Weissert and Erba, 2004). In addition, enhanced primary productivity may have been exceptionally intensified through improved hydrological cycling caused by release of huge amount of gas-hydrate methane and consequential derived CO2 , as implied by negative shifts in the carbon-isotope curve recorded in the Tethys (Vocontian Basin, Gargano Promontory) and Atlantic (off northwest Africa) (Gr¨ocke et al., 2002; Jenkyns, 2003; Luciani et al., 2004). The excess atmospheric carbon dioxide described in this scenario may have inhibited biocalcification in marine organisms. The scarcity of calcareous plankton and the “crisis” of heavilycalcified nannoconids recorded in the Albian black shales of the Gargano Promontory could reflect a biomineralisation crisis triggered by pCO2 -induced changes in climate and surface-water chemistry similar to that hypothesised for the Aptian Selli Event (Erba and Tremolada, 2004). Further analyses are needed to demonstrate whether the “Albian nannoconid crisis” recorded in the Gargano area is only a local event or if it extends supraregionally/globally. This scenario for deposition of Albian black shales in the studied area does not exclude water-column stratification linked to increased rainfall and increased input of low-salinity waters. It is probable that the cyclicity in the black shale intervals might encompass times characterised by relatively reduced productivity and stagnation of the water column alternating with phases of increased productivity, although general enhanced fertility appears to be the main control for the biotic record during deposition of the Albian black-shales. 7. Summary and conclusions This represents a new contribution, integrating original and published data. It discusses and interprets the regional response to Albian OAEs in the critical Tethyan area of the Apulian Platform Margin, thus improving knowledge of Albian black shales, so far less investigated with respect to the late early Aptian OAE1a and latest Cenomanian OAE2. Fig. 7 summarises features of the Albian black shales from the Gargano Promontory, separating those recognised here for the first time from those already observed at supraregional or

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

global scale. Regional features of both the Urbino and Amadeus Level equivalents are: (1) Low planktonic foraminifer diversity. (2) Radiolarian abundance peaks. (3) Abundant high-fertility calcareous nannofossil indices. and (4) The “nannoconids crisis”. Additionally, features of OAEs 1b and 1c already extensively documented include: (1) Impoverished benthonic fauna (dysaerobic conditions at the sea floor). (2) Orbitally-controlled cyclicity. and (3) Negative ␦13 C shift, and positive followed by negative ␦18 O trend (warming followed by cooling climate conditions) at least for the Urbino Level equivalent. Our results delineate a scenario for the Urbino and Amadeus Level equivalents of increased primary productivity due to climatic-geodynamic interactions, in many aspects similar to that proposed for the OAE1a (e.g. Jenkyns, 2003; Weissert and Erba, 2004). We have focused on the general biotic trend across the Albian anoxic events recorded in the Gargano Promontory, thus we cannot exclude that analysis of a single component of the lithological cycle might indicate rhythmic intervals of watermass stratification and stagnation alternating with episodes of increase primary productivity, as documented in the Vocontian Basin and Umbria-Marche Basin (Herrle, 2002; Herrle et al., 2003; Galeotti et al., 2003). Nevertheless, the inferred general palaeoceanographic model characterised by increased fertility is not surprising, as the climaticgeodynamic context is in many ways similar to that described for OAE1a. Changes in palaeogeography between the Aptian and Albian may have played a significant role in regional conditions, resulting in different local expression of the anoxic events. The synchronous negative shifts in ␦13 C and ␦18 O recorded in the Gargano Promontory may indicate dissociation of gas hydrates and the near-instantaneous oxidation of the released methane to carbon dioxide and consequent rapid global warming (Luciani et al., 2004). A reliable correlation exists in the ␦13 C records among the lower Albian successions of the Gargano Promontory, the Vocontian Basin (southeastern France; Herrle, 2002) and the Mazagan Plateau (Northwest Africa, DSDP Site 545; Herrle, 2002) which show a negative trend, followed by a positive shift, within the P. columnata Zone. Further analyses are necessary to confirm the occurrence of worldwide negative shifts in the carbon- and oxygen isotope records for the Albian black shales, as already document for Aptian OAE1a, in which case we could stress the influence of marked global warming during all OAEs.

Acknowledgements This research was funded by FAR ex 60% to V.L. and FAR to M.C. Thanks are due to Taniel Danelian and Silvia Gardin for insightful reviews and comments that have greatly improved the manuscript. Thanks also to R. Tamoni for preparing the thin sections. Careful correction of the English language by Denise Kulhanek and translation of the abstract and figure captions to French by Taniel Danelian have been greatly appreciated.

249

References Arthur, M.A., Brumsack, H.J., Jenkyns, H.C., Schlanger, S.O., 1990. Stratigraphy, geochemistry, and paleoceanography of organic carbon-rich Cretaceous sequences. In: Ginsburg, R.N., Beaudoin, B. (Eds.), Cretaceous Resources, Events and Rhythms. Kluwer Academic Publishers, Dordrecht, pp. 75– 119. Baccelle, L., Bosellini, A., 1965. Diagrammi per la stima visiva della composizione percentuale nelle rocce sedimentarie. Annali dell’Universit`a di Ferrara (Nuova Serie). Sezione IX. Scienze Geologiche e Paleontologiche 1, 117–153. Bernoulli, D., 1972. North Atlantic and Mediterranean Mesozoic facies: a comparison. In: Hollister, C.D., Ewing, J.I. (Eds.), Initial Report Deep Sea Drilling Project. US. Government Printing Office, Washington, pp. 801–879 (11). Bischoff, G., Mutterlose, J., 1998. Calcareous nannofossils of the Barremian/Aptian boundary interval in NW Europe: biostratigraphic and palaeoecologic implications of a high-resolution study. Cretaceous Research 19, 635–661. Bosellini, A., Morsilli, M., Neri, C., 1999. Long-term event stratigraphy of the Apulia Platform margin: the Gargano transect (Upper Jurassic to Eocene). Journal of Sedimentary Research 69, 1241–1253. Bosellini, A., Morsilli, M., Neri, C., 2000. Long-term event stratigraphy of the Apulia Platform margin: the Gargano transect (Upper Jurassic to Eocene). Journal of Sedimentary Research 69, 1241–1252. Bosellini, A., Neri, C., Luciani, V., 1993. Platform margin collapse and sequence stratigraphic organization of carbonate slopes: Cretaceous-Eocene, Gargano Promontory, southern Italy. Terra Nova 5, 282–297. Bralower, T.J., Fullagar, P.D., Paull, C.K., Dwyer, G.S., Leckie, R.M., 1997. Mid-cretaceous strontium stratigraphy of the deep-sea sections. Geological Society of American Bulletin 109, 1421–1442. Bralower, T.J., Sliter, W.V., Arthur, M.A., Leckie, R.M., Allard, D., Schlanger, S.O., 1993. Dysoxic/anoxic episodes in the Aptian–Albian (Early Cretaceous). In: Pringle, M., Sager, W.W., Sliter, W.V., Stein, S. (Eds.), The Mesozoic Pacific: Tectonics, and Volcanism. American Geophysical Union, Washington, DC, Monograph, pp. 5–37 (77). Bralower, T.J., Thierstein, H.R., 1984. Low productivity and slow deep-water circulation in mid-Cretaceous oceans. Geology 12, 614–618. Br´eh´eret, J.G., 1985. Indices d’un e´ v´enement anoxique e´ tendu a` la T´ethys alpine, a` l’Albien inf´erieur (´ev´enement Paquier). Compte Rendu de l’Acad´emie des Sciences de Paris 300, 355–358. ´ Br´eh´eret, J.G., 1988. Episodes de s´edimentation riche en mati`ere organique dans les marnes bleues d’ˆage aptien et albien de la partie p´elagique du bassin Vocontien. Bulletin de la Soci´et´e g´eologique de France 8, 349–356. Br´eh´eret, J.G., 1994. The Mid-Cretaceous organic-rich sediments from the Vocontian Zone of the French southeast Basin. In: Mascle, A. (Ed.), Hydrocarbon and Petroleum Geology of France. Special Publication of the European Association of Petroleum Geologists. Springer-Verlag, Berlin, pp. 295–320. Br´eh´eret, J.G., 1997. L’Aptien et l’Albien de la Fosse Vocontienne (bordures du ´ bassin). Evolution de la s´edimentation et enseignements sur les e´ v´enements anoxiques. Publication de la Soci´et´e g´eologique du Nord 25 (1–614). Caron, M., 1985. Cretaceous planktic foraminifers. In: Bolli, H.M., Saunders, J., Perch-Nielsen, K. (Eds.), Plankton Stratigraphy. Cambridge Earth Sciences Series. Cambridge University Press, Cambridge, pp. 17–86. Cobianchi, M., Luciani, V., Bosellini, A., 1997. Early Cretaceous nannofossils and planktonic foraminifera from northern Gargano (Apulia, southern Italy). Cretaceous Research 18, 249–293. Cobianchi, M., Luciani, V., Menegatti, A., 1999. The Selli Level of the Gargano Promontory, Apulia, southern Italy: foraminiferal and calcareous nannofossil data. Cretaceous Research 20, 255–269. Coccioni, R., 2001. The “Pialli Level” from the Latest Albian of the UmbriaMarche Apennines (Italy). FIST, Geoitalia 2001, Chieti, 5–8 Settembre 2001, Riassunti, pp. 192. Coccioni, R., Erba, E., Premoli Silva, I., 1992. Barremian–Aptian calcareous plankton biostratigraphy from the Gorgo a Cerbara section (Marche, central Italy) and implications for plankton evolution. Cretaceous Research 13, 137–517.

250

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251

Coccioni, R., Franchi, R., Nesci, O., Perilli, N., Wezel, F.C., Battistini, F., 1990. Stratigrafia, micropaleontologia e mineralogia delle Marne a Fucoidi delle sezioni di Poggio le Guaine e del fiume Bosso (Appennino Umbro-Marchigiano). Atti 2◦ Convegno Internazionale “Fossili, evoluzione, ambiente”, Pergola, 25–30 ottobre 1987. Tecnostampa, 163–201. Coccioni, R., Galeotti, S., 1991. Orbitally induced cycles in benthonic foraminiferal assemblage distribution from Aptian–Albian organic-rich Scisti a Fucoidi (central Italy). In: Abstract, Pelagic and Flysch facies, Third Meeting (IGCP Project 262 “Tethyan Cretaceous Correlation”), Grenoble, 1991, pp. 1–2. Coccioni, R., Galeotti, S., 1993. Orbitally induced cycles in benthonic foraminiferal morphogroups and trophic structure distribution patterns from the Late Albian “Amadeus segment” (Central Italy). Micropalaeontology 12, 227–239. Coccioni, R., Luciani, V., Marsili, A., 2006. Cretaceous anoxic events and radially elongated chambered planktonic foraminifera: palaeoecological and palaeoceanographic implications. Palaeogeography, Palaeoclimatology, Palaeoecology 235, 66–92. Coccioni, R., Luperto Sinni, E., 1989. Foraminiferal biostratigraphy of the Vico del Gargano section (Lower Cretaceous) from the Gargano, southern Italy. in: Coccioni, R., Monechi, S., Parisi, G. (Eds.), First Meeting of the Working group 2-Pelagic facies (IGCP Project 262 “Tethyan Cretaceous Correlation”), Centrostampa, Universit`a di Urbino, Abstract, pp. 25–27. Coccioni, R., Moneschi, S., Parisi, G. (Eds.), 1989. Abstract of the IGCP project 262, Working group 2 “Pelagic Facies”. Universit`a di Urbino, Urbino, pp. 1–114. Coccioni, R., Nesci, O., Tramontana, M., Wezel, C.F., Moretti, E., 1987. Descrizione di un livello guida “radiolaritico-bituminoso-ittiolitico” alla base delle Marne a Fucoidi nell’Appennino umbro-marchigiano. Bollettino della Societ`a Geologica Italiana 106, 183–192. De Graciansky, P.C., Deroo, G., Herbin, J.P., Montadert, L., Muller, C., Schaaf, A., Sigal, J., 1984. Ocean-wide stagnation episode in the Late Cretaceous. Nature 308, 346–349. Erba, E., 1988. Aptian–Albian calcareous nannofossil biostratigraphy of the Scisti a Fucoidi cored at Piobbico (central Italy). Rivista Italiana di Paleontologia e Stratigrafia 94, 249–284. Erba, E., 1992. Calcareous nannofossil distribution in pelagic rhythmic sediments (Aptian–Albian Piobbico core, central Italy). Rivista Italiana di Paleontologia e Stratigrafia 97, 445–484. Erba, E., 1994. Nannofossils and superplumes: The early Aptian “nannoconid crisis”. Palaeoceanography 9, 483–501. Erba, E., Castradori, D., Guasti, G., Ripepe, M., 1992. Calcareous nannofossils and Milankovitch cycles: the example of the Albian Gault Clay Formation (southern England). Palaeogeography, Palaeoclimatology, Palaeoecology 93, 47–69. Erba, E., Tremolada, F., 2004. Nannofossil carbonate fluxes during the Early Cretaceous: phytoplankton response to nutrification episodes, atmospheric CO2 and anoxia (Pa 1008; doi 10.1029/2003PA000884). Erbacher, J., Hemleben, C., Huber, B.T., Markey, M., 1999. Correlating environmental changes during early Albian oceanic anoxic event 1B using benthic foraminiferal paleoecology. Marine Micropaleontology 38, 7–28. Erbacher, J., Huber, B.T., Norris, R.D., Markey, M., 2001. Increased thermohaline stratification as possible cause for an oceanic anoxic event in the Cretaceous period. Nature 409, 325–327. Erbacher, J., Thurow, J., 1997. Influence of anoxic events on the evolution of mid-Cretaceous radiolaria in the North Atlantic and western Tethys. Marine Micropalaeontology 30, 139–158. Erbacher, J., Thurow, J., Littke, R., 1996. Evolution patterns of radiolaria and organic matter variations: a new approach to identify sea-level changes in mid-Cretaceous pelagic environments. Geology 24, 499–502. Fenner, J., 2001. Middle and Late Albian geography, and climate and the setting of the Kirckrode I and II berehole sites. Palaeogeography, Palaeoclimatology, Palaeoecology 174, 5–32. Follmi, K.B., 1995. 160 my record of sedimentary phosphorus burial coupling of climate and continental weathering under greenhouse conditions. Geology 23, 859–862. Galeotti, S., 1998. Planktic and benthic foraminiferal distribution patterns as a response to changes in surface fertility and ocean circulation: a case-

study from the late Albian “Amadeus segment” (Central Italy). Journal of Micropalaeontology 17, 87–96. Galeotti, S., Sprovieri, M., Coccioni, R., Bellanca, A., Neri, R., 2003. Orbitally modulated black shale deposition in the upper Albian Amadeus Segment (Central Italy): a multi-proxy reconstruction. Palaeogeography, Palaeoclimatology, Palaeoecology 190, 441–458. Graziano, R., 2000. The Aptian–Albian of the Apulia carbonate platform (Gargano Promontory, southern Italy): evidence of palaeoceanographic and tectonic controls on the stratigraphic architecture of the platform margin. Cretaceous Research 21, 107–126. Gr¨ocke, D., Kucera, M., Bown, P., Kanungo, S., Macdonald, E., Stoll, M., Lees, J., Schmidt, D.N., 2002. Definition of the onset of OAE1b in the Proto-Atlantic. In: Abstract, Organic Carbon Burial, Climate Change and Ocean Chemistry (Mesozoic–Paleogene), Meeting Geological Society London, 2002, pp. 16. Hallock, P., 1987. Fluctuations in the trophic resource continuum: a factor in global diversity cycles? Paleoceanography 2, 457–471. Hart, M.B., 1999. The evolution and biodiversity of Cretaceous planktonic Foraminiferida. Geobios 32, 247–255. Herrle, J.O., 2002. Paleoceanographic and paleoclimatic implications on Mid-Cretaceous black-shale formation in the Vocontian Basin and the Atlantic: evidence from calcareous nannofossils and stable isotope. T¨ubinger Mikropal¨aontologische Mitteilungen 27, 114. Herrle, J.O., Pross, J., Friedrich, O., Kossler, P., Hemleben, C., 2003. Forcing mechanisms for mid-Cretaceous black shale formation: evidence from the Upper Aptian and Lower Albian of the Vocontian Basin (SE France). Palaeogeography, Palaeoclimatology, Palaeoecology 190, 399–426. Jarvis, I., Carson, G.A., Cooper, M.K.E., Hart, M.B., Leary, P.N., Tocher, B.A., Horne, D., 1988. Microfossil assemblages and the Cenomanian–Turonian (Late Cretaceous) oceanic anoxic event. Cretaceous Research 9, 3–103. Jenkyns, H.C., 1980. Cretaceous anoxic events from continents to oceans. Journal of the Geological Society London 137, 171–188. Jenkyns, H.C., 1999. Mesozoic anoxic events and palaeoclimate. Zentralblatt Geologie und Pal¨aontologie 1997, 943–949. Jenkyns, H.C., 2003. Evidence for rapid climate change in the Mesozoic–Palaeogene greenhouse world. Philosophical Transaction of the Royal Society. Series A 361, 1885–1916. Jones, C.E., Jenkyns, H.C., 2001. Sea-water-strontium isotopes, oceanic anoxic events, and sea-floor hydrothermal activity in the Jurassic and Cretaceous. Journal of American Sciences 301, 112–149. Keller, G., Pardo, A., 2004. Age and paleoenvironment of the Cenomanian–Turonian global stratotype section and point at Pueblo, Colorado. Marine Micropaleontology 51, 95–128. Larson, R.L., 1991. Geological consequences of superplumes. Geology 19, 963–966. Leckie, R.M., 1987. Palaeoecology of mid-Cretaceous planktonic foraminifera: a comparison of open ocean and epicontinental sea assemblages. Micropaleontology 33, 164–176. Leckie, R.M., 1989. A palaeoceanographic model for the early evolutionary history of planktonic foraminifera. Palaeogeography, Palaeoclimatology, Palaeoecology 73, 107–138. Leckie, R.M., Bralower, T.J., Cashman, R., 2002. Oceanic anoxic events and plankton evolution: Biotic response to tectonic forcing during the midCretaceous. Paleoceanography, 17 10.1029/2001/PA000623. Lees, J.A., Bown, P.R., Young, J.R., Riding, J.B., 2004. Evidence for annual records of phytoplankton productivity in the Kimmeridge Clay Formation coccolith stone bands (Upper Jurassic, Dorset, UK). Marine Micropaleontology 52, 29–49. Luciani, V., 1993. Mid-Turonian planktic foraminifera and depth stratification along a carbonate paleoslope (Gargano Promontory, southern Italy). Annali Universit`a Ferrara, Nuova Serie, Sezione. Scienze della Terra 4, 47–79. Luciani, V., Cobianchi, M., 1994. Type section of the Mattinata Formation (Lower Cretaceous, Gargano Promontory, southern Italy): new biostratigraphic data (calcareous nannofossils and planktonic foraminifers). Memorie di Scienze Geologiche dell’Universit`a di Padova 46, 283–301. Luciani, V., Cobianchi, M., Jenkyns, H.C., 2001. Biotic and geochemical response to anoxic events: the Aptian pelagic succession of the Gargano Promontory (southern Italy). Geological Magazine 138, 277–298.

V. Luciani et al. / Revue de micropal´eontologie 50 (2007) 239–251 Luciani, V., Cobianchi, M., Jenkyns, H.C., 2004. Albian high-resolution biostratigraphy and isotope stratigraphy: the Coppa della Nuvola pelagic succession of the Gargano promontory (southern Italy). Eclogae Geologicae Helvetiae 97, 77–92. Luperto Sinni, E., 1996. Schema stratigarfico del Cretacico del Gargano basato su risultati di recenti ricerche. Memorie della Societ`a Geologica Italiana 51, 1019–1036. Luperto Sinni, E., Borgomano, J., 1994. Stratigrafia del Cretaceo superiore in facies di scarpata di Monte Sant’Angelo (Promontorio del Gargano, Italia Meridionale). Bollettino della Societ`a Geologica Italiana 113, 355–382. Luperto Sinni, E., Masse, J.P., 1987. Donn´ees nouvelles sur la stratigraphie et la micropal´eontologie des s´eries carbonat´ees de talus et de bassin du Cr´etac´e inf´erieur du Gargano (Italie M´eridionale). Rivista Italiana Paleontologia Stratigrafia 93, 347–378. Merla, G., Ercoli, A., Torre, D., 1969. Note illustrative della Carta Geologica d’Italia alla scala di 1:100.000, Foglio 164 “Foggia”. Servizio Geologico d’Italia (1–22). Mutterlose, J., 1989. Temperature-controlled migration of calcareous nannofloras in the northwest European Aptian. In: Crux, J.A., van Heck, S.E. (Eds.), Nannofossils and their applications. Ellis Horwood, Cheichester, pp. 122–142. Mutterlose, J., 1996. Calcareous nannofossil palaeoceanography of the Early Cretaceous of NW Europe. Mitteilungen aus dem Geologischen Staatsinstilul im Hamburg 77, 291–313. Mutterlose, J., 1998. The Barremian/Aptian turnover of biota in the northwestern Europe: evidence from belemnites. Palaeogeography, Palaeoclimatology, Palaeoecology 144, 161–173. Negri, A., Cobianchi, M., Luciani, V., Fraboni, R., Milani, A., Claps, M., 2003. Tethyan Cenomanian pelagic rhythmic sedimentation and Pleistocene sapropels: is the biotic signal comparable? Palaeogeography, Palaeoclimatology, Palaeoecology 190, 373–397. Neri, C., Luciani, V., 1994. The Monte S. Angelo Sequence (Late Cretaceous–Paleocene, Gargano Promontory, southern Italy): physical stratigraphy and biostratigraphy. Giornale di Geologia 52, 149–165. Norris, R.D., Wilson, P.A., 1998. Low-latitude sea-surface temperature for the mid-Cretaceous and the evolution of planktonic foraminifera. Geology 26, 823–826. Norris, R.D., Wilson, P.A., 1999. Low-latitude sea-surface temperature for the mid-Cretaceous and the evolution of planktonic foraminifera: Comment and Reply. Geology 27, 857–858. Premoli Silva, I., Ripepe, M., Tornaghi, M.E., 1989. Planktonic foraminiferal distribution record productivity cycles: evidence from the Aptian–Albian Piobbico core (Central Italy). Terra Nova 1, 443–448. Premoli Silva, I., Sliter, W.V., 1999. Cretaceous Paleoceanography: Evidence from planktonic foraminiferal evolution. In: Barrera, E., Johnson, C.C. (Eds.), Evolution of the Cretaceous Ocean–Climate System. Geological Society of America, Boulder, pp. 301–328 (Special Paper 332). Robaszynski, F., Caron, M., 1995. Foraminif`eres planctoniques du Cr´etac´e : commentaire de la zonation Europe-M´editerran´ee. Bulletin de la Soci´et´e g´eologique de France 166, 691–692. Robaszynsky, F., Caron, M., Dupuis, C., Amedro, F., Gonzales-Donoso, J.M., Linares, D., Hardenbol, J., Gartner, S., Calandra, F., Deloffre, R., 1990. A tentative integrated stratigraphy in the Turonian of central Tunisia: formations, zones and sequential stratigraphy in the Kalaat Senan area. Bulletin des Centres de Recherches Exploration-Production Elf-Aquitaine 14, 213–384. Robaszynsky, F., Hardenbol, J., Caron, M., Amedro, F., Dupuis, C., GonzalesDonoso, J.M., Linares, D., Gartner, S., 1994. Sequence stratigraphy in a distal environment: the Cenomanian of the Kalaat Senan region (Central Tunisia). Bulletin des Centres de Recherches Exploration-Production Elf-Aquitaine 14, 213–384.

251

Roth, P.H., 1981. Mid-Cretaceous calcareous nannoplankton from central Pacific: implications for palaeoceanography. In: Thiede, J., Vallier, T.L., et, al. (Eds.), Initial Report of Deep Sea Drilling Project 62, US. Government Printing Office Washington, pp. 471–489. Roth, P.H., 1983. Jurassic and Lower Cretaceous calcareous nannofossils in the Western Atlantic (Site 534). Biostratigraphy preservation and some observations on biogeography and paleoceanography. In: Sheridan, R.E., Gradstein, F.M., et al. (Eds.), Initial Report Deep Sea Drilling Project 76, US. Government Printing Office Washington, pp. 587–621. Roth, P.H., 1984. Preservations of calcareous nannofossils and fine-grained carbonate particles in mid-Cretaceous sediments from the southern Angola Basin, Site 530. In: Hay, W., Sibuet, J.C. (Eds.), The Deep Sea Drilling Project 75, U.S. Government Printing House, Washington, pp. 651–655. Roth, P.H., 1986. Mesozoic paleoceanography of the North Atlantic and Tethys Oceans. In: Summerhayes, C.P., Shackleton, N.J. (Eds.), North Atlantic Paleoceanography. Geological Society of London, Special Publication 21, pp. 299–320. Roth, P.H., Bowdler, J.L., 1981. Middle Cretaceous calcareous nannofossil biogeography and oceanography of the Atlantic Ocean. SEPM, Special Publication 32, 517–546. Roth, P.H., Krumbach, K.R., 1986. Middle Cretaceous calcareous nannofossil biogeography and preservation in the Atlantic and Indian oceans: implications for paleoceanography. Marine Micropaleontology 10, 235–266. Schlanger, S.O., Jenkyns, H.C., 1976. Cretaceous oceanic anoxic events: causes and consequences. Geologie en Mijnbouw 55, 179–184. Sliter, W.V., 1989. Biostratigraphic zonation for Cretaceous planktonic foraminifers examined in thin section. Journal of Foraminiferal Research 19, 1–19. Sliter, W.V., 1992. Cretaceous planktonic foraminiferal biostratigraphy and paleoceanographic events in the Pacific Ocean with emphasis of indurated sediments. In: Ishizaki, K., Saito, T. (Eds.), Centenary of Japanese Micropaleontology. Terra Scientific Publishing Company, Tokyo, pp. 281–299. Strasser, A., Caron, M., Gjermeni, M., 2001. The Aptian, Albian and Cenomanian of Roter Sattel, Romandes Prealps, Switzerland: a high-resolution record of oceanographic changes. Cretaceous Research 22, 183–199. Tarduno, J.A., Sliter, W.V., Kronenke, L., Leckie, M., Mayer, H., Mahoney, J.J., Musgrave, R., Storey, M., Winterer, E.L., 1991. Rapid formation of Onton Java Plateau by Aptian mantle Plume Volcanism. Science 254, 339–403. Thierstein, H.R., 1971. Tentative Lower Cretaceous calcareous nannoplankton zonation. Eclogae Geologicae Helvetiae 64, 459–488. Thierstein, H.R., 1973. Lower Cretaceous calcareous nannoplankton biostratigraphy. Abhandlungen der Geologischen Bundesanstalt 29, 1–52. Thierstein, H.R., 1976. Mesozoic calcareous nannoplankton biostratigraphy of marine sediments. Marine Micropaleontology 1, 325–362. Weissert, H., Erba, E., 2004. Volcanism, CO2 and palaeoclimate: a late Jurassic–early Cretaceous carbon and oxygen isotope record. Journal of the Geological Society of London 161, 695–702. Weissert, H., McKenzie, J.A., Channel, J.E.T., 1985. Natural variations in the carbon cycle during the Early cretaceous. In: Sundquist, E.T., Broeker, W.S. (Eds.), The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present. Geophysical Monographic Series 32. American Geophysical Union, Washington, pp. 531–545. Weissert, H., Lini, A., Follmi, K.B., Kuhn, O., 1998. Correlation of early Cretaceous carbon isotope stratigraphy and platform drowning events: a possible link? Palaeogeography, Palaeoclimatology, Palaeoecology 137, 189– 203. Wilson, P.A., Norris, R.D., 2001. Warm tropical ocean surface and global anoxia during the mid-Cretaceous period. Nature 412, 425–429. Zappaterra, E., 1990. Source-rock distribution model of the Periadriatic Region. American Associations of Petroleum Geologists Bulletin 78, 333–354.