焦作云台山与青龙峡景区中奥陶统马家沟组沉积特征及演化规律

通过对焦作云台山与青龙峡景区中奥陶统马家沟组的岩性、沉积构造、古生物实体化石和遗迹化石的组成和分布特征分析及其沉积环境研究,结果表明,研究区马家沟组主要为潮坪-碳酸盐岩台地沉积,可划分为潮坪相和碳酸盐岩台地相及潮上带、潮间带和潮下开阔台地3个沉积亚相;其沉积演化特征显示出7个沉积旋回,每个沉积旋回变化从潮间带(潮上带)沉积开始,海水逐渐加深变为潮下开阔台地沉积,然后海水逐渐变浅,过渡到潮间带沉积,总体上反映了马家沟组沉积期经历了7次较完整的海平面变化过程.研究云台山与青龙峡景区马家沟组沉积环境和沉积演化对于恢复该区早古生代的沉积环境和丰富云台山世界地质公园的地质信息均有重要意义.

Sedimentary characters and evolution of the middle ordovician Majiagou Formation in the Black Dragon Canyon,Yuntai Mountain,Jiaozuo area

Based on the composition and distribution characteristics of lithological characters,sedimentary structures,body fossils and ichnofossils in the Middle Ordovician Majiagou Formation within Black Dragon Canyon,Yuntai Mountain World Geopark,Jiaozuo area,detailed research on the sedimentary environment and evolution have been got.It shows that the Majiagou Formation in the study area mainly consists of the tidal-flat and carbonate platform deposits,which can be divided into two major sedimentary facies including tidal-flat facies and carbonate platform facies,and three depositional subfacies such as supratidal zone,intertidal zone and subtidal open platform.The sedimentary evolution of the Majiagou Formation in the study area experienced seven sea-level change cycles,each of the cycle begins from the deposit of intertidal zone（or supratidal zone）,change into the deposit of subtidal open platform while the sea water gradually becomes deeper,and then turn into the deposit of intertidal zone when the sea water continuously becomes shallower,seven times of sea level change process in the sedimentary period of the Majiaogou Formation can be recognized.It is of great significance to study on the depositional environment and evolution in the Majiagou Formation of the Black Dragon Canyon in recovering the sedimentary environment in early Palaeozoic as well as enriching the geological information in Yuntai Mountain World Geolpark.