Journal of Geodynamics最新文献

{"title":"Arc-like magmatism in syn- to post-collisional setting: The Ediacaran Angra Fria Magmatic Complex (NW Namibia) and its cross-Atlantic correlatives in the south Brazilian Florianópolis Batholith","authors":"Vojtěch Janoušek ,&nbsp;Luana Moreira Florisbal ,&nbsp;Jiří Konopásek ,&nbsp;Petr Jeřábek ,&nbsp;Maria de Fátima Bitencourt ,&nbsp;Petr Gadas ,&nbsp;Vojtěch Erban ,&nbsp;Veronika Kopačková-Strnadová","doi":"10.1016/j.jog.2022.101960","DOIUrl":"10.1016/j.jog.2022.101960","url":null,"abstract":"<div><p>Ediacaran syn-tectonic plutonic rocks (amphibole gabbros, quartz diorites/tonalites to biotite- and muscovite-bearing granites) of the Angra Fria Magmatic Complex (Kaoko Belt, north-western Namibia) belong to two compositionally similar, magnesian, transitional tholeiitic–calc-alkaline suites, the Older (∼625–620 Ma) and the Younger (∼585–575 Ma). Both have counterparts in the broadly contemporaneous Florianópolis Batholith (southern Brazil), from which they were separated during the Cretaceous opening of the southern Atlantic. In the Angra Fria Magmatic Complex, the only unequivocal mantle contributions are identified in mingling zones of the Younger Suite and hybrid mafic–intermediate dykes of uncertain age. Previously published Hf-in-zircon isotopic data, together with new whole-rock geochemical and Sr–Nd isotopic signatures, underline an important role of crustal anatexis of a material with late Palaeoproterozoic to early Mesoproterozoic mean crustal residence (1.9–1.5 Ga). This interval resembles some of the published Nd model ages for Tonian ‘Adamastor Rift’-related felsic magmatic rocks in the Namibian Coastal and Uruguayan Punta del Este terranes. In detail, the Older Suite probably originated mainly by fluid-present melting of metabasalts and metatonalites, followed by (near) closed-system fractional crystallization (with or without accumulation) of amphibole ± plagioclase. For the Younger Suite, the principal process was the dehydration melting of relatively felsic lower crustal protoliths (metagreywackes or intermediate–acid orthogneisses &gt;&gt; metapelites), leaving garnet in the residue. Based on the geological context, the conspicuous enrichment of hydrous-fluid-mobile large ion lithophile over the conservative high field strength elements is not interpreted through a classic model of oceanic plate subduction, devolatilization, and fluxed-melting of the overriding mantle wedge. Instead, it is thought to reflect high-grade metamorphism of deeply buried continental crust and attendant water-fluxed melting of the overlying crustal lithologies, connected with inversion of the Tonian ‘Adamastor Rift’.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"155 ","pages":"Article 101960"},"PeriodicalIF":2.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47127466","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":"Quaternary deformation patterns in East–Central Iran, constrained by coseismic–postseismic displacements of the 2017 Hojedk triplet earthquake in the Kerman Province","authors":"Marzieh Khalili ,&nbsp;Yildirim Dilek ,&nbsp;Leila Zareian Ronizi","doi":"10.1016/j.jog.2022.101941","DOIUrl":"10.1016/j.jog.2022.101941","url":null,"abstract":"<div><p><span><span>The Central Iranian Microcontinent (CIM) in east-central Iran is located north of the active Arabia–Eurasia collision zone. Here, we report on the structure, deformation patterns, and earthquake occurrences along the dextral Lakar–Kuh and Godar fault systems in the CIM. The geometry of these fault systems marks a major restraining bend responsible for surface and rock uplift in the Plio–Pleistocene that produced the Mian Kuh mountain range. The 2017 Hojedk triplet earthquake (Mw = 5.8–6.0) occurred in the Mian Kuh Range. Sentinel–1 A Interferometer Synthetic Aperture Radar (InSAR) images (descending and ascending) were used to extract the coseismic displacements associated with the earthquake and its </span>aftershocks. The results indicate a maximum displacement of ∼20 cm, corresponding to hanging wall uplift along the radar Line-of-Sight (LOS) direction. The Geodetic Bayesian Inversion (GBIS) of the coseismic deformation indicates that the causative faults of the Hojedk earthquakes were two reverse faults with NW–SE–strikes and SW–dips, with minor dextral slip components. Given the </span>focal mechanism<span> solutions and the epicenter<span> locations of the triple earthquake sequence, we infer that these faults at the southern termination of the Lakar–Kuh Fault represent two segments (with different dip angles) of a previously unrecognized, blind reverse fault (a splay of the Godar Fault at depth). The Hojedk Earthquake and the geometry and kinematics of its causative faults highlight the strong potential of seismic hazard zones along the strike-slip fault systems in the CIM.</span></span></p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"153 ","pages":"Article 101941"},"PeriodicalIF":2.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48266880","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":"Stress evolution on major faults in Tien Shan and implications for seismic hazard","authors":"Yajin Pang","doi":"10.1016/j.jog.2022.101939","DOIUrl":"10.1016/j.jog.2022.101939","url":null,"abstract":"<div><p><span>Tien Shan tectonic belt has experienced intense seismicity and a series of destructive strong earthquakes. However, earthquake triggering effects and faulting interactions in this area are poorly understood. A 3D finite element model of Tien Shan tectonic belt is constructed, to investigate stress evolutions on major faulting zones driven by interseismic tectonic loading and historical strong earthquakes with M≥ 6.0 since 1900. The numerical results show Tien Shan is dominated by nearly N-S compression, with higher tectonic loading rate in southwest Tien Shan. 1906 Manas M7.7 earthquake exerted pronounced Coulomb stress increase on its adjacent faulting zones, especially in the </span>epicenter of 2016 Hutubi M6.0 earthquake. And three large earthquakes with M≥ 8.0, e.g., Chilik M8.3 earthquake in 1889, Kemin M8.0 earthquake in 1911 and Atushi M8.2 earthquake in 1902, increased the Coulomb stress by above 100 kPa in the epicenter of 1991 Keping M6.0 earthquake. While, stress perturbations by other strong earthquakes are limited, with slight Coulomb stress changes in the epicenters of their subsequent earthquakes. Overall, strong earthquakes with M&gt; 7.0 in Tien Shan, induced substantial Coulomb stress changes on the adjacent faulting zones. Stress evolutions on major faults reveal higher stress accumulation in southwest Tien Shan, east KQX fault, west BoA fault, and HMT fault, indicating higher seismic risk.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"153 ","pages":"Article 101939"},"PeriodicalIF":2.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49542579","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":"Salt diapirism in the eastern margin of the Pre-Caspian Basin: Insight from physical experiments","authors":"Jing Ziyan ,&nbsp;Li Guobin ,&nbsp;Zhang Yajun ,&nbsp;Xie Tianfeng ,&nbsp;Feng Yuan ,&nbsp;Zhao Binbin ,&nbsp;Wang Hongbin ,&nbsp;Dai Shuang ,&nbsp;Yang Zhaoping ,&nbsp;Yuan Xiaoyu ,&nbsp;Shi Zhongsheng ,&nbsp;Tian Xin","doi":"10.1016/j.jog.2022.101940","DOIUrl":"10.1016/j.jog.2022.101940","url":null,"abstract":"<div><p><span><span>Since the 1950 s, salt diapirism has been shown to be closely related to hydrocarbon accumulation and has been a hot spot of research activity in structural and petroleum geology. Many salt structural, such as salt wall, roller, pillow, welt and </span>anticline<span> have been formed in the Pre-Caspian Basin during the post-Kungurian (Lower Permian) times. Meanwhile, mechanisms of salt structure deformation and the influence of the sub-salt strata on salt diapirism is still unclear. Based on seismic data<span> and a geological model of the eastern margin of the Pre-Caspian Basin, physical simulation experiments of salt diapirism have been conceived. Performed to analyze, the dynamic process of salt structure deformation, and to clarify mechanisms of the salt diapirism and the relationships between the salt structures and the underlying strata. Differential loading seems to a principal mechanism accounting for sediment. The sedimentation rate of the overburden formations had a great impact on the salt structure forms and geometry. The physical experiments showed that: salt diapirism starts in the basin margin with </span></span></span>progradation of sediments and then continues down-slope toward the basin center. The height and width of the salt structures are influenced by dip angle of the sub-salt. The larger-scale salt structures occurred in the inner basin zones, followed the central slope zone and the basin margin with a large dip angle.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"153 ","pages":"Article 101940"},"PeriodicalIF":2.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43216439","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":"U-Pb geochronology and geochemistry of the Torud igneous rocks: Implications for post-collision Eocene magmatism in northeast Iran","authors":"Morteza Khalatbari Jafari ,&nbsp;Hassan A. Babaie ,&nbsp;Songjian Ao ,&nbsp;Wenjiao Xiao","doi":"10.1016/j.jog.2022.101942","DOIUrl":"10.1016/j.jog.2022.101942","url":null,"abstract":"<div><p><span>New geochemical and U-Pb isotopic data from the Torud volcanic and subvolcanic rocks and their associated dikes<span><span><span><span> exposed along the southern margin of the Sabzevar-Torud zone provide new evidence for Early-Middle Eocene, post-collision </span>magmatism<span> in northeast Iran. The 52–46 Ma (late Ypresian-Lutetian) U-Pb age interval of zircons<span> separated from these rocks confirm the paleontological age of nummulite-bearing limestone interlayers. Inherited zircons separated from these igneous rocks have a much wider range of U-Pb ages that include Archean, Paleoproterozoic, Mesoproterozoic, Carboniferous, Permian, Triassic, </span></span></span>Middle Jurassic<span>, and Late Cretaceous. Most volcanics and subvolcanic rocks display high-K calcalkaline and shoshonitic trends. Distinct crystal fractionation patterns of the volcanic and subvolcanic rocks suggest </span></span>magmatic differentiation in separate </span></span>magma chambers<span>. The studied rocks, depleted in the HFSE and enriched in the LILE, display nearly homogeneous isotopic Sr (0.7039–0.7055) and Nd (0.5126–0.5129) ratios and positive ɛNd values (0.08–0.56) indicating partial melting from an enriched lithospheric mantle source that was slightly contaminated with crustal material. Fluids, especially those released from the subducted slab, affected the composition of the source for the studied rocks. The magmatism occurred in the Torud area after the Late Cretaceous-Paleocene collision of the Central Iran microcontinent and Binalud-Kopeh-Dagh blocks and the Early-Middle Eocene break-off of the subducted slab.</span></p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"153 ","pages":"Article 101942"},"PeriodicalIF":2.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43605465","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":"Lithosphere structure in the collision zone of the NW Himalayas revealed by alocal earthquake tomography","authors":"Irina Medved ,&nbsp;Ivan Koulakov ,&nbsp;Sagarika Mukhopadhyay ,&nbsp;Andrey Jakovlev","doi":"10.1016/j.jog.2022.101922","DOIUrl":"https://doi.org/10.1016/j.jog.2022.101922","url":null,"abstract":"<div><p><span><span>In this study, we obtained new 3D seismic tomography models of the crust and uppermost mantle beneath the northwestern </span>Himalayas down to a depth of 120 km. The data were provided by the India Meteorological Department (IMD) and complemented by the Global International Seismological Centre (ISC) Catalogue. The distribution of anomalies correlates with the main </span>geological features<span> of the region. Specifically, the mountain ranges of the Greater and Lesser Himalaya stand out as a low-velocity anomaly, and the Indian Plate is visible as a high-velocity anomaly underthrusting the Himalayas. The Indian Plate not only underthrusts northwards below the Himalayas, but also bends westwards as it gets closer to the Hindukush Region. A peculiar feature of the model is a high-velocity anomaly in the Kaurik Chango Rift, interpreted as a remnant of the oceanic crust, left after the Indotethys Ocean’s closure. In the seismically active Delhi-Haridwar Ridge, a low-velocity upper crustal layer is possibly associated with the sediments of the Indo-Gangetic Plain and with a large number of fault structures. The fragmentation of the Delhi-Haridwar Ridge softens the movement of the Indian Plate to the north, so that the Tethyan Himalaya crust in the area of the Kaurik Chango Fault has remained consolidated and manifests itself as a high-velocity anomaly.</span></p></div><div><h3>Data Availability</h3><p>The full directory of LOTOS code with data corresponding to this study is available at <span>https://doi.org/10.5281/zenodo.5519210</span><svg><path></path></svg> (accessed on 23 September 2021).</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"152 ","pages":"Article 101922"},"PeriodicalIF":2.3,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72121357","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":"Lithosphere Structure in the Collision Zone of the NW Himalayas Revealed by Local Earthquake Tomography","authors":"I. Medved, I. Koulakov, S. Mukhopadhyay, A. Jakovlev","doi":"10.1016/j.jog.2022.101922","DOIUrl":"https://doi.org/10.1016/j.jog.2022.101922","url":null,"abstract":"","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42064397","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":"Localization and characterization of the southern Ulsan fault (UF) using geo-electrical imaging: Implication for seismic hazard assessment in an urbanized area","authors":"Sambit Prasanajit Naik ,&nbsp;Ohsang Gwon ,&nbsp;Kiwoong Park ,&nbsp;Sang Yeol Bae ,&nbsp;Hyeon-Cho Shin ,&nbsp;Jeong-Heon Choi ,&nbsp;Young-Seog Kim","doi":"10.1016/j.jog.2022.101919","DOIUrl":"10.1016/j.jog.2022.101919","url":null,"abstract":"<div><p><span><span>In seismic hazard assessment, subsurface geophysical surveying has gained popularity in recent years towards fault mapping and determining seismic deformation parameters such as fault offset, recurrence, and depth of fault, locating proper </span>trench sites based on the subsurface information. In the present study, electrical resistivity </span>tomography<span> (ERT) was used to (1) locate the trace of the southern segment of the Ulsan fault, (2) to test the applicability of ERT techniques for active fault mapping in a close to the highly urbanized and complex geological environment with a slow tectonic activity. We have applied the ERT technique at five sites. At one place, we used the Wenner array, Schlumberger array, Dipole-Dipole array, and Seismic-profiling techniques to know which method provides a better result in complex geological conditions like Korea<span><span>. Out of these methods, the Dipole-Dipole array provided high-resolution results and was used for the other two sites. The ERT result shows high and low resistivity zones interpreted as bedrock (mainly Tertiary and Cretaceous formations) and coarse fluvial sediment<span> layer, respectively. The maximum vertical displacement recorded along the fault varies from 6 m to 12 m. Based on the ERT results, two trenches were excavated to directly investigate the deformation pattern associated with the southern segment of the Ulsan fault. The ERT and trench survey results support that the southern Ulsan fault has slipped multiple times since Quaternary. Using this multi-approach, ~5 km long active fault map was prepared for the southern Ulsan Fault. It is found from this study that the integrated approach is highly beneficial where contrasting sub-lithological units exist in terms of their physical properties, even though human activity or the ongoing urbanization process has modified the surface morphology. This study argues for judicious use of ERT techniques to delineate the shallow subsurface geology<span> across various active faults in the Korean peninsula and similar </span></span></span>tectonic settings.</span></span></p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"151 ","pages":"Article 101919"},"PeriodicalIF":2.3,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46663338","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 2021 Mw7.4 Maduo earthquake: Coseismic slip model, triggering effect of historical earthquakes and implications for adjacent fault rupture potential","authors":"Xianwen Liu ,&nbsp;Qiang Chen ,&nbsp;Yinghui Yang ,&nbsp;Qian Xu ,&nbsp;Jingjing Zhao ,&nbsp;Lang Xu ,&nbsp;Rong Liu","doi":"10.1016/j.jog.2022.101920","DOIUrl":"10.1016/j.jog.2022.101920","url":null,"abstract":"<div><p><span>On 22 May 2021 (CST), an Mw7.4 earthquake struck Maduo County, Qinghai Province, China, which was the largest seismic event in China since the 2008 Mw7.9 Wenchuan earthquake. Several scientific questions associated with the event could be addressed: (1) what fault slip model can explain the Maduo earthquake? (2) what effects do historical earthquakes impose on the Maduo earthquake? and (3) what implications does the Maduo earthquake have for future rupture potential of adjacent tectonic faults? So we conduct a comprehensive study to answer the three questions by collecting satellite SAR images, GPS data, seismic waveform data, historical earthquakes, and </span>aftershocks<span> associated with the Maduo earthquake. The estimated fault slip model shows that the Maduo earthquake ruptures<span> two faults in a manner of dominant sinistral strike-slip motion, with slip peaks of ~4.8 m occurring near the surface. The minor fault to the east dips to the south accommodating an obvious reverse slip, well consistent with reverse fault scarps, reverse faulting aftershocks, and significant upward surface displacements immediately south of this branch. Such a reverse slip is probably controlled by the motion of nearby major sinistral strike-slip faults (the Eastern Kunlun fault and the Maduo–Gande fault). Among 32 historical Mw≥ 6.0 earthquakes used in this study, we find that the 1937 Mw7.8 Huashixia earthquake may affect the Maduo earthquake most, delaying its occurrence by decreasing the Coulomb failure stress (CFS) at the hypocenter by &gt; 1 bar and on the entire causative fault by an average of 0.68 bar. Besides, the Mw6.1 Yangbi earthquake, which occurred ~4.5 h ahead of the Maduo earthquake, appears to make little influence on the Maduo earthquake because it hardly perturbates the CFS at the hypocenter of the Maduo earthquake. Furthermore, the cumulative CFS change due to both the 32 historical earthquakes and the 2021 Maduo event indicates that the Tuosuo Lake–Maqu segment of the Eastern Kunlun fault may be at high risk of future rupture.</span></span></p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"151 ","pages":"Article 101920"},"PeriodicalIF":2.3,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49145383","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":"Permian–Triassic adakitic igneous activity at Northern Mongolia: Implication for Permian–Triassic subduction system at the Siberian continental margin","authors":"Kanta Umeda ,&nbsp;Nemekhbayar Purevsuren ,&nbsp;Kazuhiro Tsukada ,&nbsp;Lodoidanzan Altansukh ,&nbsp;Bayart Nadmid ,&nbsp;Khishigsuren Sodnom ,&nbsp;Manchuk Nuramkhaan ,&nbsp;Taro Kabashima ,&nbsp;Tomoyuki Kondo","doi":"10.1016/j.jog.2022.101918","DOIUrl":"10.1016/j.jog.2022.101918","url":null,"abstract":"<div><p>The geochemistry of the Permian–Triassic large-scale igneous rock body of northern Mongolia is a key factor in understanding the subduction-related magmatism at the margin of “Siberian continent.” Several studies have been done in the Permian–Triassic igneous body; however, its detailed magmagenesis and tectonic significance remain unclear. This paper investigates the geochemistry of the Upper Permian andesites (Bugat/Baruunburen Formation) and the Late Permian–Middle Triassic plutonic rocks (Selenge plutonic rock complex) of the Permian–Triassic igneous body, and intermediate dike intruding into them, and discusses the Late Permian–Middle Triassic magmatism of the Siberian continental margin. These rocks show a linear distribution on the variation diagram. They are therefore likely to be derived from a single magmatic source. The rocks, characterized by low K₂O/Na₂O, high Sr/Y, high La/Yb, and high Sr/La ratios are adakitic rocks of basaltic slab-melt origin. The samples are enriched in Cr and Ni and have a high Mg# compared with the typical slab-melt. This is likely due to an interaction between the slab-melt and the overlying mantle peridotite during its ascent. The Nb/Ta variation of the samples may point crustal contamination to the magma. The paleolatitude of the Bugat/Baruunburen Formation is calculated to be 37.1° N based on thermal remanent magnetization. Therefore, the Late Permian–Middle Triassic large-scale adakitic igneous activity had taken place in the volcanic arc along the Siberian continental margin in the mid-latitudes of the Northern Hemisphere. The geochemical characteristics of the intermediate dike are almost the same as those of the Bugat/Baruunburen Formation and the Selenge plutonic rock complex, indicating that adakitic igneous activity continued after the Early Triassic.</p></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"151 ","pages":"Article 101918"},"PeriodicalIF":2.3,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0264370722000229/pdfft?md5=b7eeaed8e822729c8c1755b575ff2018&pid=1-s2.0-S0264370722000229-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41451444","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}