川东北地区长兴组-飞仙关组中金红石和菱锶矿的发现及成因解释

Discovery and origin explanation of rutile and strontianite of Changxing-Feixianguan Formation in the northeast of Sichuan

通过室内薄片研究,认为川东北地区长兴组-飞仙关组碳酸盐岩地层中赋存有自生金红石和菱锶矿。应用矿物学理论,并结合电子探针、扫描电镜和能谱成分等测试分析,结果表明金红石为中-晚成岩阶段形成的热水在运移过程中与富含绿泥石质泥土、黑云母碎片的碳酸盐岩围岩发生水岩反应,即从绿泥石、黑云母中析出的Ti元素结晶而成。菱锶矿为中-晚成岩期形成的地下热水与富含锶元素的碳酸盐岩发生水岩反应的产物。金红石、菱锶矿这2个自生矿物的产生,表明长兴组-飞仙关组的沉积-成岩演化过程中有热水参与。金红石、菱锶矿的形成是长兴组-飞仙关组中微量元素在沉积-成岩演化过程中层内元素再分配的结果,与深部热流体活动无关。

Based on the research of slices,the authors consider that there are authigenic rutile and strontianite in Changxing-Feixianguan Formation in the northeast area of Sichuan.The paper indicates that rutile and strontianite are generated respectively by the reactions between the geothermal hot water formed in middle-late diagenetic period and chlorite,carbonate rock in blackmica rich and between that and carbonate rock rich in strontium trough mineralogy theory and analyses including EMP,SEM,and energy spectrum.Rutile is the crystallization of Ti which is separated from chlorite and blackmica.The formation of two authigenic minerals of rutile and strontianite provides very important criteria that thermal waters affiliate the formation process considering either from the aspect of carbonate formation in the depositional-diagenetic history of Changxing-Feixianguan Formation in the northeast of Sichuan or from the aspect of Changxing-Feixianguan Formation reservoir.Mass facts approve that the formation of rutile and strontianite is the result of trace elements redistribution in Changxing-Feixianguan Formation in the process of depositional diagenetic evolvement,and this has little to do with the movement of deep lying hot fluids.