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Member 5 of the Upper Triassic Xujiahe Formation (T3X5) in central Sichuan Basin has made a breakthrough in exploration recently. However, this new stratum has not been investigated sufficiently with respect to basic geology, making its types and distribution of sedimentary facies unclear, which severely restricts its subsequent exploration evaluation. In this study, types of sedimentary microfacies in the first sand group of T3X5 (T3X51) are clarified through core observation and logging interpretation using core, log and seismic data, and then distribution of sedimentary microfacies in T3X51 is determined according to seismic waveform features and seismic prediction. The results show that T3X51 in the Dongfengchang area is mainly composed of deltaic deposits of several microfacies, such as delta front underwater distributary channel, sheet sand, and interdistributary bay. On seismic sections, different microfacies are significantly different in waveform features, the underwater distributary channel is characterized by one trough between two peaks, while diversion bay exhibits chaotic reflections between T6 and T51. The sedimentary microfacies varied greatly during the depositional period of T3X51 in the Dongfengchang area, this is because that the sediment supply was mainly controlled by the southwest and southeast provenance regions. Three superimposed underwater distributary channels are developed in the Dongfengchang area. The phase-1 superimposed underwater distributary channel in the northwest transition to sheet sand in the northeast, the phase-2 superimposed underwater distributary channel in the south extends shortly, the phase-3 superimposed underwater distributary channel in the northeast has a large development scale. These research findings are helpful to guide the subsequent exploration of T3X5 gas reservoir and also theoretically significant for investigating the depositional evolution of the Xujiahe Formation in central Sichuan Basin.

The first results of U–Th–Pb isotope dating of detrital zircons (dZr) from the Chenka sandstones of the Cimmerides of Mountainous Crimea are presented. Carboniferous–Triassic dZr dominate among dZr from Chenka sandstones. Analysis of previously obtained sets of dZr ages from the age and lithologically different formations of Cimmerides of Mountainous Crimea has revealed certain regularities in the change in the time of the provenance signal and, accordingly, of the provenance areas, whose erosion products compose the studied formations. A comparison of the obtained of U–Pb ages of dZr from Chenka sandstones with similar dates obtained for sandstones from the Upper Triassic–Jurassic formations has shown that the provenance signals of the Chenka sandstones and Upper Triassic–Lower Jurassic flysch strata are different, but the provenance signals of the Chenka sandstones and Middle–Upper Jurassic coarse clastic strata are similar. Detrital zircons from the Chenka sandstones show that the parameters of the Th–U distribution in them are intermediate between those from sandstones of flysch and coarse-grained strata, respectively. In general, the isotope-geochronological and geochemical data we obtained and some features of the internal structure of dZr grains from the Chenka sandstones can be used as a strong argument in favor of considering Chenka sandstones as an independent stratigraphic unit with an age not older than the Middle Jurassic. The similarity of the characteristics of dZr grains from sandstones of the Chenka sandstones with those from Middle–Upper Jurassic sandstones casts doubt on the correlations of the Chenka sandstones with a number of lithologically similar units of the southwestern regions of Mountainous Crimea, specified as Early Jurassic in age based on finds of fossil remains. [ABSTRACT FROM AUTHOR]

Previous studies have delved into slope break zones in faulted basins, yet foreland basins, with their gentle slopes toward the forebulge, underdeveloped large-scale structures, and small terrain undulations, have received limited research on slope-fault belts. During the deposition periods of the 4th and 5th members of the Late Triassic Xujiahe Formation, a foreland basin developed in the Sichuan Basin. Scholars have noted the control exerted by the gentle slope break zone on the sedimentary lithofacies in the central and western Sichuan, particularly in the west of the Luzhou-Kaijiang Paleo-uplift, but related studies remain limited. By interpreting the tectonic slope break zones in seismic reflection profiles of the Sichuan Basin and incorporating existing regional geological data, this study employed particle flow numerical simulation to clarify the types of slope break zones in the central and western Sichuan regions, as well as their relationship with gravity sliding structures. It also analyzed the characte-ristics of new types of oil and gas traps associated with gravity-sliding structures. The findings are as follows: (1) The study area developed a fault slope break zone, with each side bounded by a "front squeezing and rear extension" tectonic combinations formed by gravity sliding. The tectonic deformation is weaker than those of gravity-sliding structures at passive continental margins. (2) The edge fault of the tectonic slope break zone controls the sedimentary facies and sand body types. (3) In the gentle slope zone, the stretching area of gravity-sliding structures lead to the uplift of the footwalls of normal faults, forming syndepositional anticlines with developed sandstones. These sandstones, juxtaposed with organic-rich mudstones within the contemporaneous fault depression, form "side-generated and lateral storage" hydrocarbon reservoirs. (4) In the steep slope zone, gravity sliding forms syndepositional anticlines in the 5th member of the Xujiahe Formation, which are bounded by flank mudstones and post-sliding deposited mudstones, forming in-source sand body reservoirs. (5) Syndepositional anticline hydrocarbon reservoirs related to gravity-sliding structures represent a new type of in-source hydrocarbon accumulation. The 5th member of the Xujiahe Formation in the study area likely contains such reservoirs, distributed in a NE-trending pattern parallel to the slope break zone.

The Junggar Basin is known for its high potential of petroleum resources, showcasing significant oil and gas discoveries across various layers. However, the potential of utilizing the thick mudstone of the Upper Triassic as a viable source rock in the basin remains uncertain. Therefore, an urgent need exists to assess the Upper Triassic source rock across the basin and predict the distribution of effective source rocks. This evaluation is crucial for informing future exploration strategies in this layer. To shed light on the spatiotemporal distribution characteristics and hydrocarbon generation potential of the Upper Triassic source rocks in the Junggar Basin, as well as to determine the hydrocarbon generation intensity within the effective hydrocarbon kitchen's distribution range, a comprehensive evaluation was conducted. This evaluation involved assessing organic matter abundance, type, and maturity of the Upper Triassic source rock across the basin using various geochemical parameters derived from data collection, profile measurement, drill cuttings observation and sampling, and organic geochemistry testing. Key parameters were then selected, and a multi-level fuzzy mathematical evaluation method was employed to map out the development range of the effective hydrocarbon kitchen. The findings indicate that the Upper Triassic source rock exhibits a broad distribution range spanning the entire basin, with considerable thickness (reaching up to 350 m) and significant burial depth in the central region (up to 11 000 m). The total organic carbon (TOC) content of source rocks varies from 0.75% to 8.30%, with an average value of 1.74%. Additionally, the average values of S1+S2 and chloroform asphalt "A" are 2.78 mg/g and 0.354%, respectively. The predominant organic matter types in the area are type Ⅲ and type Ⅱ2, indicating a dominance of terrestrial higher plant inputs. The favorable kerogen types are primarily located from the western sag to the Fukang Sag. The thermal evolution of the organic matter ranges from low-maturity to mature stages, with some areas reaching high to over-maturity levels. As per the evaluation criteria for hydrocarbon generation potential of coal-bearing mudstone in China, the Upper Triassic mudstone generally represents poor to medium-quality source rocks with significant hydrocarbon generation potential, particularly for gas. The key hydrocarbon source kitchens are situated from the western part of the Fukang Sag to the eastern part of the Shawan Sag in the central depression, and in the Huomatu Anticline of the southern margin thrust belt. Within these areas, the Ro value of the source rock exceeds 1.3%, with oil and gas generation intensities reaching 50×104 t/km2 and 3×108 m3/km2, respectively.

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For the first time, this study presents interpretations of alluvial fans in spectral decomposition RGB Blends, analysed in seismic time slices from the Middle Triassic to Lower Jurassic stratigraphical interval of the Horda Platform (northern North Sea). The time slices record a shifting alluvial fan front, fluvial variability, uplift and erosion and reveals depositional elements that may set the common conception of the geological development of this area during the Early–Middle Mesozoic up for discussion. Results show that the Upper Triassic Lunde Formation in the eastern margin of the Horda Platform was characterized by the deposition of coalesced alluvial fans. A variable extent of the fan front through the Upper Triassic is linked to interplaying allogenic factors: uplifted source areas in the aftermath of Early–Middle Triassic rifting determined sediment availability; climate transitioning from arid to semi‐humid, with increasingly fluctuating precipitation, controlled sedimentation, and run‐off; provenance dictated bulk sedimentology and affected prevailing alluvial processes. An overall retreat of the fan system through the Late Triassic coincided with a significant change in landscape characteristics at the transition into the overlying Statfjord Group. Uplift and initial tilting of the Horda Platform caused landscape degradation and the formation of plateaus and incised valleys, contemporaneous with increased humidity and marine transgression, forming estuaries. The shift in depositional style has implications for reservoir properties, creating complexity and heterogeneity in terms of facies distribution and connectivity, which may benefit potential CO2 storage. Upper Triassic alluvial fan development in the Horda Platform (northern North Sea) depicted through spectral decomposition of seismic time slices Enhanced level of seismic stratigraphic interpretation with RGB blending Impact of allogenic factors on alluvial depositional development Implications of alluvial variability on reservoir properties [ABSTRACT FROM AUTHOR]

The Qadir coal-bearing member of the Rhaetian Nayband Formation in the Parvadeh coal mine, East-Central Iran, was investigated for palaeoenvironmental reconstruction to predict coal properties. Along with field studies, rock petrography, XRD, and SEM-EDX analyses were carried out, and petrofacies, lithofacies, and facies associations were defined in a sequence stratigraphic framework. These studies represent a river-dominated, storm- and wave-influenced coastal/delta plain setting that accumulated along the shallow marine environment. The studied Qadir member is part of a paralic system that consists of progradational delta grading into shallow marine siliciclastic shelf sediments. Apart from sea-level fluctuations, the sedimentary pattern was mainly governed by tectonic events in a post-orogenic foreland setting connected to the rising Cimmerian Mountain range in the north. Sedimentological analysis and stacking patterns of the Qadir member indicate that discrete coal seam and zones in the member were formed by peat mires that extended onto the delta plain and occurred in fourth-order sequences stacked in the transgressive system tracts of the lower sequence (TST1) and early highstand systems tract of the upper sequence (HST2). However, the main economic coal zone was formed in the lower delta plain environment, predominantly within the middle part of the TST. The detrital nature and composition of the numerous partings and high ash content in the coal seams indicate that the coal-forming environment was a low-lying, topogenous flow-fed mire near detrital sources (i.e. distributary channels). Seemingly, coal layers are thicker with less sulfur (pyrite), but more ash toward the western part of the area. [ABSTRACT FROM AUTHOR]

Mesozoic marine shale oil was found in the Qiangtang Basin by a large number of hydrocarbon geological surveys and shallow drilling sampling. Based on systematic observation and experimental analysis of outcrop and core samples, the deposition and development conditions and characteristics of marine shale are revealed, the geochemical and reservoir characteristics of marine shale are evaluated, and the layers of marine shale oil in the Mesozoic are determined. The following geological understandings are obtained. First, there are two sets of marine organic-rich shales, the Lower Jurassic Quse Formation and the Upper Triassic Bagong Formation, in the Qiangtang Basin. They are mainly composed of laminated shale with massive mudstone. The laminated organic-rich shale of the Quse Formation is located in the lower part of the stratum, with a thickness of 50–75 m, and mainly distributed in southern Qiangtang Basin and the central-west of northern Qiangtang Basin. The laminated organic-rich shale of the Bagong Formation is located in the middle of the stratum, with a thickness of 250–350 m, and distributed in both northern and southern Qiangtang Basin. Second, the two sets of laminated organic-rich shales develop foliation, and various types of micropores and microfractures. The average content of brittle minerals is 70%, implying a high fracturability. The average porosity is 5.89%, indicating good reservoir physical properties to the level of moderate–good shale oil reservoirs. Third, the organic-rich shale of the Quse Formation contains organic matters of types II1 and II2, with the average TOC of 8.34%, the average content of chloroform bitumen ‘A’ of 0.66%, the average residual hydrocarbon generation potential (S1+S2) of 29.93 mg/g, and the Ro value of 0.9%–1.3%, meeting the standard of high-quality source rock. The organic-rich shale of the Bagong Formation contains mixed organic matters, with the TOC of 0.65%–3.10% and the Ro value of 1.17%–1.59%, meeting the standard of moderate source rock. Fourth, four shallow wells (depth of 50–250 m) with oil shows have been found in the organic shales at 50–90 m in the lower part of the Bagong Formation and 30–75 m in the middle part of the Quse Formation. The crude oil contains a high content of saturated hydrocarbon. Analysis and testing of outcrop and shallow well samples confirm the presence of marine shale oil in the Bagong Formation and the Quse Formation. Good shale oil intervals in the Bagong Formation are observed in layers 18–20 in the lower part of the section, where the shales with (S0+S1) higher than 1 mg/g are 206.7 m thick, with the maximum and average (S0+S1) of 1.92 mg/g and 1.81 mg/g, respectively. Good shale oil intervals in the Quse Formation are found in layers 4–8 in the lower part of the section, where the shales with (S0+S1) higher than 1 mg/g are 58.8 m thick, with the maximum and average (S0+S1) of 6.46 mg/g and 2.23 mg/g, respectively.

Abstract Peat forming environment strongly influences the economic value of any coal seam and coal-bearing strata. Hence, palaeoenvironmental studies provide important information for coal resource exploration. In this context, detailed studies on selected coals from the Parvadeh Area, Iran, were conducted using sedimentology, coal petrology, X-ray diffraction (XRD), scanning electron microscopy- energy dispersive X-ray analyzer (SEM-EDX), and proximate analysis. The sedimentary facies above and below the coal seams are mainly marine or marine-influenced facies, supporting that the coal-forming mires in the Parvadeh Area developed in a paralic environment, where the base level must be closely related to sea level. Sulfur contents are moderate to high and mark the influence of brackish/marine water, especially during transgression after peat growth in a lower delta plain environment. The peat-forming mires extended on coastal/delta plain lobes. The lower delta plain/coastal plain coals are characterized by lateral continuity and substantial thickness, whereas few coals possibly representing the upper delta plain are thin and more discontinuous. The detrital nature and composition of the numerous partings and the overall high ash yield in the coal seams indicate an active tectonic area with high rates of creation of accommodation space over peat growth. Coal petrology and coal facies analysis exhibits a permanently high water table within a forest swamp and mostly rheotrophic conditions, sometimes with connection to the seawater. According to paleoenvironmental reconstructions, it seems that coal layers may be thicker, with less sulfur (pyrite), but more clastic minerals and partings toward the western part of the area. Although these coal seams presently have low economic potential for the mining operation, partly due to great depth, this humic, high-volatile to medium-volatile bituminous coal may be suitable for exploration of coal bed methane resources.

Copyright of Geology & Resources is the property of Geology & Resources 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.)

Peat forming environment strongly influences the economic value of any coal seam and coal-bearing strata. Hence, palaeoenvironmental studies provide important information for coal resource exploration. In this context, detailed studies on selected coals from the Parvadeh Area, Iran, were conducted using sedimentology, coal petrology, X-ray diffraction (XRD), scanning electron microscopy- energy dispersive X-ray analyzer (SEM-EDX), and proximate analysis. The sedimentary facies above and below the coal seams are mainly marine or marine-influenced facies, supporting that the coal-forming mires in the Parvadeh Area developed in a paralic environment, where the base level must be closely related to sea level. Sulfur contents are moderate to high and mark the influence of brackish/marine water, especially during transgression after peat growth in a lower delta plain environment. The peat-forming mires extended on coastal/delta plain lobes. The lower delta plain/coastal plain coals are characterized by lateral continuity and substantial thickness, whereas few coals possibly representing the upper delta plain are thin and more discontinuous. The detrital nature and composition of the numerous partings and the overall high ash yield in the coal seams indicate an active tectonic area with high rates of creation of accommodation space over peat growth. Coal petrology and coal facies analysis exhibits a permanently high water table within a forest swamp and mostly rheotrophic conditions, sometimes with connection to the seawater. According to paleoenvironmental reconstructions, it seems that coal layers may be thicker, with less sulfur (pyrite), but more clastic minerals and partings toward the western part of the area. Although these coal seams presently have low economic potential for the mining operation, partly due to great depth, this humic, high-volatile to medium-volatile bituminous coal may be suitable for exploration of coal bed methane resources. [ABSTRACT FROM AUTHOR]

Natural fractures are quite important for the high and stable production of tight sandstone gas reservoirs. However, it is commonly difficult to accurately characterize their distribution in tight sandstone gas reservoirs due to the strong heterogeneity. A comprehensive characterization of natural fractures in tight sandstone gas reservoirs of the Xujiahe Formation in the Yuanba area, Sichuan Basin, was carried out by multimethod of core description, log interpretation and seismic prediction. The results show that (1) the natural fractures in the Xujiahe Formation are mainly low-angle fractures, with a few medium- and high-angle fractures. The degree of fracture development is mainly controlled by the distance from the fault, the flexural degree of the strata and the thickness of the rock mechanical layer. (2) The fracture-sensitive seismic attributes such as the preferred maximum likelihood, structure entropy, illuminant-based symmetry and high-precision curvature are taken as the input, and the unsupervised cluster analysis algorithm based on Bayesian probability model is applied to predict the distribution of large-scale fractures at different dip angles; on the basis of narrow azimuthal pre-stack CMP gather optimization, the anisotropy detection technique of Hampson-Russell's ProAZ full CMP gather is used to characterize the distribution of small- and medium-scale fractures, and the predicted fracture development intensity matches the fracture interpretation results of the imaging logs by more than 85%. Moreover, the predicted fracture orientation is basically consistent with that of the imaging loggings. (3) The fault-genesis fractures of the Xujiahe Formation are mainly distributed near the fault on the southeast flank of the Jiulongshan anticline, and are distributed in a narrow strip in NE direction. The fold-genesis fractures are mainly developed in the Xu 3rd Member, and are located in the axis of the Jiulongshan anticline and its southeast flank where the strata are strongly flexed. This study provides a solid foundation for the development of tight sandstone gas reservoirs and extends the approaches for the accurate characterization of fractures.

The Upper Triassic Xujiahe Formation (T3x) is the most important terrigenous stratum in the Western Sichuan Depression; however, it is still insufficient for the understanding of molecular compositional characteristics of its source rocks. Based on the analysis of both saturated and aromatic fractions of extracts of source rocks from different members of the Xujiahe Formation, the indication is then discussed for sedimentary environment and thermal evolution of source rocks. The distribution of tricyclic terpanes (TTs) and dibenzothiophene/phenanthrene (DBT/P) ratio of the argillaceous source rocks in 2nd to 4th members of the Xujiahe Formation mainly display the signatures of typical lacustrine source rocks, and the relatively high gammacerane/C30 hopane (0.16-0.23), as well as 9-/1-methylphenanthrene (1.16-1.41) ratios suggest relatively high salinity of water body. The parameters such as methylphenanthrene index (MPI1), methylphenanthrene distribution fraction (F1), and methyldibenzothiophene distribution index (MDBI) are effective for the evaluation of thermal maturity, and they show positively and negatively linear correlation with maturity degree before and after Ro=1.35%. The distribution pattern of C27-C29 regular steranes, relative composition of three fluorine series, and methyldibenzothiophene/methyldibenzofuran ratios for high to over-maturity T3x source rocks are distorted due to the effect of thermal maturation.

Copyright of Journal of Northeast Petroleum University is the property of Journal of Northeast Petroleum University 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.)

Geometric morphometric approaches become increasingly applied in the fields of biology and palaeontology. Taxonomy is a good example, where a long‐standing intention of scientists is to eliminate subjectivity as much as possible. In the case of biostratigraphically important conodont elements, the application of such methods is not widespread. Only a handful of studies attempted to deal with the morphological variance of conodont elements from this aspect. The detailed description of five lower Norian (Upper Triassic) taxa (Ancyrogondolella quadrata, A. rigoi, A. triangularis, A. uniformis and Metapolygnathus mazzai) is presented here based on landmarks and Fourier analysis of the P1 element and keel outlines. Both methods led to similar outcomes regarding taxonomic differentiation and exposing shape variability. Consensus shapes were generated to objectively reveal the typical contour shape of each taxon, which allowed their comparison with each other, and with the members of their respective sample population including the holotypes. The results demonstrated that the holotype of a taxon is generally not an average representative, but rather a peripheral form with well separable morphological characteristics. Ancyrogondolella quadrata and A. rigoi turned out to represent a morphological continuum with ample transitional forms between these two end‐members that may cause bias in their biostratigraphic applicability, however their combined shape variance seems to be too large for uniting them into a single species. Given the results that may be too subtle to realize based solely on qualitative observations, future taxonomic studies and type material designation could greatly benefit from the application of similar methodologies. [ABSTRACT FROM AUTHOR]

The Upper Triassic conodont genus Primatella is important for recognizing the Carnian-Norian stage boundary in Panthalassan and Tethyan domains. Originally based on Canadian material from Black Bear Ridge in the Western Canada Sedimentary Basin, two key species are highlighted, and their occurrence is documented in the allochthonous Wrangellia and Alexander terranes in the North American Cordillera; in the Great Basin in Nevada, western United States; at Pizzo Mondello, Sicily, in western Tethys; and in Timor-Leste on the southeastern margin of the Meso-Tethys Ocean (northeastern Gondwana). The correlation potential of Primatella species is compromised by a differing nomenclature employed in Tethyan regions of Europe where Primatella species have been assigned to other genera, namely, Ancyrogondolella (formerly Epigondolella), Carnepigondolella, and Metapolygnathus. This has obscured phyletic relationships and impacted the stratigraphic utility of two demonstrably cosmopolitan species, P. asymmetrica and P. bifida. These species are shown to occur widely in a variety of paleoenvironments and have a restricted stratigraphic range around the CNB for which they can be adopted as useful indices.

Der Gattungsnamc Cucurbita Jablonsky, 1973 kann nicht als gueltig betrachtet werden, da dieser Name bereits 1882 durch Scudder (Nomenclator Zool. Suppi. Lise, 93) an eine Muschel­Gattung vergeben worden ist. Die Gattung Pseudocucurbita Borza & Samuel, 1978 wird mit der Gattung Cucurbita synonym erkliirt. Da der Name Cucurbita hinfaellig ist, wird der Name Cucurbita Jablonsky durch Pseudocucurbita Borza & Samuel (pro Cucurbita Jablonsky) ersetzt (Homonymie).

A new outcrop with Rhaetavicula contorta was found on the northeast slope of the M. Ponciv, at Pra Brusché (1065 m s.l.m.). The outcrop has the same lithologic characters of the typical « Avicula contorta levels » but its faunal content is quite peculiar. Microfauna and macrofauna were examined in detail and the results compared with the bibliographic data relevant to the « Avicula contorta levels ».

The Coastal Cordillera of Central Chile (34°–37°S) holds a series of Late Triassic granitoids classically interpreted as early Andean subduction‐related magmatism based on their arc‐like geochemical signature. Here, we present geochemical, isotopic, and geochronological data and a tomotectonic analysis that challenge this idea indicating a local interruption of the normal subduction process likely associated with a slab‐tearing event. Our results suggest that the source of the magmas is related to melting of asthenospheric mantle and crustal rocks of a metasedimentary Paleozoic complex. We suggest that partial melting of these sources was triggered by a slab tear‐related asthenosphere upwelling producing high‐silica S/I‐ and S‐Type granites of the Constitución and Hualpén areas, and anorogenic A‐Type granitoids in Cobquecura area. Also, partial melting of a metasomatized asthenospheric mantle plus continental crust that experienced previous high‐temperature hydrothermal alteration would have generated high‐silica magmas with low δ18O, high Pb, CHUR‐like 87Sr/86Sr, and 143Nd/144Nd ratios that originated La Estrella Granite. Our results offer an alternative explanation for the existence of subtle magmatic arc‐like geochemical signatures in the study area and support a segmentation of the active margin during the Late Triassic. The widespread upper‐plate magmatic record of slab‐tearing, spanning the Coastal Cordillera of Central Chile to the intraplate Neuquén basin in Argentina, and the lower mantle record of a slab gap, detected in ours and previous tomotectonic analyses, make the Late Triassic slab‐tearing event in southwestern Pangea the most robustly constrained pre‐Cenozoic slab tear process so far. Key Points: The Late Triassic granitoids of Southern‐Central Chile were emplaced from 220 to 210 MaS, S/I, and A‐type granites characterize Late Triassic magmatismSlab‐tearing was likely the driver for granite generation in Southern‐Central Chile [ABSTRACT FROM AUTHOR]

A new Mystriosuchinae phytosaur, Colossosuchus techniensis, is described from the Upper Triassic Tiki Formation of India. Colossosuchus is diagnosed by multiple apomorphies, including a strongly downturned terminal rosette (c. 70°), closely spaced mediolateral band‐like ornamentation on dorsal surface of the nasal, dorsolaterally oriented supratemporal fenestra, ventrolaterally inclined postorbital–squamosal bars depressed below the skull table, dorsally convex parietal–squamosal bar that descends ventrolaterally below the skull roof, dome‐shaped skull in lateral view, prominent neural arch laminae and fossae, three sacral vertebrae, robust proximal end of the tibia, and fibula with high anteroposterior flaring of the distal end. The total body length of the largest individual recovered from the bonebed is estimated to be more than 8 m, suggesting that Colossosuchus is one of the largest phytosaurs known. Phylogenetic analysis nests Colossosuchus and other undescribed specimens from India within Mystriosuchinae. These form a distinct clade and represent the earliest record of endemism among Gondwanan phytosaurs. This clade is recovered as sister taxa to ((Volcanosuchus + Rutiodon) + Leptosuchomorpha), where the depressed supratemporal fenestra first appeared in the phytosaur lineage, a feature previously used to diagnose the derived leptosuchomorphs. Early‐diverging phytosaur diversification may have coincided with the final stages of the Carnian Pluvial Event with their possible migratory routes along the circum‐Tethyan coastline. The lineage continued to evolve mostly through endemic radiations and experienced an extinction event during early Norian, which marked the disappearance of most of the non‐leptosuchomorph taxa. This is attributed to post‐CPE aridification, although more study is required. [ABSTRACT FROM AUTHOR]

The Puesto Viejo Group is an important unit for the knowledge Triassic faunas especially non-mammalian therapsids. This group crops out in the San Rafael Block, southwest Mendoza, Argentina. It is composed of the basal Quebrada de los Fósiles Formation (QF) which is overlaid by the Río Seco de la Quebrada Formation (RSQ). This report comprises tetrapod remains from the RSQ Formation at the Quebrada del Durazno area that includes, until now, exclusively therapsids. The aim of this study is to analyse the bone microstructure of cynodonts and dicynodonts to elucidate the histological features and growth patterns. Histological thin sections made in ribs and appendicular bones reveal a predominance of fibrolamellar bone tissue suggesting an overall fast bone growth, however, the presence of parallel-fibred bone suggest periods of slowing down of the growth. The existence of growth marks indicates periodic interruptions of growth, which is likely the expression of their ability to rapid respond to environmental changes. This contribution offers new insights into the bone microstructure of tetrapod assemblages from RSQ Formation during the Upper Triassic span. [ABSTRACT FROM AUTHOR]

The Norian "chaotic carbon episode" stands out as a compelling carbon cycle perturbation event within the Late Triassic period. This episode has been documented in marine stratigraphic sections across North America, Italy, Japan, and China. However, limited Norian chronostratigraphy available in the eastern Tethys inhibited the identification of this event in this broad area, and thus the possible global response to this carbon cycle perturbation. To address this issue, we analyzed the conodonts and carbon-isotope of the Norian Sanhedong (SHD) section in the Simao terrane, Southwest China. The identification of the Alaunian Epigondolella spiculata Zone has well documented the base of the Alaunian stage. Moreover, a conodont faunal turnover can be recognized at the base of the Alaunian, with the evolution of Mockina from Ancyrogondolella and Epigondolella , and it is characterized by a gradual decrease in specimen size. The E. spiculata conodont Zone from the SHD section correlates well with the homonymous conodont Zones documented in both the Tethys and the Panthalassa Oceans. Two carbon-isotope negative excursions (CIE1 and CIE2) have also been recorded in the Lacian to Alaunian of the SHD section that can be compared with coeval global sections. • In this study, the typical Alaunian conodont Epigondolella spiculata Zone has been identified in the eastern Tethys. • The descendants of the genus Ancyrogondolella show a significant reduction in size from the Lacian-Alaunian transition. • Two carbon-isotope negative excursions (CIEs) described in the SHD section can be correlated with global coeval sections. [ABSTRACT FROM AUTHOR]

The Triassic was a critical period for a significant increase in the generic diversity of radiolarians after the disappearance of >80% of radiolarian genera during the Permian-Triassic mass extinction. In particular, the Upper Triassic radiolarian fauna is rich and has been documented in several world regions, such as North America, Western Europe, the Mediterranean area, Japan, the Philippines, Timor, and Far East Russia. In this study, a well-preserved and high-diversity fauna from a continuous pelagic-hemipelagic section deposited in western Tethys (Sicily, Italy) provides one of the most detailed radiolarian records of the Carnian-Norian boundary interval, which can be correlated worldwide, from high to low-latitude, from both sides of the Pangea and both Hemispheres. The 99 species belonging to 50 genera from this time interval have been collected from the Pizzo Mondello section (Sicanian Basin, Western Sicily), the selected GSSP for the base of the Norian stage, and then compared to the radiolarian associations documented in other coeval regions. Based on the occurrences of characteristic radiolarian species, we defined and proposed a new radiolarian biozonation across the Carnian-Norian boundary, which consists of five new assemblages (PM assemblage 1–5) that are correlated and calibrated to the already well-defined biozonation of bivalves, ammonoids, and conodonts. • The study proposes a new radiolarian biozonation across the Carnian/Norian boundary (CNB) from the Norian GSSP section. • The new radiolarian assemblages are calibrated to bivalves, ammonoids, and conodonts zonation and compared to coeval regions. • This study provides new insights into the radiolarian biostratigraphy, radiation, and evolution across the global CNB interval. [ABSTRACT FROM AUTHOR]

The distribution and genetic mechanisms of connected pore systems in continental shale reservoirs were analyzed in this paper to enhance the high-efficiency exploration of shale gas. A case study was made with the continental shale of the Upper Triassic Xujiahe Formation in the Western Sichuan Depression. Various experimental methods such as X-ray diffraction, field emission-scanning electron microscopy, low temperature gas adsorption, high-pressure mercury injection and nuclear magnetic resonance cryoporometry were applied to study its mineral composition, distribution of pore-size and pore connectivity, and the main constrains for pore connectivity were discussed. The continental shale of the Xujiahe Formation in the study area has a high content of clay minerals, followed by quartz. The pore-size distribution is complex, and the mesopores in the range of 4-50 nm is the main contributor to pore volume (87.33%) and specific surface area (49.19%). The pores having the size between 20-50 nm appeared to have better pore connectivity and are the major type of connected pores. The continental shale developed various types of pore, predominantly composed of clay intercrystalline pores, with minor dissolved pores and organic pores. Microfractures were widely developed and formed the dominant connective pore assemblage together with clay intercrystalline pores. The development and distribution of connected pores were controlled by the contents and arrangement of brittle minerals such as clay minerals and quartz. Based on the experimental results, some development mechanisms of connected pores in continental shale were concluded. The combination of intercrystalline pores and microfractures developed on the matrix of clay minerals and brittle minerals shows the best connectivity, followed by the clay intercrystalline pores in clay minerals, while the organic pores and clay intercrystalline pores in organic-clay complexes show the lowest connectivity.

The Zhangjiatan oil shale from the Upper Triassic Yanchang Formation in the southern Ordos Basin is an important solid mineral resource, it can also be considered as the main source rock of Triassic oil and gas in the basin. Results of analytical experiments such as TOC, bitumen extraction and group composition, oil content etc. of shale samples from key typical outcrop sections and drilling cores showed that the Zhangjiatan oil shale has a high organic matter abundance. The TOC content ranges 5.11% to 36.47%, with an average value of 16.15%. The S0+S1+S2 value distributes between 16.58-230.98 mg/g, with an average value of 94.20 mg/g. The extracted bitumen abundance is between 0.42%-2.22%, with an average value of 1.25%. Based on these analytical results, Zhangjiatan oil shale can be assigned to be high-quality source rock with an excellent hydrocarbon generation potential. The oil content of oil shale is between 3.52% and 14.6%, with an average value of 8.16%, which belongs to medium- and high-quality oil shale. The kerogen type is mainly Ⅰ-Ⅱ1, and the Ro value generally ranges from 0.43% to 1.09%. Based on field outcrop and drilling core samples, a thermal evolution profile of the Zhangjiatan oil shale in the southern Ordos Basin was established. Moreover, the oil contents of oil shale before and after solvent extraction were compared, and the variations of oil content and pyrolysis hydrocarbon products during the thermal evolution of oil shale were analyzed. There are two types of resources such as oil shale and shale oil in the Zhangjiatan oil shale with a great potential in the southern Ordos Basin. Moreover, some exploration and development countermeasures of oil shale and shale oil were put forward.

The Upper Triassic Xiaotangzi and Xujiahe formations are important gas exploration targets in the Sichuan Basin. This article, based on a systematic analysis of sandstone clastic framework components, depositional structures, clay minerals, trace elements and organic geochemistry, gives a detailed discussion regarding their sedimentary environment. There exist abundant tide‐generated depositional structures in this sequence, and the sedimentary provenance was dominated by a recycled orogen belt in the north and by a continental block at an early stage then recycled orogen belt at the late stage in the south of the western Sichuan Basin. The Xiaotangzi Formation and members 2–3 of the Xujiahe Formation only have authigenic illite and chlorite. In contrast, members 4–6 contain increasing kaolinite and decreasing illite and chlorite from bottom to top. The water column salinity gradually downgraded from hyperhaline, euhaline and polyhaline of the Xiaotangzi Formation to member 2 to polyhaline and mesohaline of members 3–6. The source rocks of the Xiaotangzi and Xujiahe formations have a generally low Pr/Ph, minus the value of (Pr/nC17)‐(Ph/nC18), and high values of Pr/nC17 and Ph/nC18. They also show apparent dominance of 9‐MP in methylphenanthrene composition and different point groups of fluorenes, dibenzofurans and dibenzothiophenes from marine or salt lake facies, as well as typical swamp facies. In conclusion, the Xiaotangzi Formation and members 2–3 were deposited in a marine environment, whereas members 4–6 were deposited mainly in a transitional to the continental environment. [ABSTRACT FROM AUTHOR]

The Chang 7 member of the Upper Triassic Yanchang Formation is an important source rock in the Ordos Basin, NW China. Previous studies of the unit have in general focused on the relatively deep‐water (∼25 m) anoxic, OM‐rich lacustrine mudstones which form the main Mesozoic source rock at fields in the south of the basin. However, this paper presents an integrated geochemical investigation of the relatively shallow‐water Chang 7 facies in a study area around Jiyuan field in the western part of the basin in order to evaluate its source rock potential. The results show that the Chang 7 source rock in the study area has a high content of Type II OM, and is interpreted to have been deposited in a suboxic‐anoxic lacustrine setting with a mixed input of aquatic and terrigenous organic matter. The results of 1D modelling of a well in the study area showed that the Chang 7 member entered the oil generation window from the Middle Jurassic. Oil‐oil correlations based on hierarchical cluster analysis and correspondence analysis showed that crude oils generated by deep‐water Chang 7 source rocks from wells in the south of the basin can be distinguished from Soxhlet‐extracted petroleum from reservoir sandstones in the study area. The compositional differences are inferred to be due to variations in source rock facies compositions. An oil – source rock correlation study showed that the shallower‐water Chang 7 source rock in the western part of the basin generated the hydrocarbons in core extracts of reservoir sandstones from wells in this area. The shallow‐water Chang 7 facies may therefore constitute an effective oil‐prone source rock in the western Ordos Basin. [ABSTRACT FROM AUTHOR]

Fossil deposit first described by Franz Toula in 1890, in the Garnyovitsa area near Kotel is estimated as a geosite of a national significance with historical value for the Bulgarian geology. Here is cropping out a huge marl olistolith embedded among Middle Jurassic turbidites of the Kotel Olistostrome Formation. It contains Late Triassic (Norian) hydrozoa and corals, identified by the first explorers of the Bulgarian lands as early as the end of the 19th century. Given the high geodiversity of the area and the proximity to Kotel, this geosite has great potential for geotourism within the future geopark "East Balkan". [ABSTRACT FROM AUTHOR]

The Euphrates Graben is located in eastern Syria. The Upper Triassic Mulussa F Formation sandstones serve as the primary reservoir intervals in the majority of the graben fields. The study's findings were based on core studies: petrographic examination of thin sections, scanning electron microscope (SEM), imaging of backscatter scanning electron microscope (BSE), X-ray microprobe examinations, and carbon-oxygen stable isotope analysis of microfracture-filling cements. Three of the most common types of microfracture found in the investigated sandstones are intragranular or intracrystalline microfractures, grain boundary or grain-edge microfractures, and transgranular (crossing grains) microfractures. Sandstone microfractures that are open and free of secondary mineralization improve sandstone storage and permeability. However, microfractures that are cemented and filled with secondary mineralization reduce storage and permeability. Common siderite and pyrite cements were identified within the microfractures and the nearby sandstone matrix. Larger anhedral or euhedral siderites are thought to form during shallow burial diagenesis, whereas poikilotopic siderites are thought to form during deep burial diagenesis. Poikilotopic pyrite is believed to be a diagenetic cement, which is attributed to the reduction of iron oxides present in the sediments in the presence of hydrocarbons. Microfractures reflect tectonic, overpressure, and diagenetic origins. Microfractures of tectonic origin are associated with folding and thrust activities over the Euphrates Graben area, and they were formed at the beginning of the Upper Triassic with siderite and pyrite cement equilibration temperatures of approximately 100–105 °C, and they continued forming from the middle to the end of the Upper Triassic with cement equilibration temperatures of approximately 90–100 °C in conjunction with the first phase of the Euphrates Graben. Microfractures related to diagenetic and overpressure processes are tension microfractures and were formed in compression settings during the Upper Triassic. [ABSTRACT FROM AUTHOR]

Upper Triassic carbonate platforms from the Panthalassa Ocean remain less-understood and less-studied than their Tethyan equivalents. This imbalance is largely due to the poorer preservation state of Panthalassan carbonate rock successions in terms of rock quality and depositional geometries, which prevents good appreciation of depositional systems. In this context, carbonate exposures from Lime Peak (Yukon, Canada) represent an outstanding exception. There, the remains of an Upper Norian Panthalassan carbonate platform are well-exposed, show remarkably preserved depositional geometries and overall superior rock preservation. In this work, we analyse the carbonates from the Lime Peak area with particular attention to the vertical and lateral distribution of biotic assemblages and microfacies at the platform scale. Results demonstrate that the Lime Peak platform was surrounded by a basin with an aphotic sea bottom. The carbonate complex developed in warm waters characterized by high carbonate saturation. The area was also defined by moderate to high nutrient levels: this influenced the type of carbonate factory by favouring microbialites and sponges over corals. During its growth, Lime Peak was influenced by tectono-eustatism, which controlled the accommodation space at the platform top, primarily impacting the internal platform environments and the stability of the slope. Gaining better knowledge of the spatial distribution and dynamics of Upper Triassic organisms and sedimentary facies of Panthalassa in relation to tectono-eustatism lays the first foundations for reconstructing more robust platform models and understanding the evolution of other, more dismantled Upper Triassic Panthalassan carbonate systems through time. [ABSTRACT FROM AUTHOR]

During the Late Triassic, the southern margin of the Ordos Basin was influenced by the Indosinian Movement, in response to closure of the Paleo-Tethys Ocean. Thinly bedded tuff layers are exposed near the base of the Middle–Upper Triassic formations (Chang 8/7/6 members) in the Ordos Basin. Tuff samples from drilling core (well An-35) and outcrop (Motiangou section) samples in the Yanchang Formation were studied by the detailed field work. Igneous zircon crystals were picked and analyzed by the instruments of cathodoluminescence and laser ablation inductively coupled plasma mass spectrometery (LA-ICP-MS). The timing of volcanic activity was determined by means of high-precision zircon age. Combining tectonic setting and paleogeographic reconstruct, the ages of tuff layers indicate that volcanic activities occurred at three peaks (241.6 ± 1.1 Ma, 240.2 ± 1.1 Ma, and 233.5 ± 1.2 Ma) from the top of Chang 8 Member to the Chang 7 Member. The results implied that the volcanic activities lasted from Ladinian to Carnian, as well as define the sedimentary duration of the Chang 7 Member with a deposition rate of 1.34 cm/ka.

The study of two stratigraphic sections of the Tran Formation (upper Carnian–Norian) reveals the presence of a regressive carbonate beach succession. The interpretation of lower shoreface, upper shoreface, foreshore, and backshore deposits is based on field data, microfacies analysis and comparison with Holocene and ancient analogues. The various lower shoreface deposits include automicritic boundstones/cementstones which attest to a temporary establishment of the M factory most likely as an aftermath of the global Carnian Pluvial Episode. The upper shoreface grainstones show trough cross-bedding reflecting deposition by longshore currents. Grainstones/packstones of the foreshore subenvironment have several diagnostic features including low-angle plane lamination, keystone voids, eroded beachrock clasts, and well-sorted textures with marine phreatic and vadose cements. Their deposition was controlled by supply of granular material from the shoreface, incessant wave activity and daily tides, and early lithification protecting them from erosion and remobilization. The backshore strata comprise storm washover deposits (packstones, wackestones), mudstones deposited in marginal ponds, and agglutinated stromatolites (formed by trapping and binding in a tide-influenced setting). Some of the foreshore and backshore sediments were pedogenically modified, resulting in the formation of secondary matrix, root development, desiccation cracking, and grainification. Specific products of the early vadose alteration are laminoid fenestrae with crystal silt and diagenetic grainstones, packstones, and wackestones. The good preservation of the regressive beach succession was favored by late highstand progradation of the shoreline in a low accommodation setting. [ABSTRACT FROM AUTHOR]

Relics of the Panthalassa Ocean occur today in accretionary complexes and terranes on the entire Circum‐Pacific region. Among them, remains of shallow‐water carbonate systems provide valuable information about the ecology and environmental conditions that prevailed in this immense ocean. In this regard, the Shiriya Cape of the North Kitakami Belt (Aomori Prefecture, Honshu Island, Japan) is an essential place to study. Characterized by the presence of numerous limestone deposits embedded in typical accretionary mélange, including pluri‐kilometric massive slabs and metric bedded deposits, the cape is indeed a key vestige of carbonate deposition in the Panthalassa. All the limestone outcrop form the Shiriya Cape were sampled and studied in detail for the first time. Despite a general poor preservation, macroscopic sedimentary features such as burrows and large megalodontids patches as well as four microfacies were identified and are presented in detail in this work. On the basis of foraminifers and conodonts biostratigraphy, the age of the limestone deposits is defined as Norian. Similarities with analogous and synchronous systems from Panthalassan and Tethyan realms are extensively discussed. The closest analog to the Shiriya limestone appears to be the Panthalassan Dalnegorsk limestone (Russian Far East), both regarding microfacies and depositional setting. Sedimentary successions similar to Lofer‐cycles, well known in Tethyan synchronous systems, were also discovered in the Shiriya Cape. Along with the large limestone slabs, countless limestone‐bearing conglomerates also crop out on the Shiriya Cape. Their study and comparison with similar deposits in Japan highlighted their importance in the understanding of the dismantling of mid‐oceanic carbonates. The observations and comparison with well‐known carbonate systems permitted to establish a hypothetical depositional model of the Shiriya limestone corresponding to a Norian isolated carbonate system developed on an immerged volcanic seamount. [ABSTRACT FROM AUTHOR]

The North Dobrogean Orogen (NDO) is a NW-SE trending fold-and-thrust belt in the eastern foreland of the Alpine Carpathian Orogen, palaeogeographically representing the westernmost segment of the Palaeotethys-issued Cimmeride Orogenic System. Eastwards, the NDO structurally extends into the Romanian sector of the western Black Sea continental shelf. The Triassic development of North Dobrogea is well known for its Tethyantype facies and richness in various groups of fossils, but little attention has been paid to microfacies and fossil content of the offshore Triassic. The drill hole 817 LV of the Lebăda Vest oilfield, offshore Romania, ends in the Rhaetian (Upper Triassic) limestone olistolith, from which a rich association of foraminifers and ostracods was recovered. The limestone also contains sponge spicules, mollusc fragments, echinoderm ossicles, bryozoans, and brachiopods. Foraminiferal assemblage from the residue consists of agglutinated species only. Tolypamminids, Gaudryinopsis triadica (Kristan-Tollmann), G. triassica (Trifonova), G. kelleri (Tappan), Ammobaculites tzankovi (Trifonova), A. zlambachensis Kristan-Tollmann, Verneuilinoides racema (Trifonova), and Trochammina spp. predominate. Non-agglutinated species, determined from thin sections include Ophthalmidium spp., and rare involutinids Trocholina ex gr. intermedia/umbo and "Involutina turgida" (Involutina ex gr. liassica). The rich ostracod assemblage is dominated by Bairdiidae. Species of the Paracyprididae and Sigilliidae families are rather common. The conodont Norigondolella steinbergensis (Mosher) was also found. The deposition is suggested to take place in a relatively deep setting (outer shelf) offshore heterozoandominated platform in relatively cool waters. [ABSTRACT FROM AUTHOR]

The North Dobrogean Orogen (NDO) is a NW-SE trending fold-and-thrust belt in the eastern foreland of the Alpine Carpathian Orogen, palaeogeographically representing the westernmost segment of the Palaeotethys-issued Cimmeride Orogenic System. Eastwards, the NDO structurally extends into the Romanian sector of the western Black Sea continental shelf. The Triassic development of North Dobrogea is well known for its Tethyan-type facies and richness in various groups of fossils, but little attention has been paid to microfacies and fossil content of the offshore Triassic. The drill hole 817 LV of the Lebăda Vest oilfield, offshore Romania, ends in the Rhaetian (Upper Triassic) limestone olistolith, from which a rich association of foraminifers and ostracods was recovered. The limestone also contains sponge spicules, mollusc fragments, echinoderm ossicles, bryozoans, and brachiopods. Foraminiferal assemblage from the residue consists of agglutinated species only. Tolypamminids, Gaudryinopsis triadica (Kristan-Tollmann), G. triassica (Trifonova), G. kelleri (Tappan), Ammobaculites tzankovi (Trifonova), A. zlambachensis Kristan-Tollmann, Verneuilinoides racema (Trifonova), and Trochammina spp. predominate. Non-agglutinated species, determined from thin sections include Ophthalmidium spp., and rare involutinids Trocholina ex gr. intermedia/umbo and “Involutina turgida” (Involutina ex gr. liassica). The rich ostracod assemblage is dominated by Bairdiidae. Species of the Paracyprididae and Sigilliidae families are rather common. The conodont Norigondolella steinbergensis (Mosher) was also found. The deposition is suggested to take place in a relatively deep setting (outer shelf) offshore heterozoan-dominated platform in relatively cool waters.

Upper Triassic carbonate platforms from the Panthalassa Ocean remain less-understood and less-studied than their Tethyan equivalents. This imbalance is largely due to the poorer preservation state of Panthalassan carbonate rock successions in terms of rock quality and depositional geometries, which prevents good appreciation of depositional systems. In this context, carbonate exposures from Lime Peak (Yukon, Canada) represent an outstanding exception. There, the remains of an Upper Norian Panthalassan carbonate platform are well-exposed, show remarkably preserved depositional geometries and overall superior rock preservation. In this work, we analyse the carbonates from the Lime Peak area with particular attention to the vertical and lateral distribution of biotic assemblages and microfacies at the platform scale. Results demonstrate that the Lime Peak platform was surrounded by a basin with an aphotic sea bottom. The carbonate complex developed in warm waters characterized by high carbonate saturation. The area was also defined by moderate to high nutrient levels: this influenced the type of carbonate factory by favouring microbialites and sponges over corals. During its growth, Lime Peak was influenced by tectono-eustatism, which controlled the accommodation space at the platform top, primarily impacting the internal platform environments and the stability of the slope. Gaining better knowledge of the spatial distribution and dynamics of Upper Triassic organisms and sedimentary facies of Panthalassa in relation to tectono-eustatism lays the first foundations for reconstructing more robust platform models and understanding the evolution of other, more dismantled Upper Triassic Panthalassan carbonate systems through time.

Understanding the origins of the vertebrate brain is fundamental for uncovering evolutionary patterns in neuroanatomy. Regarding extinct species, the anatomy of the brain and other soft tissues housed in endocranial spaces can be approximated by casts of these cavities (endocasts). The neuroanatomical knowledge of Rhynchocephalia, a reptilian clade exceptionally diverse in the early Mesozoic, is restricted to the brain of its only living relative, Sphenodon punctatus, and unknown for fossil species. Here, we describe the endocast and the reptilian encephalization quotient (REQ) of the Triassic rhynchocephalian Clevosaurus brasiliensis and compare it with an ontogenetic series of S. punctatus. To better understand the informative potential of endocasts in Rhynchocephalia, we also examine the brain-endocast relationship in S. punctatus. We found that the brain occupies 30% of its cavity, but the latter recovers the general shape and length of the brain. The REQ of C. brasiliensis (0.27) is much lower than S. punctatus (0.84-1.16), with the tuatara being close to the mean for non-avian reptiles. The endocast of S. punctatus is dorsoventrally flexed and becomes more elongated throughout ontogeny. The endocast of C. brasiliensis is mostly unflexed and tubular, possibly representing a more plesiomorphic anatomy in relation to S. punctatus. Given the small size of C. brasiliensis, the main differences may result from allometric and heterochronic phenomena, consistent with suggestions that S. punctatus shows peramorphic anatomy compared to Mesozoic rhynchocephalians. Our results highlight a previously undocumented anatomical diversity among rhynchocephalians and provide a framework for future neuroanatomical comparisons among lepidosaurs., (© 2023 American Association for Anatomy.)

Late Triassic sedimentary successions in the Sichuan Basin contain records about the transition from marine to continental environments. In this study, we focused on the field profile of the Xujiahe Formation to analyze its sedimentary distribution and provenance by using petrological, sedimentary facies, geochemistry, and provenance analyses. The results have shown that the Upper Triassic Xujiahe Formation in the Guangyuan area consists of marine and continental clastic materials. The potential source areas for these sediments include the Qinling orogenic belt, Longmen Mountain structural belt, and Motianling ancient land. The tectonic setting of the Sichuan Basin during this period could be attributed to an active continental margin. • The Late Triassic in the Sichuan Basin transformed from marine to continental sedimentary environment. • The source areas of the Upper Triassic include the Qinling orogenic belt, Longmen Mountain, and Motianling ancient land. • The tectonic setting of the Sichuan basin during the Late Triassic could be attributed to an active continental margin. [ABSTRACT FROM AUTHOR]

Fossil charcoal can provide important evidence for understanding the ancient forest fires and predicting changes in vegetation, paleoclimate and paleoenvironment throughout geological history. In this research, a systematic study was conducted on fossil charcoal from the Upper Triassic Karamay Formation in the Junggar Basin, NW China. The charred wood is secondary xylem, pycnoxylic and homoxyleous, composed of tracheids and parenchymatous rays. Based on their anatomical features, the charcoal fossils are identified as Protophyllocladoxylon sp. The presence of well-preserved macroscopic charcoal fossils, along with carbonized leaves, suggests that these fossils were formed as a result of local surface fires. Based on the analysis of the mean random reflectance (Ro mean) values of charcoal from the Karamay Formation, the estimated temperature range for the production of the charcoal is between 407.49 °C and 369.17 °C. This temperature range aligns with the typical temperatures associated with surface fires, indicating that the fires in this region during the Late Triassic were of low intensity and occurred under relatively low temperatures. The presence of fossil charcoal in Junggar Basin suggests that the paleoatmospheric oxygen level in northwest China during Late Triassic was above 13% or 15%, which is the minimum required for sustained burning of natural wildfires. This finding is in accordance with the paleoatmospheric oxygen concentration models on the basis of variations in inertinite content and Phanerozoic wildfire history combined with the phosphorus cycle. The abundant presence of fossil charcoal herein suggests a humid and warm climate with intermittent droughts in the Late Triassic Junggar Basin. • The charcoal fossils from the Late Triassic Junggar Basin have been identified as Protophyllocladoxylon sp. • The macroscopic charcoal fossils are the result of microthermal and low-intensity local surface fires. • The paleoatmospheric oxygen level during the Late Triassic was estimated to be above 13% or 15%. • The climate of the Late Triassic Junggar Basin was characterized as humid and warm, with intermittent droughts. [ABSTRACT FROM AUTHOR]

Although more than one century has passed since the first studies, knowledge about the Upper Triassic shallow-water carbonates from the Panthalassa Ocean remains lower than their Tethyan counterparts. Characterising these sedimentary rocks represents a unique way to deepen our understanding of the biosphere's evolution and recovery after the major Permian–Triassic biological crisis. The Triassic Luning Formation in Western–Central Nevada is a crucial sedimentary succession due to its considerable thickness and areal extent. Among the three members forming the Luning Formation, the present study has only described the upper one in detail due to the minor areal distribution of the Lower Member and the pure siliciclastic nature of the middle Member. All accessible localities in this region, 21 in total, have been extensively sampled for facies and micropalaeontological analyses, including conodonts and poorly preserved foraminifera, leading to new insights about the depositional conditions and exact age of the Luning Formation's Upper Member. A depositional model is proposed for the first time, corresponding to a low-angle ramp with homogeneous bathymetric and hydrodynamic conditions subjected to frequent siliciclastic input from the continent. The regular terrigenous influx causes a significant cyclicity in this portion of the formation, comprising heterogeneously thick limestone beds. The environment-diagnostic fauna is characterised by pioneer organisms that regenerate carbonate production after the main break related to the pure siliciclastic Middle Member's deposition. Numerous conodont specimens indicate that the entire Upper Member is middle Norian in age. Identifying the observed organisms, tied to a reliable stratigraphic interval, allows comparing the Luning Formation with other Upper Triassic carbonates from the Panthalassa Ocean, now cropping out at different latitudes on the eastern and western coasts of the Pacific Ocean. Despite some faunal affinities, especially with carbonate build-ups developed at middle-palaeolatitudes, the Luning Formation differs from most other East Panthalassa carbonates because of its short palaeo-distance from the continent (i.e. the American craton), being deposited near the mainland coast instead of on an isolated volcanic arc. • New insights on the Triassic Panthalassa Ocean from flat ramp carbonates • Microfacies analysis of Upper Triassic carbonates from Nevada (USA) • Carbonate deposition controlled by siliciclastic input from the continent. • Biostratigraphy, based on conodonts assemblages, indicates a Middle Norian age. [ABSTRACT FROM AUTHOR]

The lack of knowledge about the relationship between carbonate sedimentary facies and pore system modifiers in northwestern and northern Iraq severely restricts carbonate oil exploration in these areas. This research aims to highlight the significance and influence of sedimentological and petrophysical heterogeneity and their impact on reservoir characterization of the Kurra Chine Formation, which have been studied in oil wells at Ain Zalah (AZ-29), Butmah (Bm-15), and Kand (K-1), in addition to the Sararu outcrop in northern Iraq. In this study, integrated methods that incorporate thin section petrography, well logs, statistical techniques and core analysis were used for the investigation. The study revealed that the Kurra Chine Formation in the studied sections mainly consists of limestone, dolomite, shale, and anhydrite, the last of which is absent in the Sararu outcrop. Its thickness in previous outcrop and wells was 848 m, 1136 m, 985 m, and 1149 m for Sararu, AZ-29, Bm-15, and K-1, respectively. Petrographically, five main microfacies types and nine submicrofacies were identified in the Kurra Chine carbonates of the studied sections. The percentages and distribution of these submicrofacies in the study area are diverse and show their heterogeneity. Diagenetic processes like micritization, dolomitization, cementation, neomorphism, compaction, stylolitization, solution, pyritization, and silicification resulted in increasing heterogeneity in the formation. They played a significant role in improving or reducing the reservoir characterizations of the formation. Dolomitization and dissolution processes enhance the petrophysical properties of the studied formation, especially the medium-to coarse-grained crystalline idiotopic dolomite. On the other hand, cementation, compaction, and neomorphism reduce the pore volume of the Kurra Chine Formation rocks. Qualitatively, porosity in the Kurra Chine Formation was divided into two main groups: interparticle (intergrain and intercrystal) and vuggy pores. The interparticle pore space is subdivided into three petrophysical classes: Class 1, Class 2, and Class 3. Class 2 represents the most common interparticle porosity type and is very important because it contains bituminous material. Moldic and intragrain pores are the most abundant separate vug pores within formation successions. The touching vug pores are represented by fractures, microfractures, and fenestrals. Quantitatively, three types of porosity have been calculated for the formation using conventional well logs: effective, interparticle, and separated vuggy porosity. The Butmah-15 well reservoir property outperformed the other two wells in terms of reservoir property indicators, particularly in the middle of the studied formation at depths ranging from 3089 to 3399 m. Porosity in this depth interval is interparticle, with values ranging between 0 and 0.35, while permeability values range from zero mD in beds cemented by anhydrite cement to 6196 mD within MF6 in limestone beds that are rich in interparticle and fracture porosity. The AZ-29 and K-1 wells have poor reservoir properties, especially effective porosity and permeability. This research provides a better understanding of the relationship between carbonate sedimentary facies and pore system modifiers of shallow marine environment carbonates, and it can aid in reservoir evaluation for better exploitation of these valuable resources in Iraq and elsewhere in carbonate sedimentary basins. • The porosity is divided into two main groups: interparticle (intergrain and intercrystal) and vuggy pores. • The variation in the distribution of carbonate rocks' microfacies and petrophysical parameters is diverse and demonstrates their heterogeneity. • Diagenetic processes have altered the pore system, resulting in significant heterogeneity in rock properties. • The relationship between sedimentary facies and the pore system modifiers of shallow marine carbonates is introduced. [ABSTRACT FROM AUTHOR]