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Mafic intrusions, lava flows, and felsic plutons in southwestern Laurentia have been hypothesized to be associated with the emplacement of a late Mesoproterozoic (Stenian Period) large igneous province. Improved geochronologic data resolve distinct episodes of mafic magmatism in the region. The ca. 1,098 Ma main pulse of southwestern Laurentia large igneous province (SWLLIP) magmatism is recorded by mafic intrusions across southeastern California to central Arizona. A younger episode of volcanism resulted in eruptions that formed the ca. 1,082 Ma Cardenas Basalt, which is the uppermost unit of the Unkar Group in the Grand Canyon. With the updated geochronological constraints, we develop new paleomagnetic data from mafic sills in the SWLLIP. Overlapping poles between the Death Valley sills and rocks of similar age in the Midcontinent Rift are inconsistent with large-scale Cenozoic vertical axis rotations in Death Valley. We also develop a new paleomagnetic pole from the ca. 1,082 Ma Cardenas Basalt (pole longitude = 183.9°E, pole latitude = 15.9°N, (Formula presented.) = 7.4°, N = 18). The new paleomagnetic data are consistent with the pole path developed from time-equivalent rocks of the Midcontinent Rift, supporting interpretations that changing pole positions are the result of rapid equatorward motion. These data add to the record of Laurentia's rapid motion from ca. 1,110 to 1,080 Ma that culminated in collisional Grenvillian orogenesis and the assembly of Rodinia.

The paleogeography of Laurentia throughout the Neoproterozoic is critical for reconstructing global paleogeography due to its central position in the supercontinent Rodinia. We develop a new paleomagnetic pole from red siltstones and fine-grained sandstones of the early Neoproterozoic Jacobsville Formation which is now constrained to be ca. 990 Ma in age. High-resolution thermal demagnetization experiments resolve detrital remanent magnetizations held by hematite. These directions were reoriented within siltstone intraclasts and pass intraformational conglomerate tests—giving confidence that the magnetization is detrital and primary. An inclination-corrected mean paleomagnetic pole position for the Jacobsville Formation indicates that Laurentia's motion slowed down significantly following the onset of the Grenvillian orogeny. Prior rapid plate motion associated with closure of the Unimos Ocean between 1,110 and 1,090 Ma transitioned to slow drift of Laurentia across the equator in the late Mesoproterozoic to early Neoproterozoic. We interpret the distinct position of this well-dated pole from those in the Grenville orogen that have been assigned a similar age to indicate that the ages of the poles associated with the Grenville Loop likely need to be revised to be younger due to prolonged exhumation.

Macrofossils of the Vendian soft-bodied organisms were found for the first time in the Vizinga and Ust'-Palega formations of the Upper Precambrian in Chetlasskii Kamen Hill (Middle Timan, Arkhangelsk oblast). Representatives of palaeopascichnids, aspidellamorphs, and possible frondomorphs, trace fossils, and microbially induced arumberiamorph structures were identified among molds and three-dimensional casts of fossils. Previously we revealed Vendian macrofossils in the Upper Precambrian in Dzhezhim-Parma Hill (South Timan, Komi Republic). The discovery of one more locality of various Ediacaran fossils in the middle part of the Timan Ridge significantly expands their paleogeography and also clarifies the time frame of deposition of the Vizinga and Ust'-Palega formations, the position of which in the Upper Precambrian section of Central Timan was debatable. [ABSTRACT FROM AUTHOR]

The Early Paleozoic paleolatitudinal position of the terranes in the northern Tibetan Plateau is the key to unraveling the evolution of the Proto‐Tethys Ocean. We present the first Late Cambrian paleomagnetic results from the Oulongbuluke terrane (OT), in the northern Tibetan Plateau. The mean paleomagnetic direction for 16 sites is Ds = 196.2°, Is = −36.9° with κs = 31.5, α95 = 6.7°, corresponding to a paleopole at 68.2°S/51.9°E with dp/dm = 4.6°/7.8°. Rock magnetic and petrologic analyses demonstrate the primary origin of the magnetic mineralogy. This paleomagnetic result defines the Late Cambrian paleolatitude of the OT as 20.6 ± 4.6°S (reference point: 37.2°N/96.6°E). Combined paleomagnetic and geological evidence suggests that the terranes in the northern Tibetan Plateau were located to the northwest of the Indian plate of Gondwana during the Late Cambrian. Plain Language Summary: The Proto‐Tethys Ocean underwent a complex process of collision and amalgamation of the terranes in the northern Tibetan Plateau during the Early Paleozoic. Unraveling the Early Paleozoic paleogeography of these terranes is important for understanding the evolution of the Proto‐Tethys Ocean and is critical for reconstructing the formation of East Asia. However, quantitative constraints on the Early Paleozoic paleogeographic position of the terranes in the northern Tibetan Plateau are limited. Paleomagnetism is the only effective approach for directly constraining the paleolatitude of terranes. We conducted a paleomagnetic study of the Late Cambrian strata in the Oulongbuluke terrane (OT), northern Tibetan Plateau. The results define the paleolatitude of 20.6 ± 4.6 °S for the OT during the Late Cambrian. Based on paleomagnetic data and geological evidence, we also present a tentative paleogeographic reconstruction of the terranes in the northern Tibetan Plateau and the Proto‐Tethys Ocean in a global setting during the Late Cambrian. Key Points: We report the first Late Cambrian paleomagnetic results for the Oulongbuluke terrane (OT)The OT was located at ∼20.6°S during the Late CambrianThe terranes in the northern Tibetan Plateau may have been located northwest of the Indian plate during the Late Cambrian [ABSTRACT FROM AUTHOR]

Cambrian subsalt dolomite is an important strategic area for natural gas exploration in the Tarim Basin. The gypsum-salt rocks, argillaceous mudstone and argillaceous dolomite strata developed in large areas of the Middle Cambrian can be used as good caprocks. The sealing ability and favorable area distribution of the Middle Cambrian caprock in the Tarim Basin are studied through the lithofacies paleogeography and microscopic evaluation of the Middle Cambrian strata in this paper. Based on the 2D seismic interpretation covering the entire basin, combined with data from drilling, outcrops, well logging, core samples and thin sections, the sedimentary characteristics and lithofacies paleogeography of the Middle Cambrian were studied and then the thickness of the Middle Cambrian gypsum-salt rocks, gypsiferous mudstone and gypsiferous dolomite was analyzed in the Tarim Basin. Studies suggest that the Middle Cambrian is primarily characterized by the development of restricted-platform facies. In the Awati Depression, the northern part of the Tazhong Uplift, the southern part of the Manxi Low Uplift, and the central and northern parts of the Bachu Uplift, the thickness of the gypsum-salt rock strata is relatively large. Moreover, centered on the northern part of the Bachu Uplift, the thickness of the gypsum-salt rocks decreases irregularly towards the periphery, forming a circumferential distribution. To investigate the sealing ability of caprocks, 64 core samples from four wells were examined under a microscope, and physical parameters as well as breakthrough-pressure tests were conducted. By establishing correlations between various parameters, the sealing ability of different rock types in the Cambrian formation within the study area was quantitatively assessed. The research suggests that gypsum-salt rocks exhibit superior sealing ability compared to gypsiferous mudstone and gypsiferous dolomite, but factors such as faults and geological conditions of gypsum can influence the sealing performance of caprocks. According to both micro- and macro-scale evaluations of the Cambrian strata in the study area, along with constraints imposed by actual drilling exploration results, a comprehensive evaluation method for assessing caprock sealing ability has been established. The results suggest that the Awat Depression, the western and southern parts of the Manxi Low Uplift, the northern and western parts of the Tazhong Uplift, and the central part of the Tabei Uplift are favorable areas for the development of caprocks. [ABSTRACT FROM AUTHOR]

Based on logging, core, thin section and geochemical analysis, the tectonic-lithofacies paleogeographic pattern of first member to third member of Ordovician Majiagou Formation (O1m1-O1m3 for short) in Ordos Basin is reconstructed, and the tectono-sedimentary evolution characteristics and oil-gas geological significance are discussed. The results are obtained in four aspects. First, a set of marginal argillaceous dolomites with high gamma ray value developed steadily and diachronously at the bottom of Majiagou Formation, which distributed over the Huaiyuan Movement unconformity, with d13C values positive drift characteristics comparable to global transgression of the Early Ordovician Floplian. Second, the global sea level rose and the ancient land was submerged into the underwater uplift in O1m1 to O1m2, and the central uplift was deposited for the first time in the Ordovician, forming a tectonic pattern of "one uplift and two depressions". Subsequently, the subduction and extrusion outside the basin and the differentiation of uplift and depression in the basin of O1m3 resulted in the activation of the Wushenqi-Jingbian bulge. Third, the evolution of the tectonic pattern had a significant impact on the sedimentary paleoenvironment. The O1m1 overlaps westward, and saline lagoon is formed in eastern depression and influenced by the transgression. The transgression continued in O1m2 and resulted in communication with the wide sea, and the large-scale grain shoal developed around eastern depression, and the late dry shrinkage formed a small scale evaporite lagoon in upper part. Under the influence of highland sealing in O1m3, the water body gradually differentiated into dolomitic gypsum and saline lagoons to the east, and the grain shoal spread along the highs around sag. Fourth, the source rocks developed diachronously at the bottom of Majiagou Formation form a favorable source-reservoir assemblage with the shoal facies reservoir distributed around the slope of O1m2-O1m3, and they have certain exploration potential for natural gas. [ABSTRACT FROM AUTHOR]

A sedimentological investigation was carried out to reconstruct the paleogeography of the Zagros Foreland Basin. Based on the study of more than 1 000 rock samples, nine carbonate microfacies and three terrigenous facies were identified. The study reveals that the Maastrichtian succession was deposited in a widespread homoclinal ramp in the High Zagros Basin. Three (Gandom Kar area), two (Ardal area), seven (Gardbishe area), five (Shirmard area), two (Kuh-e-Kamaneh area), three (Kuh-e-Balghar area), and six (Murak area) of depositional sequences (3rd order) were identified. The thickness of the lowstand systems tract (LST) due to activities of local faults and subsidence in the southeast is more than in the central and northwest of the High Zagros Basin during the Early and Early Middle Maastrichtian. During the Middle Maastrichtian, the shallow and deep marine deposits were formed during the transgressive systems tract (TST) and highstand systems tract (HST) in this basin and the rate of subsidence in the center of this basin (Gardbishe area) is higher than in other areas and the platform was drowned in this area. The falling relative sea-level due to activities of local faults led to that marine deposits were absent in all parts of the High Zagros Basin (except the south part) during the Late Maastrichtian. Paleogeographical studies on the Zagros Basin during the Late Campanian–Maastrichtian showed the following results: shallow marine environments were developed in the south-east of this basin, and the turbidite, delta, and fluvial environments in the northwest were developed more than in other areas. [ABSTRACT FROM AUTHOR]

Most knowledge about the Cretaceous–Paleogene strata in the Tarim Basin is mainly inferred from the outcrops at the basin's margin, but first time in the basin. The formation mechanism of the Paleocene basal conglomerate was determined using geochemical isotopes of the breccia from Well PBX1 in the southwestern Tarim Basin. The results showed that the global K/Pg (i.e., Cretaceous/Paleogene) clay layer boundary was located in the middle of the Paleocene basal conglomerate at the depth of 7 066.75 m in Well PBX1. In the Late Cretaceous, associated with volcanic activities and earthquakes, the caldera in the Well PBX1 Block formed an annular depression with large elevation differences in response to the Pamir Block collision. As a result, the collapsed breccia with storm tide genesis deposited at the periphery and inside of the depression, characterized by syn-sedimentary deformation. During the Paleocene, multiple sets of interbedded carbonate and collapsed breccia deposited in response to multi-phased transient transgression-regression cycles. The transportation of breccia exhibited near-source accumulation/extremely close or in-situ rapid accumulation. The studied region is located in the eastern end of the Tethys Sea, the Late Cretaceous–Early Paleocene breccia is of great significance for reconstructing the paleogeography of the Tarim basin in Tethys. [ABSTRACT FROM AUTHOR]

During the Late Paleozoic–Early Mesozoic Era, the sediment transport system and tectonic regime in the southeastern margin of the South China Block (SESCB) all changed, significantly affected by the Paleo-Pacific subduction. However, controversy exists about the Paleo-Pacific subduction's initiation time. This study uses detrital zircon U-Pb ages to discuss the Late Triassic source-to-sink system in the SESCB. It provides some references for the Paleo-Pacific subduction process based on crucial age information and zircons' trace elements. The paleogeography and similarity of detrital zircon age distribution indicate that three sinks were found in the SESCB during the Late Triassic: 1. the Yangchun-Kaiping-Gaoming area, comprising major age ranges of 260–220, 460–400, and 1 200–800 Ma, which might be sourced from the Yunkai terrane; 2. the Jiexi-Kanshi-Nanjing area, characterized by the significant age component of 2 000–1 800 Ma, which corresponded to the Wuyi terrane; 3. the Xinan area, consisting of significant age groups of 290–250 and 380–320 Ma, which might be sourced from the magmatic rocks formed by the Huinan Movement and Paleo-Pacific subduction. Note that 290–250 Ma zircons were widely distributed in the Upper Triassic strata, and their trace elements suggested the existence of a magmatic arc near the SESCB during the 290–250 Ma. Thus, we propose that the Paleo-Pacific subduction might have begun in the Early Permian. [ABSTRACT FROM AUTHOR]

In the upper part of the Dzheromo Formation (Dolborian Regional Stage, Katian Stage, Upper Ordovician) along the Moyerokan River (Northern Siberian Platform), seventeen bryozoan species were revealed, seven from which, owing to the poor preservation of the colonies, were identified in an open nomenclature. The bryozoans belong to ten genera from four orders: Cystoporata (Constellaria vesiculosa (Modzalevskaya in Modzalevskaya et Nekhoroshev), Lunaferamita? sp.), Trepostomata (Calloporella sp. 1, Calloporella sp. 2, Stigmatella sp., S. convestens Astrova in Ivanova et al., Batostoma varians (James), Orbignyella moyerokanensis sp. nov., Leptotrypa sp.), Fenestrata (Parachasmatopora sp.), and Cryptostomata (Phaenopora plebeia Nekhoroshev in Modzalevskaya et Nekhoroshev, P. pennata Nekhoroshev, P. erecta Nekhoroshev in Modzalevskaya et Nekhoroshev, P. carinata Nekhoroshev, P. viluensis Nekhoroshev in Modzalevskaya et Nekhoroshev, Phaenoporella sp., and Ph. multipora Nekhoroshev). The genera Lunaferamita, Orbignyella, and Parachasmatopora were first found in the Ordovician of the Siberian Platform, and the genus Calloporella was found in the Dolborian Regional Stage. The species O. moyerokanensis sp. nov. is endemic to Northern Siberia, while the majority of the species have a wide geographic distribution. The studied bryozoan complex demonstrates some connection with bryozoan assemblages from the Taimyr Peninsula, Kotelny Island, the Sette-Daban Ridge, and Mongolia at the species level. At the generic level, it is close to the bryozoan assemblages from Laurentia, Baltica, the Argentine Precordillera, and China. [ABSTRACT FROM AUTHOR]

A large‐scale apparent polar wander occurred during the Jurassic interval, which is interpreted as true polar wander (TPW). As the motion is nearly orthogonal to the TPW axis, the North China Block (NCB) experienced the largest latitudinal and environmental changes and provides unique constraints on Jurassic TPW. However, due to the lack and uneven quality of paleomagnetic data, TPW records in North China are controversial. Here, we report a new paleomagnetic pole (80.8°N, 13.0°E, A95 = 7.4°) from the late Jurassic sills and dykes that intrude the Nandaling and Xiahuayuan formations in the NCB. The new pole places the NCB at 36.8° ± 7.4°N at 155 ± 3.4 Ma, using Beijing as the reference site. Combined with the reliable Jurassic poles, our study reveals a large, steady southward shift of 37.3° ± 7.2° for the NCB during the Middle and Late Jurassic, and reflects a component of TPW. The position of ∼155 Ma pole also supports significant TPW prior to ∼160 Ma and agrees with proposals attributing the diachronous 165–155 Ma aridification across the Eastern Asian blocks. Plain Language Summary: True polar wander (TPW) refers to the rotation of a planet's upper solid shell relative to the spin axis, which helps stabilize its rotation and may result in rapid plate shift and environmental change. A large‐scale TPW occurred in the Jurassic but the configuration of which is controversial. Due to its unique location, North China provides unique constraints on Jurassic TPW, including paleolatitudinal, rotational and facies changes. Here we report new paleomagnetic data from a suite of sills and dykes in the North China Block (NCB). Combined with the available Jurassic paleomagnetic data, our study reveals a large, steady southward shift of ∼4,000 km for NCB between ∼174 and 147 Ma, and reflects a component of a proposed monster Jurassic TPW. The plate motion of the NCB also supports significant TPW prior to ∼160 Ma, that is compatible with the diachronous aridification through East Asia between ∼165 and 155 Ma. Key Points: A new paleopole reported from the late Jurassic sills and dykes positions the North China Block (NCB) at ∼37°N at ∼155 MaThe NCB experienced a huge, steady southward shift of ∼4,000 km during ∼174–147 Ma, reflecting a component of true polar wander (TPW)The plate shift of the NCB supports considerable TPW prior to ∼160 Ma, which is compatible with the ∼165–155 Ma aridification across East Asia [ABSTRACT FROM AUTHOR]

This paper completes the examination of results of the study of lithogeochemical characteristics of a pilot collection of the Riphean–Vendian sandstones, siltstones, and claystones (last one based on the interpretation of results) in Belarus. Data on the age of detrital zircon published in recent years suggest that Upper Precambrian rocks of this region were sourced from the Osnitsk–Mikashevichi and the Trans-Scandinavian igneous belts, the Volyn–Brest large igneous province, rapakivi granites, as well as various rock associations of Sarmatia, Danopolonian orogen and Svecofennides. Based on the lithogeochemical characteristics, the distribution of data points of the studied clastic rocks on discriminant diagrams provides insight into the possible provenance, paleogeodynamic, paleogeographic, and paleoclimatic settings and suggests several conclusions. The considered Riphean–Vendian stratons in Belarus are composed mainly of erosion products of within-plate granitoids, as well as various island-arc and syncollisional felsic igneous rocks. The share of erosion products of mafic rocks among them generally does not exceed 30%. It is significant mainly in the Volyn Group rocks (erosion products of the Volyn–Brest large igneous province), as well as in some samples of the Nizov, Selyavy, and Kotlin formations (fragments of mafic rocks from other provenances?). The source-to-sink transport was accomplished mainly by large rivers. Paleogeodynamic settings varied from quite active to quite passive. The paleoclimate in catchment areas was most likely arid/semiarid in the Riphean. In the Vendian, it was humid and varied from subtropical in the Early Vendian (except the Glusk Formation) to tropical in the Late Vendian. The obtained results also make it possible to show some peculiarities of the known methods and techniques of paleoclimate reconstruction. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt (CAOB) is one of the biggest accretionary orogens in the world. With the development of laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS), large data of detrital zircon U–Pb and Hf isotopes have been published for decades, which leads to better understanding of the tectonic evolution and geodynamics of the CAOB. We compiled the data about the information of articles, samples and their analytical methods and results, then checked and corrected. These data are available to support future research activities in the CAOB, northern China, for example, the provenance analysis, climate changes and paleogeographic reconstruction. [ABSTRACT FROM AUTHOR]

Paleogeography is the merger of sediment and volcanic facies, depositional settings, tectonic plate movements, topography, climate patterns and ecosystems through time. The construction of paleogeographic maps on tectonic plate reconstruction models requires a team effort to compile databases, data sharing standards and map projection methods. Two goals of the Paleogeography Working Group of the International Union of Geological Sciences (IUGS) program for Deep‐Time Digital Earth (DDE) are: (1) to interlink online national lexicons for all sedimentary and volcanic formations, and develop online ones for nations that currently lack these; (2) to target specific regions and intervals for testing/showcasing paleogeography output from the merger of these databases. Following those goals, we developed and applied new cloud‐based lexicon data services and interactive visualization techniques to regions in East Asia. This has been a successful collaboration among computer engineers and plate modellers and has involved stratigraphers in India (ONGC), China (Chengdu Univ. Tech., and Chinese Acad. Geol. Sci.), United States (Paleomap Project, and Purdue Univ.), Australia (GPlates visualization team) and Vietnam (Vietnam Nat. Univ.). Independent online lexicons with map‐based and stratigraphy‐based user interfaces have been developed (as of the date of this submission in March 2022) for all Proterozoic to Quaternary formations on the Indian Plate (over 800) and Vietnam (over 200), the majority of the Devonian through Neogene of China (ca. 2000) and partially for Thailand. A multi‐database search system returns all geologic formations of a desired geologic time from these four independent databases. With one click, users can plot the regional extent of one or of all of those regional formations on different plate reconstruction models of that desired age, and these polygons are filled with the lithologic facies pattern. [ABSTRACT FROM AUTHOR]

Since the advent of detrital geochronology, significant progress has been made in the study of sedimentary sources. The detrital zircon U–Pb age spectrum, especially when combined with zircon Hf isotopes, provides a powerful tool for determining the provenance location, nature, and evolutionary history of sediments. The Western Qinling–Songpan tectonic junction, located in central China, is a giant structure on the crustal scale. A total of 20,640 zircon U–Pb ages of 281 sandstone samples from the Songpan–Ganzi and Western Qinling terranes were obtained. Among these, 1,636 zircons from 33 samples contained Hf isotopic data. Moreover, we compiled data on papers, samples, analytical methods, and results and obtained a total of 76 zircon U–Pb and 60 Hf isotope data heads. The obtained dataset has multiple data interfaces, which can be well associated with research or applications in different fields, for provenance analysis, climate change, and paleogeographic reconstruction studies. [ABSTRACT FROM AUTHOR]

The stratospheric polar vortex (SPV) significantly influences current weather and climate patterns. However, its state in the geological past remains largely unexplored. This study investigates SPV variations in the past 250 million years, using a fully coupled Earth System Model. It is found that midlatitude paleogeography primarily drove substantial SPV variations in the deep time, while changes in CO2 concentrations and solar insolation play a minor role. Both the Arctic and Antarctic SPV were strengthened when the supercontinent Pangea broke up. The increased asymmetry of midlatitude land‐sea contrast tended to weaken the upward propagation of wavenumber‐1 planetary waves, thereby strengthening the SPV. This SPV strengthening correlated with the decelerated stratospheric Brewer‐Dobson circulation and uplift of the polar tropopause. Our results highlight the crucial role of paleogeography in regulating SPV variations and stratosphere–troposphere coupling in deep‐time climate. Plain Language Summary: At present, influences of the stratospheric polar vortex (SPV) on surface climate have attracted growing attention. In the geological past, however, how the SPV acted and how it impacted on the troposphere and surface climate remains unclear. This study explores SPV variations in both the Northern and Southern Hemispheres in the past 250 million years (Myr) using simulations of a fully coupled Earth System Model. Our results reveal that polar stratospheric temperatures fluctuated by up to 20 K in the geological past, which is much greater than the variations from 1850 to the present. Midlatitude paleogeography played a crucial role in SPV variations over tectonic timescales. The breakup and drift of the Pangea supercontinent altered the upward propagation of Rossby waves from the troposphere into the stratosphere. It influenced not only the SPV but also the strength of stratospheric Brewer‐Dobson circulation as well as the polar tropopause height. This work helps to understand the role of paleogeography in the stratosphere. Key Points: The stratospheric polar vortex (SPV) experienced dramatic variations in the past 250 million yearsMidlatitude paleogeography has a crucial impact on SPV variations by regulating upward propagation of planetary wavesThe SPV variation is closely associated with changes in stratospheric Brewer‐Dobson circulation over tectonic timescales [ABSTRACT FROM AUTHOR]

Coalbed methane (CBM) is a natural gas resource related with coal deposits. In general, Gas status parameters gradually with the depth of the stratum. However, in areas with complex geological structures and multiple coal seam occurrences, the gas storage situation in shallow coal seams is typically better than in deep coal seams. This research paper focuses on coal seams numbered 8, 9, and 10 within the Luling coal seam as the subject of study. The study combines the analysis of gas accumulation history, laboratory experiments, and field investigations to examine the differences in gas occurrence within the coal seam group. The findings suggest that the differences in gas occurrence state within each coal seam of the Luling coal mine is predominantly governed by tectonic processes. During the process of tectonic evolution, the thicker coal seams, such as Nos. 8 and 9, are more prone to fracturing, leading to the formation of widely distributed tectonic coal. These broken coal bodies exhibit a significant capacity to store gas, resulting in favorable gas storage conditions within these coal seams. On the other hand, the low permeability of the mudstone in the roof layer restricts the migration and seepage of gas in the No. 10 coal seam, leading to a comparatively lower sealing effect for gas. By providing a comprehensive understanding of the gas content differences in the coal seam group, this study highlights the significant influence of geological processes on the distribution and storage of gas. These findings contribute to understanding the characteristics of gas reservoirs under complex geological conditions and adopting corresponding measures to reduce the risk of coal and gas outbursts in coal seams. [ABSTRACT FROM AUTHOR]

The northwestern continental margin of the South China Sea, extending from the broad shelf and canyon-growth slope across the Xisha Trough, represents a relic crustal rift that eventually connects to the abyssal plain. However, the provenance and source-to-sink process of sediments in this special topography remains unclear. In this study, we present the detrital zircon U-Pb geochronology of surface sediments from the northwestern margin of the South China Sea to identify the sediment provenance, track the transport pathway, and understand the source-to-sink process in this margin. The results showed that detrital zircons exhibit a wide range of U-Pb ages from 3,062.9 to 41.5 Ma and are characterized by peaks centered on 140–154 Ma, 240–258 Ma, 425–452 Ma, and 738–991 Ma. Statistical analysis indicated that the clastic sediments on the shelf closely resemble those sourced from the Pearl River system. Conversely, sediments on the slope and abyssal plain demonstrated characteristics indicative of multiple sources, primarily originating from the Pearl River, with a minor contribution from the Red River. Further quantitative study revealed a progressive increase (from 8.2% to 43.2%) in the prevalence of Red River-derived sediments with ascending water depth on the shelf and slope, whereas sediment influx in the deepest sector remains predominantly sourced from the Pearl River. This study emphasizes the controls of topography and currents in modulating the transportation of coarse-grained and fine-grained sediments within the sourceto- sink system and provides a favorable solution for reconstructing the sedimentary process in continental margins. [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]

Describing the organic-inorganic pore evolution influenced by mineral composition is crucial for characterizing shale oil storage capacity and flow in shale, and it also helps predict storage capacity for sequestered CO2. Using laboratory pyrolysis experiments to artificially mature shale samples at relatively high temperatures and short times, this study compares a series of natural samples with different thermal maturations, which can better reflect the real underground pore evolution. A total of 30 natural shales spanning from low to high maturity were collected from the Cretaceous Qingshankou Formation of the Songliao Basin, and the analysis results revealed four main typical shales, namely argillaceous shale, felsic shale, calcareous shale, and mixed shale. The existence of clay minerals, quartz and feldspar promote the development of > 50 nm pores, while 0-20 nm pores are mainly developed in clay minerals and organic matter. When the content of total organic carbon is less than 2.5 wt.%, it displays a positive correlation with the specific surface area, but the correlation becomes negative for samples with a content of total organic carbon greater than 2.5 wt.%. The organic pores are most developed at the peak oil maturity, while inorganic pores are most developed during the oil window, and tend to be stable at high maturity. Argillaceous shale in the high maturity stage may be favorable for petroleum exploration in the Qingshankou Formation of the Songliao Basin. Mixed shale and calcareous shale may not be conducive to the short-term storage of CO2 due to strong reactions with CO2 at the beginning. On the other hand, argillaceous shale and felsic shale may be conducive to the long-term storage of CO2. [ABSTRACT FROM AUTHOR]

Abstract Paleogeography is the merger of sediment and volcanic facies, depositional settings, tectonic plate movements, topography, climate patterns and ecosystems through time. The construction of paleogeographic maps on tectonic plate reconstruction models requires a team effort to compile databases, data sharing standards and map projection methods. Two goals of the Paleogeography Working Group of the International Union of Geological Sciences (IUGS) program for Deep‐Time Digital Earth (DDE) are: (1) to interlink online national lexicons for all sedimentary and volcanic formations, and develop online ones for nations that currently lack these; (2) to target specific regions and intervals for testing/showcasing paleogeography output from the merger of these databases. Following those goals, we developed and applied new cloud‐based lexicon data services and interactive visualization techniques to regions in East Asia. This has been a successful collaboration among computer engineers and plate modellers and has involved stratigraphers in India (ONGC), China (Chengdu Univ. Tech., and Chinese Acad. Geol. Sci.), United States (Paleomap Project, and Purdue Univ.), Australia (GPlates visualization team) and Vietnam (Vietnam Nat. Univ.). Independent online lexicons with map‐based and stratigraphy‐based user interfaces have been developed (as of the date of this submission in March 2022) for all Proterozoic to Quaternary formations on the Indian Plate (over 800) and Vietnam (over 200), the majority of the Devonian through Neogene of China (ca. 2000) and partially for Thailand. A multi‐database search system returns all geologic formations of a desired geologic time from these four independent databases. With one click, users can plot the regional extent of one or of all of those regional formations on different plate reconstruction models of that desired age, and these polygons are filled with the lithologic facies pattern.

AbstractThe palynofloras of the Shemshak (upper part) and Dalichai (lower part) formations, Deh-Soufian, north of Semnan include 57 species of spores (34 genera), 25 species of pollen (13 genera), and 14 species of dinoflagellate cysts (8 genera). Based on the stratigraphic distribution of miospores, the Klukisporites variegatus-Striatella spp.-Contignisporites burgeri assemblage biozone (Middle Jurassic) is introduced. The co-occurrence in the palynofloras examined of Contignisporites burgeri and Striatella seebergensis allows for the Bajocian–Bathonian boundary to be located 75m below the boundary of Shemshak-Dalichai rock units. The presence in the strata below this chronostratigraphic horizon of Mendicodinium scabratum (Bajocian) supports this age assignment. The boundary of Shemshak and Dalichai (with basal sandstone) formations is discontinuous. While no significant change in the composition of miospores is discernible in palynofloras retrieved from the above rock units, the relative abundance of such terrestrial palynomorphs varies drastically. This might be attributed to side effects of the mid-Cimmerian Orogeny i.e., significant change in sedimentation rate resulting in change from the deltaic to marine depositional settings. It should be noted that 45 m below the boundary of the two rock units 24 miospore species exit whereas 11 different ones appear 20 m above that boundary. Notable correspondence of the Iranian Middle Jurassic palynofloras across the Alborz Ranges signifies to a rather significant coastal vegetation similarity of the time in the area. Whereas both Gondwanan and Eurasian miospore key species occur in the palynofloras examined those particularly endemic to the southern landmasses are missing from the palynofloras studied. Palynological evidence seemingly confirms the location of the Alborz Ranges on the northwestern margin of the Neotethys Ocean in the Middle Jurassic. The available paleontological data (ammonites and dinoflagellate cysts) apparently support this interpretation.Keywords: Palynostratigraphy, Paleogeography, Middle Jurassic, Shemshak and Dalichai formations. IntroductionJurassic strata widely distributed and exposed in the Alborz Ranges (Majidifard 2008) consist of deposits of two large sedimentary-tectonic cycles (Aghanabati 1975). Those of the first Upper Triassic–Lower Jurassic sedimentary cycle are known as the Shemshak Formation (Assereto 1966; Fürsich et al. 2009) or the so-called Shemshak Group whereas strata of the second sedimentary megacycle (Middle-Upper Jurassic) in east-central Iran are known as the Magu Group.Lithological variation, biological attributes, and depositional settings reflected by the Jurassic rocks in Iran indicate that the geologic changes were closely related to the tectonic events (Majidifard 2003). Much of the Shemshak Formation sedimentation in the Alborz Ranges took place on coastal plains in fluvial, lacustrine, or deltaic settings, paralic swamps, lakes, meandering, as well as, braided rivers, and shallow–deep shelfal environments (e.g., Seyed-Emami 2003; Seyed-Emami et al. 2008). The Upper Triassic and the lowermost Jurassic rocks are very similar, so in most cases, the two-time intervals cannot be differentiated (Majidifard 2003; Seyed-Emami 2003; Seyed-Emami et al. 2008). Due to its vast thickness in many areas (up to 4000 m), some have elevated the unit to group rank (e.g., Aghanabati 1998; Seyed-Emami 2003; Fürsich et al. 2009a). Consequently, the unit has been subdivided into various members/formations, and different lithostratigraphic schemes have been proposed (Nabavi and Seyed-Emami 1977; Nabavi 1980; Repin 1987; Aghanabati 1998; Seyed-Emami et al. 2020). It contains diverse biota such as plant fossils (e.g., Sadeghi and Hashemi 2021), and ammonites (e.g., Seyed-Emami et al. 2020). However, due to the poor preservation of palynomorphs, the Shemshak Formation has remained almost unstudied palynologically.The Magu Group, the second sedimentary megacycle consists primarily of fossiliferous marls and limestones indicating basin and platform depositional setting (Lasemi 1995). These accumulated from the end of the Mid-Cimmerian tectonic phase (Middle Jurassic) till the Late Jurassic and, in some places, continued during the Neocomian (Seyed-Emami 1975; Keshani 1988; Seyed-Emami and Alavi-Naini 1990; Majidifard 2003, 2008; Fürsich et al. 2009).The Dalichai Formation (Steiger 1966), the oldest rock unit of the Magu Group (Aghanabati 1998) comprises shale, light-grey to bluish-grey limestones with thin intercalations of marls (Majidifard 2003, 2008). It contains diverse biota such as ammonites, spores and pollen grains, dinoflagellates cysts, belemnites, bivalves, brachiopods, echinoids, sponges, bryozoans, and foraminifera (Stöcklin 1972; Alavi-Naini 1972; Sussli 1976; Nabavi and Seyed-Emami 1977; Alavi-Naini et al. 1982; Seyed-Emami et al. 1985, 1989, 1995, 1996; Wheeler and Sarjeant 1990; Schairer et al. 1991; Shahrabi 1994; Makvandi 2000; Tutunchi 2001; Ghasemi-Nejad and Khaki 2002; Shafeizad et al. 2002; Farisi Kermani 2003; Shafeizad and Seyed- Emami 2005; Alvani 2006; Shams 2007; Niknahad 2007; Ghasemi-Nejad et al. 2008, 2012; Hashemi Yazdi 2008, 2015; Majidifard 2008; Seyed-Emami et al. 2008; Sabbaghiyan 2009; Sajjadi et al. 2009; Vaziri et al. 2008, 2011; Dehbozorgi 2013; Dehbozorgi et al. 2013; Mafi et al. 2013; Navidi Izad 2013; Dietze et al. 2014; Skupien et al. 2015). Study of ammonites indicates a late Bajocian to Oxfordian age for the Dalichai Formation (Lorenz 1964, Sussli 1976; Nabavi and Seyed-Emami 1977; Seyed-Emami et al. 1985, 1995, 2013; Schairer et al. 1991; Majidifard 2003, Seyed-Emami and Schairer 2010, 2011a, b). According to paleontological and lithological evidence the Dalichai Formation was deposited in a marine environment (Lorenz 1964, Steiger 1966, Wheeler and Sarjeant 1990, Zarei 2017). Furthermore, ammonite data shows close relationships to those from epicontinental seas fringing the northern margin of the western Tethys and an intermediate position between the Subboreal and Submediterranean provinces (Seyed-Emami et al. 2013, 2018; Dietze et al. 2014; Seyed-Emami and Raoufan 2017).The aim of this study is to document the palynological content of the Shemshak and Dalichai formations boundary at Deh-Soufian, north of Semnan, to assess its stratigraphic and palaeogeographical significance and compare it to other Middle Jurassic records of Eurasia and Gondwana. Material & MethodsTwenty-one samples were collected from shale intervals at the Deh-Soufian stratigraphic section (N 35° 47' 44" and E 53° 40' 03"); nine samples from the uppermost of the Shemshak Formation and twelve samples base of the Dalichai Formation. Standard palynological procedures (e.g., Phipps and Playford 1984, Wood 1996) applied for extraction and concentration of the palynomorphs. Samples were first disaggregated into pea-sized pieces (1–2 mm in diameter) and treated with 30% HCl to eliminate carbonates. The residue was then washed to neutrality and the remaining inorganic matter dissolved in HF (ca. 40%); fluoride precipitants formed were subsequently removed using hot 30% HCl followed by washing to neutrality. The organic residue was sieved via 20 μm mesh. Heavy minerals and other remaining inorganic particles were then removed by the use of a heavy-liquid solution (ZnCl2) at appropriate specific gravity. The remaining residue was then sieved through 20 μm nylon sieve prior to mounting on permanent slides. At least three permanent strew slides per sample were prepared using Entellan as the mounting medium. Discussion of Results & ConclusionsThe palynofloras examined comprise 57 spore species (assigned to 34 genera), 25 pollen species (attributed to 13 genera), and 14 species of dinoflagellate cysts (allocated to eight genera). The vertical ranges of certain miospore species with known stratigraphic significance and/or persistence throughout the section investigated authorize the introduction of one informal local biozone as Klukisporites variegatus-Striatella spp.-Contignisporites burgeri assemblage biozone. The presence of multiple Striatella species, as well as, Contignisporites burger and Klukisporites variegatus collectively indicate a Middle Jurassic (Bajocian–Bathonian) age. The co-occurrence in the palynofloras examined of Contignisporites burgeri and Striatella seebergensis allows for the Bajocian–Bathonian boundary to be located 75 m below the boundary of Shemshak and Dalichai rock units. The presence in the strata below this chronostratigraphic horizon of Mendicodinium scabratum (Bajocian) supports this age assignment.The lithology of the Shemshak Formation includes sandstone and shale alternations, and the Dalichai Formation includes basal sandstone followed by limestone and shale alternations. The boundary between the two mentioned formations is discontinuous due to the presence of a sandstone layer at the base of the Dalichai Formation.No significant change in the diversity of miospore species is observed in the border of the mentioned rock units, but their relative abundance in this horizon is associated with a significant decrease. This might be considered a side effect of the mid-Cimmerian Orogeny, i.e., a significant change in sedimentation rate resulting difference in the sedimentation environment from the deltaic (Shemshak Formation) to the marine environment (Dalichai Formation).It should be noted that 24 miospore species disappear 45 meters below the border of the Shemshak and Dalichai formations, and 11 different miospore species appear 20 meters above this border. The comparative palynofloras found in the Iranian Middle Jurassic rocks of the Alborz Ranges recommend that there were likely comparative types of coastal plants in that area during that time. The key miospore species from both Gondwana and Eurasia are found in the examined samples, but the species that are unique to the southern landmasses (e.g. Aequitriradites norrisii, Anapiculatisporites dawsonensis, A. pristidentatus, and ….) are not present in the samples studied. The investigated palynomorphs indicate that throughout the Middle Jurassic, the Alborz Ranges were located alongside the northwestern edge of the Neotethys Ocean. The ammonites and dinoflagellate cysts apparently support this elucidation.

The Lower Cretaceous bryozoan assemblage in the environs of Gunib village in Dagestan is described for the first time. The studied section is located in the zone of development of the Gapshima Formation (Hauterivian) deposits. The bryozoan assemblage is characterized by high taxonomic diversity and includes 32 taxa from four suborders of order Cyclostomata: Tubuliporina (24 taxa), Cancellata (1 taxon), Articulina (1 taxon), and Cerioporina (6 taxa). Because of the poor preservation of the colonies, most taxa are defined in open nomenclature. Therefore, the true diversity of cyclostomes in the study area is not fully recognized. The assemblage includes the taxa which are similar to bryozoans previously described from different levels from Valanginian to Barremian of Switzerland and France and, partly, from the lower Hauterivian of Germany (Mecynoecia icaunensis (d'Orbigny), Mesenteripora marginata (d'Orbigny), M. reticulata (d'Orbigny), Poriceata ardescensis Walter, Apsendesia neocomiensis d'Orbigny, Diplocava biformis (Roemer), "Heteropora" arborea Koch et Dunker, and Elea periallos Taylor). The main difference of the Gunib assemblage from the Valanginian–Hauterivian assemblage of Switzerland and France and the lower Hauterivian assemblage of Germany is the presence of bryozoans from the family Eleidae, but it differs from the Barremian assemblage of France in the absence of Cheilostomata representatives. Among the studied cyclostomes, bryozoans with vertically growing colonies predominate. Some of these bryozoans are bilateral leaf-shaped, while others had thin cylindrical branches. Reticulate and massive colonies are rare, while encrusting bryozoans, which grow over erect colonies, are quite numerous. [ABSTRACT FROM AUTHOR]

Both tectonic settings and sedimentary environments of the oil- and gas-bearing Triassic sequences in the Caspian region are examined. It is shown that the Scythian and West Turanian plates were located at an active margin of the East European continent in Triassic. A unified thick (up to 3–5 km) cover of sedimentary and volcanosedimentary (mainly tuffaceous) rocks without the characteristic features of rifting was formed. In the northern and eastern parts of the region, the Triassic is composed of variegated continental terrigenous rocks. In many areas of the region (eastern and southern parts of the Pre-Caspian Basin, Eastern Ciscaucasia, Mangyshlak, and Middle Caspian), the Lower Triassic (Olenekian) and Middle Triassic are represented by marine terrigenous–carbonate rocks. The structural features of sequences in the Pre-Caspian Basin are associated with salt tectonics. The maximum thickness (up to 4.5–5 km) of Triassic rocks within the Scythian Plate is recorded in the southwestern part of the Middle Caspian and southeastern part of the Karpinsky Ridge, where they fill up a series of NW-extending graben-shaped troughs. Their absence in the northwestern part of the region is related to the latest shear deformations, as confirmed by their discrepancy with the facies zonation of Triassic deposits. Currently, the Permian and Triassic deposits represent a pre-platform geodynamic seismic sequence unconformably overlying the pre-Kungurian deposits. Triassic deposits of the Scythian and West Turanian plates are disturbed by faults (amplitude up to 2 km) and dislocated in some areas. Folding with faults and strike-slip faults is especially intense on the Karpinsky Ridge. Increased dislocation and Late Triassic magmatism on the Scythian and West Turanian plates are associated with the processes of collision during the closure of the Paleotethys Ocean. Oil and gas prospects of the region are assessed positively. [ABSTRACT FROM AUTHOR]

The sandstone uranium deposits in the Kelulun Depression are the first commercially viable uranium deposits discovered in the Hailar Basin and the ore-bearing strata corresponding to the Lower Cretaceous Yimin Formation. However, the source of sedimentary matter, uranium source conditions, and uranium mineralization processes in the region have not been characterized. Accordingly, we analyzed the lithology, whole-rock geochemistry, zircon U-Pb ages, and trace elements of the Yimin Formation sandstones. The Yimin Formation sandstones were primarily composed of detrital grains with low compositional maturity. A geochemical analysis indicated that the parent rocks are felsic igneous rocks formed at an active continental margin with a moderately high degree of weathering. The detrital zircon U-Pb ages of the Yimin Formation 215–287 Ma with a peak at 230–260 Ma. Based on chronological, geochemical, and lithological data, we conclude that the Yimin Formation matter is derived from the Adunchulu Uplift on the western side of the Kelulun Depression and its parent rocks are Triassic granites. The Adunchulu uplift since the late Early Cretaceous and weathering and denudation of its uranium-rich granites provided ample matter and uranium. Therefore, the Kelulun Depression is a promising area for the exploration of sandstone uranium deposits. [ABSTRACT FROM AUTHOR]

The Triassic tectonic evolution and affinity among the Yangtze Block, Qinling Orogenic Belt and Songpan-Ganzi Terrane remain subjects of ongoing scientific debate. In this context, the sedimentary rocks of Xujiahe Formation (second segment) (T3x2) represent an ideal case for addressing this issue. In this study, new stratigraphic, geochemical and detrital zircon analyses have been conducted on two sections of the T3x2. The stratigraphic assemblage and features suggests a braided delta as the depositional setting. Whole-rock geochemical results indicate that the sandstones from the T3x2 exhibit moderate palaeo-weathering and primarily originate from upper crustal felsic rocks, mostly S-type granites. The detrital zircons within these sandstones display distinctive age peaks at intervals of 200-300 Ma, 700-900 Ma, and 1800-2000 Ma, similar to those from the Qinling Orogenic Belt. Both the clastic particle composition and whole-rock geochemistry indicates that the T3x2 sections were deposited in a tectonic environment transitioning from a passive to an active continental margin, highlighted by a braided delta influenced by rivers flowing from the northeast to the southwest. [ABSTRACT FROM AUTHOR]

Detrital U-bearing minerals (e.g., zircon, apatite) U-Pb ages with specific trace-element geochemistry, are frequently used in provenance analyses. In this study, we focus on the Yarlung River drainage in South Tibet, characterized by two distinct lithologic units: The Gangdese batholith to the north (mainly granitoids) and the Tethyan Himalaya (mainly sedimentary rocks) to the south, which plays a crucial role in the erosion of the Tibetan Plateau. To constrain the provenance of the Yarlung River Basin, we performed trace-element and U-Pb age analyses of detrital apatite from the river sands of the Yarlung River and its tributaries. Our findings indicate that the detrital apatite U-Pb age patterns of the north tributaries exhibit main peaks at approximately 40 and 60 Ma, consistent with the corresponding U-Pb age patterns of detrital zircon published. Further, their trace element casts fall mainly in the Type I granite region, also indicating the Gangdese arc-dominated source. However, those of the south tributaries (∼60–20 Ma) exhibit a different age distribution from the detrital zircon U-Pb groups (∼110–150, ∼500, and 1 100 Ma), suggesting that the detailed apatite U-Pb signals can provide excellent constraints on the provenance of igneous and metamorphic rock sources but less so for sedimentary rock sources. Combined with previous detrital zircon data in the study area, our detrital apatite information can highlight young metamorphic events from a complex background (i.e., Niyang and Nianchu rivers), which offers additional constraints on the provenance of the Yarlung River Basin. Generally, a combination of geochemistry and geochronology of multi-detrital heavy minerals, such as zircon and apatite, can provide powerful tools for provenance analysis. [ABSTRACT FROM AUTHOR]

The West Qinling Orogen (WQO) is located in the western part of the Qinling Orogen and in the transition zone of Qilian Orogen, Songpan-Garze Orogen and Yangtze Block, and also the key position of Triassic collision orogenic event. The study of the Early Triassic strata in the WQO is contributed to analyze the closure process of the paleo-Tethys. We conducted LA-ICP-MS U-Pb dating studies on detrital zircons to determine the provenance, depositional age, and tectonic setting of the Early Triassic Longwuhe Formation in the Lintan area of the WQO. The results show that the majority of the detrital zircons in the Longwuhe Formation are mainly magmatic origin and have characteristic of crust source zircon. The lowest limit of sedimentation of the Longwuhe Formation is constrained to the Early Triassic, with the youngest detrital zircon age of 253 ± 3 Ma. The ages can be divided into five age groups: 3 346–1 636 Ma, with two peak ages of ca. 2 495 and ca. 1 885 Ma; 1 585–1 010 Ma, with a peak age at ca. 1 084 Ma; 992–554 Ma, with a peak age at ca. 939 Ma; 521–421 Ma, with a peak age at ca. 445 Ma; 418–253 Ma, with a peak age at ca. 280 Ma. Apparently, the sources of the Longwuhe Formation include the northern margin of the WQO, the Qilian Orogen (QLO) and the basement of the southern margin of the North China Block (NCB), of which the ancient basement of the southern margin of the NCB is the main source area of the Longwuhe Formation. Combined with previous studies, we propose that the Longwuhe Formation was formed in a fore-arc basin, which is related to the closure of the A'nyemaqen-Mianlüe Ocean from the Early Permian to Early–Middle Triassic due to the northward subduction-collision of the Yangtze Block (YZB). This also indicates that the A'nyemaqen-Mianlüe Ocean has flat subduction characteristics. [ABSTRACT FROM AUTHOR]

Molasses of foredeeps are important indicators of the newest orogenic uplifts, as well as the source of data on climate and landscape changes. One of the fullest sections of Neogene–Quaternary deposits is studied in valleys of the Belaya, Pshekha, and Psekups rivers at the junction of the Western and Northwestern Caucasus with the Eastern Kuban and Western Kuban foredeeps. The formation of the deposits corresponds to the main evolution stages of the Great Caucasus orogen, as well as the foredeeps. A summary of extensive published and original tectonostratigraphic materials has shown that the lowland and then hilly relief in an axial zone of Western Caucasus existed at least from the Middle Miocene. At the same time, the northern flank of the present-day orogen and the foredeeps were located at sea level and were repeatedly flooded by the seas up to the Kuyalnikian (Piacenzian–Gelasian) time, and the Western Kuban Foredeep was flooded even later. The main data on stratigraphy of the upper molasses and Pliocene–Quaternary tectonic movements of the region are based on facies analysis and bio- and magnetostratigraphic studies of the Upper Pliocene–Lower Pleistocene Belorechensk Formation. Its sedimentation started at the beginning of the Kuyalnikian as a result of an increase in the energy of mountain rivers due to the uplift of the riverheads. It is stated that the minimum average rate of uplift of the Western Caucasus in the basin of the Belaya River is 0.8 mm/year over last 4 mln years with acceleration up to 1.7 mm/year from the beginning of the Calabrian. The Belorechensk Formation includes three subformations, which successively become coarser clastic and correspond to the main stages of the accumulation of upper molasses in the Late Pliocene and Early Pleistocene during the intensification of uplifts and landscape-climate changes of Western Caucasus and Ciscaucasia. [ABSTRACT FROM AUTHOR]

The results of studies of the regional structure of Solenovian deposits of the Early Oligocene Rupelian Stage in the Cisсaucasian–Caspian region, which represented the northern slope of Eastern Paratethys in the Cenozoic, are presented. The geological structure and paleogeographic conditions in the basin during the Solenovian (second half of Early Oligocene) were refined based on a comprehensive interpretation of geological and geophysical materials. The spatial consequences of the sea level drop in Eastern Paratethys during the Oligocene regressions are traced. The periodic draining of shelf areas is reflected in the structure of erosional unconformities and buried river incisions. It has been established that the most significant was the late Solenovian regression with a relative sea level drop by more than 500 m. Consequently, a prominent unconformity surface, complicated by river incisions, was formed in the sedimentary sequence in the shelf part of the paleobasin (Maikop seismic sequence). Erosion ledges and landslide bodies formed on the slopes, and basin-infill complexes were accumulated in depressions. [ABSTRACT FROM AUTHOR]

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The Skagerrak basin represents the main sink area for fine-grained sediment in the North Sea region and constitutes a natural deposition center for sediments that are supplied from the Atlantic, the Baltic Sea and the surrounding continental margins and coasts. However, the exact sources and their proportional contributions to the North Sea sediments and to the Skagerrak deposits are not well understood. To trace the predominant sources of the sediment and to gain a better understanding of the sedimentary processes in the North Sea and the Skagerrak basin, radiogenic Sr, Nd, and Hf isotope signatures and clay mineral compositions of the detrital clay fraction of surface sediment samples from the North Sea, the Scandinavian margins and the Baltic Sea were measured. The results indicate that the major source for Skagerrak clay-size sediments is the northern North Sea but Scandinavia as well as the southern North Sea including the southern England coast also contribute material. Seabed and coastal erosion in the northern North Sea are enhanced by the inflowing Atlantic Currents, which provide the Skagerrak with high amounts of clay size sediments. In contrast, the southern North Sea, the Baltic Sea and mid-European rivers such as Weser, Elbe and Ems are only minor contributors. As Skagerrak deposits are dominated by clay sized material (up to 60%), the reconstructed sediment processes in this study deviate from findings in previous sediment budget studies, which were based on both clay and silt fraction and indicated predominant influences from the southern North Sea. These results highlight that coastal and seabed erosion in the North Sea is a previously underestimated source of fine-grained sediments for depocenters in the entire North Sea. With regard to climate change, the global sea-level rise will likely enhance erosional processes and can therefore significantly influence the sediment budget of the entire North Sea. [ABSTRACT FROM AUTHOR]

Continental alkaline magmatism has been suggested to play a significant role in releasing deep mantle carbon into the atmosphere, which can greatly impact the global climate. However, the temporal variations of alkaline magmatism and their potential to modulate climate over geologic time remain poorly constrained. The detrital zircon record is a frequently used proxy for tracking secular variations in particular magmatism. Here, we use a novel machine‐learning technique to discriminate zircon from carbonatites, kimberlites, and other alkaline rocks. A global compilation of detrital zircon yields continental alkaline magmatic flare‐ups between 1,050−850, 650−500, 250−200, and 50−0 Ma. Our estimates indicate relatively elevated contributions of total magmatic carbon outgassing from alkaline magmatism during the aforementioned magmatic flare‐ups. We infer that anomalous alkaline magmatism may influence global warming during specific intervals of geologic time, but when they are not that voluminous or persistent extensive arc magmatism may drive warming conditions. Plain Language Summary: The potential of volcanic CO2 emissions to modulate atmospheric CO2 levels and affect the environment of our planet has been recognized. Some specific volcanic types, such as continental arc volcanism, have been hypothesized to play a dominant role in driving long‐term climate change. Recently, the efficiency of continental alkaline magmatism in releasing carbon from the deep mantle to the atmosphere and its ability to influence Earth's climate is proposed for certain timescales and supported by empirical data. However, the quantitative estimation of the alkaline magmatic activity over geologic time and its general link to the global climate change remains poorly constrained. Here, we assess the alkaline magmatic variations based on the detrital zircon record and a novel machine‐learning model which could discriminate zircon from carbonatites, kimberlites and other related alkaline silicate rocks. The predictive result shows several peaks at 1,050−850, 650−500, 250−200, and 50−0 Ma, which is considered a minimum estimation due to the preservation bias of the detrital zircon record. Our estimates indicate that continental alkaline magmatism may influence global warming during specific intervals of geologic time such as the early Paleozoic and early Mesozoic. Key Points: Frequency of magmatic events can be assessed by a machine‐learning analysis of zirconContinental alkaline magmatism peaked between 1,050−850, 650−500, 250−200, and 50−0 MaAnomalous alkaline magmatism may contribute to global warming at certain times [ABSTRACT FROM AUTHOR]

The Kyzylkum Desert, as a transition area of different dust source in Central Asia, provides and reserves a large amount of dust transported by different atmospheric circulation systems, affecting Uzbekistan and downwind East Asia. However, there remains very few investigations about sediment sources and control factors of the desert. We hereby first present a provenance study on the Kyzylkum Desert, utilizing detrital zircon U‐Pb ages of samples composed of desert sand, alluvial sediments from Amu Darya River and piedmont of Southwest Tianshan Mountains. The results reveal that the Southwest Tianshan Mountains contribute the majority of the Kyzylkum desert sand, and the river system, dominated by Syr Darya, controls the sediment provenance of the desert. Moreover, little contribution from the Kyzylkum and Nurata segments indicates that wind erosion on the bedrocks is weak. However, the aeolian process is still crucial but deposit and storage of dust are determined by local topography. Plain Language Summary: The Arid Central Asia is commonly considered one of the most important dust sources in the world. The Kyzylkum Desert, located in the center of the multiple dust sources in Central Asia, provides and receives a large amount of dust, affecting Uzbekistan and downwind East Asia. However, research on sediment sources and control factors in the area is under debate. We investigate the potential provenance, spatial variability, and transport patterns of sand in the Kyzylkum Desert using detrital zircon U–Pb geochronology on 10 sediment samples. The results reveal that the Southwest Tianshan Mountains contribute the majority of the Kyzylkum desert sand, however, the proximal provenances also have a significant influence on the formation of the desert. The geomorphologic history shows that, the river system, dominated by Syr Darya, controls the sediment provenance of the Kyzylkum Desert. The wind displays little influence on the rework and recycle process of Kyzylkum Desert, indicated by inhomogeneous composition between northwest and southeast desert. The unmixing model results show evidence of sediments from the Kyzylkum Desert transported to the piedmont areas, but the transport and deposition of dust are primarily controlled by topography. Key Points: Detrital zircon U‐Pb dating indicates that the Southwest Tianshan Mountains are the primary sediment source of the Kyzylkum DesertThe river system controls the sediment provenance of the Kyzylkum DesertTopography determines reserve positions of the aeolian sand and dust from Central Asian deserts [ABSTRACT FROM AUTHOR]

Two hundreds calcareous benthic foraminiferal species of the Suborder Rotaliina belong to sixty genera from twenty countries in the Southern Tethys (Chile, Argentina, Angola, Nigeria, Tanzania, Mali, Algeria, Tunisia, Egypt, Palestine, Lebanon, Syria, Jordan, Saudi Arabia (SA), Yemen, Qatar, United Arab Emirates (UAE), Iraq, Iran and Pakistan) have been studied. The modern taxonomical consideration of the species is used. The recorded species were previously noted in the literatures, while two of them are believed here as new: Stainforthia abdelkarimi and Siphonodosaria misrensis. Forty species of them are recorded from Egypt (about 41%), twenty seven from Pakistan (~ 28%), ten from UAE (~ 10.5%), six from Qatar (~ 6%), four from each of Algeria and Iran (~ 4%), three from three from Jordan (~ 3%), two from each of Palestine and Iran (~ 2%), and only one from each of Iraq and India (~ 1%). Most of the Southern Tethyan recorded species are endemic to their original description, while five of them are also recorded in some other Southern Tethys, and also Northern Tethyan countries (Atlantic Ocean, France, Spain, Slovenia, Austria, Turkey, Turkmenia and Kazakhstan). [ABSTRACT FROM AUTHOR]

The late‐stage union of Pangea was associated with the convergence of Siberia with Laurussia, but the exact timing remains unclear. The orogenic duration of the Kazakhstan block can provide geochronological constraints as it connects Siberia, Baltica, and Tarim. Zircon petrochronology offers a reliable approach for ascertaining the lifespan of an ancient orogen. In this study, we explore three phases of magmatism recorded in detrital zircons from late Paleozoic and Mesozoic sandstone‐siltstones in Western Tianshan, that is, 400–470 Ma, 320–380 Ma, and 280–320 Ma. Based on their age‐propagated Hf isotopes, melt SiO2 contents, and crustal thicknesses, our findings suggest that the southern limb of Kazakhstan underwent the early Paleozoic amalgamation of microcontinents with arcs, the late Paleozoic maturation of an Andean‐like continental arc, and the late Carboniferous collision of Kazakhstan with the Junggar oceanic basin and the Tarim craton. Such characteristics manifest the long‐term orogenic progression of Kazakhstan. Combining published timelines and paleolatitudes of major orogens and blocks, we propose that the Kazakhstan block welded northeastern Pangea along with the cessation of these orogenic activities around it. Consequently, by docking Kazakhstan with surrounding cratons, the fundamental configuration of Pangea could have been established in the late Carboniferous. Plain Language Summary: Pangea was suggested to have assembled at ca. 250 Ma upon paleogeographic reconstructions. However, the assembling time remains a matter of debate due to low‐quality Permo‐Carboniferous paleomagnetic data on the northeast of Pangea; thus, other geochronological records need to be determined. Here, we employ the method of zircon petrochronology to trace the orogenic processes of Kazakhstan because it serves as a pivot in welding peripheral Siberia, Baltica, and Tarim blocks. Our results demonstrate that episodic variations in melt compositions, crustal thicknesses, and Hf isotopes reveal the long‐lived orogenic progression of the southern limb of Kazakhstan and constrain its incorporation into Pangea to the late Carboniferous. Such an event was almost contemporaneous with the assembly of Baltica and Siberia with the northern limb of Kazakhstan but occurred slightly later than the collision of Laurussia with Gondwana. As such, the fundamental configuration of Pangea could have been established in the late Carboniferous rather than the Permian, as previous paleogeographic reconstructions postulated. Key Points: Detrital zircons in Western Tianshan record three phases of Paleozoic magmatismZircon petrochronology can trace orogenic processes of the southern limb of KazakhstanDocking Kazakhstan with surrounding cratons in the late Carboniferous marked the major assembly of the northeastern Pangea [ABSTRACT FROM AUTHOR]

Underpinning almost every Paleozoic paleogeographic reconstruction and tectonic model of the Lachlan Orogen is the interpretation of the structural geology related to crustal collision and amalgamation. Bounding the eastern margin of the Lachlan Orogen is a north-trending corridor of Cambrian–Ordovician turbidites that in northeast Victoria are recognised as the Pinnak Sandstone or previously known as the Mallacoota Beds. This sequence contains an accretionary prism related early S* foliation, syn-sedimentary dykes, slump structures, early faults or décollements and early quartz veins. These indicate anisotropic compaction by fluid extraction in a shallow marine turbidite sequence that underwent localised deformation (D1), which can be attributed to the Benambran Orogeny (ca 450 Ma). There was a change in the rheological properties during the ensuing late Silurian D2 Bindian Orogeny (ca 420 Ma). This event produced north–south-trending upright, east-verging folds (F2) with a marked partitioning of strain between the different sedimentary units. Folds plunge south at ∼30°, are tight to isoclinal, with local collapsed hinges and limb thrusts. This D2 deformation along the paleo-Pacific margin involved dextral transpression and a southerly propagation of the deformation front. Superimposed on these structures is an east–west paleostress pattern and two episodes of faulting (D3 and D4). In the first, brittle strike-slip faults were accompanied by ductile folding related to east–west shortening during the Middle–Late Devonian Tabberabberan Orogeny (ca 385–370 Ma). These were accompanied by the emplacement of the Sandpatch Point Granite. The second episode (D4) of strike-slip faulting reactivated many of the earlier faults during further east–west shortening and was related to the Carboniferous Kanimblan Orogeny (ca 354–343 Ma). This is best seen close to the granite contact where the strong crystallised granite reinforced the contact metamorphosed greywacke sequence, inhibiting ductile deformation so that faults deformed in a brittle fashion. Eastern Australia was at a convergent plate boundary where a Middle–Late Ordovician turbiditic sequence was accreted to an accretionary prism. The Pinnak Sandstone contains a weak phyllosilicate alignment (S*), D1 faults and folds from localised deformation in the accretionary prism. The Silurian Bindian Orogeny produced upright east-verging, south-plunging F2 folds. Brittle faults overprint the Bindian tectonic features and are accompanied by minor folding, marking the transition into Middle Devonian and Carboniferous deformation and intrusive events. The kinematics and geometries associated with these deformation events reflect the changing tectonic regime along the paleo-Pacific margin of eastern Australia during east–west compression. [ABSTRACT FROM AUTHOR]

The U–Pb detrital zircon record of the Surat Basin, an important part of the Great Australian Superbasin, has already revealed important insights about sediment source terranes. However, owing to the high closure temperature of zircons, low-temperature thermal events that might have impacted the sediment are not recorded. Here, new 40Ar/39Ar detrital mica ages, which record low-temperature events as a result of isotopic resetting, are paired with published U–Pb detrital zircon ages from the same samples to provide a more complete interpretation of the tectonic and thermal history of the Jurassic-age Precipice Sandstone and Evergreen Formation. The 40Ar/39Ar geochronology of mica grains from five wells reveals two broad groups with distinct age populations: 1500–180 Ma and 150–45 Ma. Micas older than about 180 Ma are sourced from multiple terranes. The slight discrepancy in ages between the 40Ar/39Ar and the U–Pb systems of the same samples may represent differences in closure temperature. However, some micas, such as those dating to ca 180 Ma, may also reflect a thermal reset event. Similarly, the younger group of micas, split into Cretaceous and Paleogene populations, reflect the impact of post-depositional thermal events on the basin. Isotopic resetting of the micas was likely the result of hydrothermal fluids migrating through reactivated faults, fractures and/or porous and permeable sediments. The origin of the fluids during the Cretaceous can be linked to an eastern subduction zone and subsequent igneous underplating resulting in uplift and denudation. The exact source of the hydrothermal fluids for the micas of Paleogene age, recorded in samples collected from the base of the Evergreen Formation, however, remains uncertain. Importantly, 40Ar/39Ar dating of mica from sandstones permits the detection of post-depositional thermal events that may have implications for tracing fluid migration throughout the basin and reconstructing the Cretaceous–Paleogene tectonic history of the basin. Combining 40Ar/39Ar dating of micas with U–Pb dating of zircons reveals a more complete tectonic and thermal history of the Jurassic-age Precipice Sandstone and Evergreen Formation of the Surat Basin. 40Ar/39Ar dating of detrital micas reveals two broad groups with distinct age populations: 1500–180 Ma and 140–45 Ma. Ages older than ca 180 Ma are linked to multiple source terranes, including the Thomson and New England orogens, and the contemptuous magmatic arc. Ages younger than 150 Ma are most likely the result of post-depositional thermal resetting events, which may have implications for fluid movement throughout the basin. [ABSTRACT FROM AUTHOR]

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]

Cambrian in Sichuan basin developed thick black shale, varies carbonate and clastic rock, which deposited in different sedimentary environment. Sichuan basin in the upper Yangtze platform contained a record of environment during the Cambrian. Detail facies analyses of Cambrian enable us to discuss the sedimentary environment and palaeogeographic setting. Sedimentation commenced in the Early Cambrian with the deposition of shelf facies (Qiongzhusi Formation and Canglangpu Formation). At this stage, thick shale and clastic rock deposited in Sichuan basin. At the end of the Early Cambrian, a carbonate platform developed in upper Yangtze platform, and Sichuan basin was located in restricted platform (Longwangmiao Formation). In the Middle Cambrian, tidal flat and restricted platform developed in Sichuan basin (Douposi Formation), because of continuous regression. During the Late Cambrian, Sichuan basin was located in carbonate platform again (Xixiangchi Formation). There are three types of sedimentary system in the Cambrian of Sichuan basin: clastic sedimentary system, clastics-carbonate mixed sedimentary system and carbonate sedimentary system. Vertically, the basin shows the evolutionary character of clastic-carbonate sedimentary systems. The three sedimentary systems correspond to three "transgression-regression" cycles of the Cambrian. The transgression in the initial period of the Early Cambrian led to the formation of clastic sedimentary system in the Qiongzhusi Formation of Lower Cambrian. The transgression in the later period of the Early Cambrian led to the formation of clasticcarbonate mixed sedimentary system in the Middle-Lower Cambrian. The transgression in the initial period of the Late Cambrian led to the formation of carbonate sedimentary system in the Xixiangchi Formation of Upper Cambrian. With the end of Late Sinian continental rifting ended, Sichuan basin entered a stable evolutionary stage of the craton basin, while the paleo-land developed in the north and southwest. In Qiongzhusi-Canglangpu period, the basin developed onshore-shelf sedimentary facies from west to east; In Longwangmiao-Xixiangchi period, the basin developed tidal flat-platform-slope sedimentary facies from west to east. [ABSTRACT FROM AUTHOR]

The Tianshan range, a Paleozoic orogenic belt in Central Asia, has undergone multiple phases of tectonic activities characterized by the N–S compression after the early Mesozoic, including the far‐field effects of the Cenozoic Indian–Asian collision. However, there are limited reports on the tectonic deformation and initiation of Triassic intracontinental deformation in the Tianshan range. Understanding this structural context is crucial for interpreting the early intracontinental deformation history of the Eurasian continent during the early Mesozoic. Growth strata and syn‐tectonic sediments provide a rich source of information on tectonic activities and have been extensively used in the studies of orogenic belts. Based on detail fieldwork conducted in this study, the middle–late Triassic Kelamayi Formation of the northern Kuqa Depression in the southern Tianshan fold‐thrust belt has been identified as the typical syn‐tectonic growth strata. The youngest detrital zircon component in two lithic sandstone samples from the bottom and top of the Kelamayi growth strata yielded U‐Pb ages of 223.4 ± 3.1 and 215.5 ± 2.9 Ma, respectively, indicating that the maximum depositional age of the bottom and top of the Kelamayi growth strata is 226–220 and 218–212 Ma. The geochronological distribution of detrital samples from the Early–Middle Triassic and Late Triassic revealed abrupt changes, suggesting a new source supply resulting from tectonic activation in the Tianshan range. The coupling relationship between the syn‐tectonic sedimentation of the Kelamayi Formation and the South Tianshan fold‐thrust system provides robust evidence that the Triassic intracontinental deformation of the South Tianshan range began at approximately 226–220 Ma (during the Late Triassic) and ended at approximately 218–212 Ma. These findings provide crucial constraints for understanding the intraplate deformation in the Tianshan range during the Triassic. [ABSTRACT FROM AUTHOR]

The sedimentary sequence of the Ninama Basin is associated with the latest phase of the continental Deccan volcanism of the Indian peninsula. It occurs as inter-, intratrappeans with a 39-m thick sequence comprising Sukhbhadar Formation and Ninama Limestone. The investigation aims to reconstruct its depositional setting based on the lithofacies and inorganic geochemistry to understand the influence of paleosalinity, paleoredox, paleodepth, provenance and paleoclimate on the sedimentation pattern. It is characterized by clastic and chemically formed rocks, including shale, mudstone, siltstone, sandstone and limestone. Facies analysis has revealed seven lithofacies, amongst which four are clastic facies, shale (SH), calcareous shale (CSH), silty mudstone (SM) and lithic greywacke (LGW), and three are carbonate facies, namely, grey-black limestone (GBL), cherty limestone (CL) and marlite (ML). Using geochemical analysis of major oxides and trace elements, ratios of Ca/(Ca+Fe), Sr/Ba, V/(V+Ni), V/Cr, Fe/(Ca+Mg), Ti/Al, Na/K, K/(Fe+Mg), CIA-K and MAP were determined and used to interpret and note the changes in the depositional system. The combined results of the lithofacies and geochemistry indicate that the deposition occurred in three phases. Phase 1 is characterized by high energy conditions in the shallow to moderate depth brackish-saline lake with oxic to dysoxic conditions; Phase 2 is characterized by anoxic deep fresh to the brackish water basin; and Phase 3 is characterized by semiarid conditions, saline, anoxic waters, high evaporation leading to shallowing of the lake, and low to moderate terrestrial input. This lacustrine basin in the paleotopographic low of the Deccan Volcanic Province is characterized by distinct lithology governed by various depositional parameters. A composite depositional model is constructed for the Ninama Basin, reflecting three phases of evolution that are dominantly controlled by the paleoenvironment. Research highlights: The present study focuses on lithofacies and inorganic geochemical analysis of Ninama paleolake sediments, Saurashtra intertrappeans, to interpret their paleosalinity, paleoredox, water depth, provenance, detrital influx, and paleoclimate. Phase 1 deposition was initiated in paleotopographic low of Deccan Traps, in an oxic–dysoxic, high-energy turbulent brackish water environment, in humid conditions. Phase 2 characterizes fine-grained clastic facies deposited in anoxic, fresh-brackish, deep lake waters in humid conditions. Phase 3 marks the shallowing, evident by carbonate facies with low-moderate terrestrial input deposited in saline and anoxic paleolake in semiarid conditions with high evaporation and low-moderate precipitation. The Deccan Traps have influenced the paleolake intertrappean sequence. [ABSTRACT FROM AUTHOR]

The interplay between regional tectonics and the development of a major ocean gateway between the Pacific and the Atlantic Ocean has resulted in numerous paleogeographic reconstruction studies that describe the Cenozoic tectonic history of the Scotia Sea region. Despite the multitude of published tectonic reconstructions and the variety of geological and geophysical data available from the Scotia Sea, the geological history remains ambiguous. We present a comparative paleogeographic analysis of previously published tectonic reconstructions to identify agreements and conflicts between these reconstructions. We propose an alternative model to explain the Cenozoic evolution of the Scotia Sea region. The paleogeographic comparison shows that most reconstructions agree on the tectonic evolution of the South Scotia Ridge and the East Scotia Ridge. Major differences between the reconstructions are the role of the westward subducting plate below the South Sandwich plate, and the age and origin of the Central Scotia Sea. Tectonic reconstructions assume that the Central Scotia Sea is either part of a Cenozoic back‐arc basin, or a captured piece of Cretaceous oceanic crust. We propose a new alternative tectonic reconstruction that brings these two prevailing hypotheses elegantly together. Here, we identified new geographical blocks consisting of thinned continental or Cretaceous oceanic fragments that originate from the Paleo‐Pacific Weddell Sea gateway from high‐resolution bathymetry. These fragments are now part of the Central Scotia Sea and have been affected by early back‐arc tectonic activity of the South Sandwich subduction zone, leading locally to the formation of Cenozoic‐aged crust in the Central Scotia Sea. Key Points: New tectonic reconstruction based on qualitative comparison endmember reconstructionsThe Central Scotia Sea consists of fragments of Cretaceous and Cenozoic oceanic crustA shallow gateway at Drake Passage potentially existed already during the Eocene [ABSTRACT FROM AUTHOR]

The Devonian tectonic setting is still controversial in the Proto‒Tethyan North Qilian belt. The Hexi Corridor of the North Qilian belt occupies a key position in constraining the tectonic evolution of the Proto‒Tethyan Ocean and the growth of the Asian continent. Turbidites, as an important component of the Jiayuguan mélange in the Hexi Corridor, consist of conglomerate, pebbly sandstone, sandstone, siltstone, calcareous mudstone, and chert that feature typical Bouma sequences of Ba, Bc, Bcd, Babc and/or Bab. They are strongly deformed into NW‒trending folds with NE‒ and SW‒inclined thrust faults. Detrital zircon U‒Pb dating results demonstrate that these sediments successively young to the southwest with maximum depositional ages (MDA) ranging from 560 Ma to 411 Ma, indicating that the youngest block was deposited after 411 Ma. Petrological, geochemical and detrital zircon U‒Pb age data indicate the sedimentary rocks provenanced from weak weathering, recycling, and multiple mixing sources, and that the dominant source was the Andean‒type Alxa arc. Together with the published data, we suggest that double‒sided subduction of the North Qilian Ocean (Proto‒Tethyan Ocean) occurred between the North Qilian arc and the Andean‒type Alxa arc during the early Devonian. Key Points: Jiayuguan turbidite consist of conglomerate, sandstone, calcareous mudstone and chert with Bouma sequences of Ba, Bc, Bcd, Babc and/or BabThese turbidite fragments successive youngs to southwest and sourced from the Alxa Andean‐type arcAn archipelagic ocean paleogeography existed between the Paleo‐Asian Ocean and the Proto‒Tethys Ocean during early Devonian [ABSTRACT FROM AUTHOR]

The provenance of Upper Paleozoic sediments in the Western Carpathians was derived by a petrofacies analysis of sandstones, including the U–Pb geochronology of detrital zircons. The Upper Paleozoic sedimentary basins were formed sequentially by tectonic processes associated with the Variscan continental collision, as well as by subsequent transpressional/transtensional and extensional regimes. Fore-arc related and proforeland basins were formed in the Late Tournaisian/Visean and subsequently in the Bashkirian/Moscovian. Transpressional/transtensional and extensional basins were formed successively on both sides of the continental collisional suture, both in the proforeland and retroforeland parts in the Late Pennsylvanian and later in the Cisuralian and Guadalupian. The sandstone petrofacies, as well as the detrital zircon distribution, indicate source areas directly from the underlying crystalline basement: a magmatic arc, an uplifted continental block for the Central Western Carpathian basins, and a recycled orogen for the Inner Western Carpathian basins. Detrital zircon age spectra record distinct stages of protracted Ediacaran to Carboniferous tectonosedimentary processes. This indicates a different palinspastic position of source areas along the peri-Gonwanan realm, the West African Craton, and the Sahara Metacraton in the Neoproterozoic. [ABSTRACT FROM AUTHOR]

This study, using Jinan as a case study, systematically investigates the characteristics and geological genesis of loess-like silty clay in the middle and lower reaches of the Yellow River. The primary distribution of loess-like silty clay is revealed through field surveys, laboratory experiments, and previous literature reviews. The chemical and physical properties of the loess-like silty clay were examined, in addition to investigations into its mineral composition, microstructural characteristics, and engineering mechanical properties, in order to enhance comprehension of its attributes and formation mechanisms. The research suggests that the distinctive soil environment in the area has been influenced by numerous instances of the Yellow River overflow and channel shifts over its history, as well as the impacts of climate change, geological factors, and human activities. The primary sources of material for the loess-like silty clay consist of loess, Hipparion Red Clay, and paleosol layers. The discussion also addresses the impact of regional climate on the formation of mineral components. The aforementioned findings hold significant implications for advancing the understanding of historical climatic and paleogeographic shifts, as well as for addressing engineering challenges associated with the distribution of loess-like silty clay. [ABSTRACT FROM AUTHOR]