泌阳凹陷下第三系湖相白云岩形成条件  

Sedimentary Condition of Lacustrine Dolomite in the Lower Tertiary Biyang Depression

作　　者：黄杏珍[1] 邵宏舜[1] 闫存凤 妥进才[1] 何祖荣 张新社 王寿庆 李玉兰 

机构地区：[1]中国科学院兰州地质研究所,兰州730000 [2]河南石油局勘探开发研究院,河南南阳473132

出　　处：《沉积学报》2001年第2期207-213,共7页Acta Sedimentologica Sinica

基　　金：国家自然科学基金资助项目 !(批准号 :49872 0 4 8)

摘　　要：中国中、新生代大多数湖盆湖相碳酸盐岩以灰岩沉积为主 ,但部分湖盆像南—襄盆地泌阳凹陷则主要沉积白云岩 ,其累计厚度达 90 0余米 ,而白云岩层系的厚度 (包括白云质、灰质泥岩 ,白云质粉、细砂岩等夹层 )可达 2 2 0 0m ,并成为良好的生油岩系 ,形成小而肥的南阳油田。本文着重探讨如此巨厚的白云岩形成的古气候、古水体的物理化学性质和古环境条件。在目前湖相碳酸盐岩研究仍处于湖泊沉积学研究的极薄弱领域 ,湖相白云岩形成条件更是涉及较少的情况下 。Most of lacustrine carbonate rocks of Mesozoic-Cenozoic era consist of limestone mainly. However, in some lake basins such as the Nan-Xiang basin, it mainly deposited dolomite with a net accumulative thickness of 900 meters. While the entire dolomite sedimentary, sequence can be more than 2100 meters, which formed a set of good oil-generation source rocks, and a small and rich Nan-Yang oil field iasbeen found there. This paper describes, taking the Biyang depression as an example, the genetic conditions of the thick lacustrine dolomite of stable sedimentary fac ies: 1. A hot paleoclimate which is semi-wet to wet ; 2. A water body of carbonate type which contains plenty of K +, Na +, HCO 3 and CO 2- 3, but less Ca 2+ and SO 2- 4 ions; 3. A medium of paleowater with a pH value of ≥9, and a low water salinity of generally 3‰～10‰, which belongs to the range of slight salty <0.5‰～5‰>to semi-salty<5‰～30‰> , or even higher salinity, although the deposition of dolomite may not be so strict on the paleosalinity; 4. A stable shallow lake and deep lake condition of a broad lake basin; 5. The biological and chemical effect may be strong so that the contents of CO 2- 3 and HCO - 3, as well as the pH value will be increased while the content of SO 2- 4 decreased.

关 键 词：湖相 白云岩 形成条件 泌阳凹陷 下第三系 地球化学特征 古气候 古环境 

分 类 号：P588.245[天文地球—岩石学]