第28卷第2期 2014年4月
现代地质 GEOSCIENCE
Vol.28No.2 Apr.2014
西藏改则地区上三叠统日干配错组粒滩相灰岩
沉积特征及其环境意义
侯恩刚，高金汉，王根厚，王训练，徐涛，乔柏翰
（中国地质大学（北京）地球科学与资源学院，北京100083）
摘要：西藏改则地区上三叠统日干配错组发育了一套台地相碳酸盐岩沉积，在该套碳酸盐岩沉积中以存在大量缅粒滩为特色。粒滩可以进一步划分为开阔台地浅滩和台地边缘滩。缅粒滩岩石类型分析表明，该套碳酸盐岩为镶边台地型沉积，开阔台地内浅滩为异地缅和原地缅混杂堆积，台缘浅滩粒主要为原地缅。台缘粒滩为一个三级海侵体系域内部的次一级进积序列，具有潮下型米级旋回的特点，每层粒滩相粒灰岩的类型较为单一，大小均勾，各层缅
粒灰岩间缅粒类型不同，具有从微晶缅→放射缅一→同心缅过渡的趋势，向上缅粒粒径变大，沉积厚度明显增加。关键词：碳酸盐岩；沉积特征；缅粒；上三叠统日干配错组；西藏改则
中图分类号：P512.2；P534.51
文献标志码：A
文章编号：10008527(2014)02025609
Oolitic Limestone Sedimentary Characteristics and Its Environmental Significance
oftheUpperTriassicRiganpeicuoFormation,GaizeArea,Tibet HOU En-gang, GAO Jin-han, WANG Gen-hou, WANG Xun-lian, XU Tao, QIAO Bo-han
( School of Earth Sciences and Resources, China Unitersity of Geosciences, Bejing100083, China)
Abstract: Upper Triassic Riganpeicuo Formation in Gaize area, Tibet, developed a set of platform facies carbo-nate sediments which are a characteristic of multi-layer oolitic beaches, and these multi-layer oolitic beaches could be further divided into open platform shoal and platform margin beach. Analysis of rock types showed that this set of carbonate sedimentary succession was formed in the fringe platform sedimentary environment and the intraplatform shoal developed melange of in situ and allogeneoolitic oolitics , while the platform margin beach de-veloped mainly in situ oolitic. Platform margin oolitic beach was a subsequence of progradational sequences in three-order transgressive system tract, and had characteristics of subtidal type meter-scale cyclic. Each oolitic limestone layer was relatively single in type and uniform in size, and the oolitic type was different among the oolitic limestone layers which possessed the trend of changes from omicrite to radial, and to concentric ooides. The size of oolitic increased and sedimentary thickness increased markedly from lower to upper.
Key words: carbonate; sedimentary characteristic; oolitic; Riganpeicuo Formation of the Upper Triassic: Gaize，Tibet
0引言
在于粒在岩石记录中的密集产出、显眼的宏观形态、简单的组分特征和复杂的沉积组构。師粒
粒作为碳酸盐岩的一种颗粒类型，自17世对环境极其敏感，在研究沉积环境和成岩环境时纪早期被发现以来一直受到广泛关注1」，其原因是一种十分灵敏的标志2。正因为如此，国内外
收稿日期：2013-10-10；改回日期：2013-12-30；责任编辑：楼亚儿。
基金项目：中央高校基本科研业务费项目（2011YYL118）；中国地质调查局项目（2-5-2011-67）。
作者简介：侯恩刚，男，助理研究员，博士研究生，1981年出生，地层古生物学专业，主要从事地层学的研究工作。
Email: houengang@ cugh. edu. cn。