Basin Evolution Research Articles

Pb-Zn-Ba deposits in the Nigerian Benue Trough: A synthesis on deposits classification and genetic model

The Benue Trough stretching about 800–1000 km with a width ranging between 100 and 150 km, is a megarift structure whose origin was related to the opening of the south Atlantic during the early Cretaceous. This mega rift structure contains economically significant Pb-Zn-Ba-F deposits that form well-defined metallogenic belt about 600 km long in Nigeria. In the Southern Benue Trough (SBT), the Pb-Zn-Ba-F deposits are localized in four districts namely Abakaliki, Ishiagu, Wanikande and Gabu-Oshina and are hosted by carbonaceous shale; in the Central Benue Trough (CBT) the deposit is hosted in the silicified limestone and arkosic sandstone localized in Arufu, Akwana and Azara districts; while in the Northern Benue Trough (NBT) ores deposits occur in the arenaceous sediments of Yolo, Gombe and Gulani districts. Previously published sulfur (S) isotopic data of sulfides suggest that the ore-forming S was sourced from marine sulfates and the reduction of sulfate mainly by thermochemical sulfate reduction process in the CBT and NBT. Whereas in the SBT, bacterial sulfate reduction process is dominant. The compiled C-O isotopic compositions suggest that limestone and slightly metamorphosed sedimentary rocks supplied ore-forming materials to the hydrothermal systems through water/rock interaction. The available bulk Pb isotopic compositions for the ore minerals, the host sedimentary and crystalline rocks comprising the basement rocks as well as the basaltic rocks from the Trough suggest that the arkosic sandstone which is composed of detrital feldspars that was eroded from the Precambrian basement rocks could be the likely source of ore-forming metals. Our model proposed that the ore-forming fluids were sourced from the hot connate-brine that was expelled through compaction during the development of the deep sedimentary basins. Mesozoic magmatic events distributed throughout the basin likely provided the initial thermal flow and elevated the geothermal gradient. The hot brines could have leached the metals from the syn-rift continental formations. The tensional fractures serve as the conduit through which the metals migrated, leached abundant sulphate and precipitated their contents in the transcurrent fault system as sulfides, barite and associated polymetallic ores. The geological, mineralogical, and geochemical characteristics of the Nigerian Benue Trough Pb-Zn deposits are consistent with Mississippi Valley-type (MVT) Pb-Zn deposits in North Africa and the typical MVT ore deposits worldwide.

Incidence and Severity of Vine Rot and Wilt Disease of Telfairia occidentalis Caused by Athelia rolfii in Southern, Nigeria

Telfairia occidentalis is an important vegetable crop that is intensively grown in Southern Nigeria for its utilization in home dishes and commercialization. However, its production is being limited by vine rot infection caused by Athelia rolfsii. Information on the epidemiology in growing regions is important for the disease management. Hence, this study was conducted to investigate the incidence and severity of vine rot disease of Telfairia occidentalis in commercial fields across Abak, Akwa Ibom State. A total of nine established T. occidentalis fields in three locations, including the Cross River Basin Development Authority, Abak-Irrigation Project, were visited during the peak of dry season (November – December), 2021 and raining season (June - August), 2022 respectively. The fields were scored for vine rot disease incidence and severity using a well described scale. Random samples from symptomatic plants were collected and taken to the laboratory for fungi isolation and identification. Koch postulate was carried out to confirm the causal agents on one susceptible genotype of T. occidentalis in the study area. Overall number of plants showing varying levels of symptoms reaches 84% and total values for mean incidences’ rate (3.31 ± 0.06 and 3.19 ± 0.06) were recorded for both sampling period respectively. The result of this study revealed that the prevalent fungal pathogen that is responsible for vine rot and wilt disease of T. occidentalis in the study is A. rolfsii and presented information on the level and severity of infection that is indicative of the need to implement appropriate control measures for A. rolfsii disease in the study area.

Spatiotemporal Characteristics of Land Cover Change in the Yellow River Basin over the Past Millennium

Investigating the ecological and environmental impacts stemming from historical land use and land cover change (LUCC) holds paramount importance in systematically comprehending the fundamental human-land relationship, a pivotal focus within geographical research. The Yellow River Basin (YRB), often referred to as the cradle of Chinese civilization, ranks as the fifth-largest river basin globally. Early inhabitants made significant alterations to the landscape, resulting in substantial damage to natural vegetation, giving rise to prominent regional ecological challenges. By now, the examination of historical LUCC in the YRB over the past millennium remains in the qualitative research stage, primarily due to the limited availability of high-confidence gridded historical LUCC data. This study aims to advance the current historical LUCC research in the YRB from primarily qualitative analysis to an exploration incorporating timing, positioning, and quantification. Based on reconstructed historical cropland, forest, and grassland grid data of 10 km × 10 km from 1000 AD to 2000 AD, the degree of cropland development and the depletion of forests and grasslands were calculated, respectively. Then, the kernel density method was employed for spatiotemporal analysis and interpretation of dynamic changes in land cover. Subsequently, a cartographic visualization depicting the migration trajectories of the land cover gravity centers was generated, allowing for an assessment of the distance and direction of the centroids’ movement of cropland, forest, and grassland. The results indicate that the cropland coverage in the YRB escalated from the initial 11.65% to 29.97%, while the forest and grassland coverage dropped from 63.36% to 44.49%. The distribution of cultivated land continually expanded outward from the southeast of the Loess Plateau and the southwest of the North China Plain. All three types of land cover experienced a westward shift in their gravity centers between 1000 and 2000 AD. Besides the population growth and technological advancements, the regime shifts induced by wars, along with land use policies in distinct periods, always served as the predominant factors influencing the conversion between different land covers. This research will present a paradigmatic regional case study contributing to the investigation of historical changes in land use and land cover. Additionally, it will offer historical perspectives beneficial for the advancement of China’s objectives in “Ecological Conservation and High-Quality Development of the Yellow River Basin”.

Northwestward migration of siliciclastic sedimentation during late Tonian to Cambrian: Implications for tectonic evolution of the South China Block

The late Tonian to Cambrian sedimentary sequences in the Xiang-Gui-Yue (XGY) Basin across the potential suture zone between the Yangtze and Cathaysia blocks preserves invaluable information on the geological evolution of the South China Block, while the sedimentary provenance is not well constrained and tectonic affinity of the basin is still highly controversial. This study presents systematic provenance analysis of late Tonian to Cambrian clastic rocks to reconstruct the formation and evolution of sedimentary basin. A significant change from dominant 900–700 Ma to dominant 1300–900 Ma zircons in sediments has been observed along with the basin evolution. It has been widely considered that the 900–700 Ma detritus are largely from the Yangtze Block in the northwest, while the 1300–900 Ma detritus are from the Cathaysia Block in the southeast or terranes linked to the Cathyasia Block at that time. More remarkably, the provenance transition occurred at Cryogenian, Ediacaran and Cambrian in the southeastern, central and northwestern parts of the XGY Basin, respectively. All the above observation indicates the Yangtze-derived detritus arrived at the southeast end of the basin as early as late Tonian and gradually faded away until at least Ordovician, as probably caused by the denudation of the Jiangnan Orogenic Belt after the amalgamation of the Yangtze and Cathaysia blocks. On the other hand, the Cathaysia-derived detritus became dominant due to the uplift of the Cathaysia Block. The XGY Basin was a rift basin until ca. 660 Ma, evolved into a passive margin setting during Ediacaran-early Cambrian, and became a foreland basin after the middie-late Cambrian. Collectively, the provenance variation from late Tonian to Cambrian basin suggests that the Yangtze and Cathaysia blocks may have been amalgamated before late Tonian and an intra-plate basin has been developed along the orogenic belt, allowing the formation and evolution of the XGY Basin.

Early Cretaceous palaeogeography of the Russian Platform

Abstract This paper summarizes the data on the Early Cretaceous palaeogeography of the Russian Platform (RP) in the context of the development of the Northeastern Peritethys. One of the main features of the region is the constant mutual influence of the Tethyan and Boreal water masses (WMs) through the system of straits. The latest Volgian–Barremian development of the RP basin was under major influence of the Boreal WM. It differs from the Aptian–Albian interval, which formed under major influence of Tethyan and Peritethyan WMs. Zonal biostratigraphy reflects the type of marine biota related to the type of WM. The WM movement was interrupted by several episodes of exposition of the southern margin of the RP, the Berriasian–Barremian interval, or almost the whole platform, in the late middle–late Aptian.

On new prospects for petroleum and gas capability of Paleozoic sediments of the Karpovski projection

The article presents the geological data of recent years – the results of seismic exploration and deep drilling, which allow us to make new constructions of the model of the structure of the Paleozoic sedimentary complex of the northern side zone of the Caspian basin. In the historical development of the Caspian sedimentary basin, multiple geotectonic collisions have been observed, leading to transgressions and regressions of the Paleocean, as well as erosion of accumulated sedimentary strata, as well as interruptions in sedimentation. In the northern side zone, the determining influence of the structural sedimentation factor affected the age-varying carbonate ledges of the Karachaganak carbonate platform of the Aksaiblock, the Teplov-Tokarev zone of the Karpovsky tectonic ledge. Most of the oil, oil and gascondensate and gas condensate fields identified in the subsalt complex of the north of the Caspian Basin are associated with these zones. A comparative comparison of the deposits of the instrument zones of the Caspian basin has shown a fundamental difference in the conditions of accumulation of productive horizons, which lies in the nature of the location and in the significant variability of the filtration and capacitance properties of formations in natural reservoirs. The presence of deep-submerged carbonate structures is predicted in the deep part of the depression, on the slopes of carbonate platforms. Prospects for the detection of organogenic structures in the inner part of the paleobasin are assumed on the eastern extension of the Karpovsky ledge of the foundation and inside the Pogodaevo-Ostafyevsky trough, where, according to the results of 2D and 3D seismic surveys, promising structures Cretaceous, Orlovskaya and a number of others have been identified.

The Cretan Basin (South Aegean Sea, NE Mediterranean) in the Early Pliocene: a paleoceanographic reconstruction

The Aegean Sea (NE Mediterranean) represents a key area for climatic and oceanographic future projections, therefore it is crucial to define its environmental evolution during the Pliocene paleoclimatic analogue. The DSDP Site 378, located in the South Aegean Cretan Basin, provides an exceptional opportunity to investigate in detail the paleoceanographic conditions of the Early Pliocene and to examine the basin's paleoenvironmental evolution, through the study of calcareous nannofossil accumulation rates and hydroclimate proxies. The sequence has been dated in between ∼5.2–3.9 Ma, with the age of the first Zanclean marine sediments overlying the Messinian Primary Lower Gypsum demonstrating that the Cretan Basin was partially desiccated for at least ∼400 kyrs, as a result of being a shallow epicontinental area in the Late Miocene. A relatively sudden change to deep marine environment took place in the Early Pliocene linked to the accelerated rate of trench extension in the Cretan Basin. The multi-proxy study revealed intervals reflecting warm surface waters and low-oxygen conditions on the seafloor, associated with the orbitally driven presence of Early Pliocene rhythmic sapropelic layers. Between ∼5.2 and 4.6 Ma, the sapropelic layers were characterized by elevated abundance of Reticulofenestra spp. and Florisphaera profunda, depicting increased productivity throughout the photic zone. Both enhanced riverine inputs and weak presence of Levantine Intermediate Water (LIW) characterized this time interval. The alterations in the calcareous nannofossil patterns with increased Helicosphaera spp. and Umbilicosphaera jafari abundances, implying freshening and enhanced mid-photic productivity after ∼4.6 Ma, suggest strengthening of LIW intrusion combined with the full restoration of North-South Aegean marine gateways that led to the establishment of a hydrographic system similar to the modern Aegean Sea.

Post-rifting uplift and inversion of an intra-plate basin: The Doseo basin, Central Africa

There is a growing recognition that the post-rifting phase of basin evolution is far from being tectonically quiescent, as it can involve episodic uplift. However, the dynamic mechanisms responsible for this phenomenon remain a subject of controversy, particularly for intra-plate basins situated distant from active plate boundaries. Accurately determining the timing and magnitude of uplift is essential for elucidating the driving model behind these processes. In this study, we document the thermal history of the Doseo basin within the West and Central Africa Rift System (WCARS) using a combination of apatite fission track analysis and vitrinite reflectance data. Our findings reveal a period of accelerated exhumation during the late Eocene to Miocene epoch (∼45-20 Ma), characterized by kilometer-scale uplift, which corresponds to the formation of angular unconformities, folds, and fault-related anticlines. This specific time interval appears to be critical for the Cenozoic petroleum system, coinciding with the peak maturation of source rocks and the simultaneous formation of compressional traps. When integrated with the seismic data and previously published thermochronological data, our research reveals two significant cooling and uplift events in WCARS: a Santonian extrusion event and a late Eocene exhumation event. Both of these events have the potential to impact the entire tectonic plate, and Tethys realm. Furthermore, this two-stage exhumation event aligns closely with the timing of the Africa-Europe convergence collision. Consequently, we come to conclude that far-field lateral compression emerges as the dominant driving mechanism for intra-plate uplift, outweighing the influence of the mantle model.

Stratigraphic and geochronologic investigation of the Muddy Creek Basin: Implications for the Eocene tectonic evolution of southwest Montana, USA

Sedimentary basins record crustal-scale tectonic processes related to the construction and demise of orogenic belts, making them an invaluable archive for the reconstruction of the evolution of the North American Cordillera. In southwest Montana, USA, the Renova Formation, considered to locally represent the earliest accumulation following Mesozoic−Cenozoic compressional deformation, is widespread but remains poorly dated, and its origin is debated. Herein, we employed detrital zircon U-Pb and (U-Th)/He double dating and sanidine 40Ar/39Ar geochronology in the context of decimeter-scale measured stratigraphic sections in the Renova Formation of the Muddy Creek Basin to determine basin evolution and sediment provenance and place the basin-scale record within a regional context to illuminate the lithospheric processes driving extension and subsidence. The Muddy Creek Basin is an extensional half graben in southwest Montana that is ∼22 km long and ∼7 km wide, with a >800-m-thick sedimentary package. Basin deposition began ca. 49 Ma, as marked by multiple ignimbrites sourced from the Challis volcanic field, which are overlain by a tuffaceous fluvial section. Fluvial strata are capped by a 46.8 Ma Challis ignimbrite constrained by sanidine 40Ar/39Ar dating. An overlying fossiliferous limestone records the first instance of basinal ponding, which was coeval with the cessation of delivery of Challis volcanics−derived sediment into the Green River Basin. We attribute initial ponding to regional drainage reorganization and damning of the paleo−Idaho River due to uplift and doming of the southern Absaroka volcanic province, resulting in its diversion away from the Green River Basin and backfilling of the Lemhi Pass paleovalley. Detrital zircon maximum depositional ages and sanidine 40Ar/39Ar ages show alternating fluvial sandstone and lacustrine mudstone deposition from 46 Ma to 40 Ma in the Muddy Creek Basin. Sediment provenance was dominated by regionally sourced, Challis volcanics−aged and Idaho Batholith−aged grains, while detrital zircon (U-Th)/He (ZHe) data are dominated by Eocene cooling ages. Basin deposition became fully lacustrine by ca. 40 Ma, based on an increasing frequency of organic-rich mudstone with rare interbedded sandstone. Coarse-grained lithofacies became prominent again starting ca. 37 Ma, coeval with a major shift in sediment provenance due to extension and local footwall unroofing. Detrital zircon U-Pb and corresponding ZHe ages from the upper part of the section are predominantly Paleozoic in age, sourced from the Paleozoic sedimentary strata exposed in the eastern footwall of the Muddy Creek detachment fault. Paleocurrents shift from south- to west-directed trends, supporting the shift to local sources, consistent with initiation of the Muddy Creek detachment fault. Detrital zircon maximum depositional ages from the youngest strata in the basin suggest deposition continuing until at least 36 Ma. These data show that extension in the Muddy Creek Basin, which we attribute to continued lithospheric thermal weakening, initiated ∼10 m.y. later than in the Anaconda and Bitterroot metamorphic core complexes. This points to potentially different drivers of extension in western Montana and fits previously proposed models of a regional southward sweep of extension related to Farallon slab removal.

Provenance of the Copi North heavy mineral sands deposit, Murray Basin, Australia, based on the geochronology and geochemistry of detrital zircon, rutile and monazite

The Murray Basin hosts one of the world’s largest strandplain systems and has enormous potential for heavy mineral sand resources of titanium, zircon and rare earth elements. Further discovery of heavy mineral sand deposits can be aided via improved understanding of the source and transport of detrital heavy minerals of the basin. In this study, the provenance of two heavy mineral sand units of the Copi North deposit (western NSW) was determined using U–Pb geochronology and geochemistry of detrital zircon, rutile and monazite. Results from the two units are similar, indicating they derive from the same sources. Approximately 42% of the zircon population is aged <470 Ma and is interpreted to have been derived from the Tasmanides. Older zircon populations, up to ca 2.5 Ga, were largely derived from the Adelaide Superbasin and Delamerian Orogen, or from metasedimentary rocks of the Lachlan Orogen. Over 90% of rutile U–Pb ages are between 570 and 450 Ma, correlating either to Delamerian metamorphism or to detrital rutile from the Darling Basin; both sources are supported by rutile geochemistry that is indicative of a metasedimentary source. Most monazites have U–Pb ages of ca 600 Ma, which is consistent with an ultimate source from the Mt Arrowsmith Volcanics and/or Antarctica. A minor proportion of the monazite was sourced from igneous rocks of the New England Orogen. Temporal changes in sediment source regions can be inferred when considering the detrital mineral record for Copi North with other mineral sand deposits of the basin. Older (>ca 6.7 Ma) deposits such as Copi North feature a significant proportion of post-350 Ma detritus, reflecting the important role of the ancestral Darling River in supplying sediment from the north at the earliest stages of Murray Basin development. Post-6.7 Ma deposits lack a major component of detritus for far northern sources, and instead consist of sediment derived dominantly from western (Adelaide Superbasin) and eastern (Lachlan Orogen) sources, the latter delivered via the Murray River.

Geodynamic Mechanism of the Evolution of the South China Sea Basin: Simulation Based on the Finite Difference Method

The South China Sea is in the convergence zone of the Pacific plate, the Indo-Australian plate, and the Eurasian plate. Its formation and tectonic evolution were influenced by continental margin spreading and plate interaction between the three plates and their microcontinents. It has a complex geodynamic background. To understand how continents break up to form ocean basins, the South China Sea Basin is taken as an example to study the dynamic mechanism of its formation and evolution and the driving force of seafloor spreading, so as to understand the relationship between oceanic–continental lithosphere plates. The South China Sea basin’s opening mechanism and its principal factors of control remain controversial. To explore the influence of different extension rates, we summarized the different genesis mechanisms of the South China Sea, and combined with the tectonic section of the basin, the numerical simulation was obtained based on the finite difference method. The results obtained from numerical simulations show that the rapid extension rate was one of the important factors in the asymmetric expansion of the model, with other factors such as the thickness and rheological properties of the lithosphere held constant. The lithospheric mantle continued thinning in the stress concentration area, with the crust being pulled apart before the lithospheric mantle, eventually forming an ocean basin corresponding to the east sub-basin. However, when the extension rate was low, the model expanded almost symmetrically, and the lithosphere thinning occurred at a slow rate. The simulation results confirm that, compared with the southwest sub-basin of the South China Sea, the spreading rate of the east sub-basin was even higher. We believe that the subduction of the proto-South China Sea played a crucial role in the opening of the South China Sea, providing a more reasonable mechanism. The opposite movement of the Indo-Australian plate and Kalimantan may have inhibited the formation of the southwest sub-basin of the South China Sea, resulting in a later spreading of the southwest sub-basin than the east sub-basin, as well as a lower rate of spreading than the east sub-basin.

The characteristics and distribution of the Moho reflections in the South China Sea Oceanic Basin

The distribution and characteristics of the Moho reflections (M-reflections) in oceanic basins record the seafloor spreading process and provide crucial insights into the formation and evolution of the oceanic basins. Approximately 20,000 km of multichannel seismic reflection sections are used to characterize the M-reflections and the crustal structures in the South China Sea oceanic subbasins. The identified M-reflections are mainly distributed in the northwest subbasin, the east subbasin, and the northern and southern flanks of the southwest subbasin (SWSB). They exhibit a banded distribution pattern in two-way traveltime along the north–south direction, with shallower depths observed in the central region and gradually deepening toward the northern and southern sides. In addition, the M-reflection amplitudes generally weaken, and the reflection events become less continuous as the igneous oceanic crust thins along with the seafloor spreading prior to the second ridge jump event. Ultimately, the M-reflection becomes indistinguishable in proximity to fossil spreading centers. These observations suggest a decreasing magma supply toward the cessation of the spreading. Despite the significance of Moho interface imaging at the crust-mantle boundary, the distinct M-reflections are absent in the SWSB and the vicinity of the Zhenbei-Huangyan Seamounts Chain, which are attributed to several factors, especially the vague nature of Moho interfaces.

Tectono-stratigraphic evolution of a deep-water foreland basin: a case study from the Marnoso-arenacea basin, central Italy

Tectono-stratigraphic evolution of a deep-water foreland basin: a case study from the Marnoso-arenacea basin, central Italy

Late Neoproterozoic tectonic evolution of the northern Tarim block: New insights from integrated detrital zircon and rutile geochronology and trace element geochemistry

In the Neoproterozoic era, the breakup of the Rodinia supercontinent had a profound impact on different aspects of Earth; yet, the precise driving mechanism behind this event has been a source of ongoing controversy. The Tarim block, as a crucial component, presents an opportunity to gain valuable insights into the breakup process through its tectonic-sedimentary evolution history and dynamic background. However, the comprehension of basin evolution is limited due to the presence of an ambiguous prototype basin during the late Neoproterozoic and its intricate interconnections with surrounding blocks. In this contribution, we integrate detailed field observations, U-Pb dating of detrital zircon and rutile, and trace element analysis of detrital rutile to elucidate the source-to-sink relationships and the tectonic setting of Ediacaran sedimentary strata in the Aksu area (northern Tarim block, China). Detrital zircon age spectra exhibit consistent distributions with ages between ∼850 and ∼600 Ma and between ∼2100 and ∼1800 Ma. Rutile age groups however exhibit an abrupt transition between the lower member of the Sugatbrak Formation and the succeeding upper member to the Qigebrak Formation in the basin, with ages between ∼1800 and ∼900 Ma and nearly identical to those between ∼2100 and ∼1800 Ma. Calculated Zr-in-rutile temperatures and Cr-Nb compositions imply that the majority of the detrital rutiles were sourced from amphibolite facies metapelites, with an abrupt transition from amphibolitic schist to amphibolite-granulite facies for the ∼1800 Ma group grains. Provenance tracing shows that the detrital sediments of the lower Sugatbrak Formation are sourced from both the Central Tianshan and the Tarim blocks, and that the overlying strata have a single source in the Tarim block. A corresponding change from syn-rift detrital facies to a shallow-marine environment in on a passive continental margin is suggested in terms of depositional setting. In light of prior published evidence from petrology, geochronology and paleomagnetism, we propose that the Neoproterozoic northern Tarim margin was affected by a protracted subduction zone retreat. Associated back-arc spreading eventually was responsible for the opening of the southern Tianshan Ocean and rifting of the Central Tianshan block from the Tarim block in the late Ediacaran. This development ultimately prevented detrital material from the Central Tianshan block from reaching the northern Tarim depocenters as the latter evolved into a passive continental margin.

From the perspective of the united front, Chinese medicine colleges help the ecological protection and high-quality development of the Yellow River Basin in Shandong Province

As the birthplace of Chinese civilization, the Yellow River Basin is one of the most important ecological security barriers in China in the new era. From the perspective of ecological protection and high-quality development in the Yellow River Basin, comprehensively explore the opportunities and challenges faced by ecological protection in the Yellow River Basin, identify effective measures for TCM colleges to help ecological protection and high-quality development in the Yellow River Basin in Shandong, rationally use modern technological means, and make use of emerging strategic industries and innovative scientific and technological achievements to achieve optimal management. It can further accelerate the pace of TCM and personnel training and development.

Evolution of postcanine complexity in Gomphodontia (Therapsida: Cynodontia).

Gomphodonts form a Triassic radiation of small to medium-bodied (<0.5-2.5 m in length) quadrupedal cynodonts characterized by labiolingually expanded gomphodont postcanines. They were the dominant cynodont group in Middle and Late Triassic ecosystems from the Southern Hemisphere and the first predominantly herbivorous cynodonts to evolve. Gomphodonts were also the first therapsids to develop hypsodonty and a dentition with complex occlusal patterns, and their highly diagnostic upper and lower postcanines show many different morphologies. Here, we explored dental complexity in gomphodont cynodonts through time using geographic information system analysis and orientation patch count applied on 3D crown surfaces of upper and lower gomphodont postcanines belonging to 32 gomphodont taxa. This study reveals that the peak in postcanine complexity was reached early in the evolution of gomphodonts with the emergence in the Early Triassic of omnivorous or insectivorous forms with postcanines made of well-separated cusps and cingular cuspules. Traversodontids evolved simpler postcanines via coalescence of cusps into crests and the development of large occlusal basins, and the Middle Triassic radiation of traversodontids led to a sharp decrease in mean postcanine complexity. Simplification of the postcanines in traversodontids is interpreted as being related to a gradual increase in the consumption of plant material. Interestingly, the trend of insectivory/omnivory high postcanine complexity and herbivory low dental complexity in gomphodonts is opposite to the trend of dental complexity reported in some extant mammals, with omnivorous having low dental complexity and herbivorous higher. Postcanine complexity remained relatively stable throughout the evolution of traversodontids and only slightly diminished in the Late Triassic due to the presence of minute forms with particularly simple postcanines in the Rhaetian. The major phylogenetic diversity and taxonomic richness of Gomphodontia are represented in two periods of time: at the end of the Anisian, an age in which the postcanine complexity is simplifying, and at the early Carnian when the postcanine complexity in traversodontids, the only Gomphodontia represented, is stable.

Timing of rifting of the Dongkaco microcontinent (Central Tibet) and implications for Neo-Tethyan evolution

Rifting of continental blocks away from northern Gondwana resulted in the development of several Tethyan oceanic branches, the number of which and the timing of tectonic processes are actively debated. Within the Mesozoic Bangong-Nujiang suture, locally exposed Paleozoic strata are potential witnesses of the early development of Tethyan basins, yet their origin and tectonic significance remain poorly understood. In this study, Paleozoic limestone and sandstone units exposed in the Dongkaco area are identified as part of an independent Dongkaco microcontinent, differentiated from the South Qiangtang terrane by the Dongqiao suture on the north and from the Lhasa Block by the Beila suture on the south. The Upper Paleozoic deltaic to shallow-marine feldspatho-quartzose and quartzose sandstones within the microcontinent are interbedded with glaciogenic sequences and exhibit provenance characteristics that align with the Lhasa Block. These stratigraphic and provenance features suggest that during the Carboniferous to Early Permian the Dongkaco microcontinent was attached to the Lhasa Block. The discovery of Middle Triassic (Anisian) radiolarian chert associated with the Beila ophiolite indicates that sea-floor spreading was active within the Beila Ocean at that time. Data presented here show that the detachment of the Dongkaco microcontinent from the Lhasa Block resulted in the Beila Ocean, a branch of Bangong-Nujiang Ocean that expanded through Middle Permian to Early Triassic times. These findings shed new light on the paleogeographic evolution that preceded India-Asia collision and final amalgamation of the Himalayan-Tibetan orogen.

Seismic geomorphology: subsurface analyses, data integration and palaeoenvironment reconstructions – an introduction

Abstract Since the last Special Publication on seismic geomorphology, the application of seismic data has grown substantially, revolutionizing our understanding of basin evolution in the process. The papers presented here provide an insight into the direction of travel for seismic geomorphological analyses and how the science has evolved since 2007. New methods of data collection, new methods of processing and visualization, and the integration of new types of complementary data, all have played a role in maximizing the potential palaeo-environmental insights that can be derived from such studies. The submissions range across different geological settings, consisting of glacial, fluvial, volcanic, deltaic and slope settings. Many of these studies integrate different methods, showing what can be achieved by combining multiple datasets to understand the subsurface. As more legacy datasets become available, the observed acceleration in seismic data availability and the associated publications will likely continue. Newer methods and greater knowledge of the subsurface are yielding a greater understanding of not just the palaeoenvironments, but also what generates seismic reflectivity in the subsurface. The study of seismic geomorphology remains in its infancy, and much exciting research potential is yet to be realized.

Neoproterozoic-Early Cambrian Northern Chah-Farsakh Cu-Zn VMS-type deposit, Iran: Constraints from geology, geochemistry, fluid inclusions and geodynamic

Northern Chah-Farsakh is the first seafloor VMS described in the Torud-Chahshirin metallogenic belt of Iran. The deposit is hosted by Neoproterozoic-Early Cambrian mafic (basaltic andesitic)-siliciclastic rocks in volcano-sedimentary basin. The evolution of the ore-bearing basin is governed by the Proto-Tethys Oceanic crust subduction beneath the Central Iranian microcontinent. Three ore facies can be distinguished based on the ore textures studies: stringer zone ore facies, massive-replacement ore facies, bedded ore and distal facies. Pyrite, chalcopyrite, magnetite and sphalerite are the main minerals, together with minor amounts of pyrrhotite, bornite, tetrahedrite and tennantite. Textures include laminated, banded, replacement, massive, and vein-veinlet texture. There is a distinct metal zonation in the massive sulfide orebody; Gold, Ag, and Zn contents increase vertically from the stringer to the bedded ore facies; Cu and Co increase in the massive ore facies, and Pb is highest in the stringer zone. Ore mineralization in the Northern Chah-Farsakh deposit has emplaced in two stages. The fine-grained ore bands (stage 1) which are intricately interlayered with host rock beds, exhibit sedimentary structure such as laminae and bedding are consistent with a syn-sedimentary origin. Coarser-grained stage 2 ores have massive and vein-veinlet textures that are considered to form by replacement during sub-seafloor fluid flow. Based on SEM-EDS analysis, significant compositional variations were observed in the Py-1b grains. Py-1b is enriched in Pb compared to Py-1a. The elemental distribution map shows that the chalcopyrite (Cpy-2) minerals in Northern Chah-Farsakh deposit do not have variable composition and are homogeneous. Fluid inclusions in quartz minerals rom the footwall stringer zone have trapping temperatures between 203 and 500 °C with salinities (3.39–16 wt% NaCl equiv.) higher than modern seawater. Fluid inclusion studies suggest that the ore-forming fluids were derived from seawater. High level of Se in the massive ore facies of the Northern Chah-Farsakh supports the formation of mineralization from a high-temperature hydrothermal fluid. The Northern Chah-Farsakh Cu-Zn VMS deposit typify the mafic-siliciclastic type (Besshi-type), where the majority of the host stratigraphy is composed of a mafic flow-volcaniclastics and sedimentary rocks.

Wetter trend in source region of Yangtze River by runoff simulating based on Grid-RCCC-WBM

Exploring the future hydroclimatic conditions of source region of Yangtze River (SRYaR), an alpine affected by climate change significantly, is essential for basin water resources management and development ss global climate change intensifies and the process of climate warming and humidification in Northwest China. This study proposed a practical framework for assessing water resource response to the context of climate changes in alpine catchments from the respective of both runoff and hydroclimatic conditions. Utilizing Grid-RCCC-WBM driven by corrected climatic forcing from the global climate models, this study estimate the prospective overall warmer and wetter pattern in the source region of Yangtze River. The key results indicated that: (1) Under all future scenarios, both temperature and precipitation within the catchment exhibit a significant upward trend. Projections from multi-model ensembles (MME) suggest that during the mid-term period (2041–2060, MT), temperatures are expected to rise by [0.74 °C, 3.08 °C] compared to the baseline period (1995–2014), with precipitation changes ranging from [4.8%, 21.4%]. (2) Future runoff within the catchment exhibits a consistent increase, with a linear trend rate of 1.1 mm/decade. runoff changes in MT compared to the baseline period vary from [−5.1%, 33.7%]. Runoff decreases in the northern part of the catchment, while notable increases occur in the southeastern and western regions. (3) In the future, the ratio of catchment evaporation capacity to precipitation decreases in comparison to the baseline period with an augmentation in soil moisture, enhancing its capacity for water retention and reducing the conversion of precipitation to evaporation, resulting a wetting trend of the catchment. (4) The future snowpack in the catchment continues to decrease, with a significant reduction in both the proportion of snowfall relative to total precipitation and the proportion of snowmelt runoff relative to total runoff, the risk of water resources crisis in the watershed is escalating.