中祁连托来南山中段晚三叠世地层特征

Characteristics of Late Triassic Strata in the Middle Section of Tuolainanshan in Middle Qilian Mountain

托来南山中段晚三叠世出露比较完整,但研究程度较低。该文主要对中祁连上日木策尔地区晚三叠世开展研究。研究区晚三叠世分为阿塔寺组和尕勒得寺组。前者与下伏托赖岩群呈断层接触,主要以河流相粗粒长石石英砂岩为主,夹灰色、紫红色粉砂岩和灰黑色粉砂岩,发现有遗迹化石(垂直潜穴);后者主要为淡水湖泊相—灰黑色粉砂岩、钙质粉砂岩夹黑色页岩及细粒长石石英砂岩,局部夹有煤线(木里地区),在灰黑色粉砂岩中发育有植物化石Neocalamites rugosus和Danaeopsis fecunaa系华北延长群的标准分子,在黑色页岩层位中产化石叶肢介类Loxomegaglypta Novojilov属等。研究区二组的接触关系为整合接触,中间并没有发现沉积间断。

The late Triassic strata outcropped completely in the middle section of Tuolainanshan area with less study. In this paper, study has been mainly carried out on late Triassic strata in Shangrimuceer area. Late Triassic strata in studying area can be divided into Atasi formation and Galedesi formation. The former contacted with the underlying Tuolai rock group, and was mainly composed of fluvial facies coarse- grained feldspar and quartz sandstones with gray, purple siltstone and dark gray sihstone, and trace fossils （vertical burrows） also can be found. The latter is freshwater lacustrine facies gray sihstone, calcareous sihstones interbedded with black shale and fine -grained feld- spar and quartz sandstone with coal streak in regional areas. Neocalamites rugosus and Danaeopsis fecunaa occurred in gray siltstone are standard molecular in the northern China Yanchang group. Loxomegaglypta Novojilov genera of conchostraca fossils were found in black shale beds. The contact relation of the two formations in the study area is conformable contact. Hiatusand did not be found in contact zones.