Xiaomei Nie , Guangyan Chen , Qinglai Feng , Jianwei Zi , Hailong Gao , Zaibo Sun , Hu Zhang , Guichun Liu , Jianye Ren , Tianyu Zhao , Zhengqin Gan , Longlong Meng
{"title":"与中国西南部云南西部前太古宙和古太古宙演化有关的早石炭世板块内岩浆岩:地质年代和地球化学制约因素","authors":"Xiaomei Nie , Guangyan Chen , Qinglai Feng , Jianwei Zi , Hailong Gao , Zaibo Sun , Hu Zhang , Guichun Liu , Jianye Ren , Tianyu Zhao , Zhengqin Gan , Longlong Meng","doi":"10.1016/j.jseaes.2024.106219","DOIUrl":null,"url":null,"abstract":"<div><p>Western Yunnan in SW China preserves abundant rock records related to the eastern Proto- and Paleo-Tethys oceans, yet the transition between the two oceans remains poorly understood. This paper presents new zircon U–Pb ages and Lu–Hf isotopic data, together with whole-rock elemental and Nd isotopic data for the magmatic rocks from Mengding and Menglong in western Yunnan. The Mengding basaltic rocks show oceanic island basalt geochemical features and have similar whole-rock Nd isotopic compositions with ε<sub>Nd</sub>(t) values of +3.5–+4.4 and uniform zircon Lu–Hf compositions with ε<sub>Hf</sub>(t) values of +6.1–+8.0, similar to the modern Hainan oceanic island basalts. These rocks yielded a zircon U–Pb age of 341 ± 2 Ma, indicating their eruption in a passive continental rift basin setting during the early Carboniferous. The Menglong mafic rocks yielded a similar zircon U–Pb age of 343 ± 3 Ma. The Menglong mafic–ultramafic rocks display E-MORB geochemical signatures, suggesting a within-plate extensional setting. They exhibit uniform Nd isotopic compositions with ε<sub>Nd</sub>(t) values of +4.1–+4.4, whereas their zircon Ɛ<sub>Hf</sub>(t) values vary from −19.5 to +11.1, indicating a mixed magma source with contributions from asthenosphere mantle and decompression melting of the metasomatized mantle wedge. Our results, together with the regional geological and stratigraphical evidence, suggest that the Menglong mafic–ultramafic rocks are comparable with the Late Devonian–early Carboniferous magmatic rocks in northern Tibet, eastern Myanmar and northern Thailand, likely formed in a post-collision extensional setting in the aftermath of Proto-Tethys closure. Taking account of the zonal distribution of the Late Devonian–early Carboniferous magmatic rocks, we propose that slab detachment of the Proto-Tethys led to an overall extensional tectonic setting, resulting in a series of rift basins in western Yunnan during the Late Devonian to early Carboniferous. The Paleo-Tethys probably opened on one of the rift basins of the Proto-Tethys.</p></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":null,"pages":null},"PeriodicalIF":2.7000,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Early Carboniferous within-plate magmatic rocks related to Proto- and Paleo-Tethys evolution in western Yunnan, SW China: Geochronological and geochemical constraints\",\"authors\":\"Xiaomei Nie , Guangyan Chen , Qinglai Feng , Jianwei Zi , Hailong Gao , Zaibo Sun , Hu Zhang , Guichun Liu , Jianye Ren , Tianyu Zhao , Zhengqin Gan , Longlong Meng\",\"doi\":\"10.1016/j.jseaes.2024.106219\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Western Yunnan in SW China preserves abundant rock records related to the eastern Proto- and Paleo-Tethys oceans, yet the transition between the two oceans remains poorly understood. This paper presents new zircon U–Pb ages and Lu–Hf isotopic data, together with whole-rock elemental and Nd isotopic data for the magmatic rocks from Mengding and Menglong in western Yunnan. The Mengding basaltic rocks show oceanic island basalt geochemical features and have similar whole-rock Nd isotopic compositions with ε<sub>Nd</sub>(t) values of +3.5–+4.4 and uniform zircon Lu–Hf compositions with ε<sub>Hf</sub>(t) values of +6.1–+8.0, similar to the modern Hainan oceanic island basalts. These rocks yielded a zircon U–Pb age of 341 ± 2 Ma, indicating their eruption in a passive continental rift basin setting during the early Carboniferous. The Menglong mafic rocks yielded a similar zircon U–Pb age of 343 ± 3 Ma. The Menglong mafic–ultramafic rocks display E-MORB geochemical signatures, suggesting a within-plate extensional setting. They exhibit uniform Nd isotopic compositions with ε<sub>Nd</sub>(t) values of +4.1–+4.4, whereas their zircon Ɛ<sub>Hf</sub>(t) values vary from −19.5 to +11.1, indicating a mixed magma source with contributions from asthenosphere mantle and decompression melting of the metasomatized mantle wedge. Our results, together with the regional geological and stratigraphical evidence, suggest that the Menglong mafic–ultramafic rocks are comparable with the Late Devonian–early Carboniferous magmatic rocks in northern Tibet, eastern Myanmar and northern Thailand, likely formed in a post-collision extensional setting in the aftermath of Proto-Tethys closure. Taking account of the zonal distribution of the Late Devonian–early Carboniferous magmatic rocks, we propose that slab detachment of the Proto-Tethys led to an overall extensional tectonic setting, resulting in a series of rift basins in western Yunnan during the Late Devonian to early Carboniferous. The Paleo-Tethys probably opened on one of the rift basins of the Proto-Tethys.</p></div>\",\"PeriodicalId\":50253,\"journal\":{\"name\":\"Journal of Asian Earth Sciences\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.7000,\"publicationDate\":\"2024-06-03\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Asian Earth Sciences\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S1367912024002141\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Asian Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1367912024002141","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
Early Carboniferous within-plate magmatic rocks related to Proto- and Paleo-Tethys evolution in western Yunnan, SW China: Geochronological and geochemical constraints
Western Yunnan in SW China preserves abundant rock records related to the eastern Proto- and Paleo-Tethys oceans, yet the transition between the two oceans remains poorly understood. This paper presents new zircon U–Pb ages and Lu–Hf isotopic data, together with whole-rock elemental and Nd isotopic data for the magmatic rocks from Mengding and Menglong in western Yunnan. The Mengding basaltic rocks show oceanic island basalt geochemical features and have similar whole-rock Nd isotopic compositions with εNd(t) values of +3.5–+4.4 and uniform zircon Lu–Hf compositions with εHf(t) values of +6.1–+8.0, similar to the modern Hainan oceanic island basalts. These rocks yielded a zircon U–Pb age of 341 ± 2 Ma, indicating their eruption in a passive continental rift basin setting during the early Carboniferous. The Menglong mafic rocks yielded a similar zircon U–Pb age of 343 ± 3 Ma. The Menglong mafic–ultramafic rocks display E-MORB geochemical signatures, suggesting a within-plate extensional setting. They exhibit uniform Nd isotopic compositions with εNd(t) values of +4.1–+4.4, whereas their zircon ƐHf(t) values vary from −19.5 to +11.1, indicating a mixed magma source with contributions from asthenosphere mantle and decompression melting of the metasomatized mantle wedge. Our results, together with the regional geological and stratigraphical evidence, suggest that the Menglong mafic–ultramafic rocks are comparable with the Late Devonian–early Carboniferous magmatic rocks in northern Tibet, eastern Myanmar and northern Thailand, likely formed in a post-collision extensional setting in the aftermath of Proto-Tethys closure. Taking account of the zonal distribution of the Late Devonian–early Carboniferous magmatic rocks, we propose that slab detachment of the Proto-Tethys led to an overall extensional tectonic setting, resulting in a series of rift basins in western Yunnan during the Late Devonian to early Carboniferous. The Paleo-Tethys probably opened on one of the rift basins of the Proto-Tethys.
期刊介绍:
Journal of Asian Earth Sciences has an open access mirror journal Journal of Asian Earth Sciences: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review.
The Journal of Asian Earth Sciences is an international interdisciplinary journal devoted to all aspects of research related to the solid Earth Sciences of Asia. The Journal publishes high quality, peer-reviewed scientific papers on the regional geology, tectonics, geochemistry and geophysics of Asia. It will be devoted primarily to research papers but short communications relating to new developments of broad interest, reviews and book reviews will also be included. Papers must have international appeal and should present work of more than local significance.
The scope includes deep processes of the Asian continent and its adjacent oceans; seismology and earthquakes; orogeny, magmatism, metamorphism and volcanism; growth, deformation and destruction of the Asian crust; crust-mantle interaction; evolution of life (early life, biostratigraphy, biogeography and mass-extinction); fluids, fluxes and reservoirs of mineral and energy resources; surface processes (weathering, erosion, transport and deposition of sediments) and resulting geomorphology; and the response of the Earth to global climate change as viewed within the Asian continent and surrounding oceans.