贵州大方百纳地区上二叠统地层划分对比及沉积环境

Stratigraphic classification and contrast and sedimentary environment of Upper Permian in Baina area of Dafang County,Guizhou Province

详细描述了贵州大方县百纳乡百纳坪子上二叠统剖面,将百纳地区上二叠统划分为龙潭组和长兴组。讨论了龙潭组和长兴组的岩性组合特征、接触关系及横向变化。根据腕足、植物化石及类化石的地层分布及组合特征,建立了1个腕足组合带、1个植物组合带、1个类组合带,即腕足Orthothetina rubber-Oldhamina squamosa组合带、植物Gigantopteris nicotianaefolia-Gigantopteris dictyophylloides组合带、类Palaeofusulina组合带。根据生物组合带的时代确定了龙潭组及长兴组的年代地层归属;根据岩石组合特征及沉积构造等确定龙潭组主要为障壁海岸和滨岸沼泽相沉积、长兴组为碳酸盐台地相沉积。

The measured section of Upper Permian located at Bainapingzi, Baina Village, Dafang County is described in details. The Upper Permian in the study area is classified into the Longtan Formation and the Changxing Formation. The paper discusses their lithological association, stratigraphic contact relationship and traverse variation. A brachiopoda assemblage zone, a plant assemblage zone and a fusulinida assemblage zone have been established according to fossil association and distribution, i.e., Orthothetina rubber-Oldhamina squamosa Assemblage Zone, Gigantopteris nicotianaefolia-Gigantopteris dictyophylloidesAssemblage Zone and Palaeofusulina Assemblage Zone. Based on these zones, the Longtan Formation and Changxing Formation are Upper Permian. Sedimentary facies of the Longtan Formation have been determined as barrier coast and coastal marsh, and those of the Changxing Formation as carbonate platform based on lithological association and sedimentary structures.