岩石矿物学杂志2026，Vol.45Issue(3)：508-526,19.DOI:10.20086/j.cnki.yskw.2026.5114
扬子西缘冕宁地区新元古代辉绿岩的岩石成因及其构造意义
Petrogenesis and tectonic significance of Neoproterozoic diabase in the Mianning Area,western Yangtze Block
摘要
Abstract
Neoproterozoic mafic dyke swarms are key indicators for reconstructing the timing and dynamic processes of the Rodinia supercontinent breakup.Based on systematic analyses of zircon chronology,whole-rock geochemis-try,and zircon Lu-Hf isotopes,this study investigates the petrogenesis and geodynamic setting of a newly discov-ered diabase dyke swarm in the Mianning area on the western Yangtze Block,South China.LA-ICP-MS zircon U-Pb dating reveals that the Mianning diabase crystallized at 835.8±4 Ma,indicating its formation during the Neo-proterozoic.The diabase exhibits variable SiO2 content(45.2％to 48.0％)and MgO(6.82％to 8.15％)con-tents,as well as Mg#values(46～57),along with high Al2O3(14.00％～15.75％)content.The studied rocks display relatively flat rare earth element(REE)distribution patterns,with enrichment in Rb,Ba,and K,and de-pletion in Nb,Ta,Sr,and P.The studied rocks exhibit enriched zircon Lu-Hf isotopes[εHf(t)=-2.2 to 1.6].Petrogenetic analysis indicates that the Mianning diabase originated from low-degree partial melting of an enriched mantle wedge,with the mantle source having been modified by fluids derived from altered oceanic crust.The Neo-proterozoic Mianning diabase on the western Yangtze Block formed in an extensional continental arc setting,impl-ying that the western margin of the Yangtze Block may have been located at the periphery of the Rodinia superconti-nent during the Neoproterozoic era.关键词
扬子西缘/新元古代/基性岩/岩石成因/构造意义Key words
western Yangtze Block/Neoproterozoic/mafic rocks/petrogenesis/tectonic significance分类
天文与地球科学引用本文复制引用
孙晓彤,熊富浩,闫东东,鄢圣武..扬子西缘冕宁地区新元古代辉绿岩的岩石成因及其构造意义[J].岩石矿物学杂志,2026,45(3):508-526,19.基金项目
国家自然科学基金项目(42572066) （42572066）
四川省自然科学基金项目(2024NSFSC1991) National Natural Science Foundation of China(42572066) （2024NSFSC1991）
Natural Science Foundation of Sichuan Province(2024NSFSC1991) （2024NSFSC1991）
