西藏昂仁县孔隆地区木纠错组诺利期牙形石的发现及其地质意义

Discovery of Norian Conodonts from Mujiucuo Formation in Konglong Area of Ngamring County in Tibet and Its Geological Significance

拉萨地块晚二叠世-三叠纪地层的研究对认识青藏高原前新生代特提斯演化具有重要意义,但目前对该时期的沉积充填序列及古地理环境尚未形成统一认识.通过对西藏昂仁县孔隆地区开展的详细地层和牙形石相关研究,在木纠错组上部发现了晚三叠世诺利期Epigondolella sp.牙形石分子,在下拉组顶部发现了时代跨越晚二叠统长兴阶和早三叠统印度阶的牙形石Hindeodus typicalis;从而将研究区木纠错组时代重新厘定为晚二叠世长兴期至晚三叠世诺利期,指示拉萨地块西部三叠纪应仍为连续的浅海相沉积.

The study of the Late Permian-Triassic strata of the Lhasa Block is significant to understanding pre-Cenozoic evolution of Tethys in the Qinghai-Tibet Plateau.However,there are still disputes on the sedimentary sequence and paleogeographic environment in this period.On the basis of the detailed analyses of the stratigraphy and conodonts from the Konglong area,Ngamring County,Tibet,we found the Late Triassic Norian conodonts Epigondolella sp.from the upper part of the Mujiucuo Formation,and the Late Permian Changhsingian to Early Triassic Induan conodont Hindeodus typicalis bearing in the top of the Xiala Formation.The age of the Mujiucuo Formation in the study area was redefined to the Late Permian Changhsingian to Late Triassic Norian,indicating that the paleogeographic environment should still be a continuous neritic facies from Late Permian to Late Triassic in western Lhasa Block.