Thick Series Research Articles

The Cretaceous post-rift series from the Portuguese onshore ranges of the West Iberian Margin and their history of research

The thick post-rift series that covers the Triassic to Lower Cretaceous sedimentary succession of the Lusitanian Basin, in west central Portugal, is crucial to understanding the Mesozoic evolution of the West Iberian Margin, motivating a long history of studies, including those by Daniel Sharpe (1806–56). They record platform carbonates interbedded with marginal marine and alluvial facies. The post-rift infill was deposited above a late Aptian breakup unconformity and is organized into three unconformity bounded sequences: ‘UBS-4A’ (upper Aptian–upper Cenomanian), ‘UBS-4B’ (lower Turonian–lower Campanian) and ‘UBS-5B’ (lower Campanian–Maastrichtian). The first comprises alluvial siliciclastics and shallow-marine, carbonate sequences rich in Tethyan faunas with ammonites and rudists. During the late Cenomanian, the carbonate platform entirely covered the onshore sectors of the Lusitanian Basin. Several diapiric axes controlled the differentiation of inner platform areas with corals and rudists. The infill of ‘UBS-4B’ occurred after the tectonic uplift and emersion of the sectors located to the south of first-order Nazaré Fault Zone. The platform carbonate facies were overlain by regressive micaceous and alluvial coarse siliciclastics. The sequence ‘UBS-5’ overlies a lower Campanian unconformity and has a Campanian–Maastrichtian thick record of alluvial to lagoonal, reddish pelites, rich in vertebrate assemblages.

Evaluation of an Artificial Intelligence Model for Identification of Mass Effect and Vasogenic Edema on CT of the Head.

Mass effect and vasogenic edema are critical findings on CT of the head. This study compared the accuracy of an artificial intelligence model (Annalise Enterprise CTB) with consensus neuroradiologists' interpretations in detecting mass effect and vasogenic edema. A retrospective stand-alone performance assessment was conducted on data sets of noncontrast CT head cases acquired between 2016 and 2022 for each finding. The cases were obtained from patients 18 years of age or older from 5 hospitals in the United States. The positive cases were selected consecutively on the basis of the original clinical reports using natural language processing and manual confirmation. The negative cases were selected by taking the next negative case acquired from the same CT scanner after positive cases. Each case was interpreted independently by up-to-three neuroradiologists to establish consensus interpretations. Each case was then interpreted by the artificial intelligence model for the presence of the relevant finding. The neuroradiologists were provided with the entire CT study. The artificial intelligence model separately received thin (≤1.5 mm) and/or thick (>1.5 and ≤5 mm) axial series. The 2 cohorts included 818 cases for mass effect and 310 cases for vasogenic edema. The artificial intelligence model identified mass effect with a sensitivity of 96.6% (95% CI, 94.9%-98.2%) and a specificity of 89.8% (95% CI, 84.7%-94.2%) for the thin series, and 95.3% (95% CI, 93.5%-96.8%) and 93.1% (95% CI, 89.1%-96.6%) for the thick series. It identified vasogenic edema with a sensitivity of 90.2% (95% CI, 82.0%-96.7%) and a specificity of 93.5% (95% CI, 88.9%-97.2%) for the thin series, and 90.0% (95% CI, 84.0%-96.0%) and 95.5% (95% CI, 92.5%-98.0%) for the thick series. The corresponding areas under the curve were at least 0.980. The assessed artificial intelligence model accurately identified mass effect and vasogenic edema in this CT data set. It could assist the clinical workflow by prioritizing interpretation of cases with abnormal findings, possibly benefiting patients through earlier identification and subsequent treatment.

Evaluation of an Artificial Intelligence Model for Identification of Intracranial Hemorrhage Subtypes on Computed Tomography of the Head

Background Intracranial hemorrhage is a critical finding on computed tomography (CT) of the head. This study compared the accuracy of an artificial intelligence (AI) model (Annalise Enterprise CTB Triage Trauma) to consensus neuroradiologist interpretations in detecting 4 hemorrhage subtypes: acute subdural/epidural hematoma, acute subarachnoid hemorrhage, intra‐axial hemorrhage, and intraventricular hemorrhage. Methods A retrospective stand‐alone performance assessment was conducted on data sets of cases of noncontrast CT of the head acquired between 2016 and 2022 at 5 hospitals in the United States for each hemorrhage subtype. The cases were obtained from patients aged ≥18 years. The positive cases were selected on the basis of the original clinical reports using natural language processing and manual confirmation. The negative cases were selected by taking the next negative case acquired from the same CT scanner after positive cases. Each case was interpreted independently by up to 3 neuroradiologists to establish consensus interpretations. Each case was then interpreted by the AI model for the presence of the relevant hemorrhage subtype. The neuroradiologists were provided with the entire CT study. The AI model separately received thin (≤1.5 mm) and thick (>1.5 and ≤5 mm) axial series as available. Results The 4 cohorts included 571 cases of acute subdural/epidural hematoma, 310 cases of acute subarachnoid hemorrhage, 926 cases of intra‐axial hemorrhage, and 199 cases of intraventricular hemorrhage. The AI model identified acute subdural/epidural hematoma with area under the curve of 0.973 (95% CI, 0.958–0.984) on thin series and 0.942 (95% CI, 0.921–0.959) on thick series; acute subarachnoid hemorrhage with area under the curve 0.993 (95% CI, 0.984–0.998) on thin series and 0.966 (95% CI, 0.945–0.983) on thick series; intraaxial hemorrhage with area under the curve of 0.969 (95% CI, 0.956–0.980) on thin series and 0.966 (95% CI, 0.953–0.976) on thick series; and intraventricular hemorrhage with area under the curve of 0.987 (95% CI, 0.969–0.997) on thin series and 0.983 (95% CI, 0.968–0.994) on thick series. Each finding had at least 1 operating point with sensitivity and specificity >80%. Conclusion The assessed AI model accurately identified intracranial hemorrhage subtypes in this CT data set. Its use could assist the clinical workflow, especially through enabling triage of abnormal CTs.

Comparing fully automated AI body composition measures derived from thin and thick slice CT image data.

To compare fully automated artificial intelligence body composition measures derived from thin (1.25mm) and thick (5mm) slice abdominal CT data. In this retrospective study, fully automated CT-based body composition algorithms for quantifying bone attenuation, muscle attenuation, muscle area, liver attenuation, liver volume, spleen volume, visceral-to-subcutaneous fat ratio (VSR) and aortic calcium were applied to both thin (1.25 × 0.625mm) and thick (5 × 3mm) abdominal CT series from two patient cohorts: unenhanced scans in asymptomatic adults undergoing colorectal cancer screening, and post-contrast scans in patients with colorectal cancer. Body composition measures derived from thin and thick slice data were compared, including correlation coefficients and Bland-Altman analysis. A total of 9882 CT scans (mean age, 57.0years; 4527 women, 5355 men) were evaluated, including 8947 non-contrast and 935 contrast-enhanced CT exams. Very strong positive correlation was observed for all soft tissue measures: muscle attenuation (r2 = 0.97), muscle area (r2 = 0.98), liver attenuation (r2 = 0.99), liver volume (r2 = 0.98) and spleen volume (r2 = 0.99), VSR (r2 = 0.98), and aortic calcium (r2 = 0.92); (p < 0.001 for all). Moderate positive correlation was observed for bone attenuation (r2 = 0.35). Bland-Altman analysis showed strong agreement for muscle attenuation, muscle area, liver attenuation, liver volume and spleen volume. Mean percentage differences amongst body composition measures were less than 5% for VSR (4.6%), muscle area (-0.5%), liver attenuation (0.4%) and liver volume (2.7%) and less than 10% for muscle attenuation (-5.5%) and spleen volume (5.1%). For aortic calcium, thick slice overestimated for Agatston scores between 0 and 100 and > 400 burden in 3.1% and 0.3% relative to thin slice, respectively, but underestimated scores between 100 and 400. Automated body composition measures derived from thin and thick abdominal CT data are strongly correlated and show agreement, particularly for soft tissue applications, making it feasible to use either series for these CT-based body composition algorithms.

Geochemistry of metasedimentary rocks from the Eastern Pyrenees (Iberian Peninsula): Implications for correlation of Ediacaran terranes along the Gondwanan margin

The North African margin of Gondwana formed by subduction and accretion during Ediacaran to Cambrian times. Sections of this active margin were incorporated during the late Paleozoic to the Variscan and Appalachian orogens. In the Variscan realm, these sections define in some regions a Cadomian basement comprising thick metasedimentary series associated with coeval subduction-related magmatic rock dated in the range 650–500 Ma. In the Cap de Creus Massif (Eastern Pyrenean domain), the Cadomian metasedimentary rocks formed from sediments derived from mixed felsic and intermediate/mafic sources, intruded by granitoid and minor mafic igneous rocks. These series were formed in a peri-Gondwanan volcanic arc setting, like other Cadomian series described in the SW of the Iberian Massif, such as Serie Negra Group of the Ossa Morena Complex. However, the Nd model ages of the Cap de Creus metasedimentary samples range from 1431 to 1620 Ma and are younger than those of their SW Iberia equivalents. This result can be interpreted as an indication of an eastern location in the Ediacaran - Cambrian peri-Gondwanan magmatic arc. Furthermore, the Cadomian series in the Central Iberian Zone have even younger Nd model ages than those of SW and NE Iberia. We present two end-member paleogeographic models consistent with reconstruction of the initial location of the Cap de Creus Massif and its relations with other domains (Ossa Morena Complex and Central Iberian Zone) in this sector of the North African Gondwanan margin.

Reconstruction of the Late Miocene to Pliocene continental succession of Samos Island: Palaeoenvironmental implications for the Eastern Aegean domain

AbstractOn the Island of Samos (East Aegean region, Greece), two sedimentary basins are filled by thick continental series dated to the Late Miocene to Early Pliocene. A multidisciplinary study has been performed including (1) the definition of 21 sedimentary facies, (2) a review of the biological components and (3) carbon, oxygen and strontium stable isotope analyses. The succession is characterised by various depositional settings and hydrochemical compositions. Five main stages of basin evolution have been identified: (1) The Late Serravallian is marked by the development of alluvial fans and fan delta; (2) during the Lower Tortonian, isolated shallow lakes with variable salinity, from fresh to brackish, developed under warm and relatively humid conditions; (3) the Middle to Upper Tortonian is marked by the development of a large and deep lake with saline and alkaline waters, under colder and drier conditions; (4) the Latest Tortonian to Messinian period is represented by an ephemeral alluvial system, developed under a dry climate; (5) during the Zanclean, a palustrine and paludal wetland system, dominated by tufa carbonates, developed under moderately humid conditions. This succession is of particular interest for the reconstruction of the palaeoenvironmental evolution of the transition zone between the Mediterranean domain, and the Paratethys and circum‐Paratethys areas. The geochemical data and the presence of flora (diatoms) and fauna (gastropods) of marine affinity suggest transient ingressions of marine‐related water or groundwater inflows as early as the Lower Tortonian. The Samos succession records the complex interaction between the regional geodynamics and climate. The extensional regime of the Eastern Aegean zone generates subsidence, interrupted in the mid‐Tortonian (9 Ma) by a brief compressive event and a major exposure of the basins. Furthermore, the Late Miocene progressive aridification, followed by a change to a more humid climate (Pliocene) is also a major driver of the sedimentation.

Detailed study of geology of the lower parts of Pliocene in Kurovdagh area by use of 3D seismic survey

The article is devoted to the study of the geological structure of the lower parts of the Productive Series of the Lower Pliocene of the Kurovdagh field.&#x0D; It consists of an introduction, problem statement, research questions, research methodology, results, conclusion and list of references. The introduction provides basic information about the field under study, its geographical location, the history of geological and geophysical studies, the lithology of the section, the structure of the Kyurovdag fold and the oil and gas potential of the field.&#x0D; Oil and gas presence inthefield is related to the Absheron stage of Pleistocene, Akchagyl stage and Productive Series (horizons PS01—PS23) of Neogene. Despite the long-term production from the field, the lower parts of the Productive Series and underlying sediments have not been recovered and sufficiently studied by deep drilling due to the complicated surface and deepseismo-geological environment. It has been recommended to carry out a 3D seismic survey due to a high level of lateral one-fold reflections on seismic records.&#x0D; The major goals of the 3D seismic survey were studyingthe Kurovdagh field's geologic setting, obtaining characteristics previously unknown to geoscientists, and providing detailed research on velocity section to derive prognostic time-depth dependence.&#x0D; It was noted that thePetroalliance Services Company Limited geophysical company has performed a field seismic survey on request «The Caspian Energy Group» company. Processing of the acquired data used the FOCUS 5.4 software package manufactured by Paradigm Geophysical.&#x0D; For repeated interpretation of 3D seismic survey data, the 3D CDP data acquired from the field were used. The kinematic analysis by use of the 3 D cubes revealed the difference by the time shift, frequency spectrum, and amplitude range. The 3 D cubes were brought to a single formby time, phase, and amplitude. The further kinematic interpretation displayed the good quality of the data acquired from Kurovdagh area. The study applied PANGEYA® software for a multi-attribute geological and geophysical data analysis and the standard interpretation.&#x0D; For volumetric modeling of the productive layers of the Kurovdagh oil field, we used the PETREL.10.2 software package. The study targets included complex, lithologically, and tectonically sealed deposits of Productive Series PS01—PS09 and Akchagyl stage (AKCH). Productive layers are attributed to Neogene's Pliocene stage within the Caspian basin's limits.&#x0D; It is represented by a thick series of continental, coastal, and marine sediments (sand, clay, coarsely fragmented depositions) of 1600 m thickness and is unconformity laying over the Pontian stage and covered by the Akchagyl layers in a transgressive form. The Akchagyl stage is one of the stages of the Upper Pliocene which is made of clay, limestone, marl, sandstone, sand, and conglomerates.&#x0D; It became clear that the Kurovdagh field is characterized by a block type structure across the geological section. Block sizes are almost unchanged, evidencing conformance of structural stages and heritance of tectonic movements. Mud volcano and diapiric folding and their sizes are the major distinguishing features of the area.

Paleogeographic approach for the oil and gas potential assessment of the Khadum Formation (Lower Oligocene) in Pre-Caucasus basin

Authors used the paleogeographic approach to identify the different facies generation potential, mark out the areas with the highest organic matter and its types, analyse the reservoir quality for oil and gas potential assessment of the Pre-Caucasus basin Khadum formation. The greatest prospects in the Western and Central parts of the basin characterized by terrestrial and partly mixed organic matter types and are associated with the facies of the Sarpinsk-Armavir channel where discharge currents from the Volga-Don basin occurred. The same organic matter types can be related to clastic fans drawn from the north. In the Eastern part the main prospects are associated with unconventional black shale reservoirs with the predominantly aquatic organic matter, isolated on the top and base by the thick series of seal rock.

Characterisation of out-of-plane shear behaviour of anisotropic sheet materials based on indentation plastometry

This paper presents a new methodology for characterising the out-of-plane plastic anisotropy behaviour of sheet metal, based on indentation testing. Conventionally, advanced yield criteria are used to describe plastic anisotropy, requiring multiple in-plane mechanical tests (such as uniaxial and biaxial tests) to calibrate a model. However, in certain forming applications (e.g. blanking, ironing and incremental forming), the influence of mechanical behaviour through thickness cannot be ignored, necessitating the characterisation of out-of-plane material behaviour. To do this, a 3D plastic anisotropy model must be used and calibrated for the out-of-plane shear parameters, which can be difficult to determine. Researchers often assume an isotropic case or equal shear parameters for in-plane and out-of-plane behaviour. More advanced calibrations involve the crystal plasticity model. In this work, we propose a two-stage calibration procedure. In the first stage, we calibrate the in-plane parameters of the YLD2004–18p yield function conventionally. In the second stage, after fixing the in-plane parameters, we determine the remaining out-of-plane shear parameters based on the results of the ball indentation test. We show for the first time that out-of-plane shear parameters can be determined from a macro-mechanical test for a 2.42 mm thick cold-rolled AA5754-H22 series aluminium sheet.

Еволюція умов седиментогенезу в Карпатському флішовому басейні в крейді–палеогені

The aim of this work is to show the evolution of geological-paleoceanographic and geochemical conditions of sedimentation in the segment of Carpathians of the Tethys Ocean. And also, selection of the basic stages of sedimentogenesis, to which the formation of oil and gas parent and oil- and gas-bearing deposits is timed. In the article, the authors showed the lithologic-genetic classification of the Cretaceous-Paleogene flysch of the Ukrainian Carpathians. Authors distinguished the lithologic-geochemical types of sedimentation son the basis of geochemical terms of sedimentation, and also lithologic-facies types of sedimentation on the basis of features of terrigenous sedimentation. Four stages of sedimentogenesis in the history of geological and paleoceanographic development of the Carpathian sedimentary basinare described in the article: Early Cretaceous (stage I), Late Cretaceous (stage II), Paleocene-Eocene (stage III), Oligocene-Early Miocene (stage IV), each of which has specific geochemical conditions of sedimentogenesis and diagenesis. It is shown that forming of Cretaceous-Paleogene flysch deposits of Ukrainian Carpathians took place under action of very changeable geological-paleoceanographic and geochemical factors the joint action of that stipulated oil and gas capacity of this sedimentary complex. The thick series of psamitolites were formed in periods of avalanche terrigenous sedimentation, that are the reservoirs of hydrocarbons. Formation of bituminous parent-rocks-of-oil siliceous-clayed sedimentation is related to deceleration of processes of terrigenous sedimentation and phases of ocean anoxic events of ОАЕ-1 (Barremian–Albian) and ОАЕ-4 (Oligocene).

The eastern Kendeng Hills (Java, Indonesia) and the hominin-bearing beds of Mojokerto, a re-interpretation

The eastern Kendeng Hills (Java, Indonesia) expose a 1000 m thick series that is used as a stratigraphic standard, representing the emergence of eastern Java from the sea. The fluvial top is rich in vertebrate fossils and yielded the Mojokerto (Perning) hominin skullcap, which is regarded as the earliest evidence of Homo erectus on Java, with age estimates ranging between 1.9 and 1.49 Ma. The series is commonly regarded as an uninterrupted record of coastal progradation. However, recent studies show that the emergence of eastern Java has been a complex process, under influence of tectonism, volcanism, sea-level fluctuations and fluvial dynamics, leaving a fragmented depositional record that varies from site to site. This is at odds with the prevailing stratigraphic practice of long-distance correlations and questions the existing interpretations of the eastern Kendeng reference sections. Here we present the results of a fieldwork-based re-interpretation of this key stratigraphic record, which we identified as the fill of a previously unrecognized Plio-Pleistocene embayment, surrounded by elongate uplift zones. Clinoform-bedded sandstones relate to a stage of explosive, high-silica volcanism, supplying large volumes of ash. The embayment fill is incised and covered by fluvial deposits, which we relate to the Middle Pleistocene Brantas. The fluvial strata have a cyclic build-up, probably representing sea-level controlled stages of aggradation and degradation. Based on a reconstruction of fluvial cycles, we provisionally link the conglomerate bed in which the Mojokerto Homo erectus was found to MIS14 (∼550ka). We infer that the published radiometric ages derive from reworked volcanic clasts that make up this incisive fluvial lag and are not representative for the age of deposition. Our study places the eastern Kendeng series in a new landscape context and changes our view of the timing of hominin migration to Java.

Petrogenesis of the Paleoproterozoic Näränkävaara layered intrusion, northern Finland, Part I: The northern peridotites and their relationships with the layered series and recharge events

The Paleoproterozoic Näränkävaara layered intrusion, northern Finland, has a surface area of 25 km x 5 km and a stratigraphic thickness of ~3 km. The main body of the intrusion includes a 1.5–2 km thick basal dunite series and a 1.3 km thick peridotitic-dioritic layered series, the latter with two peridotitic reversals related to magma recharge. In addition, a series of poorly known elongate poikilitic harzburgitic intrusions (the northern peridotites) are found along the NE contact between the intrusion and the granite-gneiss basement complex. We investigate new mineral and whole-rock geochemical data from the northern peridotites, with the aim of clarifying their petrogenetic relationship to the main layered body of the intrusion. The northern peridotites form a 200–400 m thick cumulate series grading from olivine orthocumulates (OC) at the northern basement complex contact to olivine-orthopyroxene heteradcumulates (HAC) towards the main intrusion body in the south. The OC show whole-rock and mineral chemical trends consistent with origin as rapidly cooled olivine-melt mixtures. The HAC have crystallized in situ from a relatively Cr- and SiO2-rich magma. Based on lithological and stratigraphical correlations, the northern peridotites are linked to the emplacement of the magma that caused the first reversal in the layered series: marginal orthocumulates were formed at the initial emplacement of a new pulse of LREE-enriched siliceous high-MgO basaltic (SHMB) magma into the Näränkävaara chamber, followed by heteradcumulate formation from a fractionating magma with added external SiO2 and fluid. Ubiquitous granite-gneiss xenoliths and felsic veins in drill core suggest assimilation may have been a local process. The northern peridotite parental magma shows undepleted metal ratios suggesting no sulfide saturation occurred prior to emplacement.

Petrogenesis of the Paleoproterozoic Näränkävaara layered intrusion, northern Finland, Part II: U-Pb ID-TIMS age and Sm-Nd isotope systematics

Several mafic-ultramafic layered intrusions were emplaced in the NE Fennoscandian Shield during a magmatic episode at 2.44 Ga. The Paleoproterozoic Näränkävaara layered intrusion, northern Finland, is one of the largest ultramafic bodies in the Fennoscandian Shield, with a surface area of 25 km x 5 km and a magmatic stratigraphic thickness of ~3 km. The intrusion comprises a 1.3 km-thick peridotitic–dioritic layered series (2436 ± 5 Ma) with two peridotitic reversals, and a 1.5–2 km thick basal dunite series mainly composed of olivine adcumulates (dated here). The intrusion has been studied since the 1960’s, but several questions regarding its structure and petrogenesis remain. The basal dunite shows several lithological features typical of komatiitic rather than intrusive olivine cumulates; namely, &gt;1 km-thick “extreme” olivine adcumulates, some showing textures with bimodal grain sizes, oscillating variations in Mg# with stratigraphic height, and poikilitic chromite. With Archean greenstone belts nearby, it was previously hypothesized that the basal dunite series could represent an Archean komatiitic wall rock to the Paleoproterozoic layered series. However, our new U-Pb ID-TIMS baddeleyite age of 2441.7 ± 0.9 Ma for the basal dunite series shows that the basal dunite and layered series of the Näränkävaara intrusion are co-genetic. New whole-rock Sm-Nd isotope data from key stratigraphic units (initial εNd at 2440 Ma of -3.5 to -1.7) indicate that the intrusion was constructed from repeated emplacement of LREE-enriched high-MgO basaltic magmas that were mantle-derived and contaminated by crust, similarly to other Fennoscandian 2.44 Ga intrusions. The parental magmas show similar compositions regardless of stratigraphic position, suggesting that most wall rock contamination and homogenization had occurred before emplacement, with in situ contamination being a relatively minor process. The open-system features of the basal dunite suggest that it may have formed (at least partly) as a feeder channel cumulate, possibly related to the ~100 km long Koillismaa-Näränkävaara Layered Igneous Complex. The Näränkävaara parental magmas show variably depleted metal ratios and could have potential for orthomagmatic mineral deposits, given the availability of S-rich wall rocks.

СРЕДНЕЮРСКИЕ ТУРБИДИТЫ ЭЛЬГОНСКОЙ СВИТЫ УЛЬБАНСКОГО ТЕРРЕЙНА: СЕДИМЕНТОЛОГИЧЕСКИЕ ОСОБЕННОСТИ И НАПРАВЛЕНИЯ ПАЛЕОПОТОКОВ

The Ulban terrane composed of a thick sedimentary series of Jurassic clastic deposits is located at the junction of the Mongol-Okhotsk and Sikhote-Alin orogenic belts. The results of the study of the deposits assigned to the Middle Jurassic Elgon Formation are presented. The structure of the sedimentary succession and sedimentological features are considered and illustrated, which indicate sand-reach turbidite sedimentation in a setting of sandy lobe of turbidite cones or ramps. The paleocurrent directions measured in outcrops and calculated using the anisotropy of magnetic susceptibility suggest the transport of clastic material from the western or southwestern sources.

Stratigraphie dans la Galerie Ouest de la Grotte de Lorette (Rochefort, Belgique) : Apport de la coupe des gours suspendus

The Lorette Cave contains a wide variety of deposits within various stratigraphical contexts. This cave is a part of the complex underground meander cut-off of the Wamme and Lomme rivers, between some swallow-holes along their two talwegs near On, Jemelle and Rochefort, and the general resurgence at Eprave. The Lorette Cave is embedded within the Givetian limestone formations of the Calestienne. This cave displays the first part with a labyrinthic structure. Some parts of the karstic network are affected by recent tectonic activity, which dislocates some galleries and provokes collapses. The second part of the cave comprises the West Gallery, which contains the most complete sedimentary series. The “gours suspendus” (hanging gours) section is located at the western end of the gallery. The cave contains numerous and rich detrital deposits. The oldest sedimentary unit is a diamictite found in several galleries (e.g. Galerie Fontaine-Bagdad, Salle du Cataclysme). It is composed of large decametric-sized quartz and sandstone pebbles coming from the erosion of the Lower Devonian formations of the Ardenne. This deposit is older than the U/Th dating limit, i.e. 350 ka. The West Gallery exposes an area of collapsed blocks and ends in a vast room. This gallery is filled with a thick fluvial series of upper Pleistocene age and capped by speleothems of Tardiglacial to Holocene age. The large terminal chamber is clogged by flooded pits. A tributary gallery shows a sedimentary series in a subsiding pit, the “Fosse aux Lions” (Lions’ Pit). These deposits are made of a diamictite interbedded between two fluvial units, the upper part of which displays oblique stratifications. The dating of a summit stalagmite places this set at 120 ka. The present paper analyses a section made in the southern flank of the terminal room, close to the junction with the West Gallery: the “gours suspendus” section. A large part of this section consists of a complex fluvial deposit disconformably resting on top of a compact lower clay formation. This fluvial deposit is stratified, comprising mostly diamictites interstratified with thin levels of gravel and clay. It is capped by an upper clay unit and sealed by a flowstone. Thin strata of finer-grained size sediments (coarse sand), as well as clay lenses, occur within the lower clay. The diamictites indicate a torrential origin of the sediment. At the base, just above the lower clay, some sandy channelling strata testify that one or several fluvial deposition episodes occurred. Then, torrential and probably very short-living events are separated by decantation phases. The pebbles and smaller particles are made of quartz, sandstone and muscovite that most probably originated in the Lower Devonian formations. The “gours suspendus” section provides a new illustration of the succession of sedimentation and erosion phases in Belgian caves. It is now well demonstrated that speleothems grow mainly during temperate to hot and humid climatic phases and detrital infills are deposited in caves during cold/glacial phases. The physical erosion of sediments with ravine formations should be placed in the climatic history of the region. A gullying by a coarse detrital formation like that of the new section is due to a powerful heavy-loaded current. The deposits within caves were therefore available, which can only occur during a cold phase due to the absence of continuous vegetation cover. The sand and clay levels interstratified between levels of pebbles indicate nevertheless distinct flow regimes. However, this torrential lava in the new section seems different from the old diamictite. The deposition of the sedimentary units in the West Gallery seemingly happened during a glacial–interglacial transition. This sedimentological study sets a future perspective for dating flowstones and stalagmites at the top of or embedded within the deposit levels in order to propose a more robust chronological frame for the evolution dynamics of the cave infilling of the Lorette Cave in relation to the climatic history of the region.

Coeval calc-alkaline and alkaline Cadomian magmatism in the Bafq, central Iran: Insights into their petrogenesis

The Chah-Gaz and Mishdovan areas in the Bafq magmatic complex, central Iran, contain thick series of terrigenous sediments (the Rizu-Dezu complex), and arc-related calc-alkaline and alkaline igneous rocks. Geochemical analyses of igneous rocks from both areas indicate two distinct rock clans: (1) high-K, calc-alkaline-shoshonitic rocks with strong depletions in Nb, P, and Ti, and (2) an alkaline quartz gabbro-diorite, with trace element patterns resembling oceanic island basalts (OIB). New geochronological data reveal that magmatic rocks of both clans crystallized almost simultaneously, with zircon UPb ages of 534 Ma and 537 Ma, respectively. The whole-rock NdSr isotopic data ((87Sr/86Sr)(I) = 0.7052 to 0.7064 and ɛNd(t) = +1.3 to +2.7) of alkaline quartz gabbro-diorite indicate an enriched OIB-like mantle source, while the high-K, calc-alkaline-shoshonitic rocks have εNd(t) = −5.5 to −7.6, clearly reflecting significant contributions from pre-existing Proterozoic basement. Apatite in both the Chah-Gaz and Mishdovan magmatic rocks is of magmatic origin, with light rare earth element (LREE) enrichment patterns. The low Sr/Y and Eu/Eu⁎ values in apatite demonstrate the non-adakitic character of the investigated rocks, while the moderately negative Eu anomaly and inverse correlation between δCe and δEu in the analyzed apatites may reflect reduced parental magmas. The geochemical and isotopic results presented here indicate that slab rollback and opening of an extensional basin could have initiated concurrent Cadomian arc-related calc-alkaline and rift-associated alkaline magmatism in the Chah-Gaz and Mishdovan areas.

K-Ar geochronology and trace-element geochemistry of 2M1 illite from upper Paleozoic shale of SW Laurentia – Insights into sediment origin and drainage pathways in the Anadarko Basin, USA

The Anadarko Basin of Oklahoma represents a major Paleozoic depocenter that existed along the rifted margins of southwestern Laurentia. In its infancy it accumulated a thick series of Cambrian through Mississippian detritus while further subsidence caused by inversion of the Cambrian Southern Oklahoma Aulacogen resulted in voluminous Pennsylvanian to Permian sediment. This contribution reports new data on K-Ar ages and trace-element geochemistry of detrital illite from middle and upper Pennsylvanian shale used to reconstruct sediment origins at the peak period of subsidence of the Anadarko Basin. X-ray diffraction was used to unveil mineral compositions and abundances of illite polytypes in two size fractions of separated illite (˂1 and 2-1 μm). K-Ar isotopic analyses were completed for both fine fractions, while the laser ablation inductively coupled plasma mass spectrometry was done for the latter. All illite separates consisted of mixtures of authigenic (1Md) and detrital (2M1) illite. The Illite Age Analyses showed that the detrital age of Desmoinesian (Moscovian) shale is the late Ediacaran (584 Ma), while the age of Missourian (Kasimovian) shale is the middle Cambrian (512.5 Ma). Trace-element abundances of all analyzed illite, irrespectively of stratigraphic age, are consistent with those of mica from metamorphic rocks. Based on illite detrital age and geochemistry it was inferred that Desmoinesian (Moscovian) shale represents a mixture of Neoproterozoic and Cambrian detritus sourced locally, whereas Missourian (Kasimovian) shale records a provenance shift toward more distal easterly sources from the Ouachita-(Marathon) foreland. This study has proposed a sediment source transition between the middle and upper Pennsylvanian that likely reflected major changes in the basin paleogeography and progressive development of the east-west (transcontinental) fluvial systems.

A high-resolution pollen and diatom record of mid-to late-Eemian at Kozłów (Central Poland) reveals no drastic climate changes in the hornbeam phase of this interglacial

In the region of 20 newly-found fossil lakes in the Garwolin Plain (Central Poland), formed during the Eemian interglacial (MIS 5e), the Kozłów site is considered one of the longest examples of sequences of palaeolake deposits. Pollen investigations have revealed an entire Eemian interglacial (MIS 5e) with a very long hornbeam phase. Repeated coring allowed for high-resolution pollen and diatom analysis to be used in tracing climate-driven palaeoenvironmental changes during the mid- and late-Eemian. The resulting thick series of organogenic deposits from Kozłów joins the collection of existing high-resolution long records of this interglacial in central-eastern Europe. It should be emphasized that a very good correlation was found between palynological and diatom data, which allows for drawing consistent conclusions. The warm and humid climate of the Corylus phase at the onset of the mid-Eemian was marked by a great abundance of planktonic Cyclotella sensu lato species, which indicate a rising water level, increased water temperatures, thermal stratification and a warm-wet climate. In the diatom zones correlated with the Carpinus phase, a distinct change was observed, from an assemblage dominated by planktonic species to one composed of benthic ones, including Fragilaria sensu lato taxa. The greater frequency of oceanic air masses must have affected the humidity and thermal conditions in lake and its surroundings in the first part of the interglacial optimum. Climate changes are very clearly visible at the transition between Carpinus and Picea-Abies zones, which were caused by increased influence of continental air masses. However, in the Middle Eemian no drastic changes were observed in both the pollen and diatom records.In the upper part of the core, represented by Pinus pollen, the presence of cold-loving diatom species, and an increase of green algae Pediastrum spp. point to a drop in temperatures at the close of the interglacial. The pollen results were compared to the well-recognized mid-to late-Eemian successions from Poland and West Europe.

Assessment of crustal structures by gravity and magnetic methods in the Calabar Flank and adjoining areas of Southeastern Nigeria—a case study

High-resolution potential field data were used to the study of Calabar Flank. The study is aimed at mapping the tectono-sedimentary framework, and determining depth to basement of the area. The smooth magnetic/gravity curves obtained from the 2-D models reflect thick sedimentary series and deeply buried basement rocks with no significant post rift tectonic events. Also, the main basement structures (that is, the horst and graben) and associated normal fault blocks of the Calabar Flank were properly delineated. Thickness of sedimentary series in some locations in the study area was observed to be ~7000 m, and the stacked models showed that the sediment thicknesses dip gently in the southwesterly direction. The models, particularly the joint gravity and magnetic model, validate the extant conceptual geological model for the area.

Differences in the Tectonic Evolution of Basins in the Central‐Southern South China Sea and their Hydrocarbon Accumulation Conditions

AbstractTo reveal the causes of differences in the hydrocarbon accumulation in continental marginal basins in the central‐southern South China Sea, we used gravity‐magnetic, seismic, drilling, and outcrop data to investigate the tectonic histories of the basins and explore how these tectonic events controlled the hydrocarbon accumulation conditions in these basins. During the subduction of the Cenozoic proto‐South China Sea and the expansion of the new South China Sea, the continental margin basins in the central‐southern South China Sea could be classified as one of three types of epicontinental basins: southern extensional‐foreland basins, western extensional‐strike slip basins, and central extensional‐drift basins. Because these basins have different tectonic and sedimentary histories, they also differ in their accumulated hydrocarbon resources. During the Cenozoic, the basin groups in the southern South China Sea generally progressed through three stages: faulting and subsidence from the late Eocene to the early Miocene, inversion and uplift in the middle Miocene, and subsidence since the late Miocene. Hydrocarbon source rocks with marine–continental transitional facies dominated by II–III kerogen largely developed in extremely thick Miocene sedimentary series with the filling characteristics being mainly deep‐water deposits in the early stage and shallow water deposits in the late stage. With well‐developed sandstone and carbonate reservoirs, this stratum has a strong hydrocarbon generation potential. During the Cenozoic, the basin groups in the western South China Sea also progressed through the three developmental stages discussed previously. Hydrocarbon source rocks with lacustrine facies, marine‐continental transitional facies, and terrigenous marine facies dominated by II2–III kerogen largely developed in the relatively thick stratum with the filling characteristics being mainly lacustrine deposits in the early stage and marine deposits in the late stage. As a reservoir comprised of self‐generated and self‐stored sandstone, this unit also has a high hydrocarbon generation potential. Throughout those same three developmental stages, the basin groups in the central South China Sea generated hydrocarbon source rocks with terrigenous marine facies dominated by III kerogen that have developed in a stratum with medium thicknesses with the filling characteristics being mainly sandstone in the early stage and carbonate in the late stage. This reservoir, which is dominated by lower‐generation and upper‐storage carbonate rocks, also has a high hydrocarbon generation potential.