Carbonate facies evolution from the late albian to Middle Cenomanian in Southern Istria (Croatia): influence of synsedimentary tectonics and extensive organic carbonate production

Summary During the Late Albian, Early and Middle Cenomanian in the NW part of the Adriatic Carbonate Platform (presentday Istria) specific depositional systems characterised by frequent lateral and vertical facies variations were established within a formerly homogeneous area, ranging from peritidal and barrier bars to the offshore-transition zone. In southern Istria this period is represented by the following succession: thin-bedded peritidal peloidal and stromatolitic limestones (Upper Albian); well-bedded foreshore to shoreface packstones/grainstones with synsedimentary dliding and slumping (Vraconian-lowermost Cenomanian); shoreface to off-shore storm-generated limestones (Lower Cenomanian); massive off-shore to shoreface carbonate sand bodies (Lower Cenomanian); prograding rudist bioclastic subaqueous dunes (Lower to Middle Cenomanian); rudist biostromes (Lower to Middle Cenomanian), and high-energy rudist and ostreid coquina beds within skeletal wackestones/packstones (Middle Cenomanian). Rapid changes of depositional systems near the Albian/Cenomanian transition in Istria are mainly the result of synsedimentary tectonics and the establishment of extensive rudist colonies producing enormous quantities of bioclastic material rather than the influence of eustatic changes. Tectonism is evidenced by the occurrence of sliding scars, slumps, small-scale synsedimentary faults and conspicuous bathymetric changes in formerly corresponding environments. Consequently, during the Early Cenomanian in the region of southern Istria, a deepening of the sedimentary environments occurred towards the SE, resulting in the establishment of a carbonate ramp system. Deeper parts of the ramp were below fair-weather wave base (FWWB), while the shallower parts were characterised by high-energy environments with extensive rudist colonies, and high organic production leading to the progradation of bioclastic subaqueous dunes. This resulted in numerous shallowing- and coarsening-upwards clinostratified sequences completely infilling formerly deeper environments, and the final re-establishment of the shallow-water environments over the entire area during the Middle Cenomanian.     

Changes in sedimentary patterns of coastal and deep-sea successions from the North Atlantic (Portugal) linked to Early Cretaceous environmental change

Coastal mixed carbonate-siliciclastic and carbonate deposits of Late Barremian to Early Aptian age from the Lusitanian Basin (Portugal) are compared with a deep-sea succession (ODP 641) off the coast of Portugal. The coastal deposits show an abrupt cessation of rudist-dominated carbonate deposition marked by an emersion horizon and followed by the deposition of orbitolinid-rich marls during the Early Aptian. The subsequent development of the carbonate platform during the Late Aptian is masked by a hiatus. For this time interval shallow-water debris deposits of the deep-sea succession ODP 641 indicate that carbonate production in shallow-water areas resume in the early Late Aptian. Carbon-isotope stratigraphy in combination with available biostratigraphic data is used for intrabasinal correlation and for the correlation of the Portuguese with shallow-water successions from Switzerland, France, Oman and the Pacific. The correlation reveals that during the Early Aptian similar changes in their sedimentary patterns occur at the beginning of a marked negative shift of carbon-isotope values associated with the global deposition of organic rich black shales in the deep sea (OAE 1a). In all compared sections rudist-dominated carbonate deposition is stopped and followed either by orbitolinid-rich deposits, the deposition of microbial carbonates or by the drowning of the carbonate platform. The comparison shows that the deterioration for carbonate platform growth conditions during the Early Aptian occurred essentially simultaneously at the various localities. During this episode the ocean waters were in a preconditioned state of acidification stressing biocalcifying organisms. Sea level change combined with local effects like elevated nutrient levels and higher temperatures, were probably determining the nature of sedimentary change in shallow-water environments during the carbonate crisis. In the sections studied in Portugal the high abundance of orbitolinids overlying rudist limestones indicates that increased nutrient input may have played an important local role among the factors that caused an overall deterioration for carbonate producers during the late Early Aptian.     

Benthic foraminiferal assemblages of the Cretaceous platform carbonate succession in the Yavca area (Bolkar Mountains, S Turkey): biostratigraphy and paleoenvironments

The microbiostratigraphic analysis of the three outcrop sections from the Cretaceous inner platform carbonate succession in the Yavca area (Bolkar Mountains) allows to recognize the four local benthic foraminiferal zones. These are: (1) Voloshinoides murgensis and Praechrysalidina infracretacea Cenozone in the Lower Aptian; (2) Pseudorhapydionina dubia and Biconcava bentori Cenozone in the Middle-Upper Cenomanian; (3) Ostracoda and Miliolidae Interval Zone in the probable Turonian, represented by dolomitized limestones without any significant markers; (4) Moncharmontia compressa and Dicyclina schlumbergeri Cenozone in the Coniacian-Santonian. The benthic foraminiferal assemblages correspond to those in other areas of the Mediterranean realm, with the exception of a lack of alveolinids and orbitolinids due to unfavorable environmental conditions (inner platform, restricted shelf). After the regionally well-known emergence during the late Aptian, Albian and early Cenomanian, very shallow subtidal to intertidal conditions were re-established during the middle-late Cenomanian time. The Coniacian-Santonian benthic foraminiferal assemblage shows an increase in diversity and abundance as a result of open marine influence, confirmed by the presence of larger foraminifera (Dicyclina), Rotaliidae and radiolitid fragments. Thaumatoporella and Aeolisaccus-bearing wackestone intercalations still indicate the existence of sporadic restricted environment conditions. The Cretaceous shallow-water platform carbonate succession of the Yavca area is conformably overlain by gray pelagic limestones with calcispheres and planktonic foraminifera. The Campanian flooding of the Bolkar Da? carbonate platform resulted in drowning of the pre-existing biota and facies.     

Upper Aptian–albian Rudist Bivalves from Northern Sinai, Egypt

Rudist bivalves are described from two Upper Aptian–Albian sections in northern Sinai, Egypt. Independent stratigraphical evidence is provided by orbitolinid foraminifera and sequence stratigraphic correlation with other, ammonite–bearing sections of the region. With the exception of Eoradiolites liratus (Conrad) and Sellaea, this is the first record of Lower Cretaceous rudists from Egypt. A rather continuous occurrence of rudists is recorded in the more open marine deposit at Rizan Aneiza, but they occur only in the Middle–Upper Albian at Gebel Raghawi to the south–west. In the uppermost Aptian to basal Middle Albian at Rizan Aneiza, the succession of Eoradiolites plicatus–E. murgensis–E. liratus is interpreted as a lineage of chronospecies. Of particular interest is the presence of canaliculate rudists in the Upper Albian of both sections, as there exists a large gap, spanning the Upper Aptian and most parts of the Albian, in the fossil record of the Caprininae d’Orbigny. Neocaprina raghawiensis sp. nov. and Neocaprina? sp. are recognized as ancestors of Cenomanian species of Neocaprina Pleni?ar and Caprinula d’Orbigny. The inclusion of these genera in the Caprininae d’Orbigny is questioned and the phylogenetic descent from an unidentified Albian taxon with well–developed myophoral cavities is suggested.     

Platform configuration, microfacies and cyclicities of the upper Albian to Turonian of west-central Jordan

We present a comprehensive facies scheme for west-central Jordan platform deposits of upper Albian to Turonian age, discuss Cenomanian and Turonian carbonate cycles, and reconstruct the paleogeographic evolution of the platform. Comparisons with adjacent shelf areas (Israel, Sinai) emphasize local characteristics as well as the regional platform development. Platform deposits are subdivided into fifteen microfacies types that define eight environments of deposition of three facies belts. Main facies differences between Cenomanian and Turonian platforms are: rudist-bearing packstones that characterise the higher-energy shallow subtidal (transition zone) during the Cenomanian, and fossiliferous (commonly with diverse foraminifer assemblages) wackestones and packstones of an open shallow subtidal environment. On Turonian platforms high-energy environments are predominantly characterised by oolithic or bioclastic grainstones and packstones, whereas peritidal facies are indicated by dolomitic wackestones with thin, wavy (cryptmicrobial) lamination. Rhythmic facies changes define peritidal or subtidal shallowing-up carbonate cycles in several Cenomanian and Turonian platform intervals. Cyclicities are also analysed on the base of accommodation plots (Fischer Plots). High-frequency accommodation changes within lower Cenomanian cyclic bedded limestones of the central and southern area exhibit two major cyclic sets (set I and II) each containing regionally comparable peaks. Accommodation patterns within cyclic set II coincide with the sequence boundary zone of CeJo1. The lateral and vertical facies distributions on the inner shelf allow the reconstruction of paleogeographic conditions during five time intervals (Interval A to E). An increased subsidence is assumed for the central study area, locally (area of Wadi Al Karak) persisting from middle Cenomanian to middle Turonian times. In contrast, inversion and the development of a paleo-high have been postulated for an adjacent area (Wadi Mujib) during late Cenomanian to early Turonian times, while small-scale sub-basins with an occasionally dysoxic facies developed northwards and further south during this time interval. A connection between these structural elements in Jordan with basins and uplift areas in Egypt and Israel during equivalent time intervals is assumed. This emphasises the mostly concordant development of that Levant Platform segment.     

Late Cenomanian–Early Turonian facies development and sea-level changes in the Bodenwöhrer Senke (Danubian Cretaceous Group, Bavaria, Germany)

The Upper Cenomanian–Lower Turonian litho-stratigraphic units of the Danubian Cretaceous Group of the proximal Bodenwöhrer Senke (Regensburg, Eibrunn and Winzerberg formations, the latter consisting of a lower Reinhausen Member and an upper Knollensand Member), have been investigated with a focus on facies analysis and sequence stratigraphy. Analyses of litho-, bio-, and microfacies resulted in the recognition of 12 predominantly marine facies types for the Eibrunn and Winzerberg formations. Petrographic and paleontological properties as well as gradual transitions in the sections suggest that their depositional environment was a texturally graded, predominantly siliciclastic, storm-dominated shelf. The muddy–siliceous facies types FT 1–3 have been deposited below the storm wave-base in an outer shelf setting. Mid-shelf deposits are represented by fine- to medium-grained, bioturbated, partly glauconitic sandstones (FT 4–6). Coarse-grained, gravelly and/or shell-bearing sandstones (FT 7–10) developed in the inner shelf zone. Highly immature, arkosic coarse-grained sandstones and conglomerates (FT 11 and 12) characterize an incised, high-gradient braided river system. The Winzerberg Formation with its general coarsening- and thickening-upward trend reflects a regressive cycle culminating in a subaerial unconformity associated with a coarse-grained, gravelly unit of marine to fluvial origin known as the “Hornsand” which is demonstrably diachronous. The overlying Altenkreith Member of the Roding Formation signifies the onset of a new transgressive cycle in the early Middle Turonian. The sequence stratigraphic analysis suggests that the deposition of the Upper Cenomanian and Lower Turonian strata of the Bodenwöhrer Senke took place in a single cycle of third-order eustatic sea-level change between the major sequence boundaries SB Ce 5 (mid-Late Cenomanian) and SB Tu 1 (Early–Middle Turonian boundary interval). The southeastern part of the Bodenwöhrer Senke was flooded in the mid-Late Cenomanian (Praeactinocamax plenus transgression) and a second transgressive event occurred in the earliest Turonian. In the central and northwestern parts of the Bodenwöhrer Senke, however, the initial transgression occurred during the earliest Turonian, related to pre-transgression topography. Thus, the Regensburg and Eibrunn formations are increasingly condensed here and cannot be separated anymore. Following an earliest Turonian maximum flooding, the Lower Turonian Winzerberg Formation filled the available accommodation space, explaining its constant thickness of 35–40 m across the Bodenwöhrer Senke and excluding tectonic activity during this interval. Rapid sea-level fall at SB Tu 1 terminated this depositional sequence. This study shows that Late Cenomanian–Early Turonian deposition in the Bodenwöhrer Senke was governed by eustatic sea-level changes.     

Origin and resedimentation of rhodoliths in the Late Paleocene flysch of the Polish Outer Carpathians

This study analyses the rhodolith-bearing deposits in the largest and most rhodolith-rich outcrop of the Polish Outer Carpathian flysch, located in the Silesian Nappe, at the village of Melsztyn. The rhodoliths and sparse associated biota occur as resedimented components in a deep-marine succession of siliciclastic conglomerates and coarse-grained sandstones, deposited by high-density turbidity currents and debris flows. The sediment was derived from a fan-delta system located at the southern margin of the Silesian flysch basin. Stratigraphic data indicate that the succession represents the Upper Istebna Sandstone deposited during the Late Paleocene. The rhodoliths are composed mostly of coralline red algae with seven genera and eight species representing the family Sporolithaceae and the subfamilies Mastophoroideae and Melobesioideae. Rhodoliths show sub-spheroidal and sub-ellipsoidal shapes with encrusting, warty and lumpy growth forms. Lumpy growth forms show massive inner arrangements, whereas the encrusting growth forms are usually made of thin thalli and show more loosely packed inner arrangements. The rhodoliths grew on a moderately mobile siliciclastic substrate in a shallow-marine environment with a low net sedimentation rate. It is inferred that the growth of rhodoliths was favored during a relative sea-level rise. During the subsequent sea-level fall, the rhodoliths and associated siliciclastic deposits were resedimented by gravity flows into the deep-sea setting. The analyzed deposits, like other Paleocene–Eocene deposits of the Polish Outer Carpathians, provide no evidence of coeval widespread shallow-marine carbonate sedimentation along the margins of the Outer Carpathian flysch basins.     

Depositional environment and constraining factors on the facies architecture of the Qom Formation,Central Basin,Iran

In the Central Iran Basin, the mixed carbonate–siliciclastic deposits of the C member of the Qom Formation were deposited on a carbonate platform which is dominated by rhodalgal associations occurring in tropical–subtropical environment. The biogenic rhodalgal association is dominated by bryozoa, coralline red algae, bivalves and echinoids together with smaller amounts of photo-dependent biota including large benthic foraminifera and corals. The abundance of heterozoan association and the bloom of suspension-feeding organisms are the result of an increase in nutrient availability which has profound controlling effect on the biotic system. The low occurrence of symbiont-bearing benthic foraminifera and coral, typical of stable, oligotrophic condition, represents their low tolerance to unstable, nutrient-rich environment. In the investigated Oligocene–Miocene shallow marine carbonate succession, 10 different microfacies were distinguished through depositional texture and biotic components. The rock sequences investigated are referred to an open shelf carbonate platform in which the depositional environments range from outer shelf to inner shelf conditions.     

A NEW LATE CRETACEOUS MACROSEMIID FISH (NEOPTERYGII, HALECOSTOMI) FROM MOROCCO, WITH TEMPORAL AND GEOGRAPHICAL RANGE EXTENSIONS FOR THE FAMILY

Abstract:  A recent collection of actinopterygian fossil fishes from a previously unreported locality in the Cenomanian or Turonian of southeastern Morocco includes a single specimen of a macrosemiid fish. Macrosemiids are more common in Jurassic and Early Cretaceous deposits, with the previously known range of the family being Late Triassic through Aptian or Albian. This discovery therefore extends the temporal range of the family into the Late Cretaceous. Moreover, macrosemiids had not previously been reported from northern Africa or the Moroccan area of the Tethys basin; therefore, this fossil also increases the geographical range of the family. The Moroccan macrosemiid is described in a new genus and species, Agoultichthys chattertoni . A phylogenetic analysis places it basal to all other genera of the family with the exception of Notagogus . Diagnostic characters of the new species include the high number of scales laterally along the body and the greater number of dorsal fin rays than in other members of the family.     

Late Cretaceous sedimentary evolution of a northern sector of the Adriatic Carbonate Platform (Matarsko Podolje,SW Slovenia)

Cretaceous shallow-marine carbonate rocks of SW Slovenia were deposited in the northern part of the Adriatic Carbonate Platform. A 560-m-thick continuous Upper Cenomanian to Santonian carbonate succession has been studied near Hru?ica Village in Matarsko Podolje. With regard to lithological, sedimentological, and stratigraphical characteristics, the succession has been divided into nine lithostratigraphic units, mainly reflecting regressive and transgressive intervals of larger scale. During the latest Cenomanian and Early Turonian, hemipelagic limestones were deposited on top of shallow-marine lagoon and peritidal Upper Cenomanian deposits indicating relative sea-level rise. Subsequently, the deeper marine depositional setting was gradually filled by clinoform bioclastic sand bodies overlain by peritidal and shallow-marine low-energy mainly lagoonal lithofacies. Similar lithofacies of predominately inner ramp/shelf depositional settings prevail over the upper part (i.e., Coniacian to Santonian) of the succession. In the area, the Upper Cetaceous carbonate rocks are separated from the overlying Lower Eocene (Upper Paleocene?) carbonate sequence by regional unconformity denoted by distinct paleokarstic features. On the Adriatic Carbonate Platform the deeper marine carbonate setting, developed at the Cenomanian/Turonian boundary, is usually correlated with OAE2 and related eustatic sea-level rise. Similarly, subsequent reestablished shallow-marine conditions are related to Late Turonian long- and short-term sea-level fall. However, we are suggesting that deeper marine deposits were deposited in a tectonically induced intraplatform basin formed simultaneously with the uplift of the northern and northeastern marginal parts of the Adriatic Carbonate Platform.     

Cambrian (Series 2 to Miaolingian) platform facies from central Sonora,Mexico and the regional correlation

This study provides new insights about depositional paleoenvironments through siliciclastic microfacies, carbonate microfacies, and biofacies analysis from sedimentary formations of the lower and middle Cambrian (Stage 4–Wuliuan), exposed in central Sonora, northern Mexico. Results of the petrographic analysis of 48 samples revealed the following lithologies: quartzarenite, oncolytic rudstone, grainstone-packstone, wackestone, mudstone, and to a lesser extent sandy limestone. Two siliciclastic microfacies were identified: (A) quartzarenite with cross-bedded and horizontal stratification deposited in an intertidal and supratidal environment; and (B) massive quartzarenite with Skolithos ichnofacies deposited in subtidal and intertidal environments. Four carbonate microfacies were identified: microfacies 1 is a sandy limestone with trilobite fragments; microfacies 2 is a grainstone with intraclasts, salterellids, hyolithids, trilobites, and echinoderms plates; microfacies 3 is an oncolytic rudstone consisting of microbes and abundant echinoderms plates; and microfacies 4 is a packstone-grainstone with abundant ooids, trilobite fragments, and echinoderm plates. Two biofacies were identified: Agnostid-polymeroid biofacies with predominance of the trilobites Pentagnostus, Bathyuriscus, Oryctocephalites, and Elrathina; and Pagetia biofacies with abundant trilobites of the genera Pentagnostus, Pagetia and Elrathina. It is concluded by the sedimentation model that changes in sea level is the most important parameter in determining the siliciclastic microfacies, carbonate microfacies and biofacies; as well as the depositional environments that vary from the coastline (subtidal to supratidal) to shallow-water open circulation marine platform with low and high energy waters. The Cambrian deposits of northern Mexico are correlated with the deposits of California and Nevada (USA), as well as to the Precordillera (Argentina), where the species in common show a strong affinity.     

The Antimonio ramp in Sonora,Mexico

The Upper Permian to Lower Jurassic El Antimonio Group has been considered as part of the NW–SE-trending tectonostratigraphic Antimonio terrane in Sonora, Mexico. The Upper Triassic Rio Asunción Formation of the El Antimonio Group comprises a shallow-marine detrital-carbonate succession at three major localities near Caborca and Hermosillo. Previous reconstructions have proposed differing depositional environments for the Rio Asunción Formation (e.g., carbonate platform, carbonate ramp) and remained therefore nonconsensual. The present study has its focus on the Rio Asunción Formation and includes the analyses of 129 thin-sections of carbonate and mixed siliciclastic–carbonate rocks from three localities (Barra los Tanques, Sierra del Álamo, and Sierra Santa Teresa). In Sierra del Álamo, ammonite findings allowed us to confirm the position of the Triassic–Jurassic boundary. Considering the lack of biostratigraphic markers and the clastic nature of the samples, a statistical approach was used to propose a depositional model that can provide more detailed insights into this sedimentary succession. Hierarchical cluster analyses were performed on the gathered abundance data to identify microfacies and to compare the results for each outcrop. Through these analyses, 22 microfacies were defined, which describe the depositional environments of the two main localities. Furthermore, it could be demonstrated through this approach that not only the localities of Barra los Tanques and Sierra del Álamo but also the outcrops near Sierra Santa Teresa belong to the Antimonio depositional system. To gain insights into the relative depositional conditions among the microfacies, non-metric multidimensional scaling was performed. The resulting trends of water energy and proximity to the shoreline of Laurentia were then used to propose a depositional model for the mixed siliciclastic–carbonate Antimonio ramp system.     

Facies pattern and sea-level dynamics of the early Late Cretaceous transgression: a case study from the lower Danubian Cretaceous Group (Bavaria,southern Germany)

The facies development and onlap pattern of the lower Danubian Cretaceous Group (Bavaria, southern Germany) have been evaluated based on detailed logging, subdivision, and correlation of four key sections using an integrated stratigraphic approach as well as litho-, bio-, and microfacies analyses. Contrary to statements in the literature, the transgressive onlap of the Regensburg Formation started in the Regensburg–Kelheim area already in the early Early Cenomanian Mantelliceras mantelli ammonite Zone and not in the Late Cenomanian. In the Early Cenomanian, nearshore glauconitic-bioclastic sandstones prevailed (Saal Member), followed by Middle to lower Upper Cenomanian mid-shelf siliceous carbonates intercalated with fine-sandy to silty marls (Bad Abbach Member). Starting in the mid-Late Cenomanian (Metoicoceras geslinianum ammonite Zone), a considerable deepening pulse during the Cenomanian–Turonian Boundary Event (CTBE) initiated the deposition of the deeper shelf silty marls of the Eibrunn Formation, which range into the early Early Turonian. During the CTBE transgression, also the proximal Bodenwöhrer Senke (ca. 40 km NE of Regensburg) was flooded, indicated by the onlap of the Regensburg Formation onto Variscan granites of the Bohemian Massif, overlain by a thin tongue of lowermost Turonian Eibrunn Formation. A detailed record of the positive δ¹³C excursion of the global Oceanic Anoxic Event (OAE) 2 has been retrieved from this shallow-water setting. An integrated approach of bio-, event-, carbon stable isotope and sequence stratigraphy was applied to correlate the sections and to decipher the dynamics of this overall transgressive depositional system. The Cenomanian successions show five prominent unconformities, which correlate with those being known from basins in Europe and elsewhere, indicating their eustatic origin. The rate of sea-level rise during the CTBE suggests glacio-eustasy as a driving mechanism for Late Cenomanian sea-level changes. The Regensburg and Eibrunn formations of the lower Danubian Cretaceous Group are highly diachronous lithostratigraphic units. Their regional distribution and northeast-directed onlap pattern onto the southwestern margin of the Bohemian Massif can readily be explained by the lateral movements of roughly coast-parallel (i.e., NW/SE-trending) facies belts of a graded shelf system transgressing on a northeastward-rising substrate. It took the Cenomanian coastline ca. 6 Ma to transgress from southwest of Regensburg to the topographically elevated granite cliffs southeast of Roding in the Bodenwöhrer Senke (=60 km distance).     

Siliciclastic input and sedimentation rate as controls on paleoecological distribution of Lower Miocene benthic carbonate producers in a fan–delta: Zagros foreland basin,Iran

This paper aimed to study Lower Miocene (Burdigalian) mixed carbonate–siliciclastic deposits within an Upper Cenozoic synorogenic conglomerate–dominated succession in north of Shalamzar in the Zagros foreland basin, Iran. The deposits are composed of nine facies: foraminiferal mudstone, silty mudstone, sandy mudstone, fossiliferous sandy mudstone, fossiliferous argillaceous mudstone, fossiliferous calclithite, coral limestone, calcareous claystone and hybrid sandstone. The facies represent a mixed carbonate– siliciclastic shelf–type fan–delta. The subenvironments of the fan–delta include muddy pro–delta, sandy delta– front, clastic proximal mouth bar and a subordinate delta plain. Siliciclastic input and sedimentation rate controlled the paleoecological distribution of different benthic carbonate–producing fauna in the fan–delta during its progradation into a shelf marine environment. Input of siliciclastic deposits and sedimentation rate limited the diversity and development of corals and controlled their colonization and growth morphologies in the sandy delta–front. Siliciclastic input (including plant materials and coal debris) and sedimentation rate controlled the trophic habitats of many gastropods and their abundance and distribution in the sandy delta– front and clastic proximal mouth bar. Also, increased siliciclastic input favored abundance of larger benthic foraminifera in most parts of the fan–delta with the exception of the muddy pro–delta.     

Upper Albian ammonites from ODP Leg 171B off northern Florida

ODP Leg 171B investigated the sediments of the Blake Plateau off northern Florida and recovered 36 Upper Albian ammonites — one from Site 1050C, the others from Site 1052E. This unusually large number of specimens from an ODP site permits the dating of the interval between 668 to 621 m below sea-floor at Site 1052E as late Late Albian, Stoliczkaia ( S .) dispar ammonite zone. This zone is indicated by the genera Mortoniceras and Stoliczkaia ( S. ). Site 1050C (Interval 171B-1050C-31R-3, 0.80–0.86 m) cannot be dated more precisely than Late Aptian to Mid Cenomanian by ammonites. The fauna is cosmopolitan. Tetragonites jurinianus Puzosia mayoriana are widely distributed forms. Kossmatella muhlenbecki was thought to be restricted to a fairly small area around the Mediterranean, but the record off northern Florida presented here, indicates that it is not an endemic species; this is also true for Hemiptychoceras subgaultinum in the Albian. The event-like character of the ammonite-bearing interval at Site 1052E is unique. It is overlain by a laminated claystone succession; the top of this sequence is considered to represent maximum flooding (Oceanic Anoxic Event, OAE 1d). Ammonites perhaps profited from an increased nutrient supply derived from flooded coastal plains during a continuous transgression.     

Preferential dolomitization in Mio–Pliocene bioclastic clinoforms,Bonaire Island,South Caribbean: insights from petrographic and geochemical analyses

Facies - The late Aptian Lower Serdj Formation (LSF) in the Northern Atlas of Tunisia records a mixed carbonate–siliciclastic system from the southern margin of Tethys. Sedimentological...     

Tectonically controlled late cretaceous terrestrial to neritic deposition (Northern Calcareous Alps, Tyrol, Austria)

Summary The Turonian to Santonian terrestrial to neritic succession (Lower Gosau Subgroup) in the Northern Calcareous Alps of the eastern part of the Tyrol, Austria, provides an example for deposition on a compartmentalized, narrow, microtidal to low-mesotidal, wave-dominated, mixed siliciclastic-carbonate shelf. The shelf was situated in front of a mainland with a relatively high, articulated relief, and underwent distinct changes in facies architecture mainly as a result of tectonism. The investigated succession was deposited above a deeply incised, articulated truncation surface that formed when the Eo-Alpine orogen, including the area of the future Northern Calcareous Alps, was uplifted and subaerially eroded. Distinct facies associations were deposited from (1) alluvial fans and fan deltas, (2) rivers, (3) siliciclastic lagoonal to freshwater marsh environments, (4) areally/temporally limited carbonate lagoons, (5) transgressive shores, (6) siliciclastic shelf environments, and (7) an aggrading carbonate shelf. During the Turonian to Coniacian, the combination of high rates of both subsidence and sediment accumulation, and a narrow shelf that was compartmentalized with respect to (a) morphology of the substratum, (b) fluviatile input of siliciclastics and contemporaneous input of carbonate clasts from fan deltas, (c) deposition of shallow-water carbonates, and (d) water energy and-depth gave rise to an exceptionally wide spectrum of facies as a distinguishing feature of the succession. With the exception of facies association 7, which formed only once, depositional sequences in the Turonian to Coniacian interval contain all of the facies associations 1 to 6. During Turonian to Coniacian times, the shelf was microtidal to low-mesotidal, and was dominated by waves, storm waves and storm-induced currents. In vegetated marshes, schizohaline to freshwater marl lakes existed. Transgressions occurred onto fan deltas and in association with estuaries, or in association with gravelly to rocky shores. The transgressive successions, including successions deposited from transgressive rocky carbonate shores, are overlain by regressive successions of shelf carbonates or shelf siliciclastics. Deposition of shallow-water carbonates generally occurred within lagoons and over short intervals of time. A „catch-up” succession of shelf carbonates about 100 m thick accumulated only in an area protected from siliciclastic input. In its preserved parts, the Turonian to Coniacian succession does not record deposition adjacent to major active faults. Lateral changes in thickness result mainly from onlap onto the articulated basal truncation surface. Subsidence most probably was controlled by major detachment faults outside the outcrop area, and/or was distributed over a wide area in association with secondary faults above the major detachments. During Coniacian to Early Santonian times, both the older substratum and the overlying Turonian-Coniacian succession were subaerially exposed, faulted and deeply eroded. The following Early Santonian transgression ensued with rocky carbonate shores ahead of a sandy, narrow shoreface-inner shelf environment and a deeper shelf with intermittentlydysaerobic mud. The transgression was associated with the influx of cooler and/or nutrient-rich waters, and heralds an overall deepening. Still during the Early Santonian, the deepening was interrupted by another phase of subaerial exposure. Subsequently, a short phase of shelf deposition was terminated by deepening into bathyal depths.     

The Cenomanian–Turonian boundary in the northwestern part of the Adriatic Carbonate Platform (Ćićarija Mtn., Istria,Croatia): characteristics and implications

The Cenomanian–Turonian boundary (CTB) in the ?i?arija Mountain region (northern Istria, Croatia) is characterized by calcisphere limestone successions with a firmground and glauconite horizon, bioturbated intervals, tempestites, and slumped structures as well as microbially laminated and organic-rich interbeds deposited in the northwestern part of the intra-Tethyan Adriatic Carbonate Platform (AdCP). Compilation of the results from three studied sections (Vodice–Jelovica, Martinjak and Planik) of litho-, bio-, and microfacies analyses, X-ray diffraction, SEM, EDS, and stable isotope analyses allowed reconstruction of marine paleoenvironmental conditions during this time period. Shallow-marine carbonate deposits of the Milna Formation underlie a drowned-platform succession of the Sveti (Sv.) Duh Formation. The contact between these two formations is sharp and commonly marked by slumped deposits. The Sv. Duh Formation consists of about 100 m of calcisphere wackestone enriched in organic matter. The results of preliminary δ¹³C and δ¹⁸O stable isotope analyses indicate the influence of the global Oceanic Anoxic Event (OAE2) on the deposition of this carbonate succession. Anoxic and hypoxic conditions in the water column lead to major changes in the shallow-marine carbonate system of the AdCP. Numerous benthic foraminifera declined during that time, but planktonic foraminifera and calcareous dinoflagellates diversified and expanded greatly. The results of this research provide new insights into the character of the CTB interval in this part of the Tethyan realm. Local and regional synsedimentary tectonics combined with global upper Cretaceous sea-level dynamics allows the correlation of the investigated deeper-marine lithostratigraphic units with OAE2.     

Palynofloras from the upper Barremian-Aptian Nishihiro Formation (Outer Zone of southwest Japan) and the appearance of angiosperms in Japan

Palynomorphs are reported for the first time from the Nishihiro Formation (Wakayama Prefecture, Outer Zone of southwest Japan). The Nishihiro Formation consists of brackish to shallow marine deposits, dated as late Barremian to Aptian from geological correlations. Spores prevail in the assemblage, representing Filicopsida (mainly Cyatheaceae and Anemiaceae), Marchantiopsida and Lycopsida. The pollen assemblage is dominated by Coniferales, whereas Gnetales and Bennettitales/Cycadales are only rarely observed. Moreover, we report angiosperm pollen grains of the genus Retimonocolpites for the first time in the Early Cretaceous sediments of Japan. Pollen grains of the Retimonocolpites Group are typical of early angiosperms and commonly found in assemblages from the early to mid-Cretaceous of all paleofloristic provinces. Until this paper, the oldest angiosperm fossils in Japan were represented by a single seed and a wood reported from the Albian of Hokkaido. The oldest reliable angiosperm pollen grains were reported in Hokkaido from the Cenomanian, and in Honshu from the Coniacian. Thus, Retimonocolpites pollen grains reported in the present study represent the oldest record of angiosperms in Japan. They indicate an appearance of the angiosperms in Japan older than thought until now, which is consistent with that proposed elsewhere in eastern Asia.