| 塔里木盆地巴楚地区上泥盆统-下石炭统沉积-物源记录及其构造演化 |
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| 引用本文： | 郭春涛,高剑,李忠,张磊.塔里木盆地巴楚地区上泥盆统-下石炭统沉积-物源记录及其构造演化[J].地球科学,2017,42(3):421-434. |
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| 作者姓名： | 郭春涛 高剑 李忠 张磊 |
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| 作者单位： | 1.山西大同大学煤炭工程学院，山西大同 037003 |
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| 基金项目： | 国家自然科学基金项目40972085国家重大专项2011ZX05008-003国家自然科学基金项目41372120 |
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| 摘 要： | 泥盆纪-石炭纪是南天山洋-塔里木盆地北部陆缘构造演化的关键时期.选取塔里木盆地巴楚地区上泥盆统-下石炭统露头剖面，在沉积体系、碎屑组分、重矿物组合分析基础上，重点通过LA-ICP-MS分析砂岩样品.结果表明，上泥盆统-下石炭统砂岩碎屑颗粒以单晶石英为主，(变质) 结晶岩岩屑极少，物源构造属性主要指示陆块物源区；重矿物组合以锆石、电气石和TiO2矿物等稳定重矿物为主，反映相对远距离的源汇体系和稳定的构造背景；2个年代学样品具有类似的碎屑锆石U-Pb年龄组成和Hf同位素特征，主要反映了383~479 Ma、710~932 Ma、1 752~1 936 Ma、2 419~2 597 Ma共4期构造热事件，并以前两期为主.对比研究显示，上述碎屑物源以塔里木盆地内古隆起为主，同时还可能有来自阿尔金造山带、西昆仑造山带的再旋回沉积.但并没有记录到来自盆地北侧造山带和岛弧的物源信息，说明该时期南天山洋盆并没有闭合，塔里木盆地北缘西部可能不存在洋盆的向南俯冲，晚泥盆世-早石炭世其可能为被动大陆边缘.
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| 关 键 词： | 巴楚地区 上泥盆统-下石炭统 碎屑锆石 地质年代学 构造演化 地球化学 |
| 收稿时间： | 2016-09-01 |
Depositional and Provenance Records of Upper Devonian to Lower Carboniferous Sandstones from Bachu Area,Northwestern Tarim Basin: Implications for Tectonic Evolution |
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| Abstract: | Devonian-Carboniferous is the critical tectonic evolution period of the South Tianshan Ocean and the northern margin of Tarim Basin. Taking Upper Devonian to Lower Carboniferous outcrop of Bachu as the study area, this study further explores provenance, tectonic evolution and its geodynamic mechanism about the Tarim basin and the periphery orogen, based on depositional system, sandstone skeleton component, heavy minerals, especially detrial zircon geochronology analysis by LA-ICP-MS in situ U-Pb and Lu-Hf isotope.Sandstone skeleton component analysis shows that sandstone grains are dominated by mono crystalline quartz, and volcanic-metavolcanic fragments are rare.Its main provenance is the continental block provenance.The main proportions of heavy mineral assemblages are the stable heavy minerals, such as zircon, tourmaline, and TiO2 minerals. Heavy minerals analysis reflects the relatively distant source-sink systems and stable tectonic setting are possible. The geochronological samples show that the two samples have similar U-Pb age patterns and Hf isotopic compositions, mainly reflecting multiphase tectono-thermal events with age groups of 383-479 Ma, 710-932 Ma, 1 752-1 936 Ma, and 2 419-2 597 Ma respectively. Compared with the main potential source areas, the main provenance is the palaeohigh of Tarim basin. Meanwhile, the West Kunlunorogen and the Altunorogen may also have some contribution. However, there is no information about the northern orogenand island arcs. It shows the South Tianshan Ocean has not closed in this period, and there isn't subduction to the south in the northwestern margin of Tarim basin. In other words, the northwestern margin of Tarim basin is a passive continental margin during Late Devonian to Early Carboniferous. |
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