关键词: 物源分析, 碎屑成分, 岩石地球化学, 古水流, 上三叠统, 仁布, 西藏南部

Abstract:

The sandstone clastic composition, paleocurrent,  trace element and  rare earth clement are combined  to analyze    the
provenance of the Upper Triassic Langjiexue Group and the Nieru Formation in Renbu area, southern Tibet. Results of the clastic
composition and geochemistry  indicate  that most of  the clastic materials were derived  from  the  recycled orogenic belt; Some of
them were from the mixed area before the orogeny; Few was from the continental basement and recorded continental margin arc
process prior  to  the orogeny.  It  is verified  that parent  rocks came  from  the  recycled sediments of  the orogen and post-Archean.
Paleocurrent measurement shows that the Langjiexue Group and the Nieru Formation were probably sourced from the North. The
former was from the northeast, but the latter was from the northwest. The latter is closer to the source region than the former. These
are consistent with  the present distribution of strata. These results suggest  that  the upper Triassic  flysch were probably sourced
from the north or even the Lhasa Block

Key words:  provenance analysis, clastic composition, geochemistry, paleocurrent, upper Triassic flysch, Renbu, southern Tibet