Tectonophysics最新文献

{"title":"The deep electrical structure characteristics and regional seismicity of the southeastern Jiali Fault Zone","authors":"Jialin Qi ,&nbsp;Hao Dong ,&nbsp;Leizhe Ji ,&nbsp;Wenbo Wei ,&nbsp;Sheng Jin","doi":"10.1016/j.tecto.2024.230559","DOIUrl":"10.1016/j.tecto.2024.230559","url":null,"abstract":"<div><div>Located in the southeastern Tibetan Plateau, the Jiali fault zone (JLF) is an important strike-slip fault system, which delineates the southern boundary of the south-eastward extrusion of the Tibetan Plateau. The JLF features long-recurrent seismicity and plays an important role in balancing the local stress field. However, previous geophysical studies have mostly focused on regional studies in the northwestern segment and the southeastern end of the JLF. Few geophysical studies have been conducted on the JLF segment in the Eastern Himalayan Syntaxis region. To better understand the deep structures of the JLF and to provide geophysical constraints for the regional seismicity, we propose a crustal-scale resistivity model derived from magnetotelluric profile data across the three branches (Xixingla, Puqu, and Parlung faults) of the southeastern segment of JLF. The three-dimensional electrical structure shows that the JLF is generally characterized by a series of northeast dipping features. Unlike Parlung and Puqu branches, which are currently relatively inactive, the Xixingla fault is imaged to dip steeply in the shallow part of the crust and gradually turninto a gentle dip angle in the deeper section, before ultimately converging with a low-resistivity layer in the mid-to-lower crust. As the recent seismicity shows a combination of thrusting and strike-slip mechanisms, the primary strike-slip tectonic background for the regional seismicity may be modified by the northeastward compression from the subducting Indian Plate. Combined with other geological and geophysical evidence, we suggest that the reverse thrust and strike-slip displacement of faults may jointly contribute to the combined dynamic mechanism for seismicity in this area, due to the intrusion of the Namcha Barwa metamorphic complex beneath the Lhasa terrane.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230559"},"PeriodicalIF":2.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exhumation response to oceanic plateau accretion and oroclinal bending: Low-temperature thermochronology study of Wrangellia terrane on southern Vancouver Island, Canada","authors":"Xin Qiao,&nbsp;Ruohong Jiao,&nbsp;Dante Canil","doi":"10.1016/j.tecto.2024.230562","DOIUrl":"10.1016/j.tecto.2024.230562","url":null,"abstract":"<div><div>Approximately 50 Myr ago, the triple junction of the Kula-Farallon-North America plates converged with the continental margin, causing ridge subduction and the formation, accretion and translation of two oceanic plateaus. We investigate the effects of this tectonic configuration on the exhumation of southern Wrangellia terrane on southern Vancouver Island since the Eocene. We report late Cretaceous to late Oligocene (85.4 to 23.3 Ma) apatite fission track ages (AFT) and, for the first time, Oligocene to early Miocene (36.6 to 14.0 Ma) apatite (U<img>Th)/He ages (AHe) for 16 bedrock samples of Wrangellia. The thermal history modelling of these ages for 13 samples reveals variable cooling patterns between regions. Samples close to the major faults of a fold and thrust belt show accelerated cooling (4–5 °C/Myr) during the Eocene. In the central area, the modelled cooling rates have been slow and generally uniform throughout the Cenozoic (0.5–1.5 °C/Myr), whereas samples from the west coast yielded very slow cooling (&lt;0.5 °C/Myr) from 70 to 30 Ma, followed by moderate cooling (1.5–3 °C/Myr) since. Combining ages, fission track length and thermal history models in this and previous studies, we interpret the moderate-accelerated exhumation of the fold and thrust belt in the Eocene to be a response to oroclinal bending following oceanic plateau accretion. The exhumation pattern of the western side of southern Wrangellia is linked to the ongoing Cascadian Subduction zone ca.30 Ma. This exhumation pattern also supports a hypothesis that all crust of southern Wrangellia was all overlain by sedimentary strata in Eocene before ∼50 Ma, and that an accretionary complex of the Pacific Rim terrane was partly the outboard equivalent of these strata. In the southern Wrangellia, no exhumation response to the Miocene oroclinal bending associated with formation of the Olympic mountains is observed.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230562"},"PeriodicalIF":2.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Upper and lower crustal deformation and residual topography in a continental back-arc: Inferences from the Pannonian-Transylvanian Basins","authors":"Dániel Kalmár ,&nbsp;Attila Balázs","doi":"10.1016/j.tecto.2024.230572","DOIUrl":"10.1016/j.tecto.2024.230572","url":null,"abstract":"<div><div>The topography and subsidence history of sedimentary basins are commonly related to crustal and lithospheric thinning linked to isostasy, also influenced by flexure and dynamic topography. The static component of the topography relative to a reference level can be calculated by the assumption that a lithospheric column consisting of crustal layers and a lithospheric mantle lid float within the asthenosphere. Here, we discuss the observed and calculated residual topography of the Pannonian Basin, i.e. the difference between the actual and calculated isostatic topography. The residual topography calculation is based on new geophysical constraints on the sedimentary, upper and lower crustal and lithospheric thicknesses based on reflection seismic and new receiver function analysis. The crustal thickness decreases from 40 to 45 km beneath the Eastern Alps to 22 km in the eastern Great Hungarian Plain that is floored by less than 60 km thick lithosphere affected by Miocene extension. The sedimentary thickness reaches more than 6 km in the deepest depocenters. The crust is much less attenuated in the Transdanubian Range (28 km), Apuseni Mountains or Transylvanian Basin (32.5–35 km). The interpreted lower crustal thickness reaches maximum 15–20 km in the Eastern Alps, 12–15 km in the Apuseni Mountains, 10 km in the Transdanubian Range and thins to 5 km in the Great Hungarian Plain. The new four-layer lithospheric model shows a much lower residual topography value than previously suggested for the Pannonian Basin. Only the Transdanubian Range is affected by maximum 300 m of positive residual topography, whereas the Transylvanian Basin shows 300–400 m of negative residual topographic values. The former is interpreted to be affected by small-scale asthenospheric upwelling effects, likely also contributing to the Miocene-Pliocene volcanic activity of the area. While the currently uplifting Transylvanian Basin undergoes tectonic re-adjustment linked to the gradual Vrancea slab break-off. Our results demonstrate the important effects of the thick sedimentary succession and the different crustal thinning values on the observed and predicted topographic variations in extensional sedimentary basins.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"894 ","pages":"Article 230572"},"PeriodicalIF":2.7,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleolatitudinal movements of the eastern Sakarya Zone from Jurassic to Eocene","authors":"Sercan Kayın ,&nbsp;Z. Mümtaz Hisarlı ,&nbsp;Turgay İşseven ,&nbsp;Abdurrahman Dokuz ,&nbsp;Bahadırhan Sefa Algur","doi":"10.1016/j.tecto.2024.230570","DOIUrl":"10.1016/j.tecto.2024.230570","url":null,"abstract":"<div><div>The study area covers a region oriented north-south from the Black Sea coastline in the north to the Kelkit Basin in the south within the eastern Sakarya Zone in northern Türkiye. The objective of this study is to investigate the paleolatitudinal movements of the eastern Sakarya Zone during the Jurassic-Eocene time interval through paleomagnetism. Various volcanic and sedimentary units (e.g., the Şenköy, Berdiga, Mescitli, Çatak, Kızılkaya, and Çağlayan Formations) spanning the time interval from the Early Jurassic to Middle Eocene were identified. A total of 98 locations belonging to Early/Middle Jurassic to Eocene volcanic and sedimentary units were selected for paleomagnetic core sample collection. The samples were subjected to demagnetization through thermal and alternating field methods. Characteristic remanent magnetization directions (ChRM) were obtained. Isothermal remanent magnetization (IRM) and high temperature susceptibility (HTS) measurements were made to identify the minerals responsible for magnetization. To ascertain whether magnetization was acquired through rock formation or as a consequence of subsequent tectonic processes, conglomerate and fold tests were performed. The results showed that magnetization was acquired before folding, i.e., the rocks have primary magnetization. Polarity tests were also conducted using coeval normal and reverse polarity sites. The results indicate that the mean magnetization direction for the Early-Middle Jurassic is 18.1°/55.2° (D/I) and 3.3°/51.5° (D/I) for sedimentary and volcanic rocks, respectively, and 348.7°/46.7° (D/I) for Late Jurassic/Early Cretaceous sedimentary rocks. In the Late Cretaceous period, the mean magnetization direction is 8.0°/49.3° (D/I) and 9.1°/47.0° (D/I) for sedimentary and volcanic rocks, respectively. In the case of the Early/Middle Eocene, the mean magnetization direction is 348.6°/52.7° (D/I) and 5.9°/48.8° (D/I) for sedimentary and volcanic rocks, respectively. In this study, the E/I correction was applied to the Late Jurassic/Early Cretaceous sedimentary rocks, and paleolatitude data obtained from sedimentary rocks were also utilized. Our paleomagnetic results indicate that the eastern Sakarya Zone was situated at latitudes spanning from 27.9° to 35.7° during the Early Jurassic - Middle Eocene time interval. In consequence, the eastern Sakarya Zone constituted a portion of the southern margin of the Eurasian continent during the Late Jurassic and Middle Eocene periods.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"894 ","pages":"Article 230570"},"PeriodicalIF":2.7,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermotectonic history of the Longshou Shan: From Paleozoic Tethys subduction to Cenozoic Tibetan Plateau growth","authors":"Ni Tao ,&nbsp;Ruohong Jiao ,&nbsp;Yiduo Liu ,&nbsp;Meinert Rahn ,&nbsp;Yunpeng Dong ,&nbsp;Hanjie Wen ,&nbsp;Haiqing Yan ,&nbsp;Jiangang Jiao ,&nbsp;Jun Duan ,&nbsp;Chen Wang","doi":"10.1016/j.tecto.2024.230560","DOIUrl":"10.1016/j.tecto.2024.230560","url":null,"abstract":"<div><div>Constraining exhumation and tectonic processes along an orogenic plateau's boundary provides important insights into the mechanisms leading to plateau expansion and crustal evolution. The Longshou Shan thrust belt (LSSTB) is located in the foreland of the northern Qilian Shan thrust belt, which is commonly regarded as the northeastern margin of the Tibetan Plateau. The LSSTB is thus ideal for decoding the recent expansion of the Tibetan Plateau by tracking deformational pattern at its northeastern margin. In this study, the spatiotemporal characteristics of exhumation and deformation along the LSSTB are investigated by detailed analysis and numerical modeling of published and new thermochronological data. Five Proterozoic basement and intrusion samples yielded Cretaceous apatite fission-track central ages (126–74 Ma, with mean track lengths of 12.6–13.3 μm), and Late Cretaceous to Eocene apatite (U<img>Th)/He mean ages (84–51 Ma). Inverse thermal history modeling reveals multi-stage exhumation of the LSSTB in the Permo-Triassic, late Mesozoic, Paleogene, and post-middle Miocene. Permo–Triassic exhumation hints at a &gt; 250 Ma-old peneplain surface that may have formed in response to the closure of the Paleo-Tethys and Paleo-Asian oceans. Late Mesozoic exhumation likely resulted from intracontinental extensional deformation associated with tectonic processes at the Eurasian continental margin. Exhumation during the Paleogene was likely triggered by the India-Asia collision. Post-middle Miocene periods of uplifts along the reactivated Longshou Shan thrusts (no later than 10 Ma and 5 Ma on the southern and northern Longshou Shan Thrust, respectively) were driven by the northeastward expansion of the Tibetan Plateau. Our results support the LSSTB as a long-lived block boundary since the Permo-Triassic and an emerging plateau boundary that has lately been reactivated by the Tibetan Plateau expansion.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230560"},"PeriodicalIF":2.7,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heterogeneous Seasonal Deformation and Strain Budget in Himachal, NW Himalaya from new cGPS measurements: Hydrological and Seismic Hazard Implications","authors":"Prabhat Kumar ,&nbsp;Javed N. Malik ,&nbsp;Vineet K. Gahalaut","doi":"10.1016/j.tecto.2024.230561","DOIUrl":"10.1016/j.tecto.2024.230561","url":null,"abstract":"<div><div>GPS measurements from 10 new permanent sites installed in Himachal, NW Himalaya are analysed with the primary objective to decipher the seasonal crustal deformation characteristics, its origins and hydrological implications. Additionally, we focus on the seismic hazard implications of the seasonal transients as well as of the long-term secular motion of GPS sites. Our findings suggest that the global hydrological loading models can relatively well explain the temporal surface displacements resulting from the monsoon rainfall in the Indo-Gangetic plains (IGP) but poorly account for the winter snowfall in Higher Himalaya. The approximately elliptical horizontal seasonal motion of GPS sites seems to be controlled by the spatio-temporal variations in the monsoonal hydrological load over the IGP. The hydrological process derived from the GPS data suggests slow and steady recovery in the water storage in Himachal Himalaya. The more intriguing phenomena is reflected in the unusually high seasonal site uplift and the yearlong (mid-2020 – mid-2021) plunge in the water storage corresponding to the time-period of COVID-19 lockdown phases, which could be speculated as its indirect impact on the crustal deformation history. The seasonal strain analysis revealed significant spatial heterogeneity. The arc-normal and arc-parallel seasonal strain resulting from differential seasonal motion between GPS sites seems to be primarily localized in the vicinity of locking transition zone, while the locked segment is being largely translated without experiencing significant strain. The localized seasonal strain showed positive correlation with the background seismicity rate suggesting possible modulation of the earthquake nucleation process. The regional seismic hazard assessment suggests susceptibility to a future great earthquake of ∼M_w8.4. The additional observed equivalency between the updated strain budget (∼9.3 m) and the previously reported co-seismic displacement (∼9.3 m) during the last great earthquake around ∼1400–1500 CE, suggests a recurrence interval of ∼600 years for great earthquake events in Himachal Himalaya with significant reliability.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"894 ","pages":"Article 230561"},"PeriodicalIF":2.7,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mantle conduits of the K-Pg Reunion mantle plume rise beneath the Indian subcontinent revealed by 3D magnetotelluric imaging","authors":"K.K. Abdul Azeez,&nbsp;K. Veeraswamy,&nbsp;Prasanta K. Patro,&nbsp;A. Manglik,&nbsp;Arvind K. Gupta,&nbsp;Prabhakar E. Rao,&nbsp;D. Hanmanthu ,&nbsp;B. Manoj Prabhakar ,&nbsp;B.D.N. Kishore","doi":"10.1016/j.tecto.2024.230558","DOIUrl":"10.1016/j.tecto.2024.230558","url":null,"abstract":"<div><div>The central-western region of the Indian subcontinent hosts the vast geological records of its evolution from the Archean to the Recent, including the youngest (∼65 Ma) episode of the Réunion mantle plume activity that produced a large igneous province, the Deccan Volcanic Province (DVP). A three-dimensional lithospheric resistivity image of central-western India is obtained to understand the lithospheric architecture and map any major eruption channels of the Deccan volcanism as no explicit geophysical revelation of such pathways of magma ascend has yet been made. Two high conductivity (&lt; 30 Ωm) pipe-like geometric features originating from a common deep mantle conductive zone under the Malwa plateau (northernmost lobe of the DVP) and its proximity are detected in the resistivity model. These are interpreted to be remnants of the hitherto unknown primary lithospheric pathways of magma ascent from the deep mantle melt-rich zone related to the Reunion mantle plume upwelling under central-western India. This study gives first compelling geophysical evidence of key eruptive centers of the massive Deccan volcanism in central-western India at a locale not anticipated earlier. High to moderate conductivity crustal zones and weak to moderate lithospheric mantle resistivity in most parts of the study region represent an intense and multiphase tectono-magmatic evolution of the region spanning from the Neoproterozoic to the Cretaceous-Paleogene boundary.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"894 ","pages":"Article 230558"},"PeriodicalIF":2.7,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A late Paleogene erosion event in the Sanshui Basin, southern margin of the South China Block and its tectonic significance","authors":"Peng Zhao ,&nbsp;Xiaobin Shi ,&nbsp;Lu Liu ,&nbsp;Kui Liu ,&nbsp;Yongqiang Shen ,&nbsp;Ziqiang Ren ,&nbsp;Xiaoqiu Yang ,&nbsp;Yongbin Jin","doi":"10.1016/j.tecto.2024.230557","DOIUrl":"10.1016/j.tecto.2024.230557","url":null,"abstract":"<div><div>Ubiquitous onshore Cenozoic basins of the southern margin of the South China Block (SCB) systematically show a stratigraphic hiatus in the sedimentary succession. The absence of strata between the residual Paleogene and the overlying Quaternary in the onshore basin is a serious obstacle to reconstruct their evolutionary history and completely understand the tectonic evolution of the southern SCB margin. Using multiple independent methods, this study reconstructs the entire tectonic subsidence and uplift history in the Sanshui Basin. To do so, we first constrain the eroded thickness and initial erosion time between the Quaternary strata and the residual Huayong Formation (∼41 Ma). The results show that the erosion thickness at the unconformity in the northwestern Sanshui Basin was approximately 2200 m, and the erosion event lasted from approximately 29 Ma to the early Quaternary. The tectonic evolution of the Sanshui Basin during the Paleogene to early Quaternary was characterized by four successive tectonic episodes, three rifting events, and one uplift stage. The first rifting episode lasted from ca. 66–48 Ma, during which approximately 1000 m of tectonic subsidence accommodated the deposition of the Xinzhuangcun (66–59 Ma), Buxin (59–53 Ma), and Baoyue (53–48 Ma) formations. This was followed by the second and third rifting episodes from ca. 48–29 Ma, during which the average tectonic subsidence was approximately 650–850 m, and the residual Huayong Formation (ca. 48–41 Ma) and eroded strata (ca. 41–29 Ma) accumulated. From 29 Ma to the early Quaternary, a tectonic uplift of approximately 1150 m occurred, with a rate of 43 m/Myr, which triggered the erosion of most sediments deposited during the second and third rifting episodes. Our results strongly suggest that although the main depocenters were located offshore since the second rifting episode, rifting in the Sanshui Basin continued until the occurrence of the late Cenozoic erosion event. The differential evolution between uplift (and erosion) onshore and subsidence offshore since the late Paleogene is probably related to the coastward attenuation of southeastern extrusion caused by the Indo–Asian plate collision.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"894 ","pages":"Article 230557"},"PeriodicalIF":2.7,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142706689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The improved Moho depth imaging in the Arabia-Eurasia collision zone: A machine learning approach integrating seismic observations and satellite gravity data","authors":"Vahid Teknik","doi":"10.1016/j.tecto.2024.230553","DOIUrl":"10.1016/j.tecto.2024.230553","url":null,"abstract":"<div><div>The Arabia-Eurasia convergences created one of the earth's topographic highs on the Central Tethys collisional belt. Despite the area's geological significance, a comprehensive and high-resolution map of Moho depth has been lacking due to the sparse and uneven distribution of seismically constrained Moho depth data. This study addresses this deficiency by compiling an extensive dataset of nearly 2500 seismically measured Moho depth points from 68 seismic local scale studies, resulting in the development of an updated seismically constrained Moho depth model (S-Moho) at a 0.5° × 0.5° spatial resolution. Despite some coverage gaps in the remote areas, the S-Moho model offers a more detailed view than previously available. To further improve the coverage of the S-Moho depth model, an incremental data-driven approach was employed. Initially, a gravity-based regression Moho depth model (SB-Moho) was developed by correlating S-Moho depth points with corresponding Bouguer anomalies. However, its accuracy was constrained by unaccounted isostatic and non-isostatic components. To address this limitation, a sliding window approach was applied to derive a windowed SB-Moho model (WSB-Moho). Additionally, a machine learning-based Moho model (ML-Moho) was developed using seismic Moho depth points along with 11 predictive variables. Both WSB-Moho and ML-Moho models demonstrated consistent and smooth Moho depth variations. The Zagros region reveals a prominent NW-SE oriented Moho depression (45-60 km thick), attributed to the underthrusting of the Arabian Plate beneath the Iranian Plateau. The models suggest that crustal thickening extends beyond tectonic boundaries, likely influenced by the dip of suture zones. In contrast, the crustal thickening in eastern Anatolia, northwest of the Zagros, is less pronounced, indicating different geodynamic processes. Strike-slip faulting and magmatic activity in this area contribute to a broader distribution of deformation compared to the more localized crustal thickening in the Zagros. In southeastern Zagros, strike-slip faults in central Iran accommodate much of the northward convergence of the Arabian Plate, thereby limiting the extent of crustal thickening.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"893 ","pages":"Article 230553"},"PeriodicalIF":2.7,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Top-to-south shear at the base of the eastern Tethyan Himalayan Sequence during the Eocene-Oligocene Himalayan orogeny","authors":"Zhiqin Xu ,&nbsp;An Yin ,&nbsp;Hua Xiang ,&nbsp;Qin Wang ,&nbsp;Guangwei Li ,&nbsp;Hanwen Dong ,&nbsp;Hui Cao ,&nbsp;Jianguo Gao","doi":"10.1016/j.tecto.2024.230552","DOIUrl":"10.1016/j.tecto.2024.230552","url":null,"abstract":"<div><div>The early mountain building processes in the Himalayan orogen are still not clear because of extensive deformation and metamorphism since the Miocene. A large gently dipping ductile shear zone, referred as the Tethyan Himalayan Décollement (THD), is defined here as the sole décollement of the south-verging Tethyan fold-and-thrust belt in the Lhozag-Cuona area of the eastern Himalayan orogen. The ∼4 km-thick THD is characterized by a top-to-south shear sense, moderate T/P Barrovian to high T/P Buchan type metamorphism and Eocene-Miocene partial melting. Zircon U-Pb dating of metasedimentary rocks and granitic gneisses from the THD yields protolith ages of the Late Cambrian to Early Ordovician. Based on structural analysis, zircon U-Pb ages, monazite U-Pb ages and mica ⁴⁰Ar/³⁹Ar thermochronology, the THD was the boundary shear zone at the top of the Greater Himalayan Crystalline Complex (GHC) and accommodated the persistent north-south shortening in the Tethyan Himalayan Sequence (THS) from ∼50 Ma to 20–17 Ma. From ∼20–17 Ma, the top-to-north South Tibetan Detachment System (STDS) was predominantly activated to juxtapose the unmetamorphosed or low-grade THS over the GHC. This tectonic transition can be attributed to the roof collapse in the eastern Himalaya (younger than that of the central-western Himalaya), which triggered rapid exhumation of the GHC and the northern Tethyan Himalayan gneiss domes. Hence, the THD was the predecessor of the STDS and a prolonged pathway for leucogranitic melts from the Eocene to early Miocene. The transition from the THD-controlled crustal thickening in the Eocene and Oligocene to the STDS-controlled extrusion in the Miocene shed insights on a new synthesis of the tectonic wedging model for the Himalayan evolution.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230552"},"PeriodicalIF":2.7,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}