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Latest Carboniferous-Early Permian Rifting of the Northern Gondwanan Margin and the Opening of the Northern Neotethys: New Evidence from the Carboniferous and Permian Foraminiferal Assemblages from the Beyşehir-Hoyran Nappes, Central Taurides(Southern Turkey)

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Journal of Earth Science 2024年第2期35卷 394-415页

作者： Cengiz Okuyucu U.Kagan Tekin Cagri Guzgun Kaan Sayit department of geological Engineering Konya Technical UniversityKonya42250Turkey department of geological Engineering Hacettepe UniversityAnkara06800Turkey department of geological Engineering Middle East Technical UniversityAnkara06800Turkey

The Beyşehir-Hoyran Nappes,one of the tectonostratigraphic units of the Taurides,are thought to be originated from the Izmir-Ankara Ocean(northern branch of Neotethys).In this study,Late Paleozoic rock units from the blocks of Beyşehir-Hoyran Nappes were studied in detail using foraminiferal assemblages in two different locations from the southwest of Karaman City(southern Turkey).In both places,blocks/slices and pebbles of various origins are embedded within a highly sheared matrix of Late Cretaceous Age,and the whole unit can be regarded as a sedimentary mélange.The ages of the blocks from the southwest of Karaman City range from the Late Serpukhovian(Late Mississippian)to Late Capitanian(Middle Permian)with some depositional breaks(e.g.,Bashkirian,Kasimovian).Combined with the previous data from the Mersin Mélange,which also include the remnants of the Beyşehir-Hoyran Nappes,our new findings suggest that a shallowing-upward sequence,characterized by a shallow water environment with foraminifera-bearing limestones,was deposited over the Tournaisian pelagic sequence in the Beyşehir-Hoyran Nappes till the Early Moscovian(Early Middle Pennsylvanian).This shallowing-upward sequence in the Beyşehir-Hoyran Nappes could be related to the Late Paleozoic Glaciation on the Gondwana supercontinent(Glacial Ⅱ),which resulted in a sea-level drop and deposition of platform carbonates during the Viséan–Early Moscovian(Middle Mississippian to Early Middle Pennsylvanian)time interval.The absence of the main part of the Middle-Upper Pennsylvanian deposits(continental phase during the Middle Moscovian–Middle Gzhelian)in the Beyşehir-Hoyran Nappes can be mainly attributed to the occurrence of a mantle plume and partially to the effect of Late Paleozoic Gondwanan Glaciation(Glacial Ⅲ).Progressive uplifting by the buoyant mantle plume material has resulted in rifting at the center of the basin where the Beyşehir-Hoyran Nappes have deposited.The rifting process led to tectonic destabilization of the platform in the basin,causing accum

关键词： foraminifera Carboniferous and Permian Beyşehir-Hoyran Nappes plume rifting Neotethys paleontology

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Substrate control in track registration and preservation:insights across the Triassic—Jurassic boundary in southern Africa

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Journal of Palaeogeography 2024年第2期13卷 351-371页

作者： Loyce Mpangala Miengah Abrahams Emese M.Bordy department of geological Sciences University of Cape TownCape TownSouth Africa

Tracks registration is influenced by the dynamic interplay between the pedal anatomy of the trackmaker,its behaviour,and the substrate conditions it interacts with.Differences in substrate conditions,especially those linked to grain size and moisture content,often result in the most dramatic variations in track morphology.In the upper Stormberg Group,main Karoo Basin of southern Africa,diverse trace fossils,primarily comprising Late Triassic—Early Jurassic dinosaur tracks,are preserved.Numerous studies have extensively documented individual ichnosites,investigating variations between sites over time,with recent studies suggesting that track abundance and anatomical fidelity increase up-stratigraphy.Despite the well-established link between substrate and track morphology,past studies have not specifically focused on substrate conditions,often emphasizing macro-sedimentary features instead.Here,we examine the micro-sedimentary features of track-bearing units in the upper Stormberg Group using petrographic techniques to better understand the palaeosubstrate and its effect on fossil track registration and preservation.The analysis revealed that very fine-grained sandstones and substrates modified by microbial activity tend to preserve tracks with greater abundance and/or higher anatomical fidelity.Furthermore,the prevalence of very fine-grained and microbially modified strata,and their associated track trends increases in younger stratigraphic units.Across the Triassic—Jurassic boundary in southern Africa,a boom in dinosaur track abundances is observed and credited to the proliferation of dinosaur populations during the Early Jurassic.Our findings,however,suggest that the observed local increase in track abundance(and anatomical fidelity)up-stratigraphy may be linked to substrate composition differences,which were ultimately controlled by large-scale changes in the palaeoenvironment from high-energy meandering fluvial to lower-energy aeolian-lacustrine settings in the Late Triassic and Early Jurassic,respectively.The

关键词： Dinosaur tracks Footprint anatomical fidelity Micro-sedimentary features Substrate conditions Track registration Palaeoenvironmental context

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A geochemical perspective on the genesis of Cenozoic basic volcanism in northeastern Turkey:an overview of metasomatism and heterogeneity of the sub-continental lithospheric mantle in a post-collisional setting

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Acta Geochimica 2024年第3期43卷 489-506页

作者： Mehmet Arslan Irfan Temizel department of geological Engineering Karadeniz Technical University61080 TrabzonTurkey

The post-collisional Cenozoic basic volcanic rocks in NE Turkey show temporal variations in whole-rock lithophile element and highly siderophile element(HSE)systematics that are mainly associated with the nature of sub-continental lithospheric mantle(SCLM)sources and parental melt generation.So far,the traditional whole-rock lithophile geochemical data of these basic volcanic rocks have provided important constraints on the nature of SCLM sources.Integrated lithophile element and HSE geochemical data of these basic volcanic rocks also reveal the heterogeneity of the SCLM source,which is principally related to variable metasomatism resulting from previous subduction(s)and post-collisional mantle-crust interactions in an extensional setting.Lithophile element geochemical features suggest that the parental magmas have derived from metasomatized spinel-to garnet-bearing SCLM sources for Eocene and Miocene basic volcanic rocks with subduction signatures whereas originated from spinel-to garnet-bearing SCLM sources for Mio-Pliocene and Plio-Quaternary basaltic volcanic rocks without the subduction signature.Lithophile element and HSE geo-chemistry also reveal that Eocene and Miocene basic vol-canic rocks were affected by more pronounced crustal contamination than the basaltic volcanic rocks of Mio-Pliocene and Quaternary.Furthermore,the integrated lithophile element and HSE compositions of these basic volcanic rocks,together with the regional asymmetric lithospheric delamination model,reveal that the compositional variation(especially due to metasomatism)was significant temporally in the heterogeneity of the SCLM sources from which parental magmas formed during the Cenozoic era.

关键词： Basalt Lithospheric mantle Metasomatism Mantle heterogeneity Cenozoic volcanics NE Turkey

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Geomorphological responses of rivers to active tectonics along the Karahay?t Fault, Western Türkiye

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Journal of Mountain Science 2024年第5期21卷 1464-1474页

作者： Savaş TOPAL Pamukkale University Department of Geological EngineeringKınıklıCampusDenizli 20160Türkiye

Understanding the topography in active tectonic areas and assessing the rates and models of active deformation in the upper crust are primary objectives in tectonic geomorphology studies. The drainage pattern of river systems is highly sensitive to tectonically induced changes, and it often preserves the records of the formation and progression of most tectono-geomorphic processes within its boundaries. Therefore, the evolution of landforms is a consequence of the evolution of individual drainage basins in which they are formed. Assessing the rates of tectonic deformation using geomorphic data is a traditionally adopted method to characterize the nature of active faults. Globally, the Digital Elevation Model(DEM) is widely used as a crucial tool to analyze the morphotectonic features of drainage basins. In this study, some geomorphic indices were applied to investigate the impact of tectonism on landscape along the Karahay?t Fault and its associated drainage areas. These geomorphic indices are mountain front sinuosity(Smf values between 1.17-1.52), valley floor width-to-height ratio(Vf values between 0.25-1.46), basin asymmetry factor(AF values between 15-72), drainage basin shape(Bs values between 3.18-6.01), hypsometric integral and curve(HI values between 0.32-047), channel sinuosity(S values between 1-1.6), normalized steepness index(Ksn values between 1-390) and Chi integral(χ values between 200-4400). The development of drainage areas on the hanging wall and footwall block of the Karahayit Fault differs depending on the uplift. The drainage areas developed on the hanging wall present different patterns depending on the regional uplift caused by the fault. This reveals that the fault contributed significantly to the development of drainage areas and regional uplift in the region. In addition, the maximum earthquake magnitude that may occur in the future on the Karahayit Fault, whose activity is supported by geomorphic indices, is calculated as 6.23. Since an earthquake of this magnitude may cause loss of lif

关键词： Drainage basins Geomorphic indices Normalized steepness index(Ksn) Chi integral(χ) Morphotectonic features Karahayıt Fault

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Significant lake expansion has accelerated permafrost degradation on the Qinghai-Tibet Plateau

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Journal of Mountain Science 2024年第1期21卷 68-83页

作者： LI Qingpeng LIU Wenhui LIU Hairui ZHOU Guanghao SONG Xianteng LI Qing LUO Bingnan SONG Bangxu ZHANG Qi department of geological Engineering Qinghai UniversityXining 810016China College of Eco-Environmental Engineering Qinghai UniversityXining 810016China Xining Center for Integrated Natural Resources Survey China Geological SurveyXining 810000China

In recent years, lakes on the Qinghai-Tibet Plateau have become more responsive to climate change. In September 2011, Zonag Lake in Hoh Xil experienced sudden drainage, the water eventually flowed into Yanhu Lake, which caused Yanhu Lake to continue to expand. The potential collapse of Yanhu Lake could directly threaten the operational safety of the adjacent Qinghai-Tibet Highway, Qinghai-Tibet Railway. To explore the implications of expanding lakes on the surrounding permafrost, we selected Hoh Xil Yanhu Lake on the Qinghai-Tibet Plateau to study the effect of lake expansion on permafrost degradation. The permafrost degradation in the Yanhu Lake basin from October 2017 to December 2022 was inverted using Sentinel-1 satellite image data and small baseline subset interferometry synthetic aperture radar(SBAS-In SAR) technology. Additionally, permafrost degradation from February 2007 and February 2010 was analyzed using advanced land observing satellite phased array-type L-band synthetic aperture radar(ALOS PALSAR) satellite images and differential interferometric synthetic aperture radar(D-In SAR) technique. The results showed that the permafrost around Yanhu Lake experienced accelerated degradation. Prior to the expansion of Yanhu Lake, the average annual deformation rate along the line of sight(LOS) direction was 6.7 mm/yr. After the expansion, the rate increased to 20.9 mm/yr. The integration of spatial-temporal distribution maps of surface subsidence, Wudaoliang borehole geothermal data, meteorological data, Yanhu Lake surface area changes, and water level changes supports the assertion that the intensified permafrost degradation could be attributed to lake expansion rather than the rising air temperature. Furthermore, permafrost degradation around Yanhu Lake could impact vital infrastructure such as the adjacent Qinghai-Tibet Highway and Qinghai-Tibet Railway.

关键词： Lake expansion SBAS-InSAR D-InSAR Permafrost deformation Qinghai-Tibet Plateau

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Triassic integrative stratigraphy,biotas,and paleogeographical evolution of the Qinghai-Tibetan Plateau and its surrounding areas

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Science China Earth Sciences 2024年第4期67卷 1152-1194页

作者： Guichun WU Zhansheng JI Gary GLASH Qinggao ZENG Jianxin YAO Key Laboratory of Stratigraphy and Palaeontology Ministry of Natural ResourcesInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037China SinoProbe Laboratory Chinese Academy of Geological SciencesBeijing 100094China department of Geology and Environmental Sciences State University of New York-FredoniaFredoniaNY 14063USA Xizang Autonomous Region geological and Mineral Exploration and Development Burea Lhasa 850010China

Rocks of the Qinghai-Tibetan Plateau(QTP)host abundant Triassic fossils.So far,the well established marine fossil sequences based on ammonoids,conodonts,bivalves,brachiopods,radiolarians,and terrestrial spora-pollen sequence have become standard for biostratigraphic correlation of the QTP.For much of Triassic time,the QTP occupied a marine setting as suggested by the dominance of marine deposits.The main sedimentary types represented in the Triassic successions include littoral to shallow marine clastic rocks,shallow marine carbonate platform carbonates,bathyal to abyssal slope carbonates intercalated with clastic and siliceous deposits,coal-bearing clastic strata contained within paralic facies deposits,and littoral and terrestrial volcaniclastic rocks.These deposits are organized into four stages in ascending order:(1)Early Triassic deposits that record marine transgression,including extensive shallow marine carbonate platform strata.(2)Middle Triassic Ladinian to Late Triassic Carnian deposits,including thin-bedded limestone,fine clastics,and siliceous rocks,that accumulated at greater depths than underlying Early Triassic strata and reflect the peak of the transgression.Magmatic activity appears to have occurred in some areas during this stage.(3)Late Triassic Norian deposits that record the onset of marine regression as suggested by the widespread occurrence of platform carbonates.It is noteworthy that stage 3 deposits of the Qin-Qi-Kun area in the northernmost region of the QPT is dominated by terrestrial strata and displays evidence of local erosion.(4)Late Triassic Rhaetian littoral and shallow marine clastic and coal-bearing deposits that preserve the record of continued marine regression continued.The Indus-Yarlungzangbo Suture Zone(IYSZ)appears to have been the rifting axis during Triassic time as suggested by sedimentary facies trends that reflect deepening to south and north.Thus,the Himalaya Block to the south of the IYSZ was part of the passive margin of Gondwana whereas the north side of the IYSZ,

关键词： Qinghai-Tibetan Plateau Triassic Biostratigraphy Lithostratigraphy Palaeobiogeography Sedimentary palaeogeography

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A bounding surface visco-plasticity model considering generalized spacing ratio of soils

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1832-1846页

作者： Xiaosen Kang Hongjian Liao Qiangbing Huang Jianbing Peng department of geological Engineering Chang’an UniversityXi’an710054China department of Civil Engineering Xi’an Jiaotong UniversityXi’an710049China

The non-unique critical state of soils with time-dependent behaviors is a significant issue in geotechnical engineering problems.However,previous bounding surface plasticity models cannot predict accurately the non-unique critical state of soils,because the distance between the compression line and critical state line charged by strain-rate effect is basically neglected.To fill this gap,a generalized spacing ratio of soils is defined in the elasto-viscoplastic framework,and a bounding surface visco-plasticity model is formulated and verified,which can consider the generalized spacing ratio.Specifically,the generalized spacing ratio of soils reflects the distance between the compression line and the critical state line of soils with time-dependent behaviors.Then,the generalized spacing ratio is introduced into an improved anisotropic bounding surface.A new expression of the visco-plastic multiplier is derived by solving the consistency equation of an anisotropic bounding surface.In the expression,a strain rate index is proposed to account for the strain-rate effect on visco-plastic strain increment,and a visco-plastic hardening modulus is derived to predict the visco-plastic response of soils in overconsolidation conditions.The model is then verified through constant strain rate tests and creep tests.Notably,it can capture the non-unique critical states of soils with time-dependent behaviors due to the generalized spacing ratio and the creep rupture of soils due to the visco-plastic multiplier that considers the stress ratio and visco-plastic strain rate.

关键词： Soil Constitutive model Visco-plastic behavior Strain rate Creep Anisotropic

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Theory and classification of mass extinction causation

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National Science Review 2024年第1期11卷 16-36页

作者： Thomas J.Algeo Jun Shen State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences—Wuhan State Key Laboratory of geological Processes and Mineral Resources China University of Geosciences—Wuhan department of Geosciences University of Cincinnati

Theory regarding the causation of mass extinctions is in need of systematization, which is the focus of this contribution. Every mass extinction has both an ultimate cause, i.e. the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e. the specific climato-environmental changes that result in elevated biotic mortality. With regard to ultimate causes, strong cases can be made that bolide(i.e. meteor) impacts, large igneous province(LIP) eruptions and bioevolutionary events have each triggered one or more of the Phanerozoic Big Five mass extinctions, and that tectono-oceanic changes have triggered some second-order extinction events. Apart from bolide impacts, other astronomical triggers(e.***.solar flares, gamma bursts and supernova explosions) remain entirely in the realm of speculation. With regard to proximate mechanisms, most extinctions are related to either carbon-release or carbon-burial processes, the former being associated with climatic warming, ocean acidification, reduced marine productivity and lower carbonate δ13C values, and the latter with climatic cooling, increased marine productivity and higher carbonate δ13C values. Environmental parameters such as marine redox conditions and terrestrial weathering intensity do not show consistent relationships with carbon-cycle changes.In this context, mass extinction causation can be usefully classified using a matrix of ultimate and proximate factors. Among the Big Five mass extinctions, the end-Cretaceous biocrisis is an example of a bolide-triggered carbon-release event, the end-Permian and end-Triassic biocrises are examples of LIP-triggered carbon-release events, and the Late Ordovician and Late Devonian biocrises are examples of bioevolution-triggered carbon-burial events. Whereas the bolide-impact and LIP-eruption mechanisms appear to invariably cause carbon release, bioevolutionary triggers can result in variable carbon-cycle changes, e.g. carbon burial during the Late Ordovician and Late Devonian events,

关键词： biocrisis ultimate cause proximate cause bolide large igneous province bioevolutionary event

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Shear resistance characteristics and influencing factors of root-soil composite on an alpine metal mine dump slope with different recovery periods

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Journal of Mountain Science 2024年第3期21卷 835-849页

作者： PANG Jinghao LIANG Shen LIU Yabin LI Shengwei WANG Shu ZHU Haili LI Guorong HU Xiasong department of geological Engineering Qinghai UniversityXining 810016China Key Laboratory of Genozoic Resource&Environment in North Margin of the Tibetan Plateau Xining 810016China

Artificial vegetation restoration is the main measure for vegetation restoration and soil and water conservation in alpine mine dumps on the Qinghai-Tibet Plateau,China.However,there are few reports on the dynamic changes and the influencing factors of the soil reinforcement effect of plant species after artificial vegetation restoration under different recovery periods.We selected dump areas of the Delni Copper Mine in Qinghai Province,China to study the relationship between the shear strength and the peak displacement of the root-soil composite on the slope during the recovery period,and the influence of the root traits and soil physical properties on the shear resistance characteristics of the root-soil composite via in situ direct shear tests.The results indicate that the shear strength and peak displacement of the rooted soil initially decreased and then increased with the increase of the recovery period.The shear strength of the rooted soil and the recovery period exhibited a quadratic function relationship.There is no significant function relationship between the peak displacement and the recovery period.Significant positive correlations(P0.05)between the shear strength of the root-soil composite and the root length density,and the root volume ratio of the coarse roots to the fine roots.A significant negative linear correlation(P0.05)with the root traits,other soil physical property indices(the moisture content and dry density of the soil),and slope gradient.The coarse-grain content is the main factor controlling the peak displacement of the rooted soil.

关键词： Alpine mine dump Artificial vegetation restoration period Rooted soil Shear resistance characteristics Root traits Soil physical properties

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Partitioning Anatolian Kinematics into Tectonic Escape and Slab Rollback Dominated Domains

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Journal of Earth Science 2024年第3期35卷 758-768页

作者： Jiannan Meng Timothy M.Kusky Erdin Bozkurt Hao Deng Ozan Sinoplu State Key Laboratory of geological Processes and Mineral Resources Center for Global TectonicsSchool of Earth SciencesChina University of GeosciencesWuhan 430074China Badong National Observatory and Research Station for Geohazards China University of GeosciencesWuhan 430074China department of geological Engineering Middle East Technical University06800 AnkaraTurkey department of Geosciences Auburn UniversityAuburn AL 36849USA

Anatolia is the global archetype of tectonic escape,as witnessed by the devastating 2023 Kahramanmaraş Earthquake sequence,and the 2020 Samos Earthquake,which show different kinematics related to the framework of the escape tectonics.Global Positioning System(GPS)motions of the wedge-shaped plate differ regionally from northwestwards to southwestwards(from east to west).Anatolia was extruded westward from the Arabian-Eurasian collision along the North and East Anatolian fault systems,rotating counterclockwise into the oceanic free-faces of the Mediterranean and Aegean,with dramatic extension of western Anatolia in traditional interpretations.However,which is the dominant mechanism for this change in kinematics,extrusion related to the Arabia/Eurasia collision or rollback of the African slab beneath western Anatolia is still unclear.To assess the dominant driving mechanisms across Anatolia,we analyze recent GPS velocity datasets,and decomposed them into N-S and E-W components,revealing that westward motion is essentially constant across the whole plate and consistent with the slip rates of the North and East Anatolia fault zones,while southward components increase dramatically in the transition area between central and western Anatolia,where a slab tear is suggested.This phenomenon is related to different tectonic driving mechanisms.The ArabiaEurasia collision drives the Anatolian Plate uniformly westwards while western Anatolia is progressively more affected by the southward retreating African subducting slab west of the Aegean/Cypriot slab tear,which significantly increases the southward component of the velocity field and causes the apparent curve of the whole modern velocity field.The 2020 and 2023 earthquake focal mechanisms also confirm that the northward colliding Arabian Plate forced Anatolia to the west,and the retreating African slab is pulling the upper plate of western Anatolian apart in extension.We propose that the Anatolian Plate is moving westwards as one plate with an additional component of exten

关键词： tectonics neotectonics tectonic escape slab rollback Anatolian Plate GPS velocity field geodynamics.

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