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The study of several Paleogene sections in the south of the Russian Plate allowed the refinement of the taxonomic list of diatom and silicoflagellate assemblages. Using an integrated biostratigraphic approach, the stratigraphic range of the Bipalla oamaruensis diatom Zone was defined. The high degree of taxonomic diversity of the studied assemblages is associated with the shallow-water environments of the marginal part of the basin inhabited by various ecological groups of diatoms. The zone was established in the Tishki and Kasyanovka formations and, based on direct comparison, corresponds to the Bartonian–Lower Priabonian Cyrtophormis alta–Etmosphaera polysiphonia–Theocyrtis andriashevi radiolarian interval-zones. The Priabonian age of the Kasyanovka Formation is also confirmed by dinocyst data. The Bartonian-Priabonian boundary approximately coincides with the first appearance of the silicoflagellate Corbisema hexacantha. [ABSTRACT FROM AUTHOR]

The fossil mammalian assemblage of the Itaboraí Basin, located in the state of Rio de Janeiro, Brazil, was recovered from fissure fill deposits that vertically cut its limestone beds. Previous studies have considered the abundant and diversified fossil mammals excavated from such deposits of this small basin to have been deposited synchronously. An analysis comparing the whole Itaboraí mammalian assemblage with that of the Las Flores Formation, Argentina, estimated its age as early Eocene. The purpose of this study is to test the hypothesis of an asynchronous formation and infilling of the fissures and to conduct faunistic comparisons with other South American local faunas, considering the mammals of each Itaboraí fissure (MN, MCT-1 and MCT-2) separately, as these fissures were formed in distinct areas of the basin and in different topographic levels. To evaluate the faunal similarities between the Itaboraí fissures and other South American local faunas, cluster analysis and parsimony analysis of endemicity were undertaken. Both methods nest all three Itaboraí fissures with the Yacimiento Las Flores fauna, but some analysis show two fissures (MN and MCT-1) to be closer to it than the third. Based on the topographic levels of the fissures, their fossil mammals (diversity, presence/absence, and abundance), marsupial trophic structure and evolutionary stage, we conclude that the Itaboraí mammal assemblage is composed of faunas of different ages/stages: the fauna of the fissure discovered in 1968 (MCT-2) is the oldest (probably late Paleocene to earliest Eocene), and the fissure discovered in 1949 (MCT-1) is the youngest (early Eocene). [ABSTRACT FROM AUTHOR]

This is the second part of the paper on the Cretaceous of the Mountainous Crimea. A lot of new data has been received during last ten years. This paper summarizes the state of knowledge of the Upper Cretaceous stratigraphy, selected biostratigraphic groups (ammonites, belemnites, ostracods, foraminifers, gilianelles, nannoplankton) and magnetostratigraphy. Ammonite and belemnite biostratigraphic subdivisions are proposed for the first time for the Crimean Upper Cretaceous. Foraminifera-based biostratigraphy is updated, and new biostratigraphic units are proposed and correlated with the European scale. Stratigraphic hiatuses are recognised in the succession of southwestern Crimea: the base and the top of lower Cenomanian, upper Coniacian–lower Santonian, Campanian/Maastrichtian and Cretaceous/Paleogene boundary intervals. [ABSTRACT FROM AUTHOR]

Timing is a key data for understanding the origin of faulting. The Balcones fault system (BFS) extends ~600 km along the northern margin of the Gulf of Mexico oil basin and controls springs that supply the major cities in Texas, but its origin is unclear. We provide its first direct timing by applying U–Pb geochronology on seven calcite‐mineralized fault surfaces. We have found that this extensional fault system formed during the Palaeocene‐middle Eocene time (from 61.3 ± 2.7 to 45.4 ± 2.1 Ma), which is much earlier than previous estimates. We show that the formation of the BFS coincides with the largest clastic influx in the northern Gulf of Mexico basin that resulted from Laramide uplift and erosion. This timing and the location of the BFS along the Ouachita suture, support our interpretation of this fault system formed as the result of lithospheric flexure related to Paleogene sedimentary loading. [ABSTRACT FROM AUTHOR]

The aim of the currrent investigation is to date the final closure of Pakistan's portion of the northern Tethys rim in Kohat-Potwar Basin by using integrated bio-sequence stratigraphy and facies information. The Paleogene strata is divided into six biozones while its depositional profile resembles a distally steepened-homoclinal platform. Paleogene deposits in the Kohat Basin include two depositional cycles, two transgressive-highstand systems tracts, one lowstand systems tract, and separated by two sequence boundaries. Three transgressive-highstand systems tracts were observed in the Potwar Basin, which are separated by two tectonically controlled and one eustatic sequence boundary. The sequence boundaries in both basins are synchronous at 50–49.5 Ma and mark a period of drastic change in sediment character, which may have been caused by the combined effects of uplift and eustatic sea level fall. This suggests that the proto-closure of the northern rim of Tethys occurred between 50 and 49.5 Ma. Only the Kohat Basin experienced the restoration of marine conditions, which happened in the Middle Lutetian at around 45.8 Ma and may have been brought on by a combination of flexural loading of the Indian Plate and eustatic sea-level rise that persisted until the Kohat Basin's closure in the Upper Lutetian at around 41.2 Ma due to India-Asia collision. [ABSTRACT FROM AUTHOR]

The Order Pyrotheria is one of the most bizarre and least-known groups of South American native ungulates, and its biochron extends from the early? Eocene to the late Oligocene. The emblematic genus of this order is Pyrotherium, which is known by several maxillae, mandibles, and postcranial bones of adult individuals. In this paper, we describe the most complete juvenile mandible of Pyrotherium found to date, MPEF-PV 2581, which bears dp3–m1 and alveoli of di1–di2. The study of this specimen, re-study of previously published specimens (MACN-A 52-290 and MNHN-F-DES 104), and study of unpublished deciduous upper and lower cheek teeth from several collections allows us to designate MLP-PV 13-3 as the lectotype of P. romeroi, to establish dental age stages for Pyrotherium, to differentiate two juvenile stages (early and late), and to define differences between deciduous and permanent upper premolars. Our observations show that adult individuals of Pyrotherium have a narrower and posteriorly expanded mandible (due to the increase in the size of the tusk-like teeth) and a straighter mandibular incisura. We also observe that di1, di2, and dp2 are present in juveniles but not in adults, except for the i2. X-ray imaging suggests that delayed dental eruption is not present in the juvenile mandible, whereas cheek tooth wear suggests an anteroposterior eruption sequence in p3 through m3. This work adds new information about the dental age stages of Pyrotherium and proposes the following modified deciduous dental formula: dI ?/2, dC ?/0, dP 3/3. [ABSTRACT FROM AUTHOR]

Thirty-two coal (lignite-bituminous in rank) and carbonaceous shale samples, ranging from immature to overmature, were collected from the various coal-bearing basins (Saurashtra Basin, Bikaner Nagaur Basin, Damodar Basin, Mahanadi Basin, and Foreland Basin) in India and characterized petrographically (vitrinite reflectance and maceral composition), geochemically (total organic carbon and total sulfur) and chemically (Fourier Transform Infrared spectroscopy, FTIR). This paper explores utilization of FTIR study on bulk non-demineralized carbonaceous shale and coal to examine the interference between mineral and organic matter visible on FTIR spectra and application of such techniques to assess organic matter chemistry based on FTIR signal. Mineral matter is considerably affecting the organic matter FTIR signal in the region between 1700–1350 and 900–700 cm−1, while the 3100–2800 cm−1 region is unaffected. The general trends of organic matter evolution with thermal maturity, i.e. a decrease of aliphatic and oxygen-bearing groups and increase in aromatic signal, are visible in bulk non-demineralized samples; however, the interpretation of the signal is problematic due to the dilution-related signal weakening and region-specific overlapping. The quality of the FTIR signal is lower than the signal from demineralized kerogens or targeted specific maceral grains via combination of FTIR with microscopy. The spectra can still be useful for more qualitative aspects of FTIR, like assessment of organic functional groups, study of coal impurities, or as a complementary method in conjunction with other analytical techniques such as X-ray for mineral matter characterization. [ABSTRACT FROM AUTHOR]

The Mesozoic and Cenozoic tectonic evolutionary history of the East Asian continental margin has been the focus of many researchers because of the overprinting of multiple tectonic domains. Previous studies have suggested that the westward subduction of the Paleo-Pacific Plate and the Pacific Plate resulted in the deconstruction of the North China Craton and controlled the formation of the related basins on the continental margin of East Asia. However, controversy remains regarding the tectonic transition processes and mechanisms that occurred from the Mesozoic to the Cenozoic. Since the Mesozoic, the Bohai Bay Basin on the eastern margin of the North China Craton of East China has been influenced by multiple tectonic domains of the Paleo-Tethys, Paleo-Pacific, and Pacific oceans, and there are complete records of these tectonic transition processes. The Bozhong Depression is a subbasin in the Bohai Bay Basin, which is a crucial area for researching the tectonic evolution of the Bohai Bay Basin throughout the Mesozoic-Cenozoic and the regional tectonic evolution of the eastern continental margin of China. Based on 3-D seismic data, logging core data, and a balanced cross section in the Bozhong area, combined with data from the apatite fission-track inversion model, we reconstructed the tectonic evolutionary history of central Bohai Bay Basin and established a three-cycle and eight-stage tectonic model of the central Bohai Bay Basin during the Mesozoic-Cenozoic. The three cycles are the Indosinian, the Yanshinian, and the Himalayan. (1) The Indosinian was marked by two stages. During the early Indosinian, NW-trending thrust faults were formed due to the collision and northward subduction of the South China Block underneath the North China Block. In the late Indosinian, the tectonic stress in the central Bohai Bay Basin shifted from compression to extension. Consequently, the thrust faults reversed, leading to the deposition of Early-Middle Jurassic strata. (2) The Yanshanian cycle comprises three main phases. Early Yanshanian transpressional shearing led to the formation of a NE/NNE-trending, left-lateral strike-slip fault due to NWW-directed subduction of the Paleo-Pacific Plate. Middle Yanshanian transtensional shearing was driven by Paleo-Pacific Plate rollback and resulted in regional extension and the negative inversion of previous compressive faults. Late Yanshanian compression gave rise to the basin reversion, which resulted from an increased subduction speed of the Paleo-Pacific Plate and a transition from a high angle to a low angle. (3) The Himalayan cycle was marked by three phases. During the early Paleogene, the region was characterized mainly by extension, and NEtrending, right-lateral strike-slip normal faults began to form. This coincided with a decrease in the Pacific Plate's subduction speed. In the late Paleogene, the subduction rate of the Pacific Plate increased, resulting in the change of the central Bohai Bay Basin from an extensional environment to one marked by regional differential compression. In the Neogene, regional thermal subsidence and depression sedimentation occurred, which were probably induced by the increasing subduction speed and rollback of the Pacific Plate. The Bozhong Depression has experienced multiple stages of tectonic evolution, which indicates the concurrent and superimposed effects and transition of multiple tectonic domains. [ABSTRACT FROM AUTHOR]

To date, soft-tissue remains of extinct incirrate octopods have been described exclusively from Upper Cretaceous deposits. Here, three specimens of an incirrate octopodid with well-preserved soft tissue imprints are described for the first time from Paleogene strata. This material originates from the upper Ypresian (lower Eocene) fish-bearing levels of the Bolca Konservat-Lagerstätte in the Pesciara of Bolca in north-eastern Italy. Previously, these specimens had tentatively been interpreted as teuthids. Based on a detailed study of their anatomical structure, a new genus and species of octopodid, Bolcaoctopus pesciaraensis, belonging to the extant family Octopodidae, are here erected. Bolcaoctopus gen. nov. may be distinguished from the Late Cretaceous genus Styletoctopus by the presence of long and thin arms and an elongated body shape with a narrowed apical end and covered by longitudinal wrinkles. Although finds of fossil octopuses in the Bolca Konservat-Lagerstätte remain extremely rare, it is worth noting that Cenozoic marine vertebrate localities constitute an important potential source of additional finds of coleoid cephalopods, the study of which may shed light on a poorly understood period in the evolutionary history of these molluscs. [ABSTRACT FROM AUTHOR]

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The present study evaluated the Paleogene Sokor-1 clastic reservoirs in the Fana Field on the Agadem Block, Termit Basin, Niger Republic. The evaluation of the hydrocarbon prospect of the Field, which involved petrophysical analysis of six wells namely Fana_2, Fana E_1, Fana N_2, Fana W_1, Fana S_1, Fana SW_1, and sidewall core sample description of Fana_2 well. The petrophysical interpretation of the well-log data was carried out using Interactive Petrophysics software. The petrophysical properties of the hydrocarbon-bearing reservoirs were rated to be suitable reservoirs with average effective porosities varying from 25.8 to 31.6%, permeability varying from 123.6 to 427.7 mD, average water saturation values ranging from 15.2 to 33.0%, and the average range of hydrocarbon saturation is 67.0 to 84.8%. The values of volume of shale (Vsh) of the identified reservoirs indicated that the reservoirs are generally shaly to a high shale/clayey content. The dia-porosity and M-N cross plots revealed that the reservoirs of the Sokor-1 Formation are predominantly sandstone with shale/clay intercalations. The shale structural behaviour of the reservoirs revealed that the dominant shale was mainly dispersed and laminated shale volumes that could impact on the reservoir qualities. The spatial variations of petrophysical parameters indicated that lower N/G values favour the northeast and southern part of the map while the south area has a higher average effective porosity value. This study identified the southern part of the Fana Field as the most prospective and should be considered for the future exploration and development of the Fana field. [ABSTRACT FROM AUTHOR]

Protolipterna ellipsodontoides is a small bunodont South American native ungulate, generally considered an early litoptern, exclusively found in the Palaeogene Itaboraí Basin. Its dentition is well known; however, its mandibular morphology was only known by fragmentary materials. Here, we describe the first complete mandible of this species. A micro-CT scan reveals the first case of alveolus resorption in this putative early litoptern. Two accessory canals on the retromolar region are also described. Canals on the retromolar region are documented for other mammalian orders; however, this represents the first description of this feature for the Protolipternidae. Unlike more advanced litopterns, this species lacks specialisations related to strict herbivory, and its dental and mandibular morphology suggests an omnivore habit. A comparison with the mandible of another Itaboraian protolipternid, Miguelsoria parayirunhor, indicates the presence of different dietary specialisations. Body mass estimations for both species are also provided. [ABSTRACT FROM AUTHOR]

Conoryctes comma is a member of the enigmatic group Taeniodonta, Paleogene mammals that have been found only in North America. Taeniodonts were part of the first wave of placental mammal diversification after the end-Cretaceous extinction. The lack of postcranial elements has limited the understanding of the anatomy and locomotion of Conoryctes, and how it compared to other taeniodonts. We here describe the postcranial anatomy and functional morphology of Conoryctes, based largely on nine new specimens found in the San Juan Basin, New Mexico, USA. The specimens include elements of the axial column, such as the axis, sacrum, and ribs; the humerus, ulna, radius, and part of the manus; the innominate, femur, tibia, and part of the pes, including the tarsals. Conoryctes was a medium-sized mammal, with a robust humerus, radius, and femur, and with anatomical similarities to other conoryctid taeniodonts and Onychodectes. The tarsal elements of Conoryctes show characteristics of the "leptictimorph astragalocalcaneal morphology" as seen in other Paleogene mammals, such as Escavadodon, Palaeanodon, and Procerberus. Anatomical features of the forelimb and hindlimb of Conoryctes indicate that it was a scratch-digging animal with powerful forearm muscles and well-stabilized digits, features that may have helped it adapt to the subtropical forests of the San Juan Basin, approximately 63 million years ago. This corroborates the previous hypothesis that digging adaptations are seen in all members of Taeniodonta for which the postcranial elements are known, and that digging ability was present in the common ancestor of the clade and potentially central to their radiation after the environmental destruction of the end-Cretaceous extinction. [ABSTRACT FROM AUTHOR]

The initial stages of the evolutionary history of peratheriines, the European herpetotheriid metatherians, are largely unknown, primarily due to their limited morphological dental disparity throughout the Palaeogene, coupled with significant intraspecific variation. Based on eleven molars, we document a new early peratheriine species, Peratherium musivum sp. nov. which is larger than and morphologically similar to the earliest peratheriine, Peratherium constans (MP7). Subtle molar characters are shared with the largest early Eocene peratheriine, Peratherium maximum comb. nov. We illustrate the importance of studying possible changes in molar cusp – basin proportions and correlated characters that occured during peratheriine evolution. Peratherium musivum sp. nov. which spanned only part of the MP7-MP8 + 9 time interval, and the ~MP8 + 9 Peratherium maximum comb. nov. were probably widespread in Western Europe. The description of a well-preserved mandible of the latter, from La Borie (~MP8 + 9), reveals original features concerning relative size and shape of dental alveoli, partly corroborated using isolated molars. These traits are absent in the younger, most representative species of both peratheriine genera, Peratherium and Amphiperatherium. Based on the aforementioned data and a critical review, it is demonstrated that peratheriine genera lack consistent definitions, so that the Peratherium/Amphiperatherium dichotomy is plausibly inapplicable to early Eocene representatives.This article is registered in ZooBank under urn:lsid:zoobank.org:pub:A2B4DE58-855C-4CB8-BC1D-C9677E6DF97D [ABSTRACT FROM AUTHOR]

Metallogenic geochronology plays a crucial role in the study of ore genesis and mineralization evolution. Unfortunately, accurately determining the metallogenic age of the non‐sulphide Zn–Pb deposits is difficult. Herein, we employed Rb–Sr dating of smithsonite and Sm–Nd dating of coexisting calcite to explore the mineralization ages of the Huoshaoyun Zn–Pb deposit. The Rb–Sr and Sm–Nd isotopic ratios yield isochron ages of 26.6 ± 1.7 and 27.5 ± 7.6 Ma, respectively. These obtained ages are identified as the metallogenic age of the Huoshaoyun deposit. Moreover, investigations into carbonate‐hosted Zn–Pb deposits in the East Tethys Metallogenic belt suggest they have formed in similar tectonic settings and yielded consistent Cenozoic ages. In sum, our research indicates that carbonate‐hosted Pb–Zn metallogenic ages in the East Tethys Metallogenic belt are principally concentrated in the late Palaeogene, and directly related to the collisional orogeny of the Tibetan Plateau during 40–26 Ma. [ABSTRACT FROM AUTHOR]

Summary: A splinter of charred wood was recovered from late Early Eocene volcanoclastic deposits underlying the lacustrine succession of the Messel-pit near Darmstadt (Hesse, Germany). Well-preserved anatomical details due to charring allow for an attribution of the splinter to the Oleaceae family. Within Oleaceae, the wood shows good agreement with the anatomical structure of recent members of the genera Olea , Chionanthus and Noronhia. However, due to the high variability of structural features within this group of genera, a reliable taxonomic placement is restricted to the monophyletic drupaceous subtribe Oleinae. The Splinter was cut loose from a tree of the local vegetation and charred by effects of the respective phreatomagmatic eruption, even under a low-fire regime. The specimen represents a rare example of a Pre-Quarternary wood that can be related directly to a radiometric age of 48.27–48.11 Ma (±0.22 Ma). [ABSTRACT FROM AUTHOR]

The now inaccessible amber deposits of the Fushun coalfield (Guchengzi Formation; Ypresian) represent the only diverse record of Paleogene arthropods from northeastern Asia. Among the wealth of inclusions recovered from the mines before they were closed and filled, only five specimens of bees were discovered. Meager as they are, these samples provide an important paleogeographical point of reference for piecing together the fauna of forest-dwelling bees during and after the Early Eocene Climatic Optimum. Three species in two genera are recorded, one species representing a new extinct genus and tribe of Megachilinae related to Glyptapini, Ctenoplectrellini (here including Aspidosmia Brauns), and perhaps Dioxyini, and the other two species comprising a new genus of the eusocial corbiculate tribe Melikertini (Apinae). The early-diverging tribes of Megachilinae—Glyptapini, Ctenoplectrellini, and the new tribe, all possessing a distinct metatibial scopa—are briefly reviewed. Glyptosmia Engel, n. gen., with Glyptosmia hemiaspis Engel, n. sp., is the sole member of Glyptosmiini Engel, n. tribe. Although it somewhat resembles species of the genus Ctenoplectrella Cockerell (from Baltic, Bitterfeld, Oise, and Rovno ambers), Glyptosmia also shares distinctive traits of Glyptapini (areolate propodeum) and even the cleptoparasitic Dioxyini (tuberculate metanotum). The tribe can be distinguished by the bare compound eyes, dense mesosomal punctation, tuberculate metanotum, areolate propodeum, flattened mesoscutellum with a sinuate apical margin, and characteristically thickened metatibial spurs, among other characters. Two species of the corbiculate bee tribe Melikertini are described, both of the genus Thyreomelikertes Engel, n. gen. Thyreomelikertes lacks the facial protuberances found in genera such as Aethemelikertes Engel, Haidomelikertes Engel, Amelikertotes Engel, or Succinapis Engel and is superficially similar to Melissites Engel or Mochlomelikertes Engel, Breitkreuz, and Ohl, with its long, flattened, and trapezoidal mesoscutellum somewhat reminiscent of the latter genus. The genus is also noteworthy for the putatively plesiomorphic retention of relatively developed grooves on the outer surface of the mandible and dense mesosomal pubescence. The two included species, Thyreomelikertes electrosinicus, n. sp., and T. kongi, n. sp., can be distinguished by size and the development of setae on the meso- and metatibiae. All the individuals are morphologically workers, and so, like all other melikertines, Thyreomelikertes was social and, based on the phylogenetic position of the tribe, presumably lived in anchored eusocial colonies. By contrast, G. hemiaspis was likely a free-living solitary species. The species from Fushun amber are described, figured, and compared with other species of Cenozoic and living bees. The mandibular structure of Thyreomelikertes is unique among Melikertini and permits a fuller description of the diversity of structural homologies across corbiculate bee mandibles. [ABSTRACT FROM AUTHOR]

Source‐to‐sink analysis examines the effects of source areas and basin (sink) dynamics on the generation, transport, composition, distribution and deposition of sediment in modern and ancient sedimentary systems. Detrital zircon, as one of the most stable detrital minerals, its U–Pb geochronology and geochemistry is pivotal for sedimentary provenance analysis and reconstructing palaeogeography. The South China Sea (SCS), as the largest marginal sea in the Southeast Asia, is closely related to the uplift of the Tibetan Plateau and the evolution of Chinese rivers. In this study, we mainly collect published detrital zircon of Cenozoic sediments in the SCS (include Hainan and Taiwan Islands). These detrital zircon were concentrated on Cenozoic multiple episodic rift basins in the northern part of the SCS. A total of 21,760 detrital zircon U–Pb data from 293 samples and 995 detrital zircon Lu‐Hf isotope data from 22 samples were collected in this dataset, with the main study epochs being the Palaeogene and Neogene. Best ages of these grains are range from 4,691 to 10 Ma and more than half of them within age less than 500 Ma. The 176Hf/177Hf ratios of the SCS samples ranging from 0.280509 to 0.28306 and the εHf(t) values from −63.8 to 24.6. The main age group of the SCS Cenozoic sediments were at 130–95 Ma, 175–130 Ma and 265–230 Ma. The detrital zircon U–Pb age and Lu–Hf isotope data contained in this dataset is an important geological record of the sedimentary and tectonic evolution of the SCS and the evolution of rivers such as the ancient Pearl River and the ancient Red River, which can provide a basis and important clues or exploring the source of sediments in the SCS, the dynamical processes of basin evolution, the evolution of the coastal drainage system and the tectonic uplift of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The diversity of the tholeiitic, alkali or calc-alkali, high-silica, and adakitic rocks (I-, FG- and А-types) in the northeastern margin of Asia often leads to controversial conclusions about the character of magmatism and the active margin evolution in the West Pacific during the Late Mesozoic–Cenozoic. In addition, paleogeodynamic reconstructions of the Asia-Pacific region can only be made based on the synthesis of patterns identified in compositions of magma sources, evolution and character of magmatism, and strain and kinematic analysis of fault tectonics of all parts of the eastern margin of the paleo-Asian continent. The paper presents new isotopic, geochemical, and structural data on one of the largest early Paleogene structures located at the continental margin of the southern Sikhote-Alin. Based on the new and previously published data we have concluded that the tectonic and magmatic settings of the region were shaped by oblique interaction of continental and oceanic plates during the Late Cretaceous-early Paleogene. The igneous products of the frontal (FG-type), in respect to the trench, and intracontinental (А-type) parts of the area are characterized by isotopic-geochemical variations caused by thermal changes in upwelling asthenosphere and by interaction with lithospheric components. These processes accounted for the formation of initial magmas similar to the IAB- or OIB-type mantle source, respectively. [ABSTRACT FROM AUTHOR]

We described a new pair of incomplete mandibles from the Qingshuiying locality, Northwest China, and referred it to Eggysodon, E. lingwuensis sp. nov. The new species has a typical mosaic assemblage of features: dp1 (or p1) is present at adult stage, but the symphysis is posteriorly elongated and the diastema distance between the canine and dp1 (or p1) is further shortened. In terms of the evolutionary stage, E. lingwuensis sp. nov. is more advanced than E. osborni, but comparable to that of E. gaudryi. Together with other mammals from the Qingshuiying locality, we suggested that the strata-produced new material was deposited during the Early Oligocene. On the other hand, the continental fauna exchange during the Palaeogene between Europe and Asia had very scarce records. Eggysodon has four species from the Oligocene of Europe. This record definitely confirmed that there is a migration route between Central Europe and East Asia during the Early Oligocene. [ABSTRACT FROM AUTHOR]

In this work, we present several new materials collected at the pink sandstone levels from the Las Flores Formation at the Cerro Pan de Azúcar (Gaiman, Chubut Province, Argentina) and compare them with taxa present in other localities of similar age. The Metatheria taxa described here are 1) the 'Ameridelphia' Sternbergiidae indet; 2) the Didelphimorphia Protodidelphis cf. mastodontoides and Guggenheimia glykeia sp. nov. (Protodidelphidae); 3) the Polydolopimorphia Pliodolops rothi and Pliodolops cf. kamektsen (Polydolopidae); and 4) the Microbiotheria Eomicrobiotherium diluculum sp. nov. (Microbiotheriidae). On the other hand, the Cingulata Dasypodidae is represented by the Astegotheriini Prostegotherium astrifer. This fauna shares more species with those occurring in the localities from Paso del Sapo than with any other early – middle Eocene localities. However, at the generic level, it shares several taxa with the Itaboraian fauna from Sao José de Itaboraí. Finally, the faunal associations from Pan de Azúcar, Paso del Sapo, Cañadón Hondo, and Bajo de la Palangana could be, at least in part, synchronous, representing locally the Riochican SALMA, with an age spanning from 51 to 45 Ma (early Ypresian- early Lutetian). [ABSTRACT FROM AUTHOR]

South Pacific archipelagos are central in the biogeographic debate on the relative importance of vicariance and dispersal in shaping the distribution of species. However, each taxonomic group was subject to different processes and histories, and here, we reveal the historical biogeography of the diverse Eumolpinae leaf beetles, widely distributed in the region. Extensive taxon sampling focusing on South Pacific Eumolpinae was used to infer the first molecular phylogeny of the group using three single‐copy protein‐coding nuclear and two mitochondrial markers. Upon assessing the clade of interest for lineage‐specific variation in substitution rates, the age of the most recent common ancestors was estimated using out‐group calibration and multi‐gamma site models (MGSMs). Biogeographic analyses used standard event‐based inferences also incorporating phylogenetic uncertainty. Zealandian Eumolpinae are monophyletic and appear to have split from their global relatives in the transition from the Cretaceous to the Paleogene. Variation in the rates of molecular evolution affected the in‐group stem branch, with a significant drop in the substitution rate, and the MGSM correction recovered the crown age of Zealandian Eumolpinae during the Late Eocene–Oligocene transition. Biogeographic inference resolved the origin of the radiation in New Caledonia, favouring a null model without island age constraints, and repeated dispersal events to the other islands, including three independent but synchronous colonisations of New Zealand during the Miocene. New Caledonia, with a highly diverse Eumolpinae fauna of uncertain origin, acted as a hub and pump of biodiversity of these beetles in the entire South Pacific region, sending migrants to other islands through long‐distance dispersal with lineages establishing when land became available. [ABSTRACT FROM AUTHOR]

By conducting organic geochemical analysis of the samples taken from the drilled wells in Baiyun Sag of Pearl River Mouth Basin, China, the development characteristics of hydrocarbon source rocks in the sag are clarified. Reconstruct the current geothermal field of the sag and restore the tectonic-thermal evolution process to predict the type, scale, and distribution of resources in Baiyun Sag through thermal pressure simulation experiments and numerical simulation. The Baiyun Sag is characterized by the development of Paleogene shallow lacustrine source rocks, which are deposited in a slightly oxidizing environment. The source rocks are mainly composed of terrestrial higher plants, with algae making a certain contribution, and are oil and gas source rocks. Current geothermal field of the sag was reconstructed, in which the range of geothermal gradients is (3.5-5.2) °C/100 m, showing an overall increasing trend from northwest to southeast, with significant differences in geothermal gradients across different sub-sags. Baiyun Sag has undergone two distinct periods of extensional process, the Eocene and Miocene, since the Cenozoic era. These two periods of heating and warming events have been identified, accelerating the maturation and evolution of source rocks. The main body of ancient basal heat flow value reached its highest at 13.82 Ma. The basin modelling results show that the maturity of source rocks is significantly higher in Baiyun main sub-sag than that in other sub-sags. The Eocene Wenchang Formation is currently in the stage of high maturity to over maturity, while the Eocene Enping Formation has reached the stage of maturity to high maturity. The rock thermal simulation experiment shows that the shallow lacustrine mudstone of the Wenchang Formation has a good potential of generating gas from kerogen cracking with high gas yield and long period of gas window. Shallow lacustrine mudstone of the Enping Formation has a good ability to generate light oil, and has ability to generate kerogen cracking gas in the late stage. The gas yield of shallow lacustrine mudstone of the Enping Formation is less than that of shallow lacustrine mudstone of the Wenchang Formation and the delta coal-bearing mudstone of the Enping Formation. The numerical simulation results indicate that the source rocks of Baiyun main sub-sag generate hydrocarbons earlier and have significantly higher hydrocarbon generation intensity than other sub-sags, with an average of about 1 200×104 t/km2. Oil and gas resources were mainly distributed in Baiyun main sub-sag and the main source rocks are distributed in the 3rd and 4th members of Wenchang Formation. Four favorable zones are selected for the division and evaluation of migration and aggregation units: No. (1) Panyu 30 nose-shaped structural belt, No. (3) Liuhua 29 nose-shaped uplift belt and Liwan 3 nose-shaped uplift belt, No. (2) gentle slope belt of Baiyun east sag, and No. (8) Baiyun 1 low-uplift. [ABSTRACT FROM AUTHOR]

To reveal the enrichment conditions and resource potential of coal-rock gas in the Ordos Basin, this paper presents a systematic research on the sedimentary environment, distribution, physical properties, reservoir characteristics, gas-bearing characteristics and gas accumulation play of deep coals. The results show that thick coals are widely distributed in the Carboniferous-Permian of the Ordos Basin. The main coal seams Carboniferous 5# and Permian 8# in the Carboniferous-Permian have strong hydrocarbon generation capacity and high thermal evolution degree, which provide abundant materials for the formation of coal-rock gas. Deep coal reservoirs have good physical properties, especially porosity and permeability. Coal seams Carboniferous 5# and Permian 8# exhibit the average porosity of 4.1% and 6.4%, and the average permeability of 8.7×10-3 µm2 and 15.7×10-3 µm2, respectively. Cleats and fissures are developed in the coals, and together with the micropores, constitute the main storage space. With the increase of evolution degree, the micropore volume tends to increase. The development degree of cleats and fissures has a great impact on permeability. The coal reservoirs and their industrial compositions exhibit significantly heterogeneous distribution in the vertical direction. The bright coal seam, which is in the middle and upper section, less affected by ash filling compared with the lower section, and contains well-developed pores and fissures, is a high-quality reservoir interval. The deep coals present good gas-bearing characteristics in Ordos Basin, with the gas content of 7.5-20.0 m3/t, and the proportion of free gas (greater than 10%, mostly 11.0%-55.1%) in coal-rock gas significantly higher than that in shallow coals. The enrichment degree of free gas in deep coals is controlled by the number of macropores and microfractures. The coal rock pressure testing shows that the coal-limestone and coal-mudstone combinations for gas accumulation have good sealing capacity, and the mudstone/limestone (roof)-coal-mudstone (floor) combination generally indicates high coal-rock gas values. The coal-rock gas resources in the Ordos Basin were preliminarily estimated by the volume method to be 22.38×1012 m3, and the main coal-rock gas prospects in the Ordos Basin were defined. In the central-east of the Ordos Basin, Wushenqi, Hengshan-Suide, Yan'an, Zichang, and Yichuan are coal-rock gas prospects for the coal seam #8 of the Benxi Formation, and Linxian West, Mizhi, Yichuan-Huangling, Yulin, and Wushenqi-Hengshan are coal-rock gas prospects for the coal seam #5 of the Shanxi Formation, which are expected to become new areas for increased gas reserves and production. [ABSTRACT FROM AUTHOR]

Based on drilling and logging data, as well as geological experiments, the geological characteristics and factors controlling high-yield and enrichment of hydrocarbons in ultra-deep clastic rocks in the Linhe Depression, Hetao Basin, are studied. The results are obtained in four aspects. First, the inland saline lacustrine high-quality source rocks developed in the Paleogene in the Linhe Depression have the characteristics of early maturity, early expulsion, high hydrocarbon yield, and continuous and efficient hydrocarbon generation, providing an important resource basis for the formation of ultra-high pressure and high-yield reservoirs. Second, the weak compaction, early charging, and weak cementation for pore-preserving, together with the ultra-high pressure for pore-preserving and fracture expansion to improve the permeability, leads to the development of high-quality reservoirs with medium porosity (greater than 15%) and medium permeability (up to 226×10-3 µm²) in the ultra-deep strata (deeper than 6 500 m), which represents a greatly expanded space for oil and gas exploration. Third, the Linhe Formation adjacent to the trough exhibits a low net-to-gross (NTG) and good reservoir-caprock assemblage, and it is overlaid by very thick high-quality mudstone caprock, which are conducive to the continuous and efficient hydrocarbon generation and pressurization and the formation of ultra-high pressure oil and gas reservoirs. Fourth, the most favorable targets for ultra-deep exploration are the zones adjacent to the hydrocarbon generating center of the Paleogene Linhe Formation and with good tectonic setting and structural traps, mainly including the Xinglong faulted structural zone and the Nalinhu faulted buried-hill zone. The significant breakthrough of ultra-deep oil and gas exploration in the Linhe Depression reveals the good potential of ultra-deep clastic rocks in this area, and provides valuable reference for oil and gas exploration of ultra-deep clastic rocks in other areas. [ABSTRACT FROM AUTHOR]

Based on the oil and gas exploration in western depression of the Qaidam Basin, NW China, combined with the geochemical, seismic, logging and drilling data, the basic geological conditions, oil and gas distribution characteristics, reservoir-forming dynamics, and hydrocarbon accumulation model of the Paleogene whole petroleum system (WPS) in the western depression of the Qaidam Basin are systematically studied. A globally unique ultra-thick mountain-style WPS is found in the western depression of the Qaidam Basin. Around the source rocks of the upper member of the Paleogene Lower Ganchaigou Formation, the structural reservoir, lithological reservoir, shale oil and shale gas are laterally distributed in an orderly manner and vertically overlapped from the edge to the central part of the lake basin. The Paleogene WPS in the western depression of the Qaidam Basin is believed unique in three aspects. First, the source rocks with low organic matter abundance are characterized by low carbon and rich hydrogen, showing a strong hydrocarbon generating capacity per unit mass of organic carbon. Second, the saline lake basinal deposits are ultra-thick, with mixed deposits dominating the center of the depression, and strong vertical and lateral heterogeneity of lithofacies and storage spaces. Third, the strong transformation induced by strike-slip compression during the Himalayan resulted in the heterogeneous enrichment of oil and gas in the mountain-style WPS. As a result of the coordinated evolution of source-reservoir-caprock assemblage and conducting system, the Paleogene WPS has the characteristics of "whole process" hydrocarbon generation of source rocks which are low-carbon and hydrogen-rich, "whole depression" ultra-thick reservoir sedimentation, "all direction" hydrocarbon adjustment by strike-slip compressional fault, and "whole succession" distribution of conventional and unconventional oil and gas. Due to the severe Himalayan tectonic movement, the western depression of the Qaidam Basin evolved from depression to uplift. Shale oil is widely distributed in the central lacustrine basin. In the sedimentary system deeper than 2 000 m, oil and gas are continuous in the laminated limy-dolomites within the source rocks and the alga limestones neighboring the source kitchen, with intercrystalline pores, lamina fractures in dolomites and fault-dissolution bodies serving as the effective storage space. All these findings are helpful to supplement and expand the WPS theory in the continental lake basins in China, and provide theoretical guidance and technical support for oil and gas exploration in the Qaidam Basin. [ABSTRACT FROM AUTHOR]

The Rose Canyon fault is the southern extension of the larger Newport-Inglewood-Rose Canyon fault system, which represents a major structural boundary in the Inner Continental Borderland (ICB) offshore of southern California. Ten to fifteen percent of total plate boundary motion in southern California is thought to be accommodated by the faults of the ICB, but the exact distribution of slip is uncertain. With an onshore segment, the Rose Canyon fault offers an opportunity to measure the slip rate using traditional geodetic methods. In this study, we use Global Positioning System (GPS) surface velocities from a combined campaign and continuous GPS network to constrain elastic models of the Rose Canyon fault. We then compare the observed surface velocities with proposed conceptual models of regional fault connections that facilitate the transfer of slip into the Rose Canyon fault to assess how well the observations are explained by the models. The results of elastic half-space models suggest that the Rose Canyon fault may be slipping toward the higher end of geologic estimates, with the preferred model indicating a slip rate of 2.4 ± 0.5 mm/yr. Although limited in terms of near-fault benchmarks, we find an improved model fit using an asymmetrical elastic half-space model and a higher slip rate, suggesting a potential rheological contrast across the Rose Canyon fault, similar to observations from the northern Newport-Inglewood fault segments. Observed GPS surface velocities, background seismicity, and gravity anomalies south of San Diego Bay point toward a more easterly trace for the Rose Canyon fault, suggesting a possible connection with the San Miguel-Vallecitos fault system. Such a connection could increase the potential rupture lengths of future earthquakes and have important consequences for regional seismic hazards. [ABSTRACT FROM AUTHOR]

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The early Paleogene, including the Paleocene and Eocene, is characterized by Warmhouse and Hothouse climate states with superimposed transient warming events known as hyperthermals. While these paleoenvironmental changes are well‐documented in the Pacific and Atlantic Oceans, records of such changes in the Indian Ocean are limited. Here, we present a new data set of bulk chemical composition and stable isotopic ratios from the late Paleocene to middle Eocene sediments on the Exmouth Plateau in the mid‐latitude eastern Indian Ocean. The bulk δ13C and δ18O suggest a warming period called the Early Eocene Climatic Optimum (EECO) and cooling toward the middle Eocene in a long‐term perspective. In the short‐term, we identified at least six hyperthermals (Paleocene–Eocene Thermal Maximum, H2, I1, J, ETM3, and L) in the studied sections. By applying independent component (IC) analyses (ICA) to the bulk chemical composition data, we identified six ICs corresponding to sediment source materials and post‐depositional processes. The ICA result infers an increase in detrital materials or a decrease in carbonate rain flux, and an increased population of higher‐order consumers in the oceanic ecosystem during both long‐term (EECO) and short‐term (hyperthermal) warmings around the Exmouth Plateau. Furthermore, ICs representing diagenetic processes and post‐depositional remobilization of elements showed excursions across the hyperthermal horizons, indicating that changes in the redox state of pore or bottom water are associated with hyperthermals. This study provides critical insights into the paleoceanography of the Indian Ocean, highlighting the response of marine environments to both long‐term and short‐term climatic events during the early Paleogene. Plain Language Summary: This study examined marine sediments from the mid‐latitude eastern Indian Ocean dating back to the early Paleogene period, approximately 57 to 40 million years ago. During this time, Earth's climate was much warmer than today, with several short‐term warming events known as hyperthermals. By analyzing the stable carbon and oxygen isotope ratios and the bulk chemical composition of these sediments, we identified six distinct hyperthermals, including the Paleocene–Eocene Thermal Maximum, which was the severest global warming event among the early Paleogene hyperthermals. By applying a multivariate statistical method called independent component analysis to the bulk chemical composition data set, we extracted geochemical features of sediments, including the contributions of source materials (detrital materials, biogenic materials), and signatures of post‐depositional chemical processes. The analysis indicated that inputs of detrital materials from continents and populations of higher consumers in the ocean, such as fish, increased during both long‐ and short‐term warmings. Additionally, several elements were remobilized within the sediment because of changes in the redox state of pore or bottom water. This research provides valuable insights into the link between past climate events and changes in ocean and sediment chemistry, helping us understand how warm periods shaped marine ecosystems and oceanic environments. Key Points: Here, we report bulk δ13C, δ18O, and chemical compositions of early Paleogene sediments from Hole 762C in the Indian OceanWe updated age model of Hole 762C by multiple Eocene hyperthermal horizons, indicated by the bulk δ13C recordIndependent component analysis on bulk compositions revealed Paleogene climate upheavals affected depositional environments at the site [ABSTRACT FROM AUTHOR]

Based on the oil and gas exploration in western depression of the Qaidam Basin, NW China, combined with the geochemical, seismic, logging and drilling data, the basic geological conditions, oil and gas distribution characteristics, reservoir-forming dynamics, and hydrocarbon accumulation model of the Paleogene whole petroleum system (WPS) in the western depression of the Qaidam Basin are systematically studied. A globally unique ultra-thick mountain-style WPS is found in the western depression of the Qaidam Basin. Around the source rocks of the upper member of the Paleogene Lower Ganchaigou Formation, the structural reservoir, lithological reservoir, shale oil and shale gas are laterally distributed in an orderly manner and vertically overlapped from the edge to the central part of the lake basin. The Paleogene WPS in the western depression of the Qaidam Basin is believed unique in three aspects. First, the source rocks with low organic matter abundance are characterized by low carbon and rich hydrogen, showing a strong hydrocarbon generating capacity per unit mass of organic carbon. Second, the saline lake basinal deposits are ultra-thick, with mixed deposits dominating the center of the depression, and strong vertical and lateral heterogeneity of lithofacies and storage spaces. Third, the strong transformation induced by strike-slip compression during the Himalayan resulted in the heterogeneous enrichment of oil and gas in the mountain-style WPS. As a result of the coordinated evolution of source-reservoir-caprock assemblage and conducting system, the Paleogene WPS has the characteristics of “whole process” hydrocarbon generation of source rocks which are low-carbon and hydrogen-rich, “whole depression” ultra-thick reservoir sedimentation, “all direction” hydrocarbon adjustment by strike-slip compressional fault, and “whole succession” distribution of conventional and unconventional oil and gas. Due to the severe Himalayan tectonic movement, the western depression of the Qaidam Basin evolved from depression to uplift. Shale oil is widely distributed in the central lacustrine basin. In the sedimentary system deeper than 2 000 m, oil and gas are continuous in the laminated limy-dolomites within the source rocks and the alga limestones neighboring the source kitchen, with intercrystalline pores, lamina fractures in dolomites and fault-dissolution bodies serving as the effective storage space. All these findings are helpful to supplement and expand the WPS theory in the continental lake basins in China, and provide theoretical guidance and technical support for oil and gas exploration in the Qaidam Basin.

By conducting organic geochemical analysis of the samples taken from the drilled wells in Baiyun Sag of Pearl River Mouth Basin, China, the development characteristics of hydrocarbon source rocks in the sag are clarified. Reconstruct the current geothermal field of the sag and restore the tectonic-thermal evolution process to predict the type, scale, and distribution of resources in Baiyun Sag through thermal pressure simulation experiments and numerical simulation. The Baiyun Sag is characterized by the development of Paleogene shallow lacustrine source rocks, which are deposited in a slightly oxidizing environment. The source rocks are mainly composed of terrestrial higher plants, with algae making a certain contribution, and are oil and gas source rocks. Current geothermal field of the sag was reconstructed, in which the range of geothermal gradients is (3.5–5.2) °C/100 m, showing an overall increasing trend from northwest to southeast, with significant differences in geothermal gradients across different sub-sags. Baiyun Sag has undergone two distinct periods of extensional process, the Eocene and Miocene, since the Cenozoic era. These two periods of heating and warming events have been identified, accelerating the maturation and evolution of source rocks. The main body of ancient basal heat flow value reached its highest at 13.82 Ma. The basin modelling results show that the maturity of source rocks is significantly higher in Baiyun main sub-sag than that in other sub-sags. The Eocene Wenchang Formation is currently in the stage of high maturity to over maturity, while the Eocene Enping Formation has reached the stage of maturity to high maturity. The rock thermal simulation experiment shows that the shallow lacustrine mudstone of the Wenchang Formation has a good potential of generating gas from kerogen cracking with high gas yield and long period of gas window. Shallow lacustrine mudstone of the Enping Formation has a good ability to generate light oil, and has ability to generate kerogen cracking gas in the late stage. The gas yield of shallow lacustrine mudstone of the Enping Formation is less than that of shallow lacustrine mudstone of the Wenchang Formation and the delta coal-bearing mudstone of the Enping Formation. The numerical simulation results indicate that the source rocks of Baiyun main sub-sag generate hydrocarbons earlier and have significantly higher hydrocarbon generation intensity than other sub-sags, with an average of about 1 200×104 t/km2. Oil and gas resources were mainly distributed in Baiyun main sub-sag and the main source rocks are distributed in the 3rd and 4th members of Wenchang Formation. Four favorable zones are selected for the division and evaluation of migration and aggregation units: No. Panyu 30 nose-shaped structural belt, No. Liuhua 29 nose-shaped uplift belt and Liwan 3 nose-shaped uplift belt, No. gentle slope belt of Baiyun east sag, and No. Baiyun 1 low-uplift.

The second member of the Paleogene Funing Formation in the Subei Basin is a key production layer for conventional oil and an optimal target for the exploration and development of continental shale oil in East China. The analysis and testing of core samples from well QY1 in the Qintong Sag indicate that the shale features low total organic carbon (TOC) content, relatively low vitrinite reflectance (Ro), balanced mineral composition, and a complex pore network. Using petrological and geochemical methods, the lithofacies characteristics, reservoir space characteristics, oil-bearing and mobility characteristics, brittleness index, and compressibility characteristics of this shale oil reservoir were studied to identify production sweet spots. The second member of the Funing Formation is a mixed shale layered reservoir, with mineral composition mainly consisting of clay minerals, felsic minerals, and carbonate minerals. The average TOC value is 1.32%, and Ro ranges from 0.9% to 1.1%. The average porosity is 4% in the middle and lower parts and 2.2% in the upper part. Based on the abundance of organic matter, structural characteristics, and lithology, the shale of the second member of the Funing Formation can be divided into six lithofacies, with significant differences in reservoir properties. The development characteristics of the laminae are an important reason for the different reservoir space characteristics among different lithofacies. Except for low organic matter laminated/layered shale with poor calcite and dolomite, other lithofacies have good oil content. The high organic matter layered shale with rich calcite demonstrates the highest TOC content. The number of layers correlates well with oil and gas mobility, with the average OSI value decreasing from 202.62 mg/g in medium organic matter laminae shale with poor calcite and dolomite to 77.83 mg/g in high organic matter massive mudstone. High organic matter massive mudstone, due to the presence of a large amount of plastic minerals, has the worst fracturing effect among the six types of lithofacies. Medium organic matter laminae shale with poor calcite and dolomite is the optimal lithofacies, while medium organic matter layered shale with poor calcite and dolomite and medium organic matter layered shale with rich calcite and dolomite are slightly less favorable but can still be key targets for exploration and development. Based on the vertical distribution of the dominant lithofacies, sublayers ③ to ⑤ of submember Ⅰ and sublayers ② to ④ of submember Ⅱ of the second member of the Funing Formation are selected as geological sweet spots in this area.

The pilot well BYP5 is a cored well drilled to explore the oil and gas bearing properties of the highly thermally evolved lower sub-member of the third member of the Paleogene Shahejie Formation in the Bonan deep sag of the Zhanhua Sag, Bohai Bay Basin. The coring interval depth ranges from 4 267.0 to 4 338.1 m. To reveal the oil and gas bearing properties of the cored interval, pyrolysis of frozen, sealed fragments was conducted on typical samples and the escaping gas from the core was collected and quantified for composition analysis. The results show that the cored interval is a high-quality hydrocarbon source rock rich in organic matter and carbonates, with a maturity (Ro) of about 1.2%. Efficient hydrocarbon generation and expulsion likely occurred during thermal evolution, causing the current low free hydrocarbon (S1) and hydrogen index (IH) values. The content of the hydrocarbon gas from the core was generally low, ranging from 0.001 to 0.01 cm3/g, with an average of 0.005 cm3/g. Segments with relatively high levels of escaping hydrocarbon gas corresponded to those with relatively high pyrolysis S1 values. The escaping gas was mainly composed of CH4, CO2, H2, and C2H6, with mole percentages of H2 ranging from 1.08% to 19.23%, with an average of 7.09%, indicating hydrogen-rich characteristics. H2 showed a significant positive correlation with CO2 and a negative correlation with CH4. The escaping gas from the core was likely trapped in-situ, and the formation of H2 might be related to the cleavage of hetero-bonds and demethylation during the pyrolysis of organic matter. Further research is suggested on the formation mechanism, geological exploration, and evaluation of natural hydrogen released during organic matter pyrolysis, so as to provide a basis for the decision-making in the exploration and development of this type of natural hydrogen resource.

To elucidate the development patterns and influencing factors of natural fractures in deep-buried tight oil reservoirs, a comprehensive evaluation was conducted using a large amount of core samples, thin section, physical property data, imaging and conventional logging, water injection pressure testing and other data. The focus was on the tight oil reservoirs within the Ⅱ-Ⅵ oil layers of the third member of the Paleogene Hetaoyuan Formation in the southeastern An'peng area of the Biyang Depression, Nanxiang Basin. These oil formations, deposited in fan-delta front environment, are characterized by a high content of rock debris, indicating proximal deposition. A strong positive correlation between reservoir porosity and permeability was observed. Among the various sandstone lithologies, fractures predominantly developed in fine sandstone, followed by siltstone, while gravelly sandstone generally lacked fractures. High-angle and vertical fractures were predominant, constituting 87.8% of the total, while low-angle oblique and horizontal fractures accounted for 7.3% and 4.9%, respectively. The main controlling factors for fracture development in these tight reservoirs included lithology, depositional microfacies, and local structures. Thin and fine-grained single or composite sand bodies typically had more deve-loped fractures, particularly in front channel, channel flank, mouth bar, and outer edge of distal bars. Conversely, fractures were less developed in sheet sands or delta front microfacies. Moreover, fractures primarily formed at structural inflection points, predominantly at the tops and wings of forward structures and were primarily oriented along the WE and NE directions, followed by the NW direction. These fractures predominantly formed during the Neogene depression period (late Himalayan). Fractures significantly influence water channeling in tight oil reservoirs, necessitating enhanced dynamic and static monitoring of the degree, extent, and orientation of fracture development.

The El Salvador plutonic complex is a 9.2 km2 circular body within the Sierra de Tamaulipas, part of the Eastern Mexican Alkaline Province (EMAP). Three alkaline magmatic suites were identified from El Salvador from the geochemical analysis of 20 samples. Suite A (SiO2 = 58.3–65.3 wt.%) is ferroan (Fe* = 0.761–0.873) and alkalic (MALI = 4.83–9.89). In contrast, Suites B (SiO2 = 52.5–60.8 wt.%; Fe* = 0.680–0.756) and C (SiO2 = 50.5–67.1 wt.%; Fe* = 0.616–0.749) are magnesian. Suite B is alkali-calcic (MALI = -2.18–4.64), while Suite C is alkalic (MALI = 4.48–8.59). All suites display arc-related signatures. U-Pb and fission-track geochronology data reveal two uplift episodes during the cooling history of Suite A. One in the Late Eocene was based on U-Pb zircon (38.42 ± 0.21 Ma) and titanite ages (35.54 ± 3.77 Ma). The other was during the Oligocene from U-Pb apatite (29.9 ± 6.54 Ma) and fission-track titanite (30.2 ± 5.53 Ma) and apatite ages (32.7 ± 7.06 Ma). Integrating the arc-related signatures of El Salvador rocks with the well-documented Palaeogene arc magmatism of the Sierra Madre del Sur, we propose that the mantle beneath the EMAP experienced metasomatism during the Early Permian (and possibly the Early Jurassic) but not after the Late Cretaceous, ruling out Cenozoic slab subduction in eastern Mexico. In the absence of a slab to explain the El Salvador magmatism, we suggest a long-lasting, widespread mantle upwelling beneath Mexico's northern half in response to the Farallon slab's break-up. Under this context, the westward drift of the North American plate led to the Mexican Foreland Basin lithosphere reaching this massive mantle upwelling in late Eocene times to produce the EMAP magmatism. [ABSTRACT FROM AUTHOR]

Despite their importance as members of the Glires group, lagomorph diversification processes have seldom been studied using molecular data. Notably, only a few phylogenetic studies have included most of the examined lagomorph lineages. Previous studies that included a larger sample of taxa and markers used nonconservative tests to support the branches of their proposed phylogeny. The objective of this study was to test the monophyly of families and genera of lagomorphs and to evaluate the group diversification process. To that end, this work expanded the sampling of markers and taxa in addition to implementing the bootstrap, a more rigorous statistical test to measure branch support; hence, a more robust phylogeny was recovered. Our supermatrix included five mitochondrial genes and 14 nuclear genes for eighty-eight taxa, including three rodent outgroups. Our maximum likelihood tree showed that all tested genera and both families, Leporidae and Ochotonidae, were recovered as monophyletic. In the Ochotona genus, the subgenera Conothoa and Pika, but not Ochotona, were recovered as monophyletic. Six calibration points based on fossils were used to construct a time tree. A calibration test was performed (via jackknife) by removing one calibration at a time and estimating divergence times for each set. The diversification of the main groups of lagomorphs indicated that the origin of the order's crown group was dated from the beginning of the Palaeogene. Our diversification time estimates for Lagomorpha were compared with those for the largest mammalian order, i.e., rodent lineages in Muroidea. According to our time-resolved phylogenetic tree, the leporids underwent major radiation by evolving a completely new morphospace—larger bodies and an efficient locomotor system—that enabled them to cover wide foraging areas and outrun predators more easily than rodents and pikas. [ABSTRACT FROM AUTHOR]

The late Paleocene and early Eocene (LPEE) are characterized by long-term (million years, Myr) global warming and by transient, abrupt (kiloyears, kyr) warming events, termed hyperthermals. Although both have been attributed to greenhouse (CO2) forcing, the longer-term trend in climate was likely influenced by additional forcing factors (i.e., tectonics) and the extent to which warming was driven by atmospheric CO2 remains unclear. Here, we use a suite of new and existing observations from planktic foraminifera collected at Pacific Ocean Drilling Program Sites 1209 and 1210 and inversion of a multiproxy Bayesian hierarchical model to quantify sea surface temperature (SST) and atmospheric CO2 over a 6-Myr interval. Our reconstructions span the initiation of long-term LPEE warming (~58 Ma), and the two largest Paleogene hyperthermals, the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) and Eocene Thermal Maximum 2 (ETM-2, ~54 Ma). Our results show strong coupling between CO2 and temperature over the long- (LPEE) and short-term (PETM and ETM-2) but differing Pacific climate sensitivities over the two timescales. Combined CO2 and carbon isotope trends imply the carbon source driving CO2 increase was likely methanogenic, organic, or mixed for the PETM and organic for ETM-2, whereas a source with higher δ13C values (e.g., volcanic degassing) is associated with the long-term LPEE. Reconstructed emissions for the PETM (5,800 Gt C) and ETM-2 (3,800 Gt C) are comparable in mass to future emission scenarios, reinforcing the value of these events as analogs of anthropogenic change. [ABSTRACT FROM AUTHOR]

Premise: The Cenozoic Macquarie Harbour Formation (MHF) hosts one of the oldest and southernmost post‐Cretaceous fossil plant assemblages in Australia. Coinciding with the Early Eocene Climatic Optimum (EECO) and predating the breakup of Australia from Antarctica, it offers critical data to study the diversity and extent of the Austral Polar Forest Biome, and the floristic divergence between Australasia and South America resulting from the Gondwana breakup. Methods: The micromorphology and macromorphology of new fossil plant compressions from the MHF were described and systematically analyzed. Previously published non‐flowering plant records were reviewed and revised. Macrofossil abundance data were provided. The flora was compared with other early Paleogene assemblages from across the Southern Hemisphere. Results: Twelve species of non‐flowering plants were identified from the macrofossil record. Conifers include Araucariaceae (Araucaria macrophylla, A. readiae, A. timkarikensis sp. nov., and Araucarioides linearis), Podocarpaceae (Acmopyle glabra, Dacrycarpus mucronatus, Podocarpus paralungatikensis sp. nov., and Retrophyllum sp.), and Cupressaceae (Libocedrus microformis). Dacrycarpus linifolius was designated a junior synonym of D. mucronatus. Further components include a cycad (Bowenia johnsonii, Zamiaceae), a pteridosperm (Komlopteris cenozoicus, Umkomasiaceae), and a fern (Lygodium dinmorphyllum, Schizaeaceae). Conclusions: The fossil assemblage represents a mixed near‐polar forest with a high diversity of conifers. The morphology and preservation of several species indicate adaptations to life at high latitudes. The coexistence of large‐ and small‐leaved conifers implies complex, possibly open forest structures. Comparisons with contemporaneous assemblages from Argentina support a circumpolar biome during the EECO, reaching from southern Australia across Antarctica to southern South America. [ABSTRACT FROM AUTHOR]

Nummulitic Limestones deposits are preserved along the tectonic contact between the Variscan basement and Alpine units of Corsica. These marine carbonates, dated from the Late Palaeocene to the Middle Eocene, were deposited within a foreland flexural basin that is considered to be the southern continuation of the Alpine foreland basin of southeast (SE) France. However, in contrast with the Nummulitic Limestones of SE France, those of Corsica are far less documented. This field‐based study constrains the sedimentology, stratigraphy and structure of the Nummulitic Limestones of Corsica in three localities (Balagne, Corte and Sari‐Solenzara) to identify factors that controlled foreland basin development and to clarify its significance within the early alpine orogen. The microfacies, microfaunal assemblages and siliciclastic fractions are characterised throughout the succession at each locality. The results indicate the existence of an important Variscan basement relief to the west of the basin (West Corsican Massif) that supplied early alluvial fans found at the base of the foreland succession in the northernmost Balagne area. Continuous high clastic input strongly reduced the development and diversity of the overlying Nummulitic Limestones facies and fauna. Further south, limestones in the Corte and Sari‐Solenzara areas are thicker and contain richer fauna. Three depositional models corresponding to the carbonate ramp system are proposed for the Nummulitic Limestones and used to construct paleogeographic maps illustrating the transgressive evolution of the Corsican foreland basin from the Early to the Late Eocene. Based on our results and available regional tectonic data and LT thermochronological data, we propose that the Nummulitic marine transgression took place within a continuous foreland basin encompassing southern Corsica and SE France during the early development of the western alpine arc. [ABSTRACT FROM AUTHOR]

Although boron (B) is widely applied as a paleosalinity indicator for ancient lakes, the occurrence and geological controls of B enrichment in salinized lacustrine organic-rich shale (SLORS) are poorly understood. This study addresses this issue by comparing the mineral and element compositions of high-boron shale (HBS) and low-boron shale (LBS) from the Paleogene Biyang Depression, using integrated XRD, XRF, and ICP-MS analyses. The mineral composition of HBS is dominated by illite, whereas LBS primarily consists of albite; both are of detrital origin. Compared to the element composition of UCC, HBS is extremely enriched in Mo and W, whereas LBS is extremely enriched in W and U. Boron is positively correlated with Al2O3 and negatively correlated with Na2O, suggesting that B primarily occurs in illite. An enhanced extent of chemical weathering prevailed during the deposition of HBS, providing a greater supply of illite to the basin. Higher pH levels and greater reduction during HBS deposition encouraged illite absorption of B, ultimately leading to B enrichment in shale. Our findings suggest that pH and redox conditions, as well as the mineral compositions of shale, should be fully considered during the application of B and related ratios as paleosalinity indicators. [ABSTRACT FROM AUTHOR]

The Kluane Schist is a metamorphosed package of siliciclastic and lesser calcareous rocks that lies between the inboard pericratonic Intermontane terranes and outboard Insular terranes of the North American Cordillera within Yukon, Canada. The metamorphic sequence of the Kluane Schist preserves a record of the tectono-thermal evolution and timing of Insular terrane accretion. Here we document the timing of metamorphism and deformation across the Kluane Schist using in situ laser ablation–inductively coupled plasma–mass spectrometry U-Th-Pb monazite petrochronology. Monazite-bearing samples collected across an inverted metamorphic sequence preserved in the northern regions of the Kluane Schist yield dates ranging from ca. 70 Ma to 55 Ma. Complementary phase equilibria modeling and thin section analysis indicate monazite grew between ∼450 °C and 3.0–3.5 kbar to ∼700–715 °C and 4.0–4.5 kbar, coeval with the development of the Kluane Schist’s inverted metamorphic sequence. Dating the four chemical zones preserved by monazite demonstrates its protracted growth during three distinct periods of garnet crystallization and breakdown, as well as coeval with melt generation. Our data illustrate that peak metamorphic conditions were reached at progressively younger ages with decreasing structural level within the Kluane Schist. Our results are consistent with Buchan-style metamorphism associated with the terminal accretion of the outboard Insular terranes and southwest-directed overriding of the inboard Yukon-Tanana terrane from ca. 70 Ma to 55 Ma. These findings are further congruous with a Late Cretaceous timing for the terminal accretion of the Insular terranes within southwest Yukon, facilitated by eastdipping subduction beneath a westward migrating North American continent. [ABSTRACT FROM AUTHOR]

Three new fossil species of walnuts, Juglans eoarctica sp. nov., J. nathorstii sp. nov., and J. cordata sp. nov., are described on the basis of nuts recovered from the middle Eocene fossil forests of Axel Heiberg Island in the Canadian Arctic Archipelago. These represent the most northerly occurrence of Juglans and are among the oldest records of Juglans to date. The Axel Heiberg Island walnuts conform to the sections Rhysocaryon and Cardiocaryon and, together with the contemporaneous midlatitude fossil species J. clarnensis Scott, imply the establishment of two distinct Juglans lineages prior to the middle Eocene. Climatic cooling, leading ultimately to Pleistocene glaciation, has transformed high-latitude vegetation and resulted in the American/Eurasian disjunct distribution found in many north temperate families, of which Juglans is typical. With three coexisting species in the Axel Heiberg Island fossil forests, it is clear that Juglans was an important component of this ancient polar landscape and played a significant role in the evolution of northern temperate forest ecosystems. [ABSTRACT FROM AUTHOR]

Based on a single specimen in Eocene Baltic amber, Henoticus groehni sp. nov., the first extinct species of the genus, is described. The new species is studied and illustrated in detail using optical microphotography and X-ray micro-computed tomography. An additional congeneric specimen is discussed but not attributed to the species level. It is shown that exoskeletal depressions on the metaventrite with possible mycangia roles were present in Henoticus already in the Eocene. The possible involvement of the newly described species in dynamic of ecosystems at the early stages of natural pyrogenic succession in Eocene amber forests is hypothesised. [ABSTRACT FROM AUTHOR]

The Pelagornithidae are an extinct group of soaring birds that lived all over the world between the early Palaeocene and the Pliocene-Pleistocene and are characterised by the presence of hollow denticles along the tomial edges formed by the expansion of the premaxillary, maxillary, and dentary bones. The presence of distinctive sulci in the upper and lower jaws together with the absence of wearing signs on the denticles, attributable to the handling of the prey, indicates the development of a resistant and compound rhamphotheca. To reconstruct it, we turned to the evidence provided by extant representatives with similar configurations and the osteological correlates of the beak. As a result, we propose a model for the middle-latest Eocene Antarctic Pelagornithidae, in which the rhamphotheca would have been formed by thick horny plates. The culminicorn was separated from the laternicorn by an extense sulcus nasi that continuous caudally to the apertura nasi ossea, a sturdy and hooked unguis maxillaris covering the rostrum, with small nares opening at the cranial end of the apertura nasi ossea, dorsal and ventral ramicorns, and a thick unguis mandibularis with a pseudomental fold and a sulcus on the mandible. [ABSTRACT FROM AUTHOR]

Peradectidae are Paleogene ‘opossum-like’ stem-metatherians, largely Laurasian, whose evolutionary history remains unclear. Based on new remains (mainly dental) discovered in several French localities, we carry out a comprehensive systematic revision of all early Eocene peradectids from Europe (~MP7 reference level to MP10-11 interval). We describe well-preserved specimens from Palette (Southern France, MP7-MP8 + 9 interval) documenting the earliest European peradectid, Peradectes crocheti sp. nov. This new species exhibits an interesting mosaic of characters, including plesiomorphic traits found in the North American type species, Peradectes elegans Matthew and Granger, 1921. Molars allocated to the strikingly ubiquitous Peradectes crocheti sp. nov. are found in eight additional localities from northwestern and southwestern Europe, all limited to the time interval MP7-MP8 + 9. Moreover, the study of unpublished material of the MP8 + 9 and ~MP8 + 9 peradectids allows us to recognize two younger coeval species (Peradectes louisi Crochet, 1979, and Peradectes russelli Crochet, 1979). Our taxonomic conclusions are supported a posteriori by the first quantitative assessment of the variation in height of metatherian stylar cusps. The holotype of Peradectes louisi is reinterpreted, and Peradectes ‘mutigniensis’ Crochet, 1979 appears to be a junior synonym of Peradectes russelli. In addition to size, the otherwise similar Peradectes louisi and Peradectes russelli can be distinguished based on subtle yet consistent differences, such as lower molar proportions. Phylogenetic analyses using a novel matrix of dental characters shed new light on the relationships among Eocene peradectids, confirming the paraphyly of Peradectes with respect to Armintodelphys and Mimoperadectes. Our results suggest a single dispersal from North America to Europe in the evolutionary history of peradectids, which likely occurred immediately after the Paleocene-Eocene Thermal Maximum, Peradectes crocheti sp. nov. being recovered as the earliest offshoot of the European clade. Scarce lower molars from the MP10 reference locality and ~MP10 localities analyzed within this constrained phylogenetic framework reveal a trend towards shrinking of the entoconid in the European lineage throughout the early Eocene. [ABSTRACT FROM AUTHOR]

The southern Central Andes (∼25–40°S) exhibit a complex tectonic history, crucial for understanding orogenic processes in subduction-related orogens, yet debate on the timing and mechanisms of early Cenozoic topographic growth persists. We present double-dated detrital zircon U-Pb and (U-Th)/He thermochronology data from the early Oligocene–Miocene Bermejo Basin at ∼30°S to investigate source unroofing during development of the High Andes. (U-Th)/He results yield dates of ca. 565–16 Ma (n = 73), with distinct detrital modes that indicate a mixing of sediment sources characterized by variable cooling and exhumation histories. We employ a novel approach for modeling detrital thermochronology data that leverages the shared basin subsidence history of multiple detrital modes to resolve provenance and source unroofing histories. Results from the lower Oligocene Vallecito Formation (northwestern Argentina) reveal that detritus was sourced from Permian–Triassic Choiyoi Group rocks that underwent rapid late Eocene cooling, indicated by short lag time (2–5 m.y.) between source cooling and deposition. Our findings are consistent with bedrock studies of Eocene exhumation in the High Andes and establish source-to-basin connectivity during this time. Other detrital modes with pre-Cenozoic cooling histories were derived from Carboniferous Elqui-Colangüil and Choiyoi Group rocks or recycled from Paleozoic basins. We propose that an early Oligocene drainage divide in the High Andes was located west of the Punilla–La Plata fault, an active thrust front at ∼30°S. These findings challenge Paleogene neutral stress-state models for the Andes and underscore the importance of improved knowledge of erosion and deformation histories for refining models of Andean orogenesis. [ABSTRACT FROM AUTHOR]

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Copyright of Petroleum Geology & Experiment is the property of Petroleum Geology & Experiment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)