中条山西南地区基性岩墙群的地球化学特征及其地质意义

Geochemistry and Geological Implications of Mafic Dyke Swarms in the Southwestern Area of Zhongtiao Mountains

根据岩石学和地球化学组成分析,分3组讨论了中条山西南地区辉绿岩岩墙群的成因。结果表明:它们都是富集地幔源区源岩部分熔融的产物。第1组岩墙是初始岩浆经历少量的铁镁质矿物分离结晶作用的产物;第2组和第3组岩墙是玄武质岩浆又经历壳幔岩浆混合和斜长石、钛磁铁矿等分离结晶作用的产物;第3组岩墙可能受地壳混染和后期热液蚀变的影响较大。它们都形成于板内伸展环境,可能与熊耳–中条拗拉谷的发育有关。

Based on the petrographic and geochemical characteristics, petrogenesis of diabase dyke swarms in the southwestern area of Zhongtiao mountains can be discussed in three groups. The results show that the basaltic magma was derived from partial melting of an enriched mantle. Group 1 directly came from initial mantle magma and experienced a small amount of fractional crystallization of mafic minerals. Groups 2 and 3 were derived from a mixing of the mantle and the crust magmas, which experienced fractional crystallization of plagiocalse and Ti-Fe oxides. Compared with group 2, group 3 might undergo significantly crustal contamination and hydrothermal alteration. They were formed in the intraplate extensional environment, which might be related to the extension of the Xionger-Zhongtiao aulacogen.