与天山造山带大地构造解释相关的两个地层问题  

Two Stratigraphic Concerns on the Central and Northern Tianshan Tectonic Complex,Northwest China

作　　者：廖卓庭[1] 陈中强 刘陆军[1] 

机构地区：[1]中国科学院南京地质古生物研究所,南京210008 [2]School of Earth and Environment,The University of Western Australia

出　　处：《地质学报》2011年第6期925-937,共13页Acta Geologica Sinica

基　　金：国家自然科学基金重点项目(编号40839904)资助成果

摘　　要：①综合分析巴音沟蛇绿混杂岩带(以下简称巴音沟混杂带)构造地层组合所含生物化石群性质,认为安集海组不存在特提斯型早石炭世Gigantoproductus为代表的腕足动物群;巴音沟混杂带蛇绿混杂岩上覆磨拉石相地层体,不应引用含义不清、成因和构造关系无直接联系的"科古琴山组",而应使用同一构造沉积区带、构造相位关系一致、沉积组合类型相同的桃西沟群;由于巴音沟混杂带与达拉布特混杂带的构造地层组合序列、沉积类型、生物群和生物相类型发育的总体特征相似或相同,两者同属于准噶尔残留海盆最新缝合带性质。②北天山和准噶尔地区延续至石炭纪末期的海洋环境,在早二叠世萨克马尔期至亚丁斯克期之前消失,区内从此进入陆内湖河相构造沉积阶段;出现于乌鲁木齐市艾维尔沟地区的芦草沟组是含有多门类陆相生物化石组合的陆相地层,并非海相成因浊积岩,它与准噶尔盆地东南缘广泛分布的芦草沟组的岩性和生物群特征相同,时代归属晚二叠世最早期。生物地层和古生态学研究结果不支持乌(鲁木齐)艾(维尔沟)公路106km处紧伏于克拉玛依组不整合面之下的地层属于晚二叠世深海相浊积岩(Xiaoetal.,2008)的认定,也不支持将该不整合构造作为"天山造山带造山碰撞时代属于二叠纪末至三叠纪"证据之一的观察与结论,本文作者认为,塔里木板块的东北部早在石炭纪与二叠纪之交已完成与包括天山地块在内的西伯利亚晚古生代大增生体的拼接。Two tectonostratigraphic concerns on the Late Paleozoic Tianshan tectonic complex were addressed in this study：（1） the stratigraphic succession of the Bayingou ophilite mélange and（2） the timing of tectonic accretion of the Siberian craton in the Aiweiergou area by integrating the relevant data of stratigraphy,palaeontology,tectonopaleogeography and tectonopaleobiogeography.In the Bayinggou area,the detailed paleontological studies have rejected the presence of the brachiopod Gigantoproductus fauna of Early Carboniferous age in the Anjihai Formation.In contrast,the brachiopod assemblage suggests a Late Devonian age for the Anhinhai Formation.Integration of fossil assemblages and paleogeographical and paleobiogeographical settings indicates that the Bayingou area belongs to the eastern Junggar tectonic complex rather than the central-south Tianshan complex.The latter is characterized by the presence of Gigantoproductus fauna during the Early Carboniferous.Thus,the Bayinggou ophiolite m lange is late Devonian in age.The top of the stratal package of the ophiolite m lange should be re-assigned to the Taoxigou Group rather than the Keguqingshan Formation in view of lithological features and tectonostratigraphic provinces.The former was established to accommodate the stratal package of volcanics,conglomerates and mudstone in the Junggar block,while the latter is poorly defined for the conglomerates exposed in the western Tianshan areas.Accordingly,the Bayinggou ophiolite m lange succession comprises the late Devonian Anjihai Formation,the Carboniferous Bayinggou and Shadawang Formations,and the Taoxigou Group of Early Permian age.Xiao et al.（2008） figured an outcrop section showing a distinct angular unconformity between the Permian turbidite and the Middle-Upper Triassic red beds at the Aiweiergou area,about 110 km south of Urumqi,the capital city of Xinjiang Province,northwest China.These authors considered that this unconformity indicates the closure of the Tianshan Ocean and final tectonic accretion

关 键 词：天山 蛇绿混杂岩带 石炭系 二叠系 浊积岩 陆相地层 构造演化史 

分 类 号：P542[天文地球—构造地质学]