川北中三叠统沉积层序特征及陡坡封闭型镶边台地模式  

Characteristics of Middle Triassic Sedimentary Sequence and the Model of Steep-sloped Enclosed Rimmed Platform Facies,Northern Sichuan Basin

作　　者：彭博[1] 李国蓉[1,2] 罗鹏[3] 沈忠民[1,2] 赵应权[1] 姚尚胜 

机构地区：[1]成都理工大学能源学院 [2]成都理工大学"油气藏地质及开发工程"国家重点实验室 [3]中国石化西北油田分公司 [4]华北油田二连公司地质研究所

出　　处：《海相油气地质》2012年第2期26-33,共8页Marine Origin Petroleum Geology

基　　金：国家科技重大专项"海相碳酸盐岩层系大中型油气田分布规律及勘探评价"(2011ZX05005-002)资助

摘　　要：川北地区中三叠统层序地层学的对比研究表明,雷口坡组顶界面(T2/T1界面)和底界面(T3/T2界面)具有横向分异规律,由此识别出2个Ⅲ级层序,其上部SQ2层序普遍缺失高水位体系域。层序地层格架内的岩相古地理分析表明,该区中三叠世长期处于蒸发台地、局限台地环境,碳酸盐岩颗粒结构欠发育,可见少量藻屑颗粒灰岩和白云岩、细—中晶白云岩,缺少生物礁标志,藻席大量发育,白云石化作用强烈。识别出了工农镇剖面斜坡角砾,并对台地边缘位置进行了厘定。根据沉积及岩石学研究结果,得出了川北地区中三叠统典型的陡坡封闭型镶边台地模式。The characteristic correlation of sequence stratigraphy has indicated that there is a differentiation regulation in lateral at the top surface （the T2/T1） and the bottom surface （the T2/T1） of Middle Triassic Leikoupo Formation in litholo- gy in northern Sichuan Basin. Therefore, two Ⅲ-order sequences are identified, in which the high-level system tract （HST） is generally absent in SQ2, the upper subsequence. Based on analysis of lithofacies palaeogeography in the Ill-or- der sequence stratigraphic framework, it is shown that the environments of evaporative carbonate platform and restricted platform was dominant for a long time during the middle Triassic epoch in northern Sichuan Basin so that the underde- veloping carbonate grain textures indicate lack of mark of reefs but abundant algal mats, which results in existence of a little algal-clastic grainstone and dolostone and fine- to medium-crystalline dolostone. A sort of slope facies breccia is recognized at Gongnong Zhen outcrop. The location of platform margin is confirmed. According to the research results of sedimentology and lithology, a typical model of Middle Triassic steep-sloped enclosed rimmed platform Facies in epicontinental sea is s recommended for the northern Sichuan Basin.

关 键 词：中三叠统 碳酸盐岩 沉积特征 层序地层学 沉积模式 四川盆地中部 

分 类 号：TE111.3[石油与天然气工程—油气勘探]