暖水乡砒砂岩地球化学分类类型与物源区特征

Geochemical Classifications and Provenance Characteristics of Pisha Sandstones in Nuanshui Town

探究砒砂岩的地球化学分类类型与物源区特征是揭示砒砂岩成因的重要途径。基于暖水乡附近中三叠统二马营组砒砂岩的全岩地球化学分析数据,确定了该砒砂岩的地球化学分类类型、物源区母岩类型和风化强度,初步揭示了白色砒砂岩的成因。研究表明:研究区砒砂岩的地球化学分类类型主要为杂砂岩和长石砂岩,其次为石质砂屑砂岩;物源区母岩类型包括中基性和酸性火成岩以及沉积岩,物源区风化弱,并遭受了渐进风化作用;白色砒砂岩遭受了一定程度的还原性流体的影响,还原性流体可能为煤层气。

Researching the geochemical classifications and the provenance characteristics of Pisha sandstone is one of the most important ways to reveal the genesis of Pisha sandstones. Based on the whole-rock geochemical data of Pisha sandstones from the Triassic Ermaying for- mation near Nuanshui Town, this paper concluded the geochemical classifications, the type of source rocks and the weathering intensity of provenance of Pisha sandstones. It primarily revealed the genesis of the white Pisha sandstones. The research shows that： the geochemical classifications of Pisha sandstones of researching area are dominantly greywacke and arkose with litharenite secondly ; the provenance source rocks include intermediate-basic igneous rocks, acid igneous rocks and sedimentary rocks; the provenance underwent weak and sequential weathering; the white Pisha sandstones have been slightly influenced by the reductive fluid which probably was coal-bed gas.