Sedimentary Basins Research Articles

An updated chronostratigraphic framework for the Cenozoic sediments of southeast margin of the Tibetan Plateau: Implications for regional tectonics

As one of the most important accommodation zones during the India-Asia collision, the southeast margin of the Tibetan Plateau (SEMTP) is characterized by many large-scale strike-slip faults, a regional low-relief relict that has been deeply incised by several continental scale rivers that originate from central Tibet, and numerous plant and vertebrate fossil biotas residing in Cenozoic sedimentary basins. Therefore, the SEMTP not only provides a meaningful constraint on the geodynamic evolution of the Tibetan Plateau, but also serves as an exemplar to understand the various interactions among surface uplift, drainage network reorganization, climate change, and biodiversity. Precise dating of Cenozoic sediments in the basins of the SEMTP is crucial for understanding these processes. Previously, the geochronologic framework of Cenozoic sediments in the SEMTP largely relied on fossils and regional stratigraphic correlations, which often involved circular reasoning and large uncertainties. In the past two decades, high-resolution magnetostratigraphy, detrital zircon geochronology, and isotopic dating of interbedded tephra layers have been carried out on SEMTP Cenozoic sedimentary basins in Yunnan and eastern Xizang provinces, SW China. Using these new data, we build a revised chronostratigraphic framework for Cenozoic sediments in SEMTP, and use this updated temporal framework to contextualize regional tectonics and climate change. The new chronostratigraphic framework shows that (1) many of the “Neogene” sedimentary basins based on plant fossils and regional lithostratigraphic correlation in the SEMTP were actually formed in the late Eocene and early Oligocene; (2) most of the Paleogene sedimentary successions in the SEMTP ended at the late Eocene-early Oligocene and were unconformably overlaid by Middle-Late Miocene sediments. Oligocene-Early Miocene sediments are often regionally absent. Sedimentary structures within the basin successions show that Paleogene basins were generally formed in compressional settings while the Late Miocene basins were mostly developed in extensional settings. The new chronostratigraphic framework, together with analyses of sedimentary basin structures, suggests that the SEMTP began to experience crustal shortening early in the India-Asia collision (∼50 Ma), producing Paleogene sedimentary basins and giving rise to the subsequent widespread surface uplift and regional erosion in the Oligocene-Middle Miocene. Tectonic inversion from compression to extension since the Middle Miocene precludes significant uplift of the SEMTP after this time, which may be related to geodynamic changes in the evolution of the Tibetan Plateau.

Canada’s Geothermal Energy Update in 2023

Geothermal energy exploration, development, and research have been ongoing in Canada for several decades. The country’s cold climate and the push to develop renewable energy sources have driven interest in geothermal energy. Despite this drive, regulatory complexities and competition with other relatively inexpensive energy sources with existing infrastructure have hindered development. As such, interest has grown and waned with changes in the energy economy over several decades, leaving many projects at a standstill. As of January 2023, there are currently no operational geothermal power projects in Canada. Many hot spring pool and spa complexes remain active, and Canada is a leading country in the installation of ground source heat pumps (GSHPs; also called geo-exchange systems). However, in the last decade, the interest in deep geothermal systems has renewed, with many new projects starting up across several provinces and territories. Moreover, projects that had shown limited progress for many years—such as Mount Meager in British Columbia—have begun to renew their development efforts. Research is also expanding within prominent research groups and universities. The areas of focus include both building upon previous studies (such as thermal gradients and the heat flow in sedimentary basins) and researching new methods and resources (such as GSHPs, closed-loop systems, integrated geothermal operations, and hybrid systems, including heat storage). The development is supported by federal, provincial, and territorial governments through grants and the development of regulatory frameworks. Although challenges still remain for Canada to develop its geothermal energy resources, several power, thermal, and co-production projects, ongoing research, funding, and regulatory acts are all moving forward to support geothermal development. This paper aims to study Canada’s geothermal energy update in 2023 regarding the aspects mentioned above.

North Kara and Vize-Ushakov Composite Tectono-Sedimentary Elements, Kara Sea

Abstract North Kara Shelf and adjoining Severnaya Zemlya Archipelago represent a region of a complex tectonic interplay between two large Arctic fold-and-thrust belts: the Early Mesozoic Pay-Khoy-Novaya Zemlya–South Taimyr in the SW and the Late Paleozoic Taimyr–Severnaya Zemlya–in the S-SE and E, and an inferred Devonian/Carboniferous deformation zone in the N. Contractional deformations of different ages formed a series of basement highs and inverted sediment-cored swells that separate deeply subsided sedimentary basins. In the framework of the volume's terminology, this region consists of two composite tectono-sedimentary elements (CTSE), the Vize-Ushakov (VU CTSE) and North Kara (NK CTSE). The principal difference between these elements is in the age of underlying basement rocks, which, in turn, determines the stratigraphic span of the overlying sedimentary successions. In this chapter we characterize the geology of this remote Arctic region based on the available seismic data supported by the published results and our own studies.

Mesozoic intra-arc basin records the tectonic transition from the Paleo-Asian Ocean to the Paleo-Pacific Ocean in northeastern Eurasia

Since the Paleozoic, the tectonic evolution of northeastern Eurasia has been dominated by the Paleo-Asian Ocean and the Paleo-Pacific Ocean tectonic domains. However, the spatiotemporal framework and the timing of tectonic transition between these two oceanic domains remain enigmatic. To address this issue, we report petrological, geochronological, and geochemical data for eight sandstone samples deposited along the convergent margin between the Northeast China terranes and the North China craton in central Jilin Province, China. The results show that these sandstones are immature graywackes with a maximum depositional age of Early Triassic (248 ± 1 Ma), and their sediments were largely derived from coeval magmatic rocks in a juvenile continental arc. According to our new results and previous studies, we identified a sedimentary basin (most likely an intra-arc or forearc basin) intimately associated with one or more continental arcs along the northeastern edge of the North China craton, and we suggest that the southwestward subduction of the Jilin-Heilongjiang Ocean in the early Mesozoic accounts for this continental arc setting. There is a distinct temporal gap between the closure of the Paleo-Asian Ocean (ca. 260 Ma) and the onset of Paleo-Pacific plate subduction (234−220 Ma), which is essentially coeval with the southwestward subduction of the Jilin-Heilongjiang Ocean between 256 Ma and 239 Ma, meaning the latter is a key link that marks the transition between these two tectonic domains.

Sedimentological characterization of earthquake-generated turbidites in fault-proximal glacial lakes: a case study from Jenny Lake, Teton range, Wyoming

Lakes in seismically active regions preserve valuable sedimentary archives of paleoseismic activity within their catchment and beyond. A series of glacially-excavated lakes positioned directly along the surface trace of the Teton normal fault at the base of the Teton Range, WY, are ideally situated to record past fault activity since their formation approximately 15,000 years ago. Here, we focus on the sediment fill contained in Jenny Lake (5 km2; approximately 73 m max depth) located at the bottom of Cascade Canyon, in the central Tetons, where postglacial slip rates are greatest. Past earthquakes that generated slope failures in and around Jenny Lake are expressed stratigraphically as coseismic turbidite deposits. These deposits were previously identified and dated in sub-bottom profiles and in sediment cores taken from multiple locations around the basin. In this study, we focus on the six thickest turbidites (ranging from 6 to 34 cm thick) present in multiple cores recovered from the central depositional basin and analyze them at sub-centimeter resolution for changes in physical, biological, and geochemical parameters, including sediment density, magnetic susceptibility, grain size distributions, organic content, and elemental composition. Results reveal each deposit contains a well-defined, three-component sedimentary sequence composed of a relatively homogenous and thick basal sandy unit with a sharp bottom contact, a similarly thick silt-rich middle unit, and a thin top unit of very fine-grained sediments. The characteristics of these components and their similarity between individual deposits suggest consistent sediment sources and transport pathways during successive earthquake events. Based on our analyses and the unique local geomorphic setting, we create a mechanistic model of coseismic turbidite formation in Jenny Lake, which may provide an improved framework for identifying, characterizing, and correlating earthquake-generated disturbance deposits in other Teton lakes and lakes in similar tectonic-geomorphological settings, for example, in the Basin and Range Province, USA or beyond.

Formulation of Generalized Hillslope Leakage-Dependent Model for Groundwater Flow in N-Aquifer System within a Sedimentary Basin

In this study, the recently derived Hillslope Leakage-dependent (HL-D) models for groundwater flow in leaky three-aquifer system have been generalized to obtain Generalized Hillslope Leakage-dependent, GHL-D equation that model groundwater flow in leaky n-aquifer system. This generalization extends the capability of Hillslope Leakage-dependent (HL-D) equations to modeling groundwater flow in any number of aquifers (n-aquifer system) of all configurations within a sedimentary basin. The formulated GHL-D Model was tested on some aquifer types and the results have shown that it can be used to obtain groundwater flow models for both hillslope (sloping) and horizontal single aquifer (unconfined and confined) as well as for multi-aquifer system containing any number of aquifers within a sedimentary basin. This unique feature of GHL-D equation to model most aquifers types and configurations makes it a more elegant groundwater flow modeling tool with potentials for wider applications than most of the existing groundwater flow models. The GHL-D Model, when use for simulations of groundwater flow in single or multi-aquifer system, will have the capability of giving better understanding of the groundwater flow dynamics in such systems. This is important because most of the sedimentary basins of the world are multi-aquifer in nature and accurate knowledge of groundwater flow within them is important to geoscientists in determining long time yield and water sustainability in such geological structures

Methane gas flares in the forearc basin of the Andaman-Nicobar subduction zone

Gas hydrates deposits in the Andaman forearc basin are inferred from seismic data and confirmed by drilling/coring during the NGHP-01 expedition. We present new evidence of gas flares in the Andaman forearc basin, detected through water column image (WCI), subbottom profiling, and high-resolution seismic data acquired onboard RV Sindhu Sadhana (SSD-085) in November-December 2021. The gas flares are located over an elongated sedimentary ridge, featuring two prominent mounds (M1 and M2) with distinct geological features. Compressional tectonics induced by the Diligent fault (DLF) formed the ridge with varying slopes and elevations. Gas flares observed above the mound M1 in WCI and sub-bottom profiler data. Seafloor samples reveal carbonate rocks with visible pores, indicating gas/fluid migration or burrows. The regional seismic profile delineates three sedimentary sequences: folded and faulted strata, mass transport deposits, and horizontal-to-sub-horizontal sedimentary layers. Additionally, we observed a bottom simulating reflector (BSR), indicating potential subsurface gas hydrate deposits. Detailed high-resolution seismic data revealed complex fault systems near bathymetry mounds (M1 and M2), which may serve as pathways for vertical fluid/gas migration.

Coordination analysis of flood-sediment transportation, eco-environment, and socio-economy coupling in the governance of the Yellow River Basin system

The watershed system has a complex game relationship between the benign operation and coordinated development of various elements of flood-sediment transportation, eco-environment, and socio-economy (FES). With the increasing breadth, depth, and intensity of human activities in watersheds, it is urgent to coordinate the FES. The relationship of water–sediment in the Yellow River Basin (YRB) is complex, with a prominent contradiction in water supply and a fragile ecosystem. This research tries to build a comprehensive evaluation model for FES and explore the complex interaction between FES in the YRB from 2000 to 2020. The results demonstrated that (1) the comprehensive flood-sediment transportation index (CFTI) and comprehensive eco-environment index (CEI) presented fluctuating growth. In contrast, the comprehensive socio-economy index (CSI) revealed a linear growth trend. The CFTI of Sanmenxia, CEI of Toudaokuan, and CSI of Ningxia had the highest growth rates, with 36.03%, 6.48%, and 107.5%, respectively. (2) FES's positive and negative effects were alternating, with heterogeneity in both time and space. (3) The coupling coordination degree (CCD) in the YRB indicated an increasing trend, ranging from 0.53 to 0.87, from reluctantly coordinated development to good coordinated development. The lagging subsystem was CFTI (2000–2001 and 2008–2020) and CSI (2002–2007), and the CEI was not lagging. (4) Exploratory Spatial Data Analysis (ESDA) demonstrated significant differences in the CCD of the YRB, and areas with similar CCD within the basin tend to be centrally distributed in space. At the same time, there was negative spatial autocorrelation in coordination. The results provide a scientific theoretical and methodological framework for strategic research on the YRB system's governance, protection, and management.

Cenozoic Basin Evolution During Alternating Extension and Shortening in the Southern Central Andes Along the Chile-Argentina Border, 37–38°S

The south-central Chile and Argentina margin experienced a regional phase of extensional tectonics during the Oligocene–early Miocene, forming several basins across the forearc, Andean Cordillera, and retroarc regions. These basins accumulated thick successions of volcanic and sedimentary rocks. Subsequently, Neogene contractional tectonics led to the development of the current Andean Cordillera and the deposition of synorogenic clastic deposits in foreland basins. Traditionally, the Cura Mallín Formation, comprising a lower volcanic unit (CMV) and an upper sedimentary unit (CMS), has been interpreted to have formed during the Oligocene–early Miocene extensional phase. However, some studies propose deposition of the CMS in a foreland basin during the early–late Miocene. To unravel the transition from extensional to contractional tectonics in the Andes of south-central Chile and Argentina, we conducted new geochronological analyses (U-Pb, LA-ICP-MS) and integrated these results with structural, stratigraphic, and sedimentological observations in key sections within the CMS and the overlying Trapa-Trapa Formation in the Principal Cordillera along the Chile-Argentina border (37°–38°S). Our findings indicate that only the lower part of the CMS was deposited in an extensional setting, as evidenced by the presence of an inverted extensional wedge dated at ∼20 Ma. The middle-upper CMS (∼19 to 9 Ma) and contemporaneous units to the east exhibit evidence of syncontractional deformation, suggesting deposition in a foreland basin generated by shortening of the western Principal Cordillera. Around 9 Ma, uplift of the Agrio and Chos Malal fold and thrust belts, east of the Principal Cordillera, led to segmentation of the foreland basin. The Trapa Trapa Formation was deposited in a hinterland basin, with sediment sourced from the east. After ∼6.5 Ma, major contractional deformation shifted westward, resulting in intense folding of the CMS and Trapa Trapa Formation and subsequent thrusting of the western Principal Cordillera over the Central Depression. Our study suggests that deformation progressed toward the eastern foreland during the early to late Miocene and then shifted toward the western forearc during the late Miocene to Pleistocene.

The effects of weathering and sediment source mixing on whole-rock geochemical provenance studies, Cook Inlet forearc basin, south-central Alaska, USA

The provenance of most basin systems today is interpreted based on radiogenic ages or the geochemical composition of detrital minerals, which has all but replaced the use of whole-rock geochemical approaches that can effectively complement provenance information inferred from detrital approaches. Here, we further investigate previous provenance models developed using detrital zircon U-Pb geochronology by applying whole-rock major and trace element geochemistry of fine-grained clastic rocks from the late Oligocene−middle Miocene Tyonek Formation, late Miocene Beluga Formation, and Pliocene Sterling Formation in the Cook Inlet Basin, Alaska, USA. When taken alone, our new geochemical data suggest solely intermediate igneous sediment sources to the basin. When paired with existing detrital zircon U-Pb data, however, significant mixing of felsic and mafic sediment sources is evident, which indicates that thorough mixing of geochemically distinct source terranes can mask the input from individual sources in whole-rock geochemical studies. Furthermore, we demonstrate that both weathering and provenance influence the major element chemistry of sediment source terranes as well as the resultant basinal strata. Our conclusions indicate that the combination of whole-rock geochemistry with other detrital approaches provides a robust interpretation of sedimentary basin provenance.

The influence of hydraulic fracture and reservoir parameters on the storage of CO2 and enhancing CH4 recovery in Yanchang formation

The demand for a clean energy source from shale is growing day-to-day since it is not harmful to the environment like other fossil fuels. Further, shale reservoirs offer long-term geo-carbon dioxide (CO2) storage. Innovations in horizontal drilling and multi-stage hydraulic fracturing have made shale gas extraction and geo-CO2 storage economically viable. A three-dimensional Yanchang shale formation simulation model in Ordos's basin was developed using CMG-GEM, considering adsorption/desorption, diffusion, geomechanics, permeability changes, and non-Darcy flow. Two horizontally drilled wells, each 510 m long, were fractured and positioned 90 m apart. CO2 gas was injected into Well-2, producing methane (CH4) in Well-1. After simulation for 30 years, the cumulative mass of CH4 produced was 1.07×10+5kg, the cumulative mass of CO2 produced was 2.3×10+4kg, which is 1.14% of the mass injected, the cumulative mass of CO2 injected was 2.01×10+6kg and cumulative mass of CO2 gas stored was 1.987×10+6kg which is 98.86% of the injected mass of CO2 gas. The natural fracture system was the dominant factor of enhanced shale gas recovery and CO2 injection in the Yanchang shale formation. A sensitivity analysis was conducted with CMG-CMOST, examining the influence of reservoir and hydraulic fracture parameters in the storage of CO2 and enhancing CH4 recovery. Natural fracture porosity had the most significant impact on CH4 production and CO2 storage, followed by fracture permeability and half-length leading for hydraulic fracture parameters, with fracture conductivity being the least influential parameter. The approach used in this study applies to tight shale oil and gas formations in various sedimentary basins worldwide, enabling a more comprehensive understanding of reservoirs and hydraulic fracture parameters that can enhance oil and natural gas production.

Impact of multiple weak layers on deformation of the interior of Qaidam Basin, northern Tibetan Plateau

The Qaidam Basin is the largest sedimentary basin within the Tibetan Plateau, with up to ∼15-km-thick deposits accumulated in the Cenozoic. Understanding how it deformed in response to the far-field effects of India-Eurasia collision is critical to improving our knowledge of the mechanism underlying northward plateau growth. Unlike typical compressional basins, where upper-crustal deformation concentrates at their margins, the Qaidam Basin features the development of many NW- to WNW-striking folds across the entire basin. Why crustal shortening occurred in the interior of Qaidam Basin, ∼100 km away from the margins, together with the underground geometries beneath these folds, remains unknown. Herein, based on newly acquired three- and two-dimensional (3-D and 2-D) seismic reflection data, borehole logging, and scaled physical analog modeling, we investigated the geometries, kinematics, and formation mechanisms of the folds within the interior of Qaidam Basin. For the first time, we reveal three local weak layers in the Lulehe, Upper Xiaganchaigou, and Shangyoushashan Formations, respectively. They consist mainly of mudstone intercalated with evaporites and limestones, and they have different spatial distributions that are likely confined by major faults and folds. These mechanically weak layers became locally thickened or thinned in response to tectonic loading and/or facilitated detachment slip to form many décollement folds that were observed at the surface. The shallow deformation above the weak layers is largely decoupled from underlying basement-involved faulting and folding, which mostly terminate upward in these weak layers. Analog modeling results suggest that the lowermost and widely distributed décollement layer in the Lulehe Formation likely facilitated long-distance rapid propagation of deformation into the basin interior. In sum, our study highlights the significance of multiple weak layers during Cenozoic deformation in the Qaidam Basin interior.

Basin effects from 3D simulated ground motions in the Greater Los Angeles region for use in seismic hazard analyses

We develop basin-depth-scaling models (i.e. “basin terms”) from the long-period ([Formula: see text]) simulated ground motions of the Southern California Earthquake Center (SCEC) CyberShake project for use in seismic hazard analyses at sites within the sedimentary basins of southern California. Basin terms use the Next Generation Attenuation (NGA)-West-2 ground-motion models (GMMs) as reference models and use their functional forms with slight modifications. We investigate the use of two approaches to incorporate the time-averaged shear-wave velocity in the upper 30 m ([Formula: see text]) in these calculations and find that the use of site-specific and uniform [Formula: see text] has minor effects on the resulting basin terms for this data set. By centering the simulated ground motions on the basin terms, we separate the information from the simulations about absolute ground-motion level from information relating to the relative amplifications, such as the differences between shallow- and deep-basin sites. Recent observations from sedimentary basins of southern California indicate that additional amplification effect may persist at relatively shallow basin depths (i.e. the GMM basin terms should have positive values when differential depths, [Formula: see text], are near zero), and we present models for “centered” and “adjusted” basin-depth scaling models that reflect this potential. The simulation-modified GMMs are appropriate for crustal sources and for deep-basin sites ([Formula: see text]) within basins of the Greater Los Angeles region, for the magnitudes and distances defined by each of the reference NGA-West-2 GMMs.

Geological structure and petroleum systems of the Kazakhstan sector of the Caspian Sea South Mangyshlak sedimentary basin

This article discusses the results of a study of the geologic structure of Mesozoic sediments in the Kazakhstan sector of the Caspian Sea South Mangyshlak sedimentary basin. This paper includes an analysis of existing geological and geophysical data aimed at describing the characteristics of petroleum system elements. The main features of the sedimentation conditions of oil source rocks, reservoirs, and caps have been analyzed. The key hydrocarbon source zones in the territory of the Kazakhstan sector of the Caspian Sea have been determined. The correlation of existing wells to determine regional covers and main trends in reservoir sedimentation has been provided.

Large paleoearthquakes and Holocene faulting in the Southeastern Gorny Altai: implications for ongoing crustal shortening in Central Asia

ABSTRACT Shrinking of intermontane basins and expansion of their flanking ranges by reverse faulting and backthrusting in two counter-dipping systems is a typical mechanism of crustal shortening and mountain building in Central Asia. This mechanism is realized along the Kurai Fault Zone (southeastern Gorny Altai). Motions on two reverse fault systems maintained thrusting of the Kurai Range and the Kubadru Uplift on the Kurai Basin sediments and caused the growth of a foreberg before the mountain front. Forberg separates narrow Aktash Basin from the Kurai Basin. The paleoearthquakes were generated by reverse faults that delineate the foreberg. Analysis of the QuickBird satellite images, drone imagery, trenching, archaeoseismological research, radiocarbon dating, dendrochronology, and previous results show that eleven large (М W = 6.5–7.6) paleoearthquakes left traces as surface ruptures along the Kurai Fault Zone: twice before 7.5 ka BP, three events between 7.5 and 5.9 ka BP (7.0, 6.3, and 5.9–5.8 ka BP), one from 5.8 to 4.6 ka BP, four more at 4.6, 3.2, 1.5, and 1.3–1.2 ka BP, and the ultimate earthquake no older than 1450–1650 AD. The time difference between large earthquakes was from 200 to 1700 years. Surface faulting occurred mainly along the northern border of the foreberg where fault scarps are progressively younger northward and the Cenozoic sediments of the Aktash Basin thus become involved into uplift. GPR data to a depth of 12 m confirm the complex structure and slip geometry of the observed surface ruptures. The fault scarps are located < 1 km from the planned route of the gas pipeline from Russia to China, and the potential seismic hazard has to be taken into account in its design and construction.

Late Pleistocene prey mobility in southwestern France and its implications for reconstructing Neandertal ranging behaviors

As hunter-gatherers, Neandertal mobility and corresponding adaptations were influenced by the mobility of their prey; thus, it is critical to track how the movement patterns of each species varied over time at specific sites. Here, prey paleomobility is reconstructed by measuring radiogenic strontium isotope ratios (87Sr/86Sr) in herbivore teeth recovered from two archaeological sites (Pech de l’Azé IV and Roc de Marsal) in the Dordogne Valley (Aquitaine Basin) of southwestern France that span marine isotope stages (MIS) 5-3. These ratios are compared to a published isoscape as well as new environmental samples (soil, Helix shells, rodent teeth, water, and wine). Our results show that reindeer (Rangifer) likely moved within the sedimentary basins of France and did not venture into mountainous regions. Instead, reindeer, bison (Bison) and other prey species were available year-round in the Aquitaine and Paris basins. Red deer (Cervus) and horse (Equus) may have ventured into the mountains. These results suggest that Neandertals could find year-round faunal resources in these basins, at least during MIS 4 and 3.

Impact of Injection Rate for CO2 Storage Within Sedimentary Basins, a Multidisciplinary Analysis of Focused Fluid Flow

Impact of Injection Rate for CO2 Storage Within Sedimentary Basins, a Multidisciplinary Analysis of Focused Fluid Flow

Diagenesis, Provenance, Tectonic Setting and Palaeoclimate of the Eocene Kopili Sandstone, Assam, India: A Petrographic Study

Abstract The Eocene Kopili Sandstone outcropping in the North Cachar Hills (NCHs) of Assam, India, was petrographically studied to unravel its diagenetic features, provenance, tectonic setting and palaeoclimate conditions. The modal analysis of the Kopili Sandstone reveals that the detrital mineralogy is dominated by quartz (48.78 to 83.70 %), with variable amounts of rock fragments (0.37 to 7.35 %), feldspar (0.37 to 8.33 %), micas (0.36 to 7.84 %) and subordinate amount of heavy minerals. The matrix and cement content varies from 9.88 to 21.50 % and 1.12 to 19.41 % respectively. The Kopili Sandstone is classified as quartz arenite to sub lithic arenite. Compaction, cementation, dissolution and replacement are the observed diagenetic processes in the studied sandstones. Diagenetic transformations are manifested in the fractured detrital grains, overgrowth of quartz, corrosion of grain boundaries of quartz, modification of grain boundaries, and silica and iron oxide cement precipitation in the interstices of the framework grains. The provenance is of granite-gneissic rock terrain. The detritus in the depositional basin is derived predominantly from craton interior with minor input from recycled orogen. The study discerns humid palaeoclimate conditions for the Kopili Sandstone.

Seasonal dynamics of water and sediment in the permafrost basin of the Qinghai‐Tibet plateau and its driving factors

AbstractClimate change has regulated cryosphere‐fed rivers and altered interannual and seasonal sediment dynamics, with significant implications for terrestrial material cycles and downstream aquatic ecosystems. However, there has been a notable scarcity of research focusing on the patterns of water–sediment transport within these permafrost zones. Integrating 6 years (2017–2022) of in‐situ observational data from FengHuoShan basin with the partial least squares‐structural equation modelling (PLS‐SEM) method, we analyse the driving factors, characteristics and seasonal patterns of the water–sediment transport process. We observed a gradual increase in both suspended sediment flux (SSF, Mt/yr) and runoff (Q, km3/yr) within the basin, with annual growth rates of 1.34%/yr and 0.75%/yr, respectively. It is worth noting that these growth rates exhibit seasonal variations, with the highest values observed in spring (SSF: 1.76%/yr, Q: 1.71%/yr). This indicates that the response to climate change is more pronounced in spring compared with summer and autumn. Through mathematical statistics and the PLS‐SEM model, we found that temperature plays a predominant role in the dynamics of water–sediment in both spring and autumn, whereas rainfall exerts a more significant impact during the summer. Most suspended sediment concentration (SSC, kg/m3) peak events throughout the year are primarily driven by rainfall. Affected by the freeze–thaw cycle of permafrost, SSC and discharge (Q, m3/s) exhibit distinct seasonality. SSC and Q demonstrate a clockwise trend; both Q and SSC begin to increase from May and peak in August before declining. The insights gleaned from this study hold significant implications for water resource management and soil conservation strategies in the region, particularly in the face of ongoing climatic changes characterized by warming and increased humidity.

Ammonite families Phylloceratidae, Gaudryceratidae, Oppeliidae and Desmoceratidae from Kopet Dagh Basin NE of Iran; Palaeobiogeographical and palaeoecological application

The Kopet Dagh sedimentary basin is situated in the northeast of Iran and the south of Turkmenistan. The present work focuses on the systematic representative's species of the Family Phylloceratidae Zittel, 1884, of the Family Gaudryceratidae Spath 1927, of the Family Oppeliidae H. Douvillé, 1890, and of the Family Desmoceratidae Zittel, 1895, all of which are for the first time in the basin. Based on previous studies and assemblage fauna in this study, a late Barremian-early Aptian age is suggested for the measured sequences. The palaeobiogeographical distribution of the ammonites indicates that during the late Barremian to the late Aptian the basin formed part of the Tethyan realm, Mediterranean-Himalayan Province. The studied fauna and other reported ammonites in previous publication might suggest nearshore to offshore an epipelagic to pelagic environment. There is also a relation between the lithology and the morphotype of ammonites.