Gondwana Research最新文献

{"title":"Synchronous felsic volcanism and carbonate sedimentation as a setting for VMS deposits localization at the Salair terrane, NE Central Asian Orogenic Belt","authors":"N.I. Vetrova,&nbsp;E.V. Vetrov","doi":"10.1016/j.gr.2024.08.014","DOIUrl":"10.1016/j.gr.2024.08.014","url":null,"abstract":"<div><p>The Salair terrane located in the northern part of the Central Asian Orogenic Belt (CAOB) contains many epithermal deposits including volcanogenic massive sulphide (VMS) deposits. The host rocks mainly consist of felsic volcanic rocks such as lavas, volcanic breccias and tuffs that associated with thick strata of carbonates. In this study, we present zircon U–Pb ages, whole rock geochemistry, and Nd isotope data from the volcanic rocks, and results of geochemical and isotope (Sr, C, O) studies of carbonates to constrain their age and petrogenesis, and to characterize the tectonic setting. Zircon U–Pb dating reveals that the ore-bearing felsic lavas have age of 519.3 ± 1.9 Ma, while the felsic tuffs have age of 516.0 ± 0.9 Ma. These volcanic rocks are characterized by high SiO₂ and Na₂O contents, enrichment in light rare-earth elements, remarkable negative Eu anomalies, and pronounced depletion in Nb, Ta, P, and Ti. They have depleted ɛNd(t) values ranging from +4.9 to +6.3, and young two-stage Nd model ages (from 0.82 to 0.64 Ga). The felsic volcanic rocks from the Salair terrane are interpreted as highly evolved I-type magmatic rocks that might be produced by high degree partial melting of juvenile lower crust without a significant contribution of ancient crust and without crustal reworking.</p><p>Felsic volcanism was accompanied by the formation of thick strata of carbonates. These carbonates are marine limestones with Mg/Ca ratios less than 0.007, δ¹⁸O_(SMOW) values from 17.1 to 23.8 ‰ and δ¹³C_(PDB) values between –0.9 and +0.9. Their Sr isotope composition varies in a narrow range within 0.70844–0.70859 that interpreted as representing proxy for coeval seawater. These values are consistent with depositional ages of 520–510 Ma and confirms the synchronicity of the formation of carbonates and felsic volcanism. Based on the regional geology and geochemistry, the ore-host rocks of the Salair terrane were formed in the back-arc setting where the marine transgression occurred as a result of graben subsidence. It is important for better understanding epithermal deposits in the northern CAOB and might provide new insights about prospecting the VMS deposits in similar tectonic settings.</p></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"136 ","pages":""},"PeriodicalIF":7.2,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142147926","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":"Scheelite as a microtextural and geochemical tracer of multistage ore-forming processes in skarn mineralization: A case study from the giant Xintianling W deposit, South China","authors":"Hongfei Di ,&nbsp;Yong-Jun Shao ,&nbsp;Yi-Qu Xiong ,&nbsp;Han Zheng ,&nbsp;Xiang Fang ,&nbsp;Wenjie Fang","doi":"10.1016/j.gr.2024.08.010","DOIUrl":"10.1016/j.gr.2024.08.010","url":null,"abstract":"<div><p>The Xintianling deposit is one of the largest skarn-type scheelite deposit in China. Recent discoveries of quartz-vein-type scheelite mineralization within the deposit have raised questions about its origin and the evolution of ore-forming fluids, hindering a comprehensive understanding of the ore-forming process. We investigate the microtextures, trace elements, and oxygen isotope compositions of scheelite from different stages in both skarn-type and quartz-vein-type W mineralizations. Combined with apatite geochemistry and U–Pb dating, we determine the timing of quartz-vein-type mineralization and the evolution of magmatic-hydrothermal system. Based on detailed petrological observation, three types (seven subtypes) of scheelite and two types of apatite are identified. The Mo contents and Eu/Eu* ratios of scheelite, along with the Ce/Ce* ratios of apatite indicate the oxygen fugacity of fluids during the skarn metallogenic episode is generally higher than that during the quartz-vein metallogenic episode. Furthermore, the Y/Ho ratios and REE patterns of scheelite indicate the presence of at least three significant stages of fluid influx and fluid-rock interactions throughout entire ore-forming process. The O isotope compositions of scheelite in the quartz-vein-type metallogenic episode reveal that the ore-forming fluids are originated from a magmatic source, and meteoric water was mixed into the system, leading to the precipitation of the latest stage of scheelite. The apatites closely coexist with scheelite, from the early and the late stages of quartz-vein metallogenic episode, yield consistent U–Pb ages within error of 160.4 ± 2.4 Ma and 158.4 ± 1.3 Ma, respectively, indicating a close genetic link between quartz-vein-type W mineralization and the fine-grained porphyritic biotite granite. Our study highlights the significance of pulsed fluid exsolution and the combined effects of multiple mechanisms, including fluid-rock interaction, fluid mixing, and physicochemical condition changes, in the formation of large W deposits.</p></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"136 ","pages":"Pages 104-125"},"PeriodicalIF":7.2,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142147929","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":"Pollution level and distribution characteristics of heavy metals and microplastics in the soils from the Qionghai Lake Wetland, Southwest China","authors":"Jinjin Wang ,&nbsp;Zailin Chen ,&nbsp;Xuemei Wang ,&nbsp;Yanqun Wang ,&nbsp;Huibin Shi ,&nbsp;Yi Huang","doi":"10.1016/j.gr.2024.07.027","DOIUrl":"10.1016/j.gr.2024.07.027","url":null,"abstract":"<div><p>Urban wetlands are reported to be ideal habitats for accumulation of HMs and MPs. However, study on combined pollution of HMs and MPs in soil is rare in urban wetland environment. In this study, the characteristics of HMs and MPs in the soils of the Qionghai Lake wetland in southwest China were studied by using ICP–MS, and FTIR. The results showed that the average concentration of HMs in soil ranges from 0.84 to 552.75 (mg/kg). According to the EF and Igeo analysis results, Cd and Cr in the soil were significant enriched (EF=12.64) and moderately enriched (EF=2.09), and were at the moderate to heavy pollution level (I_geo = 2.83) and the unpolluted to moderate pollution level (I_geo = 0.23), and the other elements were at a low level. MPs are emerging micropollutants in the soil environment, and the abundance (pieces/g) of MPs in the soil was 3.90, 7.00, 3.10, 3.40, 14.80, and 1.10 at Stations M1, M2, M3, M4, M8, and M9, respectively, with an average of 5.55 ± 4.92. Films represented the main microplastic shape, accounting for 81.55 %, followed by fibers, accounting for 11.33 %. The proportion of MPs with a particle size of 0.1–0.5 mm is the highest. Black, blue, and green are the predominant colors found in MPs. Polyethylene (PE) and polypropylene (PP) were the main MP materials based on FTIR identification, accounting for 52.16 % and 42.31 % of the total MPs, respectively. The pollution load index (PLI) of MPs was 2.2, which is a level Ⅰ pollution. The research on HMs and MPs in urban wetland soil is still in its preliminary stage. Our aim is to offer a fresh perspective for evaluating the pollution status and risk associated with these two pollutants in urban wetland soil, while also providing a valuable reference for subsequent studies on wetland soil pollutants.</p></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"136 ","pages":"Pages 73-83"},"PeriodicalIF":7.2,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142147927","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":"Editorial Board (IFC)","authors":"","doi":"10.1016/S1342-937X(24)00234-X","DOIUrl":"10.1016/S1342-937X(24)00234-X","url":null,"abstract":"","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"134 ","pages":"Page IFC"},"PeriodicalIF":7.2,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1342937X2400234X/pdfft?md5=b8c20c0195f9e3de5d1498230f1dac06&pid=1-s2.0-S1342937X2400234X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083224","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":"A mid-Cretaceous carbon isotope reference curve for the SE Neo-Tethys region (Zagros, W Iran)","authors":"Amin Navidtalab ,&nbsp;Ulrich Heimhofer ,&nbsp;Elaheh Zarei","doi":"10.1016/j.gr.2024.07.025","DOIUrl":"10.1016/j.gr.2024.07.025","url":null,"abstract":"<div><p>Stable carbon isotope chemostratigraphy and the associated reference curves have proved to be valuable tools for stratigraphic calibration and long-distance correlations. Nonetheless, the reference curves covering the Cretaceous have mostly been produced from localities located within the W Neo-Tethys. In order to establish a reference curve for the SE Neo-Tethys margin, an Aptian–Albian hemipelagic carbonate-rich succession deposited along the Zagros Basin (SW Iran) was examined for planktic foraminifera biostratigraphy, carbon isotope stratigraphy, and sedimentological characteristics. Eight biozones including <em>Globigerinelloides ferreolensis, Globigerinelloides algerianus, Hedbergella trocoidea, Paraticinella bejaouaensis, Muricohedbergella planispira, Ticinella (T.) primula, Biticinella breggiensis,</em> and <em>Pseudothalmanninella (P.)ticinensis</em> as well as two subzones enclosing <em>T. praeticinensis</em> and <em>P. subticinensis</em> assign the strata to the early late Aptian–late Albian age. A carbon isotope record constrained by the planktic foraminifera zonation scheme shows good concordance with existing composite reference curves from the W Neo-Tethys region. Several carbon isotope excursions (CIEs) characterizing global marine events including Oceanic Anoxic Event (OAE) 1a, OAE1b, OAE1c and associated sub-events can be identified in the studied section. Deoxygenated bottom waters associated with the formation of OAE1a and OAE1b are indicated by distinct lithological signatures including enrichment in pyrite and glauconite, nodular and stratiform chert beds, as well as enhanced organic matter contents. We integrate the here-studied interval with a previously published upper Albian−Turonian succession from the same outcrop section, forming a composite, stratigraphically well-constrained section. This results in a high-resolution carbon isotope record for the SE Neo-Tethys margin, considered to represent an expedient reference Aptian–Turonian curve for this region. Correlation of this new curve with previously published records from the Middle East has helped to address ambiguities regarding the stratigraphic positions of the early/late Aptian and Aptian/Albian boundaries identified by previous studies.</p></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"136 ","pages":"Pages 14-32"},"PeriodicalIF":7.2,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095069","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":"Discovery of mafic dikes in northeastern Tibet plateau belonging to the Emeishan large igneous province: Implications for paleocontinental reconstruction and mineral exploration","authors":"Kang Yang ,&nbsp;Wei-Guang Zhu ,&nbsp;Chusi Li ,&nbsp;Zhong-Jie Bai ,&nbsp;Yan-Jun Wang ,&nbsp;Shi-Ji Zheng ,&nbsp;Peng-Cheng Hu","doi":"10.1016/j.gr.2024.07.026","DOIUrl":"10.1016/j.gr.2024.07.026","url":null,"abstract":"<div><p>Due to the lack of paleomagnetic data and paleoclimatic records, the paleocontinental belonging of the Yidun terrane in northeastern Tibet plateau is debated. In this paper, we use the distribution of the Emeishan large igneous province (ELIP) to put the issue to rest. The ELIP is the product of mantle plume activity, which took place at 260 ± 3 Ma in the western margin of the Yangtze craton. The Yangtze craton is the northern part of the South China paleocontinental block. Our new discovery of four mafic dikes in the Yidun terrane with ages and chemistry like the ELIP strongly supports a new interpretation that this terrane was an integral part of the Yangtze craton during the ELIP magmatic event. Baddeleyites from these mafic dikes yield the U–Pb ages of 257.1 ± 4.8, 259.8 ± 8.5, 260.2 ± 4.5 and 261.5 ± 6.8 Ma for each of these dikes, which are similar to the zircon U-Pb ages of the mafic–ultramafic intrusions of the ELIP within the Yangtze craton. The Yidun mafic dikes and some high-Ti basalts of the ELIP within the Yangtze craton have similar Sr-Nd isotope compositions and mantle-normalized incompatible trace element distribution patterns, indicating similar mantle source compositions. Mixing calculation using Sr-Nd isotope compositions shows that the parental magmas for the Yidun mafic dikes experienced only 2–3 % crustal contamination. Partial melting modelling shows that the primary magmas for the Yidun mafic dikes were produced by 5–6 % mantle partial melting at the depths &gt; 85 km below surface, consistent with mantle plume-related magmatism in a continental setting. The Yidun terrane is a new exploration frontier for magmatic Fe-Ti-V oxide deposits that are present elsewhere in the ELIP.</p></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"136 ","pages":"Pages 1-13"},"PeriodicalIF":7.2,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095068","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":"Pollution index and distribution characteristics of soil heavy metals among four distinct land use patterns of Taojia River Basin in China","authors":"Wei Liu ,&nbsp;Chenglin Yuan ,&nbsp;Taimoor Hassan Farooq ,&nbsp;Peirou Chen ,&nbsp;Miao Yang ,&nbsp;Ziyi Ouyang ,&nbsp;Yao Fu ,&nbsp;Yitao Yuan ,&nbsp;Guangjun Wang ,&nbsp;Wende Yan ,&nbsp;Jun Wang","doi":"10.1016/j.gr.2024.07.024","DOIUrl":"10.1016/j.gr.2024.07.024","url":null,"abstract":"<div><p>The accumulation of heavy metals (HMs) in soil has become a pressing global concern due to their persistent and non-degradable nature, resulting in the accumulation of toxic levels in the environment. In recent years, human activities have significantly altered land use patterns, leading to a marked increase in soil HM levels and subsequent land degradation. This research focused on four distinct land use patterns (vegetable fields (VGF), woodland (WDL), cultivated land (CVL), and wasteland (WSL)) commonly found in the Taojia River Basin, Hunan, China, which is facing severe HM pollution. Soil samples were collected from three different depths (0–10 cm, 10–20 cm, and 20–30 cm) to investigate HM distribution and intensity (cadmium (Cd), lead (Pb), copper (Cu), nickel (Ni), and zinc (Zn)), comprehensive soil pollution index, and their relationship with soil microbial and enzymatic activities. The results revealed that the Cd content exceeded the national standard for soil environmental quality, whereas concentrations of other HMs did not exceed the national standard across the four land use patterns. Most soil HMs were concentrated in the surface layer, with Cu, Pb, and Zn concentrations gradually decreasing with increasing soil depth. Conversely, Ni and Cd concentrations tended to increase with greater soil depth. There were significant positive correlations among HMs, indicating homogeneity among them. The pollution index across the HMs ranked as Cd &gt; Ni &gt; Zn &gt; Cu and Pb, with land uses following the order of VGF (2.70) &gt; CVL (2.12) &gt; WSL (1.72) &gt; WDL (1.63). Soil microbial and enzymatic activity was not the primary factor influencing HM concentration. The specific impacts of land use changes on soil HMs depend on management practices, local conditions, and the distribution characteristics of the HMs involved.</p></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"135 ","pages":"Pages 198-207"},"PeriodicalIF":7.2,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142089041","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":"First multi-proxy chronostratigraphy of the lower Cambrian Byrd Group, Transantarctic Mountains and correlation within East Gondwana","authors":"Marissa J. Betts ,&nbsp;Thomas M. Claybourn ,&nbsp;Lars E. Holmer ,&nbsp;Christian B. Skovsted ,&nbsp;Paul M. Myrow ,&nbsp;Lars Stemmerik ,&nbsp;Timothy P. Topper ,&nbsp;Tae-Yoon S. Park ,&nbsp;Nigel C. Hughes ,&nbsp;James L. Crowley ,&nbsp;Elizabeth A. Jagodzinski ,&nbsp;Glenn A. Brock","doi":"10.1016/j.gr.2024.07.022","DOIUrl":"10.1016/j.gr.2024.07.022","url":null,"abstract":"<div><p>Antarctica and Australia were sutured together at the equator during the major pulse of animal biodiversification associated with the Cambrian radiation. However, the lack of detailed systematic chemostratigraphic and biostratigraphic sampling of lower Cambrian sedimentary successions from Antarctica has significantly impeded precise age determination and correlation with Cambrian strata on other palaeocontinents. This study is the first to present integrated, simultaneously sampled biostratigraphic and chemostratigraphic (δ¹³C isotopes) data from the same measured stratigraphic sections through the lower Cambrian Byrd Group in the Transantarctic Mountains. Shelly fossil assemblages (brachiopods, tommotiids, molluscs, bradoriids, trilobites) from the Holyoake Range and Churchill Mountains facilitate direct correlation with the <em>Dailyatia odyssei</em> Zone of South Australia (Cambrian Stages 3–4), and trilobites provide strong correlation between the Starshot Formation and the Cymbric Vale Formation in western New South Wales. A new ID-TIMS radiometric date of 514.96 ± 0.16 Ma from a tuff in the lower Cymbric Vale Formation is similar to dates from tuff beds in the Third Plain Creek Member of the Mernmerna Formation in the Flinders Ranges, providing an important absolute-age tie point between these lower Cambrian successions. Chemostratigraphic data from the upper Shackleton Limestone in the Holyoake Range capture a negative δ¹³C excursion that can be correlated to negative values within the multi-peaked MICE (cycles V–VIII in Siberia). Integrated faunal and chemostratigraphic data indicate a Cambrian Stages 3–4 age, giving robust chronostratigraphic context for the upper Shackleton Limestone–Holyoake Formation–Starshot Formation succession for the first time, permitting reconstruction of the depositional history of the lower Cambrian of Antarctica and global correlation of Byrd Group strata.</p></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"136 ","pages":"Pages 126-141"},"PeriodicalIF":7.2,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142147930","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":"Interaction of accretion mechanisms and deep fluids in continental orogenesis","authors":"G. Giacomuzzi,&nbsp;C. Chiarabba","doi":"10.1016/j.gr.2024.08.009","DOIUrl":"10.1016/j.gr.2024.08.009","url":null,"abstract":"<div><p>Mountain-building often involves the subduction of continental margins during the convergence of tectonic plates. Rheological heterogeneities and structural inheritance in the subducting lithosphere are main factors controlling the evolution of the process and deformation partitioning in orogenic wedges. Here, we present tomographic evidence of a main along-strike change in the structure of the Apennines belt, where frontal accretion diminishes laterally, as well as plate bending, and the contribution of underplating to crustal thickening becomes evident. We hypothesize that the diverse mechanisms of mountain formation can be attributed to rheological heterogeneity in the crust and interactions with fluids liberated during the subduction process. The development of shallow decollements versus underplating is favored by differing amounts and styles of deep fluid liberation from the subducting crust.</p></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"135 ","pages":"Pages 266-281"},"PeriodicalIF":7.2,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142089023","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":"Supra-subduction thickening of a continental back-arc: Ediacaran–early Cambrian (Baikalian) metamorphism in the NE Baidrag block (Mongolian Collage)","authors":"Pavla Štípská ,&nbsp;Karel Schulmann ,&nbsp;Igor Soejono ,&nbsp;Vít Peřestý ,&nbsp;Andrew R.C. Kylander-Clark ,&nbsp;Stephen Collett ,&nbsp;Carmen Aguilar ,&nbsp;Petra Maierová ,&nbsp;Martin Racek ,&nbsp;Pavel Hanžl","doi":"10.1016/j.gr.2024.08.007","DOIUrl":"10.1016/j.gr.2024.08.007","url":null,"abstract":"<div><p>In-situ monazite geochronology with <em>P–T</em> modelling of Barrovian-type metasediments was carried in the Burd Gol zone, NE Baidrag block. The <em>P–T</em> peak recorded by Grt−Sil migmatite is ∼780 °C, 7.5 kbar; by Grt–St–Ky gneiss ∼690 °C, 10 kbar and by Grt schist ∼590 °C, 8 kbar. Monazite ages related to metamorphic peaks indicate diachronous burial events, c. 570–565 Ma for the Grt–Sil migmatite, c. 565–560 Ma for the Grt–St–Ky gneiss, and at c. 538 Ma for the Grt schist. Tonian Grt–St schist recorded new monazite crystallization at c. 546–543 Ma. By c. 545–542 Ma, the Grt–Sil migmatite and Grt–St–Ky gneiss experienced exhumation to ∼5 kbar, while the Grt schist underwent burial. Further exhumation is dated by xenotime, rutile and monazite alteration down to c. 515 Ma. The data suggest a prolonged orogenic cycle initiated by burial of distal orogenic core to the depths of ∼35 km at c. 570–565 Ma while the proximal continental margin was buried at c. 545–538 Ma. The higher-grade core was subsequently exhumed to the middle crust at c. 550–540 Ma and the orogenic activity ceased at c. 515 Ma. The difference in metamorphic gradients around 570–560 Ma, with ∼27–28 °C/km for the Grt–Sil migmatite and ∼18–19 °C/km for the Grt–St–Ky gneiss suggests lateral variations as a result of localized juxtaposition of migmatite-magmatite lower-middle crust with colder regions. A new model shows the Burd Gol zone as a progressively thickened and exhumed continental back-arc system beneath the supracrustal 590–570 Ma continental back-arc represented by the adjacent Ulziit Gol unit. The data provide important constraint on the timing and mechanisms of orogenic Baikal cycle at the margin of the Siberian Craton.</p></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"135 ","pages":"Pages 234-265"},"PeriodicalIF":7.2,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142089022","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}