康滇古陆东缘筇竹寺组沉积物源的风化特征——以云南省楚雄市武定县乌龙村剖面为例

Weathering Characteristics of Sedimentary Source Area of Qiongzhusi Formation,Eastern Margin of Ancient Kangding-Yunnan Land:Case study of the Wulongcun section of Wuding district,Chuxiong city,Yunnan province,China

【目的】扬子地区筇竹寺组是目前页岩气勘探的重要层位,为了揭示康滇古陆东缘筇竹寺组沉积岩的风化程度、古气候、构造背景以及物源等。【方法】选择位于康滇古陆东缘的武定县乌龙村剖面进行采样,并对样品的主量元素和微量元素进行分析,研究了康滇古陆东缘乌龙村剖面筇竹寺组沉积岩的风化程度、源区古气候、构造背景以及物源特征。【结果与结论】(1)筇竹寺组沉积岩的母岩经历了强烈的化学风化作用,物源区在该时期处于温暖湿润的气候;(2)筇竹寺组沉积岩主要形成于被动大陆边缘环境,沉积岩源岩形成于大陆岛弧环境;(3)筇竹寺组沉积岩主要来自康滇古陆元古界东川群、会理群和汤丹群的凝灰岩、凝灰质砂岩、凝灰质板岩、花岗岩以及基性岩。

[Objective]The Qiongzhusi Formation in the Yangtze region is an essential horizon for shale gas explora-tion.This study was conducted to determine the weathering degree,paleoclimate,tectonic background and prove-nance of the sedimentary rock in the Qiongzhusi Formation at the eastern margin of the Ancient Kangding-Yunnan Land[.Methods]Quantitative geochemical data was obtained from profile measurement,sample collection and analy-sis for major elements and trace elements in the Wulongcun profile.[Results and Conclusions](1)The Qiongzhusi Formation sedimentary rock is mainly strongly weathered,and the climate of the provenance area was warm and hu-mid during the period of deposition.(2)The rock was mainly formed in a passive continental margin environment.The source rocks were formed in a continental island-arc environment.(3)The sedimentary rocks were mainly tuff,tuffaceous sandstone,slate and granite,together with some basic rocks of the Proterozoic Dongchuan Group,Huili and Tangdan Groups in the Ancient Kangding-Yunnan Land.