新疆伊犁果子沟晚前寒武纪地层沉积特征及对比研究

摘要

Guozigou in Yili of Xinjiang is located at the west margin of north Tianshan.The Precambrian strata in Guozigou are exposed relatively completely,which can be subdivided into Kayingdi Formation,Tarqiate For-mation and Talisayi Formation from bottom to top.Kayingdi Formation and Tarqiate Formation are interglacial deposits,and Talisayi Formation is a glacial deposit.Kayingdi Formation mainly consists of argillaceous silt-stone,silty mudstone, lithic sandstone and feldsarenite, in which sedimentary structures are developed, including parallel bedding,horizontally laminated bed,flaser bedding,sand lens and trough cross stratifica-tion.Kayingdi Formation can be subdivided into littoral subfacies (mixed flat microfacies and sand flat microfa-cies)and neritic shelf subfacies (normal neritic microfacies and storm deposit microfacies).Tarqiate Formation consists of argillaceous siltstone and silty mudstone with high shale content,in which a great quantity of hori-zontally laminated beds are developed,and this formation is a shallow-marine detrital deposit with three sedi-mentary sequences from deep to shallow.Talisayi Formation is a tillite deposit and can be subdivided into basal till subfacies,proglacial littoral subfacies and typical ice rafting-marine subfacies.According to sedimentation type,depositional combination,sedimentary facies and stratigraphic correlation with Quruqtagh area in Xin-jiang,and combined with previous research results,it is inferred that these strata belong to Nanhua System. Meanwhile,Kayingdi Formation and Tarqiate Formation can be correlated with Huangyanggou Formation in Quruqtagh area,and Talisayi Formation can be correlated with Teruiaiken Formation.The existence of the ancient land in the study area is also discussed by analysis of Nanhua System petrology,and the evidence is pro-vided in the end.%北天山西段果子沟地区晚前寒武纪地层由下到上分为喀英迪组、塔尔恰特组和塔里萨伊组。喀英迪组和塔尔恰特组为间冰期沉积，塔里萨伊组为冰期沉积。喀英迪组主要由泥质粉砂岩、粉砂质泥岩、岩屑粗砂岩和长石岩屑砂岩组成，平行层理、水平纹层、脉状层理、透镜状层理及槽状交错层理等沉积构造发育，为海相沉积，可划分为滨海亚相（包括混合坪微相和沙坪微相）和浅海陆棚亚相（包括正常浅海微相和浅海风暴沉积微相）；塔尔恰特组主要由泥质粉砂岩、粉砂质泥岩组成，泥质含量较高，大量发育水平纹层，具3个由深变浅的沉积序列，为浅海亚相碎屑沉积；塔里萨伊组为冰期沉积的冰碛岩，划分出基底冰碛亚相、冰前滨海亚相以及冰筏海洋亚相。通过沉积类型、沉积序列、沉积相划分以及与新疆库鲁克塔格地区地层对比等方面的研究，并结合前人研究结果，认为该套地层不应该属于震旦系，而应归属于南华系，并认为该区喀英迪组和塔尔恰特组可以与库鲁克塔格地区南华系中统的黄羊沟组对比，塔里萨伊组可以与库鲁克塔格地区南华系上统的特瑞爱肯组对比。此外，还根据南华系岩石学特征对伊犁地区是否存在古陆进行探讨。