Geological Magazine最新文献

Diversification inside a lamprophyric dyke and cone sheet complex converging onto a hidden carbonatite centre (Frederikshåbs Isblink, SW Greenland) 汇聚到一个隐藏的碳酸盐岩中心（格陵兰西南部，弗雷德里克沙布伊斯布林克）的灯心堤和圆锥片复合体内部的多样化现象

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-09-19 DOI: 10.1017/s0016756824000165

Martin Bromann Klausen, Madelaine R Frazenburg

{"title":"Diversification inside a lamprophyric dyke and cone sheet complex converging onto a hidden carbonatite centre (Frederikshåbs Isblink, SW Greenland)","authors":"Martin Bromann Klausen, Madelaine R Frazenburg","doi":"10.1017/s0016756824000165","DOIUrl":"https://doi.org/10.1017/s0016756824000165","url":null,"abstract":"Both radiating dykes and proximal cone sheets converge onto a positive aeromagnetic anomaly of an inferred carbonatitic centre, hidden beneath a retreating edge of the Frederikshåbs Isblink glacier. This convergence, together with sub-parallel incompatible element patterns by all intrusions, suggests a cogenetic relationship that warrants investigation into potential diversification processes. More primitive high- and low-Mg damtjernites, which for three dykes conform to more porphyritic dyke cores and aphyric margins, respectively, can be explained by high-Mg trends being controlled by the fractionation/accumulation of mainly augite and olivine (or other mafic phases), while discordant low-Mg trends require additional decoupled magnetite fractionation. It is proposed that each dyke intrusion tapped the differentiated top of a central magma chamber, occasionally followed by an unconsolidated mafic cumulate mush, excluding denser magnetites, with in situ flow segregation playing a subordinate additional role. Beyond the most differentiated damtjernite, more evolved phonolitic nephelinites to carbonaceous alnöites split into bulk rock geochemical T-trends that can only relate to late-stage segregations into magmas with varying proportions of interstitial igneous (not secondary) analcime and carbonate – collectively increasing in volume with differentiation. While the analcime component also appears to segregate more readily into veins and ocelli than carbonatite, it is speculated if such low viscosity, density and liquidus rest melts, inside igneous centres, more efficiently aggregated into voluminous, buoyant analcime caps above slightly denser carbonatites. Similar converging plumbing systems and diversification processes are proposed for other complexes, where kimberlitic parents were simply extracted from deeper mantle sources.","PeriodicalId":12612,"journal":{"name":"Geological Magazine","volume":"1 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253240","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}

引用次数: 0

The affinity of microcontinents in northern East Gondwana in the Silurian: Hainan Island response to the closure of the Proto-Tethys Ocean 志留纪东冈瓦纳北部微大陆的亲缘关系：海南岛对原特提斯洋关闭的响应

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-05-14 DOI: 10.1017/s0016756824000116

Shiyao Gao, Zhongjie Xu, Jintao Kong, Hua Tan, Yingming sun, Hexue Fu, Yin Ming

{"title":"The affinity of microcontinents in northern East Gondwana in the Silurian: Hainan Island response to the closure of the Proto-Tethys Ocean","authors":"Shiyao Gao, Zhongjie Xu, Jintao Kong, Hua Tan, Yingming sun, Hexue Fu, Yin Ming","doi":"10.1017/s0016756824000116","DOIUrl":"https://doi.org/10.1017/s0016756824000116","url":null,"abstract":"During the existence of Proto-Tethys Ocean (550–430 Ma), microcontinents in northern East Gondwana merged with the northern margin of India-Australia, completing the assembly of Gondwana. Ongoing controversy surrounds the disappearance of the Proto-Tethys Ocean, the dynamic mechanisms of suturing and the palaeogeographic relationships among microcontinents in northern East Gondwana, contributing to the uncertainty about the tectonic evolution of the region. This paper concerns the lower Silurian Zusailing Formation in the Hainan Island and focuses on the affinity between Hainan Island and various microcontinents in northern East Gondwana during the early Silurian. We use detrital zircon geochronology to reconstruct the closure process of the Proto-Tethys Ocean and show that the detrital zircon U–Pb age groups of the lower Silurian Zusailing Formation are 2800–2200, 2100–1350, 1250–950, 600–480 and 480–430 Ma, with a significant age peak of ca. 449 Ma. Furthermore, the analysis of detrital zircon geochemistry and europium anomalies shows that the Hainan Island crust continued to thicken during 600–434 Ma. Comparing the age spectrum of early Palaeozoic detrital zircons from Hainan Island and various microcontinents in northern East Gondwana, as well as the affinity among them during the Silurian, we conclude that the closure of the eastern Proto-Tethys Ocean evolved from unidirectional subduction (600–480 Ma) to bidirectional subduction (480–430 Ma).","PeriodicalId":12612,"journal":{"name":"Geological Magazine","volume":"137 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140938501","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}

引用次数: 0

Towards a refined Norian (Upper Triassic) conodont biostratigraphy of the western Tethys: revision of the recurrent ‘multidentata-issue’ 努力完善特提斯西部的纪元（上三叠世）同形生物地层学：对反复出现的 "多同形问题 "的修订

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-05-03 DOI: 10.1017/s0016756824000104

Viktor Karádi

引用次数: 0

Late Silurian event stratigraphy and facies of South Wales and the Welsh Borderland, United Kingdom 英国南威尔士和威尔士边境地区的晚志留纪事件地层和地貌

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-04-29 DOI: 10.1017/s0016756824000086

Robert D Hillier, Richard A Waters, Jeremy R Davies, Kenneth T Higgs, Stewart G Molyneux

{"title":"Late Silurian event stratigraphy and facies of South Wales and the Welsh Borderland, United Kingdom","authors":"Robert D Hillier, Richard A Waters, Jeremy R Davies, Kenneth T Higgs, Stewart G Molyneux","doi":"10.1017/s0016756824000086","DOIUrl":"https://doi.org/10.1017/s0016756824000086","url":null,"abstract":"Lithofacies and biostratigraphical analysis has enabled the establishment of a stratigraphic event framework for Ludfordian and Pridoli strata in south Wales and the Welsh Borderland. In SW Wales, the Golden Grove Axis acted as a structural hinge separating the shallow marine storm-influenced Cae’r mynach Seaway from a pediment surface above which Ludfordian colluvium (Abercyfor Formation) was deposited. The Axis seeded four NW-derived river-influenced delta progrades of Leintwardinian to early Pridoli age (Tilestones Formation). A NE-sourced early Pridoli wave-influenced delta deposited the Downton Castle Sandstone Formation (DCSF), coeval to the youngest Tilestones prograde, with a lateral interface existing between Mynydd Epynt and the Clun Forest area. Except for the Malverns area, the DCSF is no longer recognized south of the Neath Disturbance. Early Pridoli forced regression promoted widespread subaerial exposure north of the Neath Disturbance, with incision into tracts close to the Welsh Borderland Fault System. The basinward-shift in facies belts resulted in marine erosion and deposition of a phosphatic ravinement pebble lag. The wave-influenced Clifford’s Mesne Sandstone Formation delta subsequently seeded on the Gorsley Axis with tidally influenced Rushall Formation accumulating in a back-barrier setting. The Pwll-Mawr Formation records the easterly advance of coeval coastal deposits on the western side of the remnant Cae’r mynach Seaway. Behind migrating delta coastlines, green muds accumulated on coastal plains (Temeside Mudstone Formation) with better drained red dryland alluvium (Moor Cliffs Formation) charting expansion of Old Red Sandstone lithofacies. Mid-Pridoli incision preserves the Pont ar Llechau Formation estuarine valley fill.","PeriodicalId":12612,"journal":{"name":"Geological Magazine","volume":"40 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140808878","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}

引用次数: 0

The onset of Neo-Tethys subduction in the Early Jurassic: evidence from the eclogites of the North Shahrekord Metamorphic Complex (Sanandaj-Sirjan Zone, W Iran) 侏罗纪早期新特提斯俯冲的开始：来自北沙赫雷科德变质岩群（伊朗西部萨南达季-锡尔詹地区）蚀变岩的证据

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-04-17 DOI: 10.1017/s0016756824000098

Chiara Montemagni, Stefano Zanchetta, Nadia Malaspina, Hamid Reza Javadi, Andrea Zanchi

{"title":"The onset of Neo-Tethys subduction in the Early Jurassic: evidence from the eclogites of the North Shahrekord Metamorphic Complex (Sanandaj-Sirjan Zone, W Iran)","authors":"Chiara Montemagni, Stefano Zanchetta, Nadia Malaspina, Hamid Reza Javadi, Andrea Zanchi","doi":"10.1017/s0016756824000098","DOIUrl":"https://doi.org/10.1017/s0016756824000098","url":null,"abstract":"Geodynamic models implying subduction of continental crust either consider this process happening during collision, when the continental margin of the lower plate attempts subduction, or in pre-collisional stages, when tectonic erosion of the upper plate or subduction of continental extensional allochthons drag continental crust in the subduction channel. In the Zagros orogen (W Iran), high-pressure rocks are known only from the Sanandaj-Sirjan Zone, NE of the Main Zagros Thrust. Here, eclogites of the North Shahrekord Metamorphic Complex suggest subduction of continental crust slices derived from the upper plate (Central Iran) during the onset of the Neo-Tethys subduction along the southern margin of Iran. Eclogites record a clockwise pressure-temperature-time path, with pre-eclogitic epidote-amphibolites-facies phase assemblages preserved in garnet cores, a high-pressure stage, and a subsequent retrogression at amphibolite-facies conditions. By means of forward thermodynamic modelling and 40Ar/39Ar geochronology, the peak metamorphism has been constrained at 1.9-2.1 GPa and 550-600 °C, in the 191-194 Ma time span. The following retrogression during exhumation lasted at least until 144 Ma. Our data suggest that the onset of the Neo-Tethys subduction traces back prior to 190 Ma, involving together with the Neo-Tethys oceanic lithosphere also slices of the upper plate continental crust scraped off by means of tectonic erosion processes.","PeriodicalId":12612,"journal":{"name":"Geological Magazine","volume":"39 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140616106","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}

引用次数: 0

Geology, fluid inclusions and C−O−S−Pb isotopic compositions of the Chahmileh Pb-Zn deposit, Central Iran: Implications for ore genesis 伊朗中部 Chahmileh 铅锌矿床的地质、流体包裹体和 C-O-S-Pb 同位素组成：对矿石成因的影响

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-04-04 DOI: 10.1017/s0016756823000766

Behzad Mehrabi, Nafiseh Chaghaneh, Ebrahim Tale Fazel, Fernando Corfu

{"title":"Geology, fluid inclusions and C−O−S−Pb isotopic compositions of the Chahmileh Pb-Zn deposit, Central Iran: Implications for ore genesis","authors":"Behzad Mehrabi, Nafiseh Chaghaneh, Ebrahim Tale Fazel, Fernando Corfu","doi":"10.1017/s0016756823000766","DOIUrl":"https://doi.org/10.1017/s0016756823000766","url":null,"abstract":"The Chahmileh Pb–Zn deposit, located northwest of the Central Iran Zone, is a sediment-hosted Pb–Zn deposit in the ‘Yazd-Anarak Metallogenic Belt’. It is hosted in Middle Triassic carbonate rocks and is mainly controlled by NW-trending faults. The main ore minerals are galena and sphalerite with minor chalcopyrite, pyrite, and quartz, dolomite, along with minor calcite and baryte as gangue minerals. Cerussite, hemimorphite, wulfenite, mimetite, smithsonite, malachite and iron oxy-hydroxides are the main non-sulphide ore minerals. The main styles of mineralization are vein-veinlet, breccia, disseminated and replacement in association with silicification and dolomitization. Microthermometry of fluid inclusions in dolomite and quartz indicates that the ore precipitated from a warm to hot basin-derived saline fluid. Dolomite samples have δ13CVPDB and δ18OVSMOW values of −0.99 to +1.99‰ and +20.74 to +25.48‰, respectively, and are plotted in the marine carbonate rocks field. These isotopic values suggest that CO2 in the hydrothermal fluids mainly originated from marine carbonate rock. The δ34S values range from +6.3 to +8.2‰ for galena, +5.9 to +6.2‰ for sphalerite, +1.4 to +3.4‰ for chalcopyrite and +15.0 to +17.4‰ for bayite are compatible with a predominant thermochemical sulphate reduction process, and with sulphur sourced from Triassic seawater. Galena samples have a homogeneous Pb isotopic composition that is indicative of a continental crustal reservoir as the main source of lead and probably for the other ore metals. Based on geology, mineralogy, texture and fluid characteristics, the Chahmileh deposit is classified as a carbonate-hosted Mississippi Valley-type deposit.","PeriodicalId":12612,"journal":{"name":"Geological Magazine","volume":"36 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140585877","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}

引用次数: 0

Disruption and localization of sediment pathways by continental extension: Detrital-zircon provenance change from upper Triassic to lower Jurassic in the northern Sverdrup Basin, Nunavut 大陆延伸对沉积路径的破坏和定位：努勒维特斯维尔德鲁普盆地北部从上三叠世到下侏罗世的碎屑锆石出处变化

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-04-02 DOI: 10.1017/s0016756824000050

Derrick Midwinter, Thomas Hadlari, Keith Dewing, William A Matthews

{"title":"Disruption and localization of sediment pathways by continental extension: Detrital-zircon provenance change from upper Triassic to lower Jurassic in the northern Sverdrup Basin, Nunavut","authors":"Derrick Midwinter, Thomas Hadlari, Keith Dewing, William A Matthews","doi":"10.1017/s0016756824000050","DOIUrl":"https://doi.org/10.1017/s0016756824000050","url":null,"abstract":"Constraints on the tectonic setting of the upper Triassic to lower Jurassic in the Sverdrup Basin can be elucidated from detrital-zircon U-Pb ages. During the Triassic, there was a dual provenance system into sedimentary basins along the western and northern margins of Laurentia. One of the sediment sources was from an extra-basinal igneous source of Permian-Triassic zircon while the other source was recycled sediment eroded from older sedimentary basins. The Heiberg Formation/Group was deposited during a period of significant siliciclastic sedimentation into the basin from the upper Triassic to the lower Jurassic and comprises three members: Romulus, Fosheim and Remus. Previous work has interpreted that the Carboniferous-Permian-Triassic detrital zircon had stopped reaching the northern part of the Sverdrup Basin by deposition of the upper Heiberg Formation (lower Jurassic). New detrital-zircon age analyses from samples along the northern part of the basin spanning different horizons in the Heiberg Formation show that the typical extra-basinal signature, with abundant Carboniferous-Permian-Triassic ages, was no longer recorded during the initial deposition of the Fosheim Member during the latest Triassic. Previously published basin analysis from the Sverdrup Basin interprets syn-Jurassic extensional faults and so we relate the provenance change to the onset of extension. It is interpreted that the Sverdrup Basin transitioned from a basin that received sediment from a northern extra-basinal igneous source during deposition of the Romulus Member to an extensional basin by the deposition of the Fosheim Member in the latest Triassic, as the northern sediment source was interrupted by intervening extensional basins of the proto-Amerasia Basin.","PeriodicalId":12612,"journal":{"name":"Geological Magazine","volume":"31 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140585853","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}

引用次数: 0

Entophysalis in the Rhynie chert (Lower Devonian, Scotland): implications for cyanobacterial evolution 雷尼石灰岩（苏格兰下泥盆纪）中的 Entophysalis：对蓝藻进化的影响

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-02-26 DOI: 10.1017/s0016756824000049

Sean McMahon, Corentin C. Loron, Laura M. Cooper, Alexander J. Hetherington, Michael Krings

{"title":"Entophysalis in the Rhynie chert (Lower Devonian, Scotland): implications for cyanobacterial evolution","authors":"Sean McMahon, Corentin C. Loron, Laura M. Cooper, Alexander J. Hetherington, Michael Krings","doi":"10.1017/s0016756824000049","DOIUrl":"https://doi.org/10.1017/s0016756824000049","url":null,"abstract":"The ∼407-myr-old Rhynie chert of Scotland contains exquisite body fossils of land plants, animals and microorganisms, which provide our earliest reasonably complete snapshot of a Phanerozoic terrestrial ecosystem. These fossils have been instrumental to our understanding of the ‘greening of the land’, a major transition in the history of the Earth–life system. Among the primary producers preserved in the chert are cyanobacteria, of which only a fraction have been formally described. Here, we report the occurrence of the colony-forming cyanobacterium Eoentophysalis in the Rhynie chert. To our knowledge, this represents the first bona fide record of Entophysalidaceae from any post-Cambrian fossil assemblage or any non-marine fossil assemblage of any age. The Rhynie Eoentophysalis appears remarkably similar in appearance both to modern marine and freshwater Entophysalis ssp. and to Eoentophysalis belcherensis, a shallow-marine fossil from the ∼2 Ga Belcher Group of Canada that is perhaps the oldest convincing cyanobacterium on record. Darkened cell envelopes in the Rhynie Eoentophysalis correspond well with both E. belcherensis and modern Entophysalis, whose cell envelopes often contain the photoprotective brown pigment scytonemin. The occurrence of Eoentophysalis in the Rhynie chert supports previous claims that the fossilisable traits of entophysalid cyanobacteria are evolutionarily static through geological time. These organisms may be such effective generalists that major changes in their environment – in this case, the transition to a fully non-marine habitat – have not imposed significant selection pressure on these traits.","PeriodicalId":12612,"journal":{"name":"Geological Magazine","volume":"34 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139968069","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}

引用次数: 0

Chinese stalagmite δ18O records reveal the diverse moisture trajectories during the middle to late last glacial period 中国石笋δ18O记录揭示了末次冰川中后期不同的水分轨迹

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-02-19 DOI: 10.1017/s0016756824000013

Huihui Yang, Yu-Min Chou, Xiuyang Jiang, Wei Zheng, Yaoqi He, Yogaraj Banerjee, Chuan-Chou Shen, Tsai-Luen Yu, Yi Zhong, Fabien Humbert, Qingsong Liu

{"title":"Chinese stalagmite δ18O records reveal the diverse moisture trajectories during the middle to late last glacial period","authors":"Huihui Yang, Yu-Min Chou, Xiuyang Jiang, Wei Zheng, Yaoqi He, Yogaraj Banerjee, Chuan-Chou Shen, Tsai-Luen Yu, Yi Zhong, Fabien Humbert, Qingsong Liu","doi":"10.1017/s0016756824000013","DOIUrl":"https://doi.org/10.1017/s0016756824000013","url":null,"abstract":"Based on 30 high-resolution U-Th dating controls, we reconstruct stalagmite δ18O records from 45 to 15 thousand years ago (ka B.P., before AD 1950) from the Shizhu Cave, which is located in southwestern China under the influence of both the Indian Summer Monsoon (ISM) and the East Asian Summer Monsoon (EASM). By integrating with the other stalagmite δ18O records in Asia during the middle to late last glacial, our results reveal two main moisture trajectories: one from the Indian Ocean, through the Shizhu Cave towards central China, and the other from the Pacific Ocean to central and northern China. The systematic decrease of the average values of stalagmite δ18O records from oceans to inland China reveals a spatial pattern of water vapour fractionation and moisture trajectory during the middle to late last glacial. In contrast, the variation amplitude, which is defined as the departures apart from the background δ18O records during Heinrich stadials 1 to 4 (HS1–HS4), show an increasing trend from the coastal oceans to mid-latitude inland China, presenting a ‘coastal-inland’ pattern, which can be interpreted by the enhanced East Asian Winter Monsoon (EAWM) and the weakened EASM. More specifically, the enriched stalagmite δ18O records in the EASM region during HS1 to HS4 are caused by the decreased summer rainfall amount or/and the increased proportion of summer moisture resources from the Pacific Ocean. These new observations deepen our understanding of the complicated stalagmite δ18O records in the EASM region.","PeriodicalId":12612,"journal":{"name":"Geological Magazine","volume":"39 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139910444","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}

引用次数: 0

Structural, lithostratigraphic and thermal features of a Permian lower crust from the Western Italian Alps (Valpelline Series, Valle d’Aosta) 意大利西阿尔卑斯山二叠纪下地壳的结构、岩石地层学和热特征（Valpelline 系列，Valle d'Aosta）

IF 2.3 3区地球科学

Geological Magazine Pub Date : 2024-02-06 DOI: 10.1017/s0016756824000037

Fabiola Caso, Antonella Strambini, Michele Zucali

{"title":"Structural, lithostratigraphic and thermal features of a Permian lower crust from the Western Italian Alps (Valpelline Series, Valle d’Aosta)","authors":"Fabiola Caso, Antonella Strambini, Michele Zucali","doi":"10.1017/s0016756824000037","DOIUrl":"https://doi.org/10.1017/s0016756824000037","url":null,"abstract":"The Valpelline Series (Dent-Blanche Tectonic System, Western Italian Alps) is a sector of lower continental crust, which consists of Permian migmatitic metapelite with different mineral assemblages (i.e., garnet-, cordierite- and orthopyroxene-bearing), minor amphibolite and marble, intruded by aplite and pegmatite. Widespread melt production in metapelite and locally in amphibolite occurred during the development of the regional foliation. The P–T conditions during migmatisation, estimated using conventional geothermobarometers, range between 800–900 °C and 0.5–0.8 GPa, with a difference of up to ∼50 °C between cordierite- and orthopyroxene-bearing migmatites, the latter reaching higher temperatures. The Valpelline Series shows rock types, metamorphic assemblages, P–T conditions and published ages of high-temperature regional metamorphism like the archetypal lower crust section of the Ivrea-Verbano Zone in the Southern Western Alps. The latter likely represents an external portion of the same extending lower crust, at the onset of the Tethyan rifting due to lithospheric extension and asthenospheric rising.","PeriodicalId":12612,"journal":{"name":"Geological Magazine","volume":"12 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139770769","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}

引用次数: 0