黔西南晚二叠世龙潭组物源分析及区域沉积古地理重建

发布时间：2018-05-05 16:27

本文选题：晚二叠世龙潭组 + 右江盆地　；参考：《地质学报》2017年06期

【摘要】：黔西南上二叠统龙潭组为一套以海陆交互相细屑岩为主的沉积地层,与下伏茅口组平行不整合接触。龙潭组砂岩碎屑组分以板片状—微晶状的玄武—安山质火山岩岩屑为主,并含少量霏细晶—隐晶质的酸性火山岩岩屑。泥质岩全岩主量元素以低SiO_2(28.3%~51.9%)、高TiO_2(1.0%~4.1%)和低Al_2O_3/TiO_2比值(3.9~6.9)为特征,与峨眉山高Ti玄武岩的Al_2O_3/TiO_2比值(集中在2.5~5.0之间)较为接近。龙潭组的碎屑锆石显示峰期年龄为~260Ma,与峨眉山大火成岩省的火山喷发期(258~263Ma)相吻合。锆石微量元素指示其与板内/非造山环境的岩浆活动有关,结合同时期北部陆相和南部深水盆地相的沉积物源研究,该结果表明龙潭组碎屑岩的源岩为峨眉山玄武质和长英质火山岩。基于此,本文对晚二叠世滇黔桂地区峨眉山源区—河流—滨岸—右江深水盆地的沉积古地理格局进行重建。
[Abstract]:The upper Permian Longtan formation in southwestern Guizhou is a set of sedimentary strata dominated by marine and continental intercross microclastic rocks, which is in parallel unconformity with the Xiafumaokou formation. The sandstone clastic components of the Longtan formation are mainly composed of plate-microcrystalline Black Tortoise -Anshan volcanic rocks and a small amount of felsite-cryptonite acid volcanic rocks. The main elements of the argillaceous rocks are characterized by low SiO2CO2 + 28.3K, high TiO2O1.0 and 4.1% and low Al_2O_3/TiO_2 ratio of 3.90.0.It is close to the Al_2O_3/TiO_2 ratio of Emeishan high Ti basalt (concentrated in the range of 2.5 ~ 5.0). The detrital zircon of the Longtan formation shows a peak age of 260 Ma, which coincides with the volcanic eruption stage of the Emeishan great igneous province. Zircon trace elements indicate that they are related to magmatic activity in the intraplate / non-orogenic environment, and are studied in the same period in the northern continental facies and the southern deep-water basin facies. The results show that the source rocks of the clastic rocks of the Longtan formation are Black Tortoise and felsic volcanic rocks. Based on this, the sedimentary paleogeographic pattern of the Emeishan source, river, shore and Youjiang deep water basin in the late Permian Yunnan, Guizhou and Guangxi regions is reconstructed in this paper.
【作者单位】：中国地质大学(武汉)地球科学学院;贵州省地质矿产勘查开发局;
【基金】：国家自然科学基金(编号41302083,41572078) 中央高校基本科研业务费专项资金(CUGL140402,CUG160604) 贵州黔西南整装勘查项目(12120114016301) 生物地质与环境地质国家重点实验室自主课题(GKZ15Y671)资助成果
【分类号】：P531;P534.46

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