镁同位素示踪白云石化流体迁移路径——以四川盆地石炭系黄龙组为例  

Magnesium isotope trace dolomitization fluid migration path: A case study of theCarboniferous Huanglong Formation in the Sichuan basin

作　　者：朱光有[1] 李茜 李婷婷[1] 周磊 吴雨轩[1,2] 沈冰 甯濛 ZHU Guangyou;LI Xi;LI Tingting;ZHOU Lei;WU Yuxuan;SHEN Bing;NING Meng(PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China;China University of Geosciences,Beijing 100083,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国地质大学(北京),北京100083 [3]北京大学地球与空间科学学院,北京100871

出　　处：《地质学报》2023年第3期753-771,共19页Acta Geologica Sinica

基　　金：中国石油天然气股份有限公司科学研究与技术开发项目“海相碳酸盐岩成藏理论与勘探技术研究”(编号2021DJ05)资助的成果。

摘　　要：镁(Mg)是组成白云石的核心元素,直接参与了白云石化过程,因此白云岩Mg同位素能够用于示踪白云岩成因和白云石化流体迁移路径。四川盆地东部上石炭统黄龙组白云岩发育,也是重要储集层。通过对黄龙组连续取芯的七里53井开展详细的沉积学研究,系统选取样品开展元素地球化学和Mg同位素分析,发现Mg同位素波动变化与沉积旋回存在密切关联,旋回边界为白云石化流体迁移界面,即白云石化流体迁移通道;依据Mg同位素值垂向演化规律,识别出黄龙组白云岩5个流体交换界面通道,逐层白云石化。因此,厚层白云岩是由若干个薄层灰岩层逐层白云石化叠加而成。这一发现为预测白云岩成因及储层分布提供了重要理论依据。Magnesium(Mg)is the core element of dolomite,which is directly involved in the dolomitization process.Therefore,Mg isotope of dolomite may be used to trace the origin of dolomite and the migration path of dolomitization fluid.The dolomite of Upper Carboniferous Huanglong Formation is developed in the eastern Sichuan basin,which is also an important reservoir.Through the detailed sedimentology study of Qili53 well of Huanglong Formation,the element geochemistry and Mg isotope analysis of samples were systematically selected.It is found that the fluctuation of Mg isotope is closely related to the sedimentary cycle,and the cycle boundary is the migration interface of dolomitization fluid,that is,the migration channel of dolomitization fluid.According to the vertical evolution of Mg isotope values,five fluid exchange interface channels are identified and stratified in the dolomite of Huanglong Formation.Therefore,thick dolostone is composed of several thin limestone layers superimposed by layer-by-layer cloud.This discovery provides an important theoretical basis for the prediction of dolomite genesis and reservoir distribution.

关 键 词：MG同位素 白云石化 黄龙组 石炭系 四川盆地 

分 类 号：P618.13[天文地球—矿床学]