{"title":"确定凯尔盖朗地幔羽流的EMII型地幔末段及其对冈瓦纳东部最初解体的影响:来自特提安喜马拉雅山白垩纪辉绿岩的新制约因素","authors":"Fanxue Meng , Yuanku Meng , Youqing Wei","doi":"10.1016/j.jseaes.2024.106250","DOIUrl":null,"url":null,"abstract":"<div><p>The breakup of eastern Gondwana during the Early Cretaceous has been well-documented. However, the relationship between Cretaceous mafic magma and the Kerguelen mantle plume has not been well-constrained. It is also unknown if the Kerguelen mantle plume in the Tethyan Himalaya played a key role in triggering the breakup of eastern Gondwana. The petrogenesis and geodynamic processes of the coeval magmatism in the Tethyan Himalaya might provide value insights into this issue. In this study, we conducted petrological, geochronological, and geochemical investigations on a recently identified diabase from the Yamdrok Lake. The diabase contains zircon grains with a U-Pb age of 138 ± 8 Ma, suggesting the emplacement at the Early Cretaceous. Geochemically, the studied samples display OIB-like trace elemental features that are enriched in light rare earth elements (LREEs) but no significant depletion in high field strength elements (HFSEs), such as Nb, Ta, and Ti. Furthermore, they have relatively uniform Sr-Nd-Pb-Hf-O isotopic compositions with initial <sup>87</sup>Sr/<sup>86</sup>Sr ratios varying from 0.70563 to 0.70623, ε<sub>Nd</sub>(t) and ε<sub>Hf</sub>(t) values range from 0.6 to 0.8 and 1.0–2.4, respectively, whole-rock δ<sup>18</sup>O values of 6.42 ‰ to 7.50 ‰, and (<sup>208</sup>Pb/<sup>204</sup>Pb)<sub>i</sub> = 38.995 ∼ 39.285, (<sup>207</sup>Pb/<sup>204</sup>Pb)<sub>i</sub> = 15.673 ∼ 15.698, and (<sup>206</sup>Pb/<sup>204</sup>Pb)<sub>i</sub> = 18.689 ∼ 18.914, similar to an EMII-type enriched mantle. And recycled shallow continental crustal materials into the OIB-like mantle source might account for the EMII-type mantle features observed in this study. Considering the Kerguelen mantle plume locating beneath the triple junction of Australia, Antarctica, and Greater India, we propose that the mafic rocks in this study might be genetically related to the early activity or even initiation of the Kerguelen plume during the Early Cretaceous. Our study further indicates that the Kerguelen mantle plume contains EMI- and EMII-type isotopic compositions, which are characterized by geochemical complexity and variation.</p></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":null,"pages":null},"PeriodicalIF":2.7000,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Identification of the EMII-type mantle end-member of the Kerguelen mantle plume and its implications for the initial breakup of eastern Gondwana: New constraints from the Cretaceous diabase in the Tethyan Himalaya\",\"authors\":\"Fanxue Meng , Yuanku Meng , Youqing Wei\",\"doi\":\"10.1016/j.jseaes.2024.106250\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The breakup of eastern Gondwana during the Early Cretaceous has been well-documented. However, the relationship between Cretaceous mafic magma and the Kerguelen mantle plume has not been well-constrained. It is also unknown if the Kerguelen mantle plume in the Tethyan Himalaya played a key role in triggering the breakup of eastern Gondwana. The petrogenesis and geodynamic processes of the coeval magmatism in the Tethyan Himalaya might provide value insights into this issue. In this study, we conducted petrological, geochronological, and geochemical investigations on a recently identified diabase from the Yamdrok Lake. The diabase contains zircon grains with a U-Pb age of 138 ± 8 Ma, suggesting the emplacement at the Early Cretaceous. Geochemically, the studied samples display OIB-like trace elemental features that are enriched in light rare earth elements (LREEs) but no significant depletion in high field strength elements (HFSEs), such as Nb, Ta, and Ti. Furthermore, they have relatively uniform Sr-Nd-Pb-Hf-O isotopic compositions with initial <sup>87</sup>Sr/<sup>86</sup>Sr ratios varying from 0.70563 to 0.70623, ε<sub>Nd</sub>(t) and ε<sub>Hf</sub>(t) values range from 0.6 to 0.8 and 1.0–2.4, respectively, whole-rock δ<sup>18</sup>O values of 6.42 ‰ to 7.50 ‰, and (<sup>208</sup>Pb/<sup>204</sup>Pb)<sub>i</sub> = 38.995 ∼ 39.285, (<sup>207</sup>Pb/<sup>204</sup>Pb)<sub>i</sub> = 15.673 ∼ 15.698, and (<sup>206</sup>Pb/<sup>204</sup>Pb)<sub>i</sub> = 18.689 ∼ 18.914, similar to an EMII-type enriched mantle. And recycled shallow continental crustal materials into the OIB-like mantle source might account for the EMII-type mantle features observed in this study. Considering the Kerguelen mantle plume locating beneath the triple junction of Australia, Antarctica, and Greater India, we propose that the mafic rocks in this study might be genetically related to the early activity or even initiation of the Kerguelen plume during the Early Cretaceous. Our study further indicates that the Kerguelen mantle plume contains EMI- and EMII-type isotopic compositions, which are characterized by geochemical complexity and variation.</p></div>\",\"PeriodicalId\":50253,\"journal\":{\"name\":\"Journal of Asian Earth Sciences\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.7000,\"publicationDate\":\"2024-07-04\",\"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/S1367912024002451\",\"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/S1367912024002451","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}
Identification of the EMII-type mantle end-member of the Kerguelen mantle plume and its implications for the initial breakup of eastern Gondwana: New constraints from the Cretaceous diabase in the Tethyan Himalaya
The breakup of eastern Gondwana during the Early Cretaceous has been well-documented. However, the relationship between Cretaceous mafic magma and the Kerguelen mantle plume has not been well-constrained. It is also unknown if the Kerguelen mantle plume in the Tethyan Himalaya played a key role in triggering the breakup of eastern Gondwana. The petrogenesis and geodynamic processes of the coeval magmatism in the Tethyan Himalaya might provide value insights into this issue. In this study, we conducted petrological, geochronological, and geochemical investigations on a recently identified diabase from the Yamdrok Lake. The diabase contains zircon grains with a U-Pb age of 138 ± 8 Ma, suggesting the emplacement at the Early Cretaceous. Geochemically, the studied samples display OIB-like trace elemental features that are enriched in light rare earth elements (LREEs) but no significant depletion in high field strength elements (HFSEs), such as Nb, Ta, and Ti. Furthermore, they have relatively uniform Sr-Nd-Pb-Hf-O isotopic compositions with initial 87Sr/86Sr ratios varying from 0.70563 to 0.70623, εNd(t) and εHf(t) values range from 0.6 to 0.8 and 1.0–2.4, respectively, whole-rock δ18O values of 6.42 ‰ to 7.50 ‰, and (208Pb/204Pb)i = 38.995 ∼ 39.285, (207Pb/204Pb)i = 15.673 ∼ 15.698, and (206Pb/204Pb)i = 18.689 ∼ 18.914, similar to an EMII-type enriched mantle. And recycled shallow continental crustal materials into the OIB-like mantle source might account for the EMII-type mantle features observed in this study. Considering the Kerguelen mantle plume locating beneath the triple junction of Australia, Antarctica, and Greater India, we propose that the mafic rocks in this study might be genetically related to the early activity or even initiation of the Kerguelen plume during the Early Cretaceous. Our study further indicates that the Kerguelen mantle plume contains EMI- and EMII-type isotopic compositions, which are characterized by geochemical complexity and variation.
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.