首页|Plume-lithosphere interaction in the Comei Large Igneous Province:Evidence from two types of mafic dykes in Gyangze,south Tibet,China

Plume-lithosphere interaction in the Comei Large Igneous Province:Evidence from two types of mafic dykes in Gyangze,south Tibet,China

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Two suites of mafic dykes,T1193-A and T1194-A,outcrop in Gyangze area,southeast Tibet.They are in the area of Comei LIP and have indistinguishable field occurrences with two other dykes in Gyangze,T0902 dyke with 137.7±1.3 Ma zircon age and T0907 dyke with 142±1.4 Ma zircon age reported by Wang YY et al.(2016),indicating coeval formation time.Taking all the four diabase dykes into consideration,two different types,OIB-type and weak enriched-type,can be summarized.The"OIB-type"samples,including T1193-A and T0907 dykes,show OIB-like geochemical features and have initial Sr-Nd isotopic values similar with most mafic products in Comei Large Igneous Provinces(LIP),suggesting that they represent melts directly generated from the Kerguelen mantle plume.The"weak enriched-type"samples,including T1194-A and T0902 dykes,have REEs and trace element patterns showing within-plate affinity but have obvious Nb-Ta-Ti negative anomalies.They show uniform lower εNd(t)values(-6‒-2)and higher 87Sr/86Sr(t)values(0.706‒0.709)independent of their MgO variation,indicating one enriched mantle source.Considering their closely spatial and temporal relationship with the widespread Comei LIP magmatic products in Tethyan Himalaya,these"weak enriched-type"samples are consistent with mixing of melts from mantle plume and the above ancient Tethyan Himalaya subcontinental lithospheric mantle(SCLM)in different proportions.These weak enriched mafic rocks in Comei LIP form one special rock group and most likely suggest large scale hot mantle plume-continental lithosphere interaction.This process may lead to strong modification of the Tethyan Himalaya lithosphere in the Early Cretaceous.

OIB type diabaseComei Large Igneous ProvinceWeakly enriched diabasePlume-lithosphere interactionNb-Ta-Ti negative anomalyKerguelen plumeGeological survey engineeringTibet Plateau

Ya-ying Wang、Ling-sen Zeng、Li-e Gao、Li-long Yan、Ling-hao Zhao、Jia-hao Gao、Ying-long Di、Guang-xu Li、Yi-hong Tian

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Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China

National Research Center for Geoanalysis,Chinese Academy of Geological Sciences,Beijing 100037,China

China Nonferrous Metals(Guilin)Geology and Mining Co.,Ltd,Guilin 541004,China

国家自然科学基金国家自然科学基金China Geological SurveyChina Geological Surveybasic scientific research funding in CAGSSecond Tibetan Plateau Scientific Expedition and Research Program(STEP)

4210205992055202DD20221817DD20190057J22042019QZKK0702

2024

10.31035/cg2023023

中国地质(英文)
中国地质调查局,中国地质科学院

中国地质(英文)

CSTPCD
ISSN：2096-5192
年,卷(期)：2024.7(1)
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