川东南地区林1井震旦系灯影组电子探针分析:热液白云岩化过程中的元素变化

发布时间：2018-05-16 18:41

本文选题：四川盆地 + 热液白云岩　；参考：《矿物岩石地球化学通报》2017年02期

【摘要】：以电子探针分析为主要研究方法,结合白云岩岩石学特征对四川盆地东南地区林1井上震旦统灯影组热液白云岩进行了研究。其特征表现为基质白云岩晶体较小,中-巨晶鞍形白云石充填溶蚀孔洞和裂缝。鞍形白云石晶体上常发育数条由内到外铁元素含量依次降低的明亮条带,表明其受到多期次的深部热液侵入的影响。通过对电子探针样品的分析,发现在热液白云石形成过程中,Mg~(2+)取代Ca~(2+)的同时伴随Fe~(2+)、Mn~(2+)、Sr~(2+)参与结晶。热液白云岩刚开始沉淀时,热液中的Fe~(2+)与Mn~(2+)进入原岩,随着Mg离子大量取代Ca~(2+),使Fe~(2+)与Mn~(2+)进入率下降;或是前期热液白云石的沉淀大量消耗了热液中的金属Fe~(2+)和Mn~(2+),导致金属离子供应不足,造成沉淀过程中Fe~(2+)与Mn~(2+)含量随着Mg~(2+)含量增加而减少,反映着热液白云岩化过程的流体改造进程。
[Abstract]:Based on the electron probe analysis and the petrological characteristics of dolomite, the hydrothermal dolomite of the Upper Sinian Dengying formation in Lin1 well in southeast Sichuan Basin was studied. Its characteristics are that the matrix dolomite crystal is small and the mesomorphic saddle dolomite is filled with dissolved pores and fractures. There are several bright bands on the saddle dolomite crystal which decrease the iron content from inside to outside, indicating that it is affected by the invasion of deep hydrothermal solution for many periods. Through the analysis of the samples with electron probe, it was found that the Ca~(2) was replaced by Ca~(2 during the formation of hydrothermal dolomite. When the hydrothermal dolomite began to precipitate, the Fe~(2) and Mn~(2) in the hydrothermal solution entered the original rock, and with mg ions replacing the Ca~(2 + in large quantities, the Fe~(2) and Mn~(2) entry rate decreased. Or the precipitation of hydrothermal dolomite consumes a lot of metal Fe~(2 and Mn~(2 in hydrothermal solution, which leads to insufficient supply of metal ions, resulting in the decrease of Fe~(2) and Mn~(2) content with the increase of Mg~(2) content in the precipitation process. It reflects the process of fluid transformation in the process of hydrothermal dolomitization.
【作者单位】：成都理工大学沉积地质研究院;
【基金】：国家自然科学基金资助项目(41572085,41272131)
【分类号】：P585;P534.31

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