贵州盘县土城向斜南西翼二叠系龙潭组地球化学特征及意义

摘要

To explore Longtan Formation provenance and sedimentary environment carried out trace elements and rare earth elements testing analysis for Longtan Formation samples from borehole ZK402. The result has shown that the water body Longtan Formation de-posited was in brackish water-fresh water environment, not obviously stratified anaerobic environment-stratified with bottom layer presented H2S anaerobic environment;high rare earth elements content in mudstone, source rocks mainly have calcareous mudstone and alkali basalt. Based on integrated analyses of sandstone grain-size, thin section authentication, electron probe etc., have identified delta and barrier bar-lagoon sedimentary facies and delta front, lower delta plain, upper delta plain, tidal flat, lagoon subfacies. Dur-ing early and later stages of Longtan Formation were mainly lagoon facies, middle stage characterized by widely developed distributary channel and interdistributory bay.%为探讨盘县土城向斜龙潭组物源及沉积环境，对ZK402号孔龙潭组样品进行微量元素及稀土元素测试分析，结果显示：龙潭期的水体为微咸水-半咸水的淡水环境，水体分层不强的厌氧环境-水体分层及底层水体呈现H2S的厌氧环境；泥岩中稀土含量高，源岩主要为钙质泥岩和碱性玄武岩。根据砂岩粒度分析、薄片鉴定、电子探针等综合分析，在龙潭组中识别出三角洲和障壁砂坝-潟湖沉积相以及三角洲前缘、下三角洲平原、上三角洲平原、潮坪、潟湖等亚相，龙潭早、晚期以潟湖相为主，龙潭中期以分流河道和分流间湾广泛发育为特征。