| 日喀则弧前盆地碎屑铬尖晶石地球化学与物源判别 |
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| 引用本文： | 郭荣华,胡修棉,王建刚.日喀则弧前盆地碎屑铬尖晶石地球化学与物源判别[J].地学前缘,2012,19(6):213-220. |
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| 作者姓名： | 郭荣华 胡修棉 王建刚 |
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| 作者单位： | 南京大学地球科学与工程学院 |
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| 基金项目： | 国家自然科学基金项目(41172092);国家重点基础研究发展计划“973”项目(2012CB822001) |
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| 摘 要： | 该工作在藏南日喀则弧前盆地砂岩中发现了大量碎屑铬尖晶石。电子探针化学成分分析显示这些铬尖晶石具有高铬(铬指数Cr#为0.52～0.89)、低Fe3+含量(Fe3+/Fe2+<0.5)、低TiO2含量(多小于0.2%)的特征,指示这些铬尖晶石来源于与洋壳俯冲作用有关的橄榄岩和火成岩,因此弧火山岩和SSZ型蛇绿岩套是其最可能的物源。考虑到日喀则弧前盆地的碎屑物主要来源于拉萨地体,而拉萨地体北侧的班公—怒江缝合带的碎屑物质不可能穿过晚白垩世时期已经隆起的冈底斯岩浆弧。笔者推测,铬尖晶石可能来自于冈底斯弧和拉萨地体内部已经消失的古蛇绿岩套。
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| 关 键 词： | 铬尖晶石 日喀则弧前盆地 藏南 物源区 |
Chemical compositions and provenance significance of the detrital Cr-spinels from the Xigaze forearc basin,southern Tibet |
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| Guo Ronghua,Hu Xiumian,Wang Jiangang.Chemical compositions and provenance significance of the detrital Cr-spinels from the Xigaze forearc basin,southern Tibet[J].Earth Science Frontiers,2012,19(6):213-220. |
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| Authors: | Guo Ronghua Hu Xiumian Wang Jiangang |
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| Institution: | School of Earth Sciences and Engineering,Nanjing University,Nanjing 210093,China |
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| Abstract: | Significant amounts of detrital Cr-spinels were observed in the sandstones from the Xigaze forearc basin,southern Tibet.Electron microprobe results show that those detrital spinels are characterized by high Cr(Cr#=0.520.88),low Fe3+(Fe3+/Fe2+<0.5) and low TiO2 concentrations(less than 0.2%),which indicates a source of peridotites and volcanics related to oceanic subduction,and thus an ophiolite suite was the mostly possible provenance for those detrital Cr-spinels.Taking account of that the sediments in Xigaze forearc basin are mainly derived from the Lhasa terrane,while materials from the BangongNujiang suture can not transport across the Gangdese arc during the Late Cretaceous,we inferred that the detrital Cr-spinels found in the Xigaze forearc basin may have been derived from an palaeo-ophiolite suite which has been already eroded out and was originally in the Gangdese arc or within the Lhase terrane. |
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| Keywords: | Cr-spinel Xigaze forearc basin southern Tibet provenance |
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