首页|西准噶尔构造带包古图组的岩石组合及其时限

西准噶尔构造带包古图组的岩石组合及其时限

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包古图组是新疆西准噶尔增生造山带西北缘石炭纪密西西比亚纪重要沉积记录.确认其完整的沉积序列、岩石组合及其与上覆和下伏地层的接触关系,对解析本区晚古生代盆地构造演化具有重要意义.本文新实测的白碱滩北红山梁剖面上,出露了岩石组合截然有别,色调区分性极强的两大套地层,上部深灰—灰黑色调"(含碳)细碎屑岩"与其下伏鲜红色调的"硅质岩-凝灰质硅质粉砂岩间夹中基性火山岩"为连续沉积(整合接触),分属包古图组和红山梁组.本文于包古图组底部和红山梁组顶部分别获得345.1 Ma和365.9 Ma的LA-ICP-MS锆石U-Pb年龄,限定其时代分别为密西西比亚纪和晚泥盆世.这一新发现,不仅确立了包古图组是区内石炭纪最老地层单位,佐证了包古图组老于希贝库拉斯组这一久争悬疑,而且使得区内密西西比亚系有了完整的地层序列,揭秘了石炭系最底部的沉积建造及其岩石组合,也为完整认识泥盆纪—石炭纪这一重要时期的盆地沉积特征及其构造演化提供了新资料.
Age and lithology of Baogutu Formation in West Junggar tectonic belt
The Baogutu Formation,located in the southern margin of the West Junggar accretionary orogenic belt,constitutes a significant Mississippian sedimentary record.A comprehensive understanding of its lithostratigraphic sequence,lithology,and contact relationships with overlying and underlying strata is paramount for unraveling the Late Paleozoic tectonic evolution of the Junggar basin.A newly measured stratigraphic section at Hongshanliang,located in northern Baijiantan,reveals two distinct lithostratigraphic units,each characterized by unique lithological assemblages and marked color differentiation.The upper unit,composed of gray-black carbonaceous fine clastic rock,exhibits a conformable contact with the underlying bright red unit comprised of chert,silty chert,and tuffaceous chert sandwiched with basic to intermediate volcanic rocks.These units are assigned to the Baogutu Formation and Hongshanliang Formation,respectively.LA-ICP-MS zircon U-Pb dating,conducted on samples from the bottom of the Baogutu Formation and the top of the Hongshanliang Formation,yielded ages of 345.1 Ma and 365.9 Ma,respectively.These ages firmly establish the Mississippian and Late Devonian depositional ages for the respective formations.This new discovery unequivocally confirms the Baogutu Formation as the oldest Carboniferous lithostratigraphic unit in the region,further establishing its precedence over the Xibeikulasi Formation.The establishment of this complete Lower Carboniferous lithostratigraphic sequence provides invaluable insights into the sedimentary construction and rock assemblage at the bottom of the Carboniferous system within the region.These findings contribute significantly to theunderstanding of the sedimentary characteristics and tectonic evolution of the Junggar basin during the critical Devonian-Carboniferous transition.

Mississippian Baogutu Formationlithologyroof and floor rock ageszircon U-Pb agesWest Junggar tectonic belt

李永军、李伟、王绪龙、段丰浩、朱钊、郑孟林、杨高学、张越迁

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长安大学地球科学与资源学院,陕西西安,710054

中国石油新疆油田公司勘探事业部,新疆克拉玛依,834000

长安大学地质工程与测绘学院,陕西西安,710054

中国石油新疆油田公司勘探开发研究院,新疆克拉玛依,834000

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密西西比亚系包古图组 岩石组合 顶底时限 锆石U-Pb年龄 西准噶尔构造带

国家科技重大专项国家重点研发计划项目中国石油天然气股份有限公司科学研究与技术开发项目中国博士后科学基金资助项目陕西省自然科学基础研究计划项目陕西省自然科学基础研究计划项目

2017ZX05008-006-003-0012018YFC0604002022DJ05072022M7104792024JC-YBQN-02922024JC-YBQN-0324

2024

10.19762/j.cnki.dizhixuebao.2023337

地质学报
中国地质学会

地质学报

CSTPCD北大核心
影响因子：2.17
ISSN：0001-5717
年,卷(期)：2024.98(7)
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