镇巴地区灯影组岩石微相研究与沉积环境分析

Analysis of Rock Types and Sedimentary Environment of Dengying Formation, Zhenba Area

侯明才 何亮 徐胜林 汤智江

HOUMingcai HELiang XUShenglin TANGZhijiang

成都理工大学沉积地质研究院, 四川 成都 610059 油气藏地质及开发工程国家重点实验室·成都理工大学, 四川 成都 610059

Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, Sichuan 610059, China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan 610059, China

上扬子地区灯影组可以作为优质储层已经被油气勘探所证实。但是，由于灯影组储层的展布规律一直不清楚，制约了对灯影组的进一步勘探。基于镇巴地区鹿池灯影组剖面，开展了详细的岩石微相研究，结合碳、氧同位素和微量元素分析，深入探讨了镇巴地区灯影组的沉积环境。研究表明，镇巴地区震旦系灯影组岩石微相有：泥-粉晶云岩、残余砂屑云岩、叠层石云岩、凝块石云岩、微生物黏结砂屑云岩、泥质粉砂岩、泥质云岩和含云质硅质岩。研究区灯影组沉积环境为开阔碳酸盐岩台地，经历了两次海侵-海退旋回，灯一段-灯二段和灯三段灯四段分别为两个相对完整海侵-海退序列。相对于灯二段，灯四段海平面振荡更频繁，可能与拉张活动在灯四期更活跃有关。碳氧同位素和微量元素数据表明，灯影组的沉积古环境发生了较为剧烈的变化。整体而言，灯影期大致是一个海水盐度下降，温度上升，含氧量逐步增加的过程。

As a high-quality reservoir of the lower assemblage, the Dengying Formation have been proved by the oil and gas exploration. However, the distribution of reservoir is not yet clear. Based on the outcrop of Dengying Formation at Luchi section, Zhenba Area, this paper carries out a detailed study of the sedimentary microfacies. Furthermore, combined with microscopic characteristics, the sedimentary characteristics and genesis of eight types of rocks are sorted out and explained. These rock types include micritic dolostones, residual dolarenite, stromatolite dolostones, thrombolite dolostones, microbe-bonded dolarenite, argillaceous siltstone, argillaceous dolostones and (dolomite-bearing) siliceous rock. The sedimentary environment of Dengying Formation in the study area is open carbonate platform, which has experienced two transgression-regressive cycles.The carbon and oxygen isotope and trace element data indicate that the sedimentary paleoenvironment during deposition of Dengying Formation changed dramatically. On the whole, the deposition period of the Dengying Formation is roughly featured with the decreasement of seawater salinity, increasement of seawater temperature and gradual increasement of oxygen content, but the environmental fluctuations may exist.

10.11885/j.issn.1674-5086.2020.02.19.02