地质学报2017，Vol.91Issue(5)：1083-1096,14.
滇西户撒盆地芒棒组砂岩地球化学特征及物源区和构造背景分析
Geochemical Characteristic of Sandstones from the Mangbang Formation in the Husa Basin, Western Yuannan, and Its Constraints on Provenances and Tectonic Setting
摘要
Abstract
Geochemical analysis was conducted in this study for sandstones samples from the Mangbang Formation in the Husa basin,western Yunnan.The analysis results show that sandstones from the Mangbang Formation mainly comprise of feldspar sandstone and greywacke sandstone as well as minor shale,and the mineral assemblage mainly contains quartz,K-feldspar,plagioclase and illite.The sandsontes have a consistent REE pattern,enrichment of LREE relative to HREE,with LREE/HREE of 9.75～15.91 (averaging 13.24) and (La/Yb)N of 13.06～26.41 (averaging 19.21).The SiO2/Al2O3 ratio of 2.06 ～6.01 and index of the chemistry variation (ICV) of 0.54～ 1.09 together with the features of sedimentation make it clear that these sandstones resulted from recycling deposition in the passive tectonic setting,rather than the first cycle of sediments due to the relatively strong weathering.Furthermore,the Th/U values of 5.44～12.10％ and CIA of 59～76 reflect a chemical weathering environment of medium intensity in warm and moist climate.A/CNK discrimination diagram shows that the sandstone clastics have a higher content of K-feldspar relative to plagioclase and low CIA value due to metasomation.The Th/Sc ratio of 4.43～25.35 (averaging 8.18) and the diagrams of Co/Th versus La/Sc,K2O versus Re,and La/Yb versus ～ REE all suggest that sandstones in the study area were mainly derived from the previously formed granites.Besides,the tectonic discrimination diagrams of TiO2 versus Fe2O3T+ MgO,Al2O3/(Cao+-Na2O) versus Fe2O3T +MgO,K2O/Na2O versus SiO2,and La-Th-Sc all reflect that these granites were formed in the setting of passive continental margin and possibly corresponded to the long term steady state of the Meso-Tethys Ocean which has been open during the Late Jurassic to Early Cretaceous.The Husa basin was formed due to the extension along the previous Husa transpressional fault and started to deposition sourced from the peripheral granites during this period.关键词
滇西地区/户撤盆地/地球化学/物源属性/构造背景Key words
western Yunnan/Husa basin/geochemistry/provenance/tectonic setting引用本文复制引用
张建军,牟传龙,周恳恳,冯丽霞,伍皓,陈小炜..滇西户撒盆地芒棒组砂岩地球化学特征及物源区和构造背景分析[J].地质学报,2017,91(5):1083-1096,14.基金项目
本文为中国地质调查局项目”西南地区铀矿调查选区及含煤岩系放射性地质环境调查”(编号DD20160133)资助成果. （编号DD20160133）
