西藏普兰石炭纪地层的厘定及其地质意义

Delineation and geological implications of the Carboniferous strata in Burang,Xizang

通过区域地质调查,利用确定上覆、下伏地层时代与区域地层对比方法,结合邻区古生物年代特征,对西藏普兰北喜马拉雅分区下石炭统进行了厘定。普兰地区早石炭世受沉积环境与物质供应量等因素影响,岩性、岩石组合特征与邻区略有差异,其下部以变质粉晶灰岩为主夹变质泥质粉砂岩,厘定为亚里组;上部以变质细粒砂岩为主夹变质粉晶灰岩,厘定为纳兴组。

The Lower Carboniferous strata within the Northern Himalayan stratigraphic subprovince in Burang, Xizang are delineated in the light of the ages of the overlying and underlying strata and regional stratigraphic correlation referenced to the palaeobiologic times in the surrounding areas. Controlled by sedimentary environments, the lithologic associations vary slightly from those in the surrounding areas. The metamorphic micritic limestone intercalated with metamorphic muddy siltstone in the lower part is assigned to the Yali Formation, while the metamorphic fine-grained sandstone intercalated with metamorphic micritic limestone in the upper part to the Naxing Formation. The delineation has important geological implications for the reconstruction of tectonic-palaeogeographic framework in the Northern Himalayan Tethys folded belts during the Carboniferous.