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通过对渝东—湘西地区野外露头及相关室内研究,分析了区内志留纪小河坝组沉积环境、层序特征、沉积相展布及其演化特征。将该区小河坝组划分为2个沉积层序,每个沉积层序都由海侵和高位体系域组成。以体系域为编图单元,采用体系域压缩法,编制了渝东—湘西地区小河坝组4张层序岩相古地理图,结果表明:更加精确真实地反映了海陆分布、物源方向及其演化过程,更好地反映了层序格架下的物质聚集分布规律。揭示出研究区早志留世小河坝期碎屑岩沉积的物质主要来自东南部的江南雪峰山隆起,沉积环境由东往西逐渐变深,三角洲平原位于湘西地区,三角洲前缘发育于渝东地区;碳酸盐台地发育于靠近黔中隆起的南部浅水区,沉积环境由南往北逐渐变深,深水陆棚沉积区位于宜宾—重庆一带,该新认识对于更准确地预测渝东-湘西志留系储集体的分布以及下一步油气勘探部署具有重要实际指导意义。
Through the study of the outcrop in the Yudong-Xiangxi area and related interior studies, the sedimentary environment, sequence characteristics, sedimentary facies distribution and evolution characteristics of the Xiaoheba Formation in the Silurian were analyzed. The Xiaoheba Formation in this area is divided into two sedimentary sequences, each of which consists of transgressive and highstand system tract. Using the systematic domain as a unit, the authors used systematic domain compression method to compose four facies palaeogeographic maps of Xiaoheba Formation in the eastern Chongqing-Xiangxi region. The results show that: the distribution of land and sea, The evolutionary process better reflects the law of material accumulation and distribution under the framework of sequence order. It is revealed that the sedimentary material of the Early Silurian Xiaohe Dam clastic rocks in the study area comes mainly from the upwelling of the Xuefeng Mountain in the southeastern part of Jiangnan. The depositional environment gradually deepens from east to west, the delta plain is located in western Hunan and the delta front develops in the east of Chongqing . The carbonate platform developed in the southern shallow water area near the Qianzhong uplift. The depositional environment gradually deepened from south to north, and the deep-water shelf depositional area was located in the Yibin-Chongqing area. This new understanding is more accurate for the prediction of the Yudong-Xiangxi The distribution of reservoirs and the exploration and deployment of oil and gas in the next step have important practical significance.