燕山地区中新元古界高于庄组和雾迷山组风暴沉积特征分析

The storm deposits from the Meso-to Neoproterozoic Gaoyuzhuang and Wumishan Formations in the Yanshan region, northern China

关键词:  风暴岩  高于庄组  雾迷山组  中新元古界  燕山  沉积序列

Key words:  tempesitite  Gaoyuzhuang Formation  Wumishan Formation  Meso-to Neoproterozoic  Yanshan sedimentary sequence

摘要:

燕山地区中、新元古界高于庄组和雾迷山组地层发育典型的风暴沉积,主要有砂砾屑白云岩和灰岩、风暴硅岩、泥晶白云岩、含硅质条带白云岩和藻叠层白云岩5种岩石类型,砾屑放射状构造、底模构造、冲刷构造、丘状交错层理和波状层理等5种沉积构造。在野外剖面和岩心观察的基础上,根据风暴沉积的岩石学特征、沉积构造类型、规模和组合特点,并结合区域沉积背景分析,在辽宁凌源地区雾迷山组识别出一个标准的5单元垂向沉积序列。通过野外和室内的观察、分析和研究认为,研究区风暴岩形成于碳酸盐台地相中水体较浅的潮间环境。该风暴岩的发现对重建燕山地区中新元古界古地理及区域地层对比具有重要意义。

Abstract:

Abundant storm deposits are developed in the Meso-to Neoproterozoic Gaoyuzhuang and Wumishan Formations in the Yanshan region, northern China, and dominantly made up of sandy-gravelly dolostone and limestone, siliceous tempesitite, micritic dolostone, siliceous banded dolostone and algal stromatolitic dolostone in which five sedimentary structures are observed, including radial structure, sole cast, scour structure, hummocky cross-bedding and wavy bedding. Five representative vertical sedimentary sequences have also been identified for the Wumishan Formation in the Lingyuan region, Liaoning on the basis of lithology and types and scales of the sedimentary structures in integration with regional sedimentary background. These storm deposits were originated from the shallower water intertidal environment in the carbonate platform facies, and thus may be potential hydrocarbon reservoirs because of high structural maturity, developed primary porosity and proximal to the source rocks. The discovery of the storm deposits is believed to be significant to the Meso-to Neoproterozoic palaeogeographic reconstruction and regional stratigraphic correlation in the Yanshan region, northern China.