黔西地区织纳煤田峨眉山玄武岩地球化学特征及成因

Geochemical Characteristics and Genesis of E'meishan Basalt in Zhina Coalfield in Western Guizhou Province

结合岩石取样分析结果,讨论了黔西地区织纳煤田玄武岩的主、微量元素地球化学特征,并对其成因进行了研究。结果表明:(1)岩体Si O2含量变化范围较大(30.98%~57.19%),主要属于基性火山熔岩,TAS分类图解显示以亚碱性系列为主,主要富集高场强元素(Nb、Zr、Hf、Ti)和Th等,亏损Y,Ba、Sr含量有明显波动,Mg O含量与Fe2O3含量、Ca O/Al2O3含量比值呈较明显的负相关关系,而与Ni、Cr等含量呈明显的正相关关系;(2)岩体的源区可能为下地幔,形成于板内拉张构造环境,发生了磁铁矿、橄榄石等矿物的分离结晶作用,在玄武岩形成过程中,遭受了一定的混染作用,且源区混染作用对其影响大于地壳混染作用。

Based on the rock sampling analysis results, the geochemical characteristics of the main and trace elements of Etneishan basalt in Zhina Coalfield in Western Guizhou Province is discussed, and the genesis of the rock mass is also studied. The study results show that ： （1）the contents variation range of SlOE （from 30.98% to 57. 19% ） is large,the properties of the rock mass is belongs to basic volcanic la- va, the TAS classification diagram show that the property of the rock mass is mainly for alkaline series, the rock mass is mainly enriched for the high field strength element （Nb, Zr, Hf, Ti） and Th, loss of Y, the volatility characteristics of Ba and Sr is significant, MgO content has significant negative correlation with FeE O3 content and content ratio of CaO and A1E O3 , and it has significant positive correlation with the con- tents of Ni and Cr ; （2）the source of the rock mass may be the lower mantle, the rock mass is formed in the internal tensile structure environment, the isolated crystallization of the minerals （magnetite and olivine） is occurred, during the formation process of basalt, a certain mixed dyeing effect is suffered, the influence degree of sources area mixed dyeing effect to the formation of basalt is larger than the one of crustal mixed dyeing effect to the formation of basalt.