Gondwana Research最新文献

{"title":"The lithosphere of South America from seismic tomography: Structure, evolution, and control on tectonics and magmatism","authors":"Bruna Chagas de Melo ,&nbsp;Sergei Lebedev ,&nbsp;Nicolas Luca Celli ,&nbsp;Sally Gibson ,&nbsp;Janneke Iza de Laat ,&nbsp;Marcelo Assumpção","doi":"10.1016/j.gr.2024.10.012","DOIUrl":"10.1016/j.gr.2024.10.012","url":null,"abstract":"<div><div>The thickness, temperature and mechanical strength of the lithosphere vary greatly across South America and have controlled tectonic and magmatic processes during its evolution. Here, we introduce a new tomographic model of South America’s lithosphere and underlying mantle, SACI-24, and analyse this and other state-of-the-art models together with other geological and geophysical data. The new model is obtained by waveform inversion of surface, S and multiple S waveforms globally, but is optimised for South America and the surrounding oceans. SACI-24 is constrained by ∼ 970,000 seismograms from 9259 stations and maps detailed structure of cratonic lithosphere across the continent, highlighting previously unknown complexities and fragmentation. Within the Amazon Craton, the Guiana and Central Brazil blocks show high Vs exceeding 4.8 km/s in the 80–150 km depth range but are separated by lower velocities below the Amazon Basin, matching the locations of ancient rifting and the flood basalts of the Central Atlantic Magmatic Province. In the São Francisco Craton, high velocities extend north and southwest beyond the previously proposed boundaries. Warmer, thinner lithosphere underlies the Paramirim and Pirapora aulacogens, locations of magmatic and rifting cycles. A fragmented cratonic root underlies the Paraná Basin, with thinner lithosphere along its central rift. High velocities south of the Paraná Block indicate the northern Rio de la Plata Craton’s thick root. The Cenozoic intraplate basalts in the Borborema province, along the southern Atlantic coast and in Paraguay occurred in areas of thin lithosphere and near thick-thin lithospheric boundaries. Most flood basalts of the Phanerozoic large igneous provinces also map on low velocity areas. Smaller flood-basalt portions sit atop cratonic lithosphere and offer new evidence on lateral flow of flood-basalt lava and magma within the crust. About 80 % of known diamondiferous kimberlites are on thick lithosphere, with the exceptions indicating cratonic erosion and thinning since their emplacement.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"138 ","pages":"Pages 139-167"},"PeriodicalIF":7.2,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142672823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anatomy of the late Pennsylvanian to early Triassic failed rift system of the Cooper Basin, eastern Australia","authors":"Carmine C. Wainman ,&nbsp;Peter J. McCabe","doi":"10.1016/j.gr.2024.09.017","DOIUrl":"10.1016/j.gr.2024.09.017","url":null,"abstract":"<div><div>The onshore intracratonic Cooper Basin of eastern Australia developed during the Late Pennsylvanian to Middle Triassic periods at paleolatitudes of approximately 50°S within the Gondwanan sector of Pangea. Despite the wealth of data available, including the drilling of over 4,800 boreholes, there is limited knowledge about the Cooper Basin’s origins and evolution. To better understand the basin’s geological history, legacy data sets, including composite 2D seismic sections, well logs, measured sections, and 1D burial history models from the west of the basin, are integrated to reinterpret the basin’s tectonic and sedimentary evolution. Interpretation of the seismic sections and calculated subsidence rates indicates an earlier active rift phase with grabens and half-grabens that transitioned, in the latest Permian, into a regional sag phase. The evolution of tectonic styles heavily influenced the paleogeographic evolution of the basin fill and resulting depositional architecture. The basin sediments are entirely terrestrial in nature and facies reflect a transition from glacial environments in the late Pennsylvanian to warmer and drier conditions in the early Triassic. During much of the Permian the basin was underfilled and the relative low influx of fluvial sediment did not keep pace with creation of accommodation, allowing the development of extensive mire and lake systems. Coal beds are up to 30 m thick. By contrast, the basin appears to have been overfilled during the latest Permian to Triassic with rivers flowing along the central axis of the basin. The synchroneity of commencement of rifting, termination of rifting, and commencement of a sag phase within the failed rift systems of the Cooper Basin, the East Gondwana Interior Rift, and the East Australian Rift strongly suggests a continent-wide period of extension related to significant changes in plate motions during the Late Pennsylvanian to Middle Triassic.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"138 ","pages":"Pages 47-69"},"PeriodicalIF":7.2,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Hydrothermal overprinting of the Li-rich strata deposited in the Mesoproterozoic Wumishan Formation, Hebei Province, North China","authors":"Fei Xu ,&nbsp;Baoqiang Zhao ,&nbsp;Hanjie Wen ,&nbsp;Hefan Liu ,&nbsp;Xiaofeng Li ,&nbsp;Yu Chen ,&nbsp;Yi Cui ,&nbsp;Chengyu Mi ,&nbsp;Jian Yang ,&nbsp;Chuan Wang","doi":"10.1016/j.gr.2024.10.009","DOIUrl":"10.1016/j.gr.2024.10.009","url":null,"abstract":"<div><div>Lithium (Li), as a strategic critical metal, plays a pivotal role in the emerging energy landscape, particularly in the context of Li-ion batteries driving the new energy economy. Recently, Li-rich strata (with Li₂O &gt; 0.3 wt%) have been discovered in the Mesoproterozoic Wumishan Formation in Hebei Province, North China, suggesting a prospective Li reservoir. This study investigates these Li-rich strata using geochemical and in-situ micro-analytical techniques to explore the occurrence of Li and the formation mechanism of Li-host minerals, aiming for a comprehensive understanding of the supernormal enrichment of Li. The Li-rich samples are predominantly composed of dolomite and quartz, followed by clay minerals such as illite, interstratified illite–smectite (I/S), and chlorite, with minor amounts of K-feldspar, albite, biotite, calcite, baryte, fluorite and fluorapatite. In-situ analysis and ⁷Li NMR spectroscopy reveal that Li predominantly occupies the octahedral sites within the structures of authigenic illite and I/S, while its absence in clastic illite, clastic chlorite, unaltered K-feldspar, and dolomite. The presence of veined minerals (e.g., fluorite, baryte, and calcite) and a strong positive correlation between Li and F imply that post-depositional hydrothermal fluids have significantly contributed to the formation of Li-host minerals. The paragenesis of these minerals suggests that Li-bearing illite has formed through the hydrothermal alteration of K-feldspar. These Li-bearing illites subsequently transformed into Li-bearing I/S, consisting of illite-rich I/S and smectite-rich I/S, under continuous hydrothermal alteration. Lithium could have been leached from the surrounding carbonate rock and tuff through water–rock interaction and subsequently enriched by post-depositional hydrothermal fluids in specific regions, leading to mineralization. These findings provide valuable insights for targeting exploration of this promising Li resource.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"138 ","pages":"Pages 16-30"},"PeriodicalIF":7.2,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 impact of Pangean subducted oceans on mantle dynamics: Passive piles and the positioning of deep mantle plumes","authors":"Philip J. Heron ,&nbsp;Juliane Dannberg ,&nbsp;Rene Gassmöller ,&nbsp;Grace E. Shephard ,&nbsp;Jeroen van Hunen ,&nbsp;Russell N. Pysklywec","doi":"10.1016/j.gr.2024.10.007","DOIUrl":"10.1016/j.gr.2024.10.007","url":null,"abstract":"<div><div>Seismic imaging of the Earth’s interior reveals plumes originating from relatively hot regions of the lowermost mantle, surrounded by cooler material thought to be remnants of ancient subducted oceans. Currently, there is no clear consensus on the internal composition of the hot regions, with end-member conditions being that they are thermo-chemical in nature or purely thermal plume clusters. Previous modelling studies have shown a range of scenarios where deep chemical heterogenities or purely thermal anomalies are essential in developing appropriate present-day mantle dynamics. Here, we add to this discussion by quantifying the location of rising mantle plumes using numerical 3-D global mantle convection models constrained by 410 million years of palaeo-ocean evolution (encompassing the formation and breakup of supercontinent Pangea). Our study compares numerical simulations with purely thermal convection to those where a deep thermo-chemical anomaly is laterally mobile. The results show that models both with and without large-scale chemical heterogeneities can generate appropriate present-day plume dynamics, which illustrate the power of sinking ocean plates to stir mantle ow and control the thermal evolution of the mantle. Our models add to the discussion on bottom-up and top-down mantle dynamics, indicating the difficulty in unravelling the processes using numerical models alone.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"138 ","pages":"Pages 168-185"},"PeriodicalIF":7.2,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Responding to green finance with emission reduction and value-added: The role of enterprise environmental investment","authors":"Yao Wang ,&nbsp;Shengling Zhang ,&nbsp;Zihao Wu ,&nbsp;Yu Hao ,&nbsp;Ruijie Li","doi":"10.1016/j.gr.2024.10.008","DOIUrl":"10.1016/j.gr.2024.10.008","url":null,"abstract":"<div><div>Responding to China’s green finance policy with enterprise environmental investment (EEI) constitutes a crucial link in achieving environmental governance objectives, exerting crucial influence on the nation’s green transformation and high-quality development. Taking the pilot policy of China’s Green Finance Reform and Innovation Experimental Zone (GFRP) in 2017 as a quasi-natural experiment, this study systematically evaluates the effect of GFRP policy on the decisions of EEI and further explore whether the investments are used for passive end-of-pipe treatment (EOP) or positive source prevention (SP) by using firm-level data. The results indicate that GFRP policy can significantly promote EEI, and mainly reflected in SP, rather than EOP. Through potential mechanism analysis, it can be concluded that GFRP policy facilitates EEI by alleviating financial constraint, reducing agency cost, and enhancing environmental information disclosure. Heterogeneity analysis suggests that there exists asymmetry in policy effects, with greater impacts in high green finance development areas, low concentration industries and large-scale enterprises. Furthermore, micro-level performance consequences examination reveals that the enterprises’ decision to increase EEI under GFRP policy not only effectively realizes energy conservation and emission reduction but also contribute to facilitating enterprise value, to achieve green transformation. This study holds significant policy implications, providing empirical evidence to policymakers for the refinement and dissemination of green finance policy, and offering valuable insights for enterprise investment and management decisions.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"138 ","pages":"Pages 1-15"},"PeriodicalIF":7.2,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tectono-magmatic evolution of the Indian crust in western Himalayas during Paleoproterozoic: Insights from Nanga Parbat and Indus syntaxis in northern Pakistan","authors":"Muhammad Sajid ,&nbsp;Michael Wiedenbeck ,&nbsp;Muhammad Arif ,&nbsp;Johannes Glodny ,&nbsp;Nowrad Ali ,&nbsp;Humaad Ghani ,&nbsp;Jessica A. Stammeier","doi":"10.1016/j.gr.2024.10.006","DOIUrl":"10.1016/j.gr.2024.10.006","url":null,"abstract":"<div><div>The Paleoproterozoic tectono-magmatic history of the Indian plate has been modelled mostly based on investigations of the Indian parts with limited studies considering the Pakistani domains of the mountain range. In this study we investigate basement rocks and younger intrusions of the Indian crust from within the core of the Indus Syntaxis and the Nanga Parbat Syntaxis in northern Pakistan, with the goal of establishing a chronology for the entire tectono-magmatic progression of northwestern Indian plate margin, including the source rocks that were ultimately involved in the formation of younger magmatic pulses. We present in-situ zircon U-Pb geochronology and O-isotopes complemented by whole rock geochemistry of granitoids and paragneisses that yielded evidence for two distinct, large-scale Paleoproterozoic magmatic events that took place in ∼ 1860 Ma and ∼ 2200 Ma in the Indian crust. Later, leucogranites (6.4 ± 0.1 Ma) intruded into the Nanga Parbat basement that were the result of melting of the basement induced by rapid uplift. The δ¹⁸O_SMOW compositions of zircons from our basement samples range between 7.5 to 9.1 ‰, indicating the derivation of parental magma from the crustal source while the younger leucogranite is somewhat lighter with δ¹⁸O ranging between 7.06 to 8.23 ‰. Geochemical data show extensional tectonic settings for the basement rocks that have an A-type affinity, again pointing to a crustal precursor. We propose little to no δ¹⁸O exchange took place between the young anatectic melt and basement rocks during crustal evolution. Moreover, geochemical signatures record the crystallization of basement rocks dominated the northwestern margin of Indian plate in a post-orogenic setting in an overall extensional tectonic realm. Based on these observations, we infer that the northwestern Indian margin has experienced a large-scale magmatism during Paleoproterozoic associated with the amalgamation of the Columbia supercontinent.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"137 ","pages":"Pages 299-317"},"PeriodicalIF":7.2,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 water distribution in between peridotite xenoliths from Kaapvaal Craton kimberlites: Constraints on diamond barren nature of kimberlites","authors":"Sahroz Khan ,&nbsp;Nóra Liptai ,&nbsp;István J. Kovács ,&nbsp;Yana Fedortchouk ,&nbsp;Tivadar M. Tóth","doi":"10.1016/j.gr.2024.10.004","DOIUrl":"10.1016/j.gr.2024.10.004","url":null,"abstract":"<div><div>Nominally anhydrous mantle minerals (olivine, pyroxenes, garnets, etc.) in 11 peridotite xenoliths from four different uneconomic and economic Kaapvaal Craton kimberlite pipes (Matsoku, Thaba Putsoa, Pipe 200 and Bultfontein) have been investigated using Fourier transform infrared spectroscopy (FTIR). All xenoliths contain accessories of garnet, diopside, chromite, and phlogopite. High orthopyroxene content (&gt;30 mol vol.%) in most xenoliths from all kimberlites and its interconnected channel-like nature hint towards hydrous siliceous fluid metasomatism. Peridotite xenoliths from uneconomic kimberlites show development of phlogopite and clinopyroxene (± chromite) forming veins and in garnet rims suggesting metasomatism by alkaline silico-carbonatite (possibly kimberlite-related) melt. The xenoliths contain significant H₂O in olivine (17–62 ppm), orthopyroxene (21–230 ppm), and clinopyroxene (87–833 ppm), whereas garnets are dry and only show IR absorbance bands at &gt; 3,670 cm⁻¹ for contamination of hydrous minerals. Compared to the economic kimberlites in the Kaapvaal Craton, the uneconomic kimberlite xenoliths from this study have lower orthopyroxene and olivine H₂O content. In the xenoliths affected by garnet breakdown metasomatism, the H₂O content of orthopyroxene and olivine is higher and lower, respectively. The structural hydroxyl distribution profile across olivine and higher inter-mineral water partition coefficient, suggest diffusion of hydrogen and possible re-equilibration. Statistical analysis of the olivine spectra suggests that hydrogen bands at 3540, 3624, 3638, and 3672 cm⁻¹ are a good discriminant of economic and uneconomic kimberlites and in literature, they are associated with metasomatism, weathering-associated processes, high water activity, and oxygen fugacity. The lower water concentration in xenoliths from uneconomic kimberlite from the margin of the craton than the economic kimberlites from the interior of the Kaapvaal Craton and identified metasomatism hints towards dehydration of xenoliths by water-poor and CO₂-rich melts in tectonized cross-lithospheric zones causing diamond resorption and may be responsible for the diamond-poor nature of uneconomic kimberlites in northern Lesotho.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"137 ","pages":"Pages 331-348"},"PeriodicalIF":7.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"The Permian – Triassic boundary in Peninsular India and the extinction of the Glossopteridales","authors":"Anju Saxena ,&nbsp;Christopher J. Cleal ,&nbsp;Kamal Jeet Singh","doi":"10.1016/j.gr.2024.10.005","DOIUrl":"10.1016/j.gr.2024.10.005","url":null,"abstract":"<div><div>The Glossopteridales was a distinctive order of gymnospermous seed-plants that occurred widely in the Permian of Gondwana. Some authors have suggested that they may also have occurred in the Triassic and so had survived the catastrophic Permian – Triassic extinction event. This suggestion was mainly based on records from peninsular India such as from the Panchet Formation, which traditionally was regarded as Triassic in age. This paper reviews the evidence for a Triassic age for these floras and it is argued that they are in fact late Permian. There is no clear evidence that the Glossopteridales survived the P/T biotic crisis in India and only unequivocal evidence is in China that they survived into the Triassic.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"137 ","pages":"Pages 318-330"},"PeriodicalIF":7.2,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 mantle scale enrichment of Cenozoic intraplate magmatism in Northeast Asia: He-Sr-Nd-Pb-O isotope geochemistry of the basalts around the Korean peninsula","authors":"Donghwan Kim ,&nbsp;Hyunwoo Lee ,&nbsp;Mi Jung Lee ,&nbsp;Changkun Park ,&nbsp;Andrea Luca Rizzo","doi":"10.1016/j.gr.2024.09.016","DOIUrl":"10.1016/j.gr.2024.09.016","url":null,"abstract":"<div><div>The Earth’s mantle is considered to be geochemically heterogeneous, which is reflected by the diverse compositions of oceanic island basalts (OIB). The mantle enrichment resulting in this is primarily attributed to the influx of recycled crustal materials into the mantle through subduction. Additionally, the sub-continental lithospheric mantle (SCLM) complicates the elucidation of mantle heterogeneity. From this perspective, Northeast Asia, where the Pacific stagnant slab in the mantle transition zone and the SCLM distribution are presented, is the suitable site for examining the upper mantle scale enrichment. Here we report He-Sr-Nd-Pb-O isotope compositions of Cenozoic basalts found around the Korean Peninsula to illustrate the source lithology and components that caused mantle heterogeneity. Our measured helium isotope ratios ranging from 5.7 to 7.3 R_a (³He/⁴He ratio of air, R_a = 1.39 x 10^-6) are mostly within the SCLM range (6.1 ± 0.9 R_a) but lower than the mid-ocean ridge basalt range (MORB; 8 ± 1 R_a). The Sr-Nd-Pb isotope compositions of the basalts generally display a mixture of depleted MORB mantle (DMM), enriched mantle 1 (EM1), and enriched mantle 2 (EM2) components. In addition, the basalts have δ¹⁸O_olivine (vs. V-SMOW) values ranging from 4.7 to 5.7 ‰ that deviate from the DMM range (δ¹⁸O_olivine = 5.1 ± 0.2 ‰). Our isotopic analysis results highlight the role of a pyroxenite source in the metasomatized SCLM in the genesis of basalts, and the low ³He/⁴He ratios of the basalts indicates a significant contribution of SCLM. Moreover, the delaminated cratonic SCLM and asthenosphere-lithosphere interaction are scenarios for the low ³He/⁴He ratios. Therefore, we propose that mixing of DMM (high ³He/⁴He ratio; 7 to 9 R_a) and the metasomatized SCLM (low ³He/⁴He ratio; 5 to 7 R_a) allowed enrichment within the upper mantle scale for the Cenozoic intraplate magmatism in Northeast Asia.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"137 ","pages":"Pages 349-364"},"PeriodicalIF":7.2,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cuartel Ophiolite: Structure, timing and exhumation mechanisms for a Cadomian suture zone in the peri-Gondwanan Realm (SW Iberia)","authors":"Diana Moreno-Martín ,&nbsp;Rubén Díez Fernández ,&nbsp;Richard Albert ,&nbsp;Sonia Sánchez Martínez ,&nbsp;Esther Rojo-Pérez ,&nbsp;Axel Gerdes ,&nbsp;Ricardo Arenas","doi":"10.1016/j.gr.2024.10.002","DOIUrl":"10.1016/j.gr.2024.10.002","url":null,"abstract":"<div><div>The Cadomian Orogeny formed as an accretionary orogen surrounding Gondwana. The structure resulting from the Cadomian Orogeny is pervasively reworked during the Paleozoic, within the frame of the Variscan Cycle. In SW Iberia (Mina Afortunada Massif), a tectonometamorphic and geochronological analysis revealed two Cadomian deformation phases. The first phase (D_C1; 586 Ma, U-Pb dating in inherited metamorphic garnet from Mina Afortunada Gneiss) is associated with ophiolite accretion during the closure of a back-arc or intra-arc basin (Cuartel Ophiolite). A metamorphic fabric related to this phase is preserved as an internal foliation in Ediacaran (meta)sedimentary rocks. The second phase (D_C2; 515–485 Ma) is constrained by the age of the igneous protolith of Mina Afortunada Gneiss (∼515 Ma), which is affected by a penetrative foliation formed during D_C2, and by the unconformable deposit of Ordovician sediments, which are not affected. The telescoping of metamorphic isograds during D_C2 and the geometry of detachment faults associated with this phase suggest extensional tectonics as the driving mechanism for the early exhumation of the Cadomian suture zone in Mina Afortunada Massif. The superimposition of Variscan folds and shear zones onto the Cadomian structures contributed to the subsequent exhumation of the Cadomian suture zone. The analysis and reconstruction of Cadomian and Variscan structures, plus the geochronological data, allow us to correlate the Cuartel Ophiolite with the Mérida Ophiolite, being two pieces of the same, yet dismembered, Cadomian suture zone. The number of Cadomian suture zones in Gondwana does not coincide with that of Cadomian suture zone exposures. Reworked orogens such as the Cadomian could be subjected to duplication of their suture zones. Assessments regarding the Cadomian paleogeography should consider the multiplier effect of the structural overprints after ophiolite accretion.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"137 ","pages":"Pages 255-273"},"PeriodicalIF":7.2,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}