摘要
塔里木盆地塔中—古城地区奥陶系碳酸盐岩台缘带的存在早已被证实,但由于地层深度大、钻井少、地震资料品质有限且经历多次构造运动,导致台缘带的空间展布、位置迁移等都尚无确凿定论。综合分析钻测井、地震剖面、岩心等资料,按时间顺序将研究区奥陶系台缘相带的发育分为3个阶段:下奥陶统蓬莱坝组有明显的镶边型台缘发育,近南北走向,整体呈"S"型展布;中下奥陶统鹰山组的台缘带与蓬莱坝组的展布范围大体相似,但在古隆1井处呈现反"S"型分布,镶边型和缓坡型都存在,相带变窄,略向台地内部收缩;上奥陶统恰尔巴克组—良里塔格组时期存在塔中南、北两个台缘相带,北坡台缘为缓坡型,南坡宽度略大且坡度变陡,为镶边型。奥陶纪台缘带的平面迁移整体呈现从南北向近"S"型逐渐变为开口向西的"V"型的特点;早中奥陶世台地边缘相带开始向盆地内部迁移,台地边缘—斜坡带也主要呈退积-加积式发育。奥陶纪晚期,海平面大幅下降,地层遭到严重剥蚀,残余的台缘带分布明显缩小。大规模迅速海退之后,晚奥陶世的新一轮海进导致台地边缘相带向台地高部位逐步退缩。
The existence of Ordovician carbonate platform margin has already been proved in Tazhong-Gucheng area,Tarim Basin.However,the distribution,thickness and migration of it are ambiguous because of the great depth of strata,less drilling and limited seismic data quality.Based on analysis of the residual strata,combined with drilling and well logging data,seismic profiles and core samples,the development of Ordovician carbonate platform margin in research area can be chronologically divided into three stages：（1）Lower Ordovician Penglai-ba Formation develops an obvious rimmed platform margin,nearly N-S trending,showing “S”-shape distribu-tion;（2）Lower-Middle Ordovician Yingshan Formation generally has similar range of platform margin’s distribu-tion to Penglaiba Formation,but shows reverse “S”-shape around GL1 well;Rimmed and ramped types both exist,and slightly retract inward;（3）Upper Ordovician Qiaerbake Formation-Lianglitage Formation develops two separate platform marginal facies belts in the north and south of Tazhong uplift;the northern one is ramped type;the southern one is rimmed type,with larger width and steeper slope.Generally,in Ordovician period,＆amp;nbsp;the platform marginal facies migrated from the overall N-S trending “S”-shape to the westward opening “V”-shape.The carbonate platform margins migrated to center of the basin,and the platform edge-slope facies main-ly showed a retrogradational-aggradational development in Early-Middle Ordovician.In Late Ordovician,the Ta-rim basin experienced a significant decline in sea level.Thus,the remnants of platform edge’s distribution un-derwent a significant narrowing.After the rapid regression,a new round of transgression began,resulting in that the platform marginal facies retreated towards the high part of the Tazhong platform.
出处
《现代地质》
CAS
CSCD
北大核心
2014年第5期995-1007,共13页
Geoscience
基金
国家"973"项目"中国早古生代海相碳酸盐岩层系大型油气田形成机理与分布规律下古生界碳酸盐岩优质储层形成与分布预测"(2012CB214802)
关键词
塔中-古城地区
奥陶系
碳酸盐岩台地边缘相
类型
展布
演化
Tazhong-Gucheng area
Ordovician
carbonate platform marginal facies
type
distribution
evo-lution
