伊犁科古琴山地区南华系沉积特征研究

摘要

The well-preserved Neoproterozoic Nanhua stratum in the Keguqinshan area of Yili,Western Tianshan can be divided into Kulutieliekti Formation,Tulasu Formation and Biexibasitao Formation from bottom to top,which may repre-sent the deposition during two ice age events and an interglacial period. The lowest Kulutieliekti Formation is mainly composed of till conglomerates and pebble-bearing tuffs.Biexibasitao Formation mainly consists of till conglomerates and pebble-bearing tuffaceous lithic sandstones.The Tulasu Formation,as the interglacial deposit is mainly composed of siltstone and fine sandstone and tuffs.Based on the study of lithofacies paleogeography, the Nanhua system in the study area is considered to represent a neretic environment along with glaciations and volcanic activities.Therefore,it can be di-vided into three facies, i.e.glacial sedimentary facies,marine facies and volcanic eruption facies. Moreover,the glacial sed-imentary facies can be further divided into basal tillite subfacies, proglacial littoral subfacies and ice rafting neritic subfa-cies,while the marine facies can be divided into neritic detrital subfacies and neritic carbonate subfacies. In addition,com-pare the Nanhua system in the Kuluketage region with the Nanhua system in the study area of this article%　　西天山伊犁科古琴山地区出露较完整新元古代南华纪地层，自下而上为库鲁铁列克提组、吐拉苏组和别西巴斯套组，可划为两个冰期和一个间冰期沉积。下冰碛地层库鲁铁列克提组为一套冰碛砾岩、含砾凝灰岩组合。上冰碛地层别西巴斯套组岩性主要为冰碛砾岩、含砾凝灰质岩屑砂岩。两冰碛地层间间冰期沉积吐拉苏组主要为一套粉砂岩、细砂岩和凝灰岩沉积。通过岩相学分析，认为研究区南华系整体处于浅海陆棚环境，伴有冰川作用和火山活动。可划出冰川沉积相、海相和火山喷发相3种沉积相，其中冰川沉积相又可细划为基底冰碛岩亚相、冰前滨海亚相和冰筏海洋亚相。海相主要划为浅海碎屑沉积亚相和浅海碳酸盐岩亚相。