Journal of Geodynamics最新文献

{"title":"Quantitative modelling of multiphase tectonic subsidence mechanism and lithospheric stretching controls on the evolution of the Central Kotla Graben, Sirt Basin, Libya","authors":"Mohammed.S. Gumati ,&nbsp;J. Redfern","doi":"10.1016/j.jog.2025.102112","DOIUrl":"10.1016/j.jog.2025.102112","url":null,"abstract":"<div><div>The Kotla Graben remains a poorly investigated region. Understanding the architecture of the graben and adjacent basement highs through time is critical for resolving due to the impacts of transitional accelerated subsidence to thermal sagging and basin-bounding fault reactivation mechanisms that create such a graben. This study attempts to restore the Late Cretaceous-Middle Eocene geometry of the Central Kotla Graben, using a combination of well data from 47 boreholes and twenty-six 2D seismic reflection profiles, nine of which are selected to show examples of the new information on the present-day architecture of the deeply buried graben. This geological and geophysical integration has enabled many variables to be involved in backstripping and lithospheric stretching calculations. The shape of backstripped subsidence curves reveals four discrete tectonic (I–IV) phases of subsidence-uplift that are recognised with variable rates and separated by three different types of unconformities. The rifting initiated during the Cenomanian, and both highs were uplifted during the Santonian. The rifting peaked during the Palaeocene and was terminated by a thermal sagging phase during the Eocene. Seismic interpretation indicates that the acoustic basement is generally characterised by three main intra-basement reflection (IRP) packages, located within the Dahra Platform basement and referred to as the Dahra Shear Zone in this study. However, seismic analysis has also enabled the recognition of four different seismic facies units. These facies units are integrated with three recognised gamma-ray log trends to correlate lithological variations within the distinctive boundaries of the tectonic subsidence phases. The tectonic subsidence maps of the graben geometry indicate that during the syn- and post-rift phases, the depocentre of the Central Kotla Graben is located in the south. Two different techniques used to estimate the stretching factor (β): The subsidence-derived stretching revealed lithospheric stretching ranged from 1.0 to 1.5. Moreover, the fault-derived stretching across the Central Kotla Graben ranged from 1.5 to 2, suggesting that the maximum crustal stretching in the graben axis ranges from 50 % to 100 %. This discrepancy is described as “extension discrepancy”.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"165 ","pages":"Article 102112"},"PeriodicalIF":2.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144904410","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":"In situ U–Pb dating of upper triassic magmatic flows (Spilite) in the External Western Alps (Pelvoux massif): A peripheral CAMP activity?","authors":"Dorian Bienveignant ,&nbsp;Stéphane Schwartz ,&nbsp;Yann Rolland ,&nbsp;Matthias Bernet ,&nbsp;Adrien Vezinet ,&nbsp;Julien Léger ,&nbsp;Maxime Bertauts ,&nbsp;Martin Huraut ,&nbsp;Carole Cordier ,&nbsp;Thierry Dumont ,&nbsp;Valérie Magnin ,&nbsp;Mélanie Balvay ,&nbsp;Antonin Bilau ,&nbsp;Louise Boschetti ,&nbsp;Jerome Nomade","doi":"10.1016/j.jog.2025.102113","DOIUrl":"10.1016/j.jog.2025.102113","url":null,"abstract":"<div><div>Magmatic activity during the Triassic-Jurassic transition coincided with the breakup of Pangea, marking a pivotal period in Western European tectonic evolution. However, this activity remains poorly documented in the External Western Alps. Dating the emplacement and alteration of Triassic magmatic rocks such as the spilites in the Alps has long been challenging due to the complex alteration history and the scarcity of suitable mineral phases. This study employs <em>in situ</em> U-Pb dating of carbonate to constrain the timing of hydrothermal alteration of spilites from the Pelvoux massif (France), offering a new temporal framework for these processes. Dolomite and calcite filling vesicles and veins in the spilites yield ages of 201 ± 15 Ma and 202 ± 47 Ma, respectively, consistent with the stratigraphic emplacement interval of these lavas during the Upper Triassic. Notably, the U-Pb system in dolomite has preserved hydrothermal conditions related to magmatic emplacement, without resetting during two subsequent geological events at temperatures approaching 300°C, emphasizing its reliability as a chronometer in this context. The obtained ages overlap with the temporal framework of the Central Atlantic Magmatic Province (CAMP) and geochemical signatures of the spilites correspond to medium/high-Ti transitional to alkaline basalts, comparable to continental basalts such as those of the CAMP. This suggests a shared tectono-magmatic context with mantle-derived magmatism. Furthermore, the spatial proximity of the studied spilites to lower crustal CAMP-related magmatism in the Internal Alps supports a potential genetic relationship, with magma ascent likely facilitated by inherited tectonic structures during the Upper Triassic extension and the opening of the Alpine Tethys. Hydrothermal alteration, marked by spilitization and carbonate precipitation, occurred under low- to moderate-temperature conditions (70–360°C), possibly driven by marine or continental-derived fluids. By providing the first absolute geochronological constraints on spilites in the External Western Alps, this study expands the recognized extent of CAMP. It underscores the utility of carbonates as reliable archives for unraveling hydrothermal and magmatic histories.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"165 ","pages":"Article 102113"},"PeriodicalIF":2.1,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144908524","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":"Viscoelastic relaxation and afterslip following the 2008 Mw 7.9 Wenchuan earthquake","authors":"Weicheng Gong ,&nbsp;Yunqiang Sun","doi":"10.1016/j.jog.2025.102111","DOIUrl":"10.1016/j.jog.2025.102111","url":null,"abstract":"<div><div>Post-seismic deformation following big earthquakes can help to better analyze the rheological structure of the lithosphere and geodynamic processes. The extensive and long-lasting post-seismic deformation following the 2008 <em>M</em>_<em>w</em>7.9 Wenchuan earthquake offers a unique opportunity. This study constructed a three-dimensional (3D) viscoelastic finite element model of the eastern Tibetan Plateau and calculate the post-seismic deformations of the 2008 <em>M</em>_<em>w</em>7.9 Wenchuan earthquake using four rheological models (Maxwell, Kelvin, Poynting-Thomson, and Burgers). The results show that among these four viscoelastic models, the Burgers model provides the best fit to the post-seismic deformation of the Wenchuan earthquake, but there is still a lack of early deformation near the co-seismic rupture zone. We then also analyze the impact of the afterslip on post-seismic deformation using three different afterslip models. The results show that afterslip plays a dominant role in the early post-seismic deformation, especially in the near field of the rupture zone. The optimal Burgers model combined with afterslip can better explain the post-seismic deformation of the Wenchuan earthquake. The optimal steady-state viscosities for the middle-lower crust and upper mantle of the Songpan-Ganzi block are 7 × 10¹⁸ Pa·s and 6 × 10¹⁹ Pa·s, respectively.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"165 ","pages":"Article 102111"},"PeriodicalIF":2.1,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780706","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":"Geodynamics of East Asia marginal sea basins: Stress field modelling","authors":"Shangxin Wu,&nbsp;Guiting Hou,&nbsp;Ruizhe Wang,&nbsp;Lunyan Wei","doi":"10.1016/j.jog.2025.102109","DOIUrl":"10.1016/j.jog.2025.102109","url":null,"abstract":"<div><div>The East Asian marginal sea basins (EAMSB) are located at the junction between East Asia and the western Pacific plates, displaying a typical NE-trending en echelon pattern. Their formation is closely related to intense marginal extensional deformation since the Cenozoic. Owing to their intricate geological architecture and varied mechanisms of formation, these basins have emerged as a research hotspot in Earth science. However, due to limitations in geological observations and uncertainties in traditional tectonic models, the formation mechanisms of marginal sea basins remain highly controversial. This study integrates multi-source observational data and 3D spherical shell finite element method to systematically investigate the formation and evolution of the EAMSB, particularly focusing on their NE-trending en echelon pattern. The results indicate that the basin development in this region is primarily controlled by the far-field compressional stress generated by the India–Eurasia plate collision zone, as well as the extensional and radially downward shear stress imposed by the subduction of the Pacific and Philippine Sea plates. In addition, the episodic changes in regional tectonic stress play a key role in the formation of the EAMSB. The model delineates three principal evolutionary stages of the EAMSB: 1. In the early Eocene, the subduction of the Izanagi-Pacific ridge induced surface extension rather than compression along the eastern Asian margin due to shell bending. Meanwhile, under the combined influence of the India-Eurasia collision, rifting occurred along the East Asian margin. 2. In the late Eocene, the transition to subduction toward the Pacific Plate and the arrival of the Philippine Sea plate intensified boundary loads, triggering tectonic reversal and localised stress concentration. Simultaneously, as the India-Eurasia convergence zone entered the “hard collision” period, rifting was further facilitated. 3. From the Oligocene to early Miocene, the subducting plate became older and colder, with a steepening subduction angle, while the India–Eurasia collision continued. The rollback of the subducting plate induced eastward extension, which favored the development of eastward extensional deformation and led to the formation of a NE-trending en echelon pattern of the EAMSB.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"165 ","pages":"Article 102109"},"PeriodicalIF":2.1,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703235","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 dating of carbonate gangue with associated As–Sb mineralization in the Matra Fault (Alpine Corsica, France): Constraints for the rifting stage in the Tyrrhenian Sea","authors":"Maria Di Rosa ,&nbsp;Danis I. Filimon ,&nbsp;John A. Groff ,&nbsp;Michele Marroni","doi":"10.1016/j.jog.2025.102110","DOIUrl":"10.1016/j.jog.2025.102110","url":null,"abstract":"<div><div>This paper presents results of the first attempt to date a normal fault system that affected the eastern side of the Alpine Corsica (France). The U–Pb method was employed to date carbonate material with associated As–Sb mineralization in the Matra Fault, a N–S striking normal fault located southward of the Castagniccia dome. This fault cuts the Alpine nappe stack, here consisting of two oceanic-derived tectonic units, including Middle–Late Jurassic metaophiolites and/or related Early Cretaceous metasediments. From the Late Cretaceous onward, these units were involved in subduction processes and record peak eclogite facies metamorphism. After a complex exhumation path to the surface, these units then experienced long-lasting extensional tectonics linked to the collapse of the Alpine wedge, followed by two rifting stages. The first rifting stage occurred in the Oligocene-Early Miocene and the second in the Middle Miocene to Quaternary that caused the opening of the Liguro–Provencal and the Tyrrhenian back-arc basins, respectively. The U–Pb dating of the Matra Fault yields a weighted age of 9.80 ± 0.37 Ma. Therefore, the Matra Fault developed, in association with syndeformational As–Sb–Fe sulfide mineralization, during the opening of the Tyrrhenian back-arc basin. This finding represents a significant advance in understanding the extensional tectonics in Corsica during the opening of the Tyrrhenian back-arc basin.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"165 ","pages":"Article 102110"},"PeriodicalIF":2.1,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703236","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 North Dobrogea Orogen revisited: Late Miocene structural reactivation along the Trans-European Suture Zone","authors":"William Cavazza ,&nbsp;Thomas Gusmeo ,&nbsp;Antoneta Seghedi ,&nbsp;Ioan Munteanu ,&nbsp;Silvia Cattò ,&nbsp;Massimiliano Zattin ,&nbsp;Lorenzo Gemignani ,&nbsp;Irene Albino","doi":"10.1016/j.jog.2025.102101","DOIUrl":"10.1016/j.jog.2025.102101","url":null,"abstract":"<div><div>The Northern Dobrogea Orogen is the onshore segment of the southeastern termination of the Trans-European Suture Zone, the most prominent tectonic boundary of Europe, and was affected by multiple superposed deformation episodes in the Paleozoic and Mesozoic. Contrary to the widely held notion that the North Dobrogea Orogen has experienced only very mild and local deformation since the mid-Cretaceous, our (U-Th)/He analyses on apatites from Precambrian, Paleozoic, and Triassic basement and cover rocks indicate a well-defined and widespread episode of cooling/exhumation starting in the late Miocene. The high level of data coherence and the fact that all tectonic units of North Dobrogea have been affected by such episode warrants a geological explanation of supra-regional extent. Miocene cooling/exhumation in Dobrogea can be placed in a larger framework of coeval intraplate compressional deformation affecting a wide area ranging from the Greater Caucasus to the Romanian sector of the Black Sea continental shelf. We propose that the structural inversion of inherited structures in the study area is a distant echo of the Arabia-Eurasia hard collision, which started in the mid-Miocene some 1200 km away to the southeast. Low-temperature thermochronologic data for the area north of the Bitlis-Pütürge suture zone of SE Anatolia indicate that the tectonic stresses related to the Arabian collision were transmitted efficiently in the Eurasian hinterland over large distances, focusing preferentially at rheological discontinuities located as far as the northern shores of the Black Sea. Late Miocene far-field deformation in the hinterland of the Arabia-Eurasia collision zone decreases gradually westward from the rapidly exhuming Greater Caucasus, located in front of the area of maximum indentation, through Crimea, to the Odessa shelf and Dobrogea, where deformation has been significantly less and therefore remained underestimated until now.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"164 ","pages":"Article 102101"},"PeriodicalIF":2.1,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143941515","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":"Probing the active kinematics in northwestern Himalayan foreland, Pakistan: Insights from seismicity and gravity data","authors":"Mohammad Tahir,&nbsp;Bilal Saif,&nbsp;Tahir Muhammad Iqbal,&nbsp;Raja Adnan Habib,&nbsp;Talat Iqbal,&nbsp;Muhammad Awais,&nbsp;Muhammad Ali Shah","doi":"10.1016/j.jog.2025.102100","DOIUrl":"10.1016/j.jog.2025.102100","url":null,"abstract":"<div><div>Active tectonic forces and elements along northwestern Himalayan foreland have been probed through determination of seismic parameters duly substantiated by gravity data analysis. Local broadband waveform data of seven moderate to small size earthquakes recorded by CES and PMD networks was analyzed for resolving focal mechanisms and stress orientation. These predominantly strike-slip seismic events represent NW-SE oriented causative faults while the maximum horizontal stress (SHmax) is oriented in the NNW–SSE direction that mimics the Indo-Eurasian plate convergence. Depicted structure was corroborated through analysis of TOPEX satellite gravity data. Shallow right-lateral strike-slip faults observed in gravity data are consistent with the determined focal mechanism solutions. The residual and regional gravity data validates variation in faulting styles with depth as observed in seismic studies. The predominant shallow strike-slip faulting may be associated with interaction of Himalayan thrust and fold-belt with the Indian flexural forebulge known as Sargodha-Delhi basement ridge. Considering these faults to be R-shears of the western plate boundary, i.e. Chaman fault system may provide an alternate tectonic explanation. Total slip in the area, seems to be occurring partly aseismically along viscous decollement in the Himalayan Front i.e. Salt Range and partly seismically through brittle deformation of the basement ridge.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"164 ","pages":"Article 102100"},"PeriodicalIF":2.1,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931819","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":"Sub-Moho lithospheric modification beneath the western Deccan Volcanic Province adjoining the Konkan plains: Evidence from Magnetotellurics","authors":"N.N. Chakravarthi ,&nbsp;G. Pavankumar ,&nbsp;Raj Sunil Kandregula ,&nbsp;A. Manglik","doi":"10.1016/j.jog.2025.102102","DOIUrl":"10.1016/j.jog.2025.102102","url":null,"abstract":"<div><div>The western continental margin of India consists of significant geomorphological features, namely the Konkan Coastal Plains (KCP), the coast parallel Western Ghat Escarpment (WGE), and the elevated Deccan plateau covered by massive lava flows, a product of mantle plume – lithosphere interaction. The region has also experienced multiple episodes of rifting. As a result, geophysical characterisation of the crust and mantle lithosphere is necessary to better understand the plume-lithosphere interaction process and its impact on the cratonic lithosphere beneath the western Deccan Volcanic Province (DVP). We present the results from 2-D and 3-D inversion of magnetotelluric (MT) data acquired along a 200 km long profile traversing in E-W direction across the KCP and the western Deccan plateau. The results reveal a distinct change in the regional geoelectric strike direction from N-S in the KCP to NW-SE in the Deccan plateau with the WGE forming the boundary between these two regions. The geoelectric model constructed from 2-D inversion of the MT data yields highly resistive fragmented eastward thickening cratonic blocks of the Dharwar Craton, dissected by faults/fracture zones of pre-eruptive times. The 3-D full-impedance tensor inversion shows similar resistive blocks along with a pronounced low electrical conductivity zone beneath the Deccan Plateau. The moderate-to-high conductivity zones underlying the resistive cratonic blocks possibly represent the relics of the interaction between the Indian lithosphere and the Réunion plume, and a zone of volatiles /long lived sulfide fluids due to the effect of residual thermal anomaly. We interpret this feature as an evidence for lithospheric modification through upwelling and decompressional melting of the volatile-enriched mantle. We infer that the persistent dynamic topography of the WGE is due to the presence of such fluids at the sub-Moho depths and uplifting of a low-to-intermediate strength lithosphere.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"164 ","pages":"Article 102102"},"PeriodicalIF":2.1,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143928152","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":"Late Carboniferous-Early Permian geodynamic evolution of NW Iran: Zircon U-Pb ages, Hf isotopes, and whole rock geochemistry of Salmas amphibolites","authors":"Robab Hajialioghli ,&nbsp;Mohssen Moazzen ,&nbsp;Sorraya Saeidi ,&nbsp;Ali Mohammadi ,&nbsp;Oscar Laurent","doi":"10.1016/j.jog.2025.102089","DOIUrl":"10.1016/j.jog.2025.102089","url":null,"abstract":"<div><div>We present new geochronological, petrological, and geochemical data from the amphibolites of the Salmas metamorphic complex in NW Iran. This region is where the Sanandaj-Sirjan magmatic-metamorphic zone, the Urmia-Dokhtar magmatic arc, and the Eastern Anatolian Plateau converge, creating a complex geodynamic context. The amphibolites alternate with gneisses and metamorphosed limestone layers and appear as enclaves of varying sizes within the gneisses. Fine- to medium-grained amphibole and plagioclase, exhibiting a granoblastic texture, are the dominant minerals, indicating basaltic and diabasic protoliths. The amphiboles show simple foliation along lineation, which is occasionally folded. These amphibolites are overlain by Permian to Jurassic sedimentary rocks and, in some places, by Miocene sediments with angular unconformity. Based on whole-rock geochemistry, the amphibolites have relatively high TiO₂ (1.23–2.62 wt%) and low MnO (0.18–0.21 wt%) contents, classifying them as ortho-amphibolites. The parental magma was sub-alkaline basaltic with tholeiitic affinities, formed in a within-plate tectonic setting. This is characterized by enrichment in LREE relative to HREE, a lack of Nb, Ta, and Ti anomalies, and the presence of negative Eu and positive Ba anomalies. The ɛHf(t) and ¹⁷⁶Hf/¹⁷⁷Hf ratios of dated zircons suggest a depleted mantle to lower crust origin for the parental magma of the amphibolites. U-Pb dating of zircon grains yields a mean age of 304.8 Ma, corresponding to Late Carboniferous-Early Permian magmatism related to the opening of the Neotethys Ocean. The thermal effects of Late Cretaceous to Early Cenozoic subduction-related magmatic events are recorded by overgrown metamorphic zircon around original magmatic grains.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"164 ","pages":"Article 102089"},"PeriodicalIF":2.1,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725967","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 Varillar Basin: An example of basement-involved tectonism in the Central Andes of northern Chile","authors":"F. Martínez,&nbsp;C. Torres,&nbsp;L. Díaz,&nbsp;C. Arriagada","doi":"10.1016/j.jog.2025.102090","DOIUrl":"10.1016/j.jog.2025.102090","url":null,"abstract":"<div><div>The Frontal Cordillera in the Central Andes of northern Chile is a basement-involved fold-and-thrust belt characterized by large ranges composed of Paleozoic crystalline rocks, and intermontane contractional basins that have recorded much of the Mesozoic to Cenozoic deformation history of the orogen. At the core of the Frontal Cordillera, along the transition zone between the normal and flat-slab subduction segments, the Varillar Basin serves as a natural laboratory for studying the styles and mechanisms of basement-involved deformation resulting from Andean orogenesis. In this study, we present a novel structural analysis of the basement-involved structures present in this basin by combining field and seismic data with balanced and restored cross-sections. On the surface, the dominant structural features include NNE-striking basement-cored anticlines associated with steeply east and west-dipping reverse faults. These faults uplifted and exhumed large Paleozoic blocks, which are interpreted to be the pre-rift basement for Late Permian to Jurassic rift-related basins. The available seismic line revealed the existence of partially inverted half-graben structures beneath the basin, suggesting that the tectonic inversion of preexisting normal faults is responsible for the basement-involved deformation. This is further evidenced by the occurrence of folded Triassic and Jurassic syn-rift strata, which have been partially expelled from their original depocenters and are now elevated nearly 3 km above their regional datum. Restoration of three cross-sections to their pre-shortening state indicates that steeply dipping reverse faults (e.g., Varillar and Cerro Guerrita faults) accommodated approximately 3 km of crustal shortening on average. Some of these faults have also truncated and overthrust inverted normal faults (e.g., Border Fault), resulting in complex structural arrays. While the exact timing of basement-involved deformation remains uncertain, previous K-Ar age determinations of synorogenic strata suggest that the contractional structures were active during the Paleocene. However, other previously reported low-temperature thermochronological data (apatite fission track) from surrounding areas indicate an Eocene age for the basement-involved tectonism of the Frontal Cordillera.</div></div>","PeriodicalId":54823,"journal":{"name":"Journal of Geodynamics","volume":"164 ","pages":"Article 102090"},"PeriodicalIF":2.1,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704463","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}