Late Aptian Albian Research Articles

Microfacies analysis and paleoenvironmental interpretation of the late Aptian–Albian (Early Cretaceous) carbonates of the Riachuelo Formation in the Sergipe Sub-basin, northeastern Brazil

The beginning of the drift phase, in the Aptian–Albian transition, marked the development of marine conditions in the South Atlantic Ocean, characterized by the deposition of evaporites, followed by the development of carbonate platforms. The carbonate rocks of this interval were deposited in a passive margin context as part of the Riachuelo Formation in the Sergipe-Alagoas Basin, northeastern Brazil. The objective of present study was to analyze the microfacies of the Aptian–Albian interval in the northern portion of Sergipe State, near the city of Pacatuba. The mainly carbonates of two cores were investigated and five carbonate microfacies were identified: oncoidal rudstone, bioclastic rudstone, oncoidal packstone, peloidal packstone/wackestone, and mudstone with planktonic bioelements that suggest the paleoenvironments were relatively shallow marine. The microfacies were dominated by oncoids in almost every sample, which occurred in association with stromatolites. The biostratigraphic results were based on palynomorphs and calcareous nannofossils. The palynomorphs assemblages indicated a late Aptian age. Paleoecological results of these fossil groups show paleoenvironmental conditions of the shallow waters with proximal characteristics, with the predominance of pollens and spores associated with rare dinoflagellates and ascidians. A striking feature was the presence of authigenic glauconite which filled skeletal cavities and partially replaced the oncoids and their nuclei, mostly in the oncoidal packstone facies. Together, these findings suggest that the samples formed at the basal portion of the Riachuelo Formation in a transgressive systems tract, corresponding to the first depositional stage of the Riachuelo Formation.

Cretaceous (Hauterivian–Cenomanian) palaeoceanographic conditions in southeastern Tethys (Matruh Basin, Egypt): Implications for the Cretaceous climate of northeastern Gondwana

Quantitative palynological, sedimentological, and geophysical data analyses of the Cretaceous Abu Tunis 1X well from the Matruh Basin, northwestern Egypt indicate deposition of four major alternating regressive–transgressive successions. Sedimentation was largely affected by the Tethyan 2nd order sea level changes, with minor overprints by regional tectonics. The Lower Cretaceous part of the succession shows regressive sequences of deltafront to delta-top (upper Hauterivian–lowermost upper Barremian), delta channel (upper Aptian–middle Albian), and distal deltaic (upper Albian) settings that were interrupted by transgressive inner–proximal middle shelf deposits (uppermost Barremian–middle Aptian). These sediment packages correspond to Tethyan sea level fall from the late Hauterivian to late Barremian, and to the early–middle Aptian long-term sea level high stand. The Tethyan late Aptian–middle Albian long-term (2nd order) sea level rise was masked by regional late Aptian–Albian uplift, which affected deposition of the later regressive sequence. The Cenomanian shows a change in depositional setting from a proximal inner shelf (lower Cenomanian) to a middle shelf setting (middle–upper Cenomanian), corresponding to the Tethyan long-term latest early–late Cenomanian sea level rise.We demonstrate that northeastern Gondwana (Egypt) experienced different climatic conditions from other parts of the Northern Gondwana Phytogeographic Province. The climate in Egypt shifted from less warm and more humid conditions of the Hauterivian–early Barremian to a warmer and drier climate during the late Barremian–middle Aptian, although never becoming as dry as western Northern Gondwana. Warmer and more humid conditions were reestablished during the late Aptian and became even more accentuated during the Albian–Cenomanian, in contrast to the warm and much drier climate of Northern Gondwana at that time. Turonian climatic conditions may have been less humid as a result of the breakup of the Western Gondwanan supercontinent and the northeasterly drift of the African continent. The climatic conditions experienced in northeastern Gondwana developed through the early-mid Cretaceous as a result of changes in palaeolatitudinal position, variations in sea level, and shifts in the Intertropical Convergence Zone, which drove fluctuations between periods of warm humid and warm dry conditions.

Early Cretaceous tectonostratigraphic evolution of the Erlian Basin, NE China: A record of Late Mesozoic intraplate deformation in East Asia

Abstract The Erlian Basin is one of the largest intracontinental Meso-Cenozoic basins in Northeast China. The basin is filled with extra-thick Cretaceous sediments and offers unique opportunities to untangle the Late Mesozoic intraplate deformation in East Asia. However, despite decades of petroleum exploration in the basin, the Early Cretaceous chronostratigraphy and structural evolution of the Erlian Basin have been poorly studied. Based on newly obtained zircon U-Pb geochronological data, well lithological logs, and seismic reflection profiles, the present study carries out a detailed analysis of the tectonostratigraphic evolution of the Erlian Basin during the Early Cretaceous. The depositional ages of the Lower Cretaceous strata in the basin are refined, and the Early Cretaceous evolution of the basin is reestablished. The Lower Aershan, Upper Aershan, Lower Tenggeer, Upper Tenggeer, and Saihan formations are constrained to the middle Valanginian (ca. 138–135 Ma), late Valanginian (ca. 135–133 Ma), Hauterivian–early Aptian (ca. 133–121 Ma), middle Aptian (ca. 119–115 Ma), and latest Aptian–Albian (post ca. 115 Ma), respectively. The Early Cretaceous syn-rift subsidence of the basin was intermittent rather than continuous, and was punctuated by multiphase contractional deformation during the earliest Cretaceous (prior to ca. 138 Ma), middle Valanginian (ca. 135 Ma), latest Valanginian (ca. 133 Ma), middle Aptian (ca. 120 Ma), late Aptian (ca. 115 Ma), and Early/Late Cretaceous boundary. We tentatively attribute the extensional and contractional deformation in the Erlian Basin to a series of continental collisions along Asian margins: Karakoram-Lhasa/Qiangtang collision, Kolyma-Omolon/Siberia collision, Siberia/Amuria collision, Chukotka/Kolyma-Omolon collision, West Philippines/South China collision, and Okhotomorsk/East Asia collision.

Carbonate REE + Y signatures from the restricted early marine phase of South Atlantic Ocean (late Aptian – Albian): The influence of early anoxic diagenesis on shale-normalized REE + Y patterns of ancient carbonate rocks

Rare earth elements plus yttrium have been extensively applied in paleoenvironmental studies of ancient carbonate successions due to their fractionation in the marine environment. However, in modern marine anoxic environments, seawater REE + Y signatures can be suppressed in reducing conditions (e.g. stagnant basins and/or early diagenesis) by REE remobilization from several sedimentary components (e.g. detrital siliciclastics, oxides, organic compounds). We present the shale-normalized REE + Y signatures for a transgressive marine carbonate succession of the primitive South Atlantic Ocean (latest Aptian-Albian), in a restricted marine setting with anoxic bottom conditions, to provide and evaluate the REE + Y record deposited in such conditions. Based on well-constrained paleoenvironmental reconstruction through microfacies analysis, three shale normalized REE + Y patterns were identified, varying according to the microfacies associations (MA) and related diagenetic environments: a) light REE-enriched patterns in the more proximal MA associated with burial diagenesis at the base of section; b) flat patterns towards distal MA related to anoxic and sulfidic early diagenesis; and c) middle REE-enriched patterns in MA related to dissolution of FeMn oxy-hydroxide grains under reducing early diagenesis. Cerium anomalies are absent due to stagnant water mass conditions, in accordance with previous studies for the early marine South Atlantic. Y/Ho ratios are lower than modern seawater values, with an increasing trend towards more distal facies. The “non-seawater” shale-normalized REE + Y patterns of the marine carbonates from the primitive South Atlantic Ocean corroborate studies in modern marine reducing environments, in which REE can be remobilized from detrital phases, oxides and organic compounds, suppressing the primary seawater REE + Y signature of authigenic minerals. Caution is suggested for the sole use of carbonate REE + Y signatures as paleoenvironmental proxies, especially in ancient successions lacking proper microfaciological components.

Inversion of the Erlian Basin (NE China) in the early Late Cretaceous: Implications for the collision of the Okhotomorsk Block with East Asia

A significant transition in tectonic regime from extension to compression occurred throughout East Asia during the mid-Cretaceous and has stimulated much attention. However, the timing and driving mechanisms of the transition remain disputed. The Erlian Basin, a giant late Mesozoic intracontinental petroliferous basin located in the Inner Mongolia, Northeast China, contains important sedimentary and structural records related to the mid-Cretaceous compressional event. The stratigraphical, sedimentological and structural analyses reveal that a NW–SE compressional inversion occurred in the Erlian Basin between the depositions of the Lower Cretaceous Saihan and Upper Cretaceous Erlian formations, causing intense folding of the Saihan Formation and underlying strata, and the northwestward migration of the depocenters of the Erlian Formation. Based on the newly obtained detrital zircon U-Pb data and previously published paleomagnetism- and fossil-based ages, the Saihan and Erlian formations are suggested as latest Aptian–Albian and post-early Cenomanian in age, respectively, implying that the inversion in the Erlian Basin occurred in the early Late Cretaceous (Cenomanian time). Apatite fission-track thermochronological data record an early Late Cretaceous cooling/exhuming event in the basin, corresponding well with the aforementioned sedimentary, structural and chronological analyses. Combining with the tectono-sedimentary evolutions of the neighboring basins of the Erlian Basin, we suggest that the early Late Cretaceous inversional event in the Erlian Basin and the large scale tectonic transition in East Asia shared the common driving mechanism, probably resulting from the Okhotomorsk Block–East Asia collisional event at about 100–89 Ma.

The geological history of the Istria ‘Depression’, Romanian Black Sea shelf: tectonic controls on second-/third-order sequence architecture

Abstract The Istria ‘Depression’ or sub-basin of offshore Romania lies at the intersection of the trans-European Tornquist–Teisseyre ‘Zone’ and the Black Sea back-arc basin, just outboard of the East Carpathian orogenic welt. Its Late Mesozoic–Cenozoic succession records an extraordinary polyphase history of subsidence and sedimentation, interrupted by several quite spectacular second-/third-order erosional unconformities, reflecting the interplay between these tectonic domains. The unconformities divide the succession into a number of stratigraphic sequences. The sub-basin first developed as a transtensional rift in the Triassic–Early Jurassic, evolving into a narrow oceanized trough in the later Jurassic. This was tilted west during the Early Cretaceous, and the residual Late Jurassic topography was filled and buried by a west-facing clastic–evaporite wedge. Following Late Aptian–Albian(?) rifting, post-rift subsidence and spreading in the Western Black Sea imposed a strong easterly tilt, encouraging the partial evacuation of its Early Cretaceous sedimentary fill by gravity-driven mass wastage. The incised valley topography was subsequently infilled and buried during the later Cretaceous and Early Cenozoic. During the mid-Late Cenozoic, the Black Sea Basin experienced intermittent periods of partial to complete isolation from the world ocean and significant base-level drawdown. The first major sea-level fall occurred in the Eocene when the Istria ‘Depression’ was deeply incised, to be healed by Oligocene shales during the subsequent rise. Yet another period of drawdown and exposure occurred in the mid-Miocene, with extensive shelf-margin mass wastage and erosion, followed by re-flooding and deposition of a transgressive backstepping sequence in the middle-late Miocene. Messinian drawdown in the Mediterranean caused a further period of isolation and falling base level. The shelf margin was again exposed, and experienced widespread mass wastage and slumping. Rising sea level eroded the earlier slumped sequence and the margin was healed by a lowstand prograding wedge in the late Miocene–early Pliocene. This was followed by shelf sedimentation in the Plio-Pleistocene periodically interrupted by canyon-incision events, testifying to continued climatically or tectonically imposed base-level fluctuations. Several direct and indirect tectonic factors were responsible for valley/canyon incision within the Istria Depression and erosion of the Romanian Black Sea shelf margin. These include: (1) the local structural framework; (2) direct tectonic uplift and tilting; and (3) more indirect tectonically imposed isolation encouraging significant base-level falls.

Cretaceous sedimentation along the Romanian margin of the Black Sea: inferences from onshore to offshore correlations

Abstract It is generally believed that the western part of the Black Sea opened during the Early Cretaceous. However, recent data and interpretation from the Turkish margin suggest rifting continued into the Coniacian or Santonian. In this review, the evidence related to the Black Sea rifting on the conjugate Romanian margin is reassessed. Our integrated interpretation of this region, supported by outcrop observations, core and detrital zircon data, suggests that rifting started during the Aptian and continued intermittently until the mid-Turonian in two distinct stages. These stages are bounded by significant unconformities and reflect the progressive widening of the rift system. The first synrift stage started in the Aptian with the deposition of fluvial and lacustrine clastic successions, and locally marine carbonates in semi-isolated depocentres. These sinks began to coalesce during the latest Aptian–Albian with shallow-marine transgression from the east, and deposition of coastal swamp, deltaic and littoral facies. The second phase of rifting during the Cenomanian was marked by transgressive shallow-marine deposits overstepping the earlier Albian depocentres. Continental break-up followed in the mid-Turonian associated with regional uplift and erosion of the basin margin and the local deposition of fluvial conglomerates.

Oursins toxasteridés du genre Heteraster dans le Crétacé inférieur du haut bassin du Zagros, Sud de l'Iran

Two species of spatangoid echinoid belonging to Heteraster Orbigny, 1853, are described from Lower Cretaceous deposits (Gadvan and Dariyan formations) at the Kuh-e Gadvan and Banesh sections situated in Zagros Mountains, south of Iran. Heteraster couloni (Agassiz, 1839) is confirmed in the Barremian and Heteraster delgadoi (Loriol, 1884) in the late Aptian-Albian of Iran. The occurrences of Heteraster and other spatangoid echinoids in Iran show a clear distinction between assemblages from the southern and northern margins of the Tethys during the Early Cretaceous.

Development history of the southern terminus of the Central Atlantic; Guyana–Suriname case study

Abstract The study focuses on the offshore Guyana–Suriname–French Guiana region. It draws from seismic, well, gravimetric and magnetic data. They indicate that the continental break-up along the western margin of the Demerara Plateau took place during the Callovian–Oxfordian, associated with the Central Atlantic opening, and accommodated by normal faults. The continental break-up in the SE offshore Guyana accommodated by strike-slip faults was coeval. The continental break-up along the NE and eastern margins of the Demerara Plateau took place during the late Aptian–Albian, associated with the opening of the Equatorial Atlantic, and accommodated by dextral strike-slip and normal faults, respectively. Different spreading vectors of the Central and Equatorial Atlantic required development of the Accommodation Block during the late Aptian/Albian–Paleocene in their contact region, and in the region between the Central Atlantic and its southernmost portion represented by the Offshore Guyana Block, which were separated from each other by the opening Equatorial Atlantic. Its role was to accommodate for about 20° mismatch between the Central and Equatorial Atlantic spreading vectors, which has decreased from the late Aptian/Albian to Paleocene down to 0°. Differential movements between the Central and Equatorial Atlantic oceans were also accommodated by strike-slip faults of the Guyana continental margin, some active until the Paleocene. Supplementary material: Extended methods and discussion chapters are available at http://www.geolsoc.org.uk/SUP18875

Rudist bivalves and the Pacific in the Late Jurassic and Early Cretaceous

Although rudists of Late Jurassic to earliest Cretaceous age are known from Nova Scotia to Japan, the oldest specimens recovered from Pacific seamounts are Barremian (or possibly Hauterivian). The lack of evidence for disjunct endemism limited to either side of the ocean, then, precludes the inference that earlier rudists might have been present within it. Yet trans-Pacific range expansion of Caribbean-derived taxa, by means of larval ‘island-hopping’, was accomplished by the Early Aptian. Following a mid-Aptian mass extinction, the Pacific then became an important nursery of rudist re-diversification. Late Aptian rudists in Japan and derivative Late Aptian–Albian polyconitids in the Japanese Seamounts and Cebu show affinities with those from the eastern (Himalayan) sector of the northern Tethyan margin. By contrast, the caprinid Caprina mulleri in the Mid-Pacific Mountains is most closely allied with the C. choffati–C. adversa lineage known from the Atlantic–Mediterranean Tethyan region. However, the Pacific species could have been derived from an Early Aptian Caribbean Caprina that survived in some Pacific refuge, later reintroducing the genus to the Tethyan region in the Late Albian. Colonization of Pacific volcanic prominences ceased in the latest Albian, with the demise of carbonate platforms there, and was not resumed until the Campanian–Maastrichtian.

Carbon and oxygen-isotope stratigraphy of the Early Cretaceous carbonate platform of Pădurea Craiului (Apuseni Mountains, Romania): A chemostratigraphic correlation and paleoenvironmental tool

Stable C and O isotope records were obtained from carbonate rocks spanning the Hauterivian to Cenomanian interval collected in several sections from the carbonate platform of Pădurea Craiului (Apuseni Mountains, Romania). In the absence of some key biostratigraphic marker species, stable isotopes were applied as a tool for stratigraphic correlation and dating. The composite δ13C and δ18O curves for the Early Cretaceous shows variable conditions with large positive and negative excursions and provide information on past environmental changes. The Hauterivian and the Barremian limestones (Blid Formation) display lower δ13C values (−2.8‰ to +2.9‰) relative to the Aptian–Albian deposits (−2.6‰ to +5.4‰) (Ecleja, Valea Măgurii and Vârciorog Formations). The red detrital formation (Albian–Cenomanian) is characterized by a highly variable distribution of the δ13C values (−3.5‰ to +3.9‰). Based on the similarities between the C-isotope curve established in Pădurea Craiului and from other sections in the Tethyan and the Pacific regions, two major oceanic anoxic events characterized by δ13C positive excursions were clearly recognized. The first is the OAE1a event (Early Aptian) in the upper part of the Ecleja Formation and the Valea Măgurii Formation. The second is the OAE1b event (Late Aptian–Albian) in the upper part of the Vârciorog Formation and in the Subpiatră Member. The position of the Aptian/Albian boundary is estimated to be at the upper part of the Vârciorog Formation, immediately after the beginning of the δ13C positive excursion. The δ13C data show major negative excursions during the Barremian (Blid Formation), Early Aptian (Ecleja Formation), and Late Aptian (Vârciorog Formation). The O isotope variation pattern (−10.2‰ to −2.1‰) is consistent with progressively warming temperatures during the Early Barremian followed by a cooling period. A subsequent warming period culminated in the Early Aptian. A significant cooling phase corresponds to the Late Aptian and Early Albian and the climate cooled again during the Late Albian and into the Early Cenomanian stage. The data provide a better understanding of the Early Cretaceous sedimentation cycles in Pădurea Craiului and create a more reliable framework for regional correlations.

Barremian–Cenomanian palaeotemperatures for Australian seas based on new oxygen-isotope data from belemnite rostra

Oxygen‐isotope ratio (δ18O) data are presented for 55 belemnite rostra specimens of late Aptian–Albian age from the Great Artesian Basin of eastern Australia and of late Barremian–early Cenomanian age from the Carnarvon Basin of Western Australia. The belemnites were carefully screened for diagenesis by means of catholuminescence and trace element geochemistry. The δ18O record for the Carnarvon Basin (palaeolatitude ~40°S) is interpreted to show a long‐term warming trend from ~10°C in the Aptian to a maximum of ~15°C in the Cenomanian. Shorter-term fluctuations in the mid-Albian are also apparent. Data from the Great Artesian Basin (palaeolatitude 40°–55°S) show a wider δ18O range which is attributed to the epeiric sea context of this sample set. The larger range in δ18O is interpreted to reflect differing water mass characteristics, due possibly to a combination of variable freshwater dilution, seasonal temperature fluctuations and isotopic exchange between seawater and pyroclastic sediment within the epeiric sea. Nevertheless, the Aptian–Albian δ18O trends are still comparable to those obtained for the Carnarvon Basin. The inferred palaeotemperature trends for the Australian sedimentary basins are consistent with records from other regions and demonstrate that broadly synchronous palaeotemperature variations can be recognised on a global scale during the Cretaceous. Although our data do indeed show cool temperatures within the Aptian (and the Albian) reaching a low of ~10°C, these estimates are somewhat warmer than those based on glendonite genesis. However, the exact position of the glendonite-bearing and dropstone-rich parts of the Bulldog Shale is poorly constrained with respect to our isotope data, and the warmest temperatures were of late Albian and early Cenomanian age. However, to conform to greenhouse warmth and equability, and to achieve parity with other palaeotemperature records, the δ18Oseawater estimate of −1.0‰ that is generally used for Cretaceous oceans in an ice-free world needs to be adjusted to a slightly higher value.

Sedimentary succesion of the Lower Cretaceous deposits from the north-western part of Pădurea Craiului (Apuseni Mountains, Romania)

Within the general succession of the Lower Cretaceous deposits from the Vârciorog-Dobreşti area (Pădurea Craiului Mountains), carbonate and terrigenous deposits were identified. The limestones were assigned to two distinctive lithostratigraphic units: the Valea Măgurii and Vârciorog formations. Based on the orbitolinids Palorbitolina lenticularis and Mesorbitolina texana their ages are assigned to the early Aptian, and respectively late Aptian–Albian. The terrigenous facies mainly include fine grained deposits (clays, siltites, marls) and, to a lesser extent, coarser ones (glauconitic sandstones and conglomerates), and they are attributed to the Ecleja and Vârciorog formations. The marls of the Ecleja Formation have been observed in a single section. The lack of fossils prevents assigning an age to this marl succession. Based on their relative location, i.e., at the base of the late Bedoulian Valea Măgurii Limestones, they may be assigned to the early Aptian (early Bedoulian). The siliciclastic deposits of Vârciorog Formation cover the largest areas in the region. Their late Aptian–Albian age is established based on the presence of Mesorbitolina texana. Additional arguments are represented by an ammonite fauna assigned to the terminal Bedoulian–early Gargasian. This fauna is located at the base of the Vârciorog Formation. The Lower Cretaceous deposits cropping out in this area have been investigated in seven geological sections. The data interpretation allowed a synthetic reconstruction of the succession and of the depositional environments.

Mathesia darderi (Astre) (Bivalvia, Hippuritoidea, Monopleuridae): Morphological, biogeographical and ecological changes in the Mediterranean domain during the late Barremian–Albian

Mathesia darderi, a slender cylindrical monopleurid genus, formerly documented from the late Aptian–Albian of Spain, France, Tunisia, Algeria, Egypt and Turkey, has been discovered in the upper Barremian and the lower Aptian of Bulgaria and Spain. Notwithstanding some morphological changes, Barremian–lower Aptian forms and those of the upper Aptian–Albian possess the same myocardinal organisation and the same microstructural attributes. The inner shell margin of the right valve displays scalloped, festooned, tubular and vermiform microstructures. The most prominent evolutionary trait of M. darderi is the increase in body size through time. A statistical analysis of size distributions show that populations of the late Barremian–early Aptian, and the late Aptian, and those of the early to middle Albian, are significantly different; a pattern which has a biostratigraphic potential. Ecological changes through time are expressed by a displacement of communities from the central/distal part, to the proximal part of carbonate platforms. M. darderi is present locally in the upper Barremian–lower Aptian, and has its major spreading over the European and Arabo–African margins of the Mediterranean Tethys during the Clansayesian–lower to middle Albian. The disappearance of the species at the Middle–Upper Albian boundary, correlates with a critical, spatial reduction of carbonate platforms.

Sedimentology and sequence stratigraphy from outcrops of the Kribi-Campo sub-basin: Lower Mundeck Formation (Lower Cretaceous, southern Cameroon)

The Kribi-Campo sub-basin is composed of an Early to Mid Cretaceous series from West Africa’s Atlantic coast and is located in southern Cameroon in the Central African equatorial rain forest. It is the smallest coastal basin in Cameroon and forms the southern part of the Douala/Kribi-Campo basin known as Douala basin ( s.l.). Until now, no detailed sedimentological studies have been carried out on the outcrops of this basin located in the Campo area. The aim of this study was to characterise the depositional environments, vertical evolution and tectonic context of these Lower Cretaceous series in order to make a comparison with adjacent basins and replace them in the geodynamic context. Facies analysis of the Lower Mundeck Formation (Lower Cretaceous) indicates the presence of four major, interfigered facies associations, that are inferred to represent elements of an alluvial to lacustrine–fan delta system. The clast lithologies suggest proximity of relief supplying coarse-grained sediment during the deposition of the Lower Mundeck Formation at Campo. The general dip and direction of the bedding is approximately 10°–12°NW, which also corresponds to the orientation of the foliations in the underlying metamorphic basement. The main sedimentary succession is characterised by a major retrogradational/progradational cycle of Late Aptian age, evaluated at about 3 Ma, with a well-developed progradational trend characterised by fluctuations of the recognised depositional environments. Fluctuations in lake level and sediment supply were possibly controlled by active faults at the basin margin, although climatic changes may have also played a role. The consistently W–WNW palaeoflow of sediments suggests that the palaeorelief was located to the east and could be oriented in a NNE–SSW direction, downthrown to the west. Local outcrops dated as Albian, both north and south of the main outcrop, display some marine influence. These deposits are cut by 040–060 faults parallel to the oceanic transform. Similarly, the Lower Mundeck Formation of the Campo outcrops is considered to be associated mainly with the early drift period of Late Aptian–Albian age. This study is also the first step of knowledge of these African margin deposits, to realise in the future the correlations between outcrops and offshore data.

Mathesia Mainelli (Hippuritoidea, Monopleuridae) from the Late Aptian−Albian of the Mediterranean Region: A Revision

Agria darderi Astre and Mathesia terticolloquiirudistarum Mainelli represent a single taxonomic entity: Mathesia darderi (Astre). Mathesia is characterized by an erect posterior myophoral plate and an anterior myophoral crest in the LV, the RV myophores being on the shell wall. A peculiar shell structure is observed in the RV: the junction between the outer calcitic shell layer and the inner formerly aragonitic shell layer is scalloped or festooned and usually includes longitudinal tubes. The overall morphological traits and myocardinal organisation of Mathesia are similar to those of Debrunia, although the latter lacks the scalloped or tubular inner shell features of the former. Debrunia is regarded as the ancestor of Mathesia. The palaeobiogeographical distribution of Mathesia darderi includes the southern and northern margins of the Mediterranean Tethys, and its maximum geographical extent coincides with the late Aptian-Albian.

Controls and evolution of facies patterns in the Upper Barremian–Albian Levant Platform in North Sinai and North Israel

Abstract The Upper Barremian–Albian Levant Platform was studied in North Sinai and Israel (Galilee and Golan Heights) by bio- and lithostratigraphy, facies analyses, and sequence stratigraphy. Integrating shallow-marine benthic foraminifera (mainly orbitolines), ammonite, and stable isotope data resulted in a detailed stratigraphic chart. Transects across the shallow shelf in both regions are based on facies analysis and form the basis for depositional models. In both transects five platform stages (PS I–V) were identified, which differ significantly in their stratigraphic architecture, mainly controlled by local tectonics, climate and second-order sea-level changes. In North Sinai, a transition from a shallow-shelf that is structured by sub-basins through a homoclinal ramp into a flat toped platform is recognized, while the sections in North Israel show a transition from a homoclinal ramp into a fringing platform. Local normal faults influenced the depositional architecture of the Upper Barremian–Lower Aptian strata in North Sinai and were attributed to syn-rift extensional tectonics. Four second-order sequence boundaries were identified, bounding Mid-Cretaceous Levant depositional sequences. These well-dated second-order sequence boundaries are MCL-1 (Late Barremian), MCL-2 (earliest Late Aptian), MCL-3 (Lower Albian), and MCL-4 (Late Albian). The sea-level history of the Levant Platform reflects the Late Aptian–Albian global long-term transgression, while the second-order sea-level changes show good correlation with those described from the Arabian plate.

Debrunia, a new Barremian genus of petalodontid Monopleuridae (Bivalvia, Hippuritoidea) from the Mediterranean region

Abstract: Debrunia gen. nov. is characterized by asymmetric myophoral apophyses on the left valve: the posterior one a plate, the anterior a crest. The myophores on the right valve are on the shell wall. It belongs to a group of cylindro‐conical petalodontid Monopleuridae including Petalodontia and Pseudopetalodontia, and possesses some affinities with Agriopleura. Monopleura mutabilis Matheron is the type species of Debrunia gen. nov., and Monopleura (Petalodontia) bruni Douvillé is also ascribed to this genus. The two species are found in late Barremian beds from SE France. Evolutionary trends regarding the myophores of the left valve are comparable and nearly coeval with those of Agriopleura. Debrunia may be the root of the late Aptian–Albian genera Pseudopetalodontia and Mathesia. and may range throughout the Barremian‐Aptian.

Praecaprotina kashimae nov. sp.(Bivalvia, Hippuritacea) from the Daiichi-Kashima Seamount (Japan Trench)

Praecaprotina kashimae nov. sp. is described from the Daiichi-Kashima Seamount in the Japanese group of guyots. This species differs in size, radial bands, longitudinal ornamentation, and some internal characters from the Japanese Praecaprotina yaegashii. Associated microfossils, mainly Orbitolinidae, point to the late Aptian–Albian p.p., whereas the associated requieniid rudist Kugleria sp. merely reflects an Albian age. Our finding illustrates the biogeographic affinity of the Daiichi-Kashima fauna with that of Japan and tends to support a “Japanese Province,” with Praecaprotina as index taxa. The latitudinal extent and configuration of the Japanese province in the Western Pacific during the late Aptian–Albian depends on palaeotectonic reconstructions dealing with the original geographic position of the Daiichi-Kashima Guyot.

Radiolarian age constraints on Mesotethyan ocean evolution, and their implications for development of the Bangong–Nujiang suture, Tibet

Abstract: Radiolarian discoveries indicate that deep-marine conditions prevailed in central Tibet from the early Middle Jurassic until well into the Early Cretaceous (late Hauterivian–early Aptian; 131–121 Ma) and help to constrain the temporal extent of oceanic conditions along the Bangong–Nujiang suture. These new fossils occur in chert or siliceous mudstone blocks associated with the Lagkor Tso ophiolitic mélange. Basin inversion associated with closure of Mesotethys between the Qiangtang and Lhasa terranes was accompanied by mélange formation and predated regionally widespread deposition of overlying shallow-marine late Aptian–Albian orbitolinid limestones.