巴颜喀拉盆地岩相、相组及其演化
SEDIMENTARY FACIES,FACIES GROUPS AND THEIR EVOLUTION IN THE BAYAN HAR BASIN
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摘要: 巴颜喀拉盆地北以东昆仑南缘蛇绿混杂岩带为界,东与龙门山-锦屏山前陆褶冲带相邻,西以甘孜-理塘结合带为界,总体呈斜三角形状展布。黄汲清(1962)称之为松潘-甘孜褶皱系,张勤文(1983)称马尼干戈-理塘残余后弧盆地,余如龙(1989)称松潘-甘孜前缘复理石推覆带。笔者认为本区是在被动边缘基础上由弧后盆地转换为前陆盆地。Abstract: According to vertical sedimentary sections of sedimentary facies and facies groups of Permian to Triassic age in the Bayan Har Basin, five substages of sedimentary evolution may be distin-guished.
1. Early Permian to Early Triassic substage. In the basin occur, from base upwards, the following facies groups: Carbonate platform slope→bathyal→abyssal plain→neritic and littoral facies groups.
2. Middle Triassic substage. The sediments from bottom to top of the basin may be divided into six facies groups in the following order: continental→littoral and neritic→slope→abyssal basin→slope→neritic and littoral facies groups. The depocentre of the basin lies in the Sertar-Lixian-Luhuo-Dawu zone.
3. Carnian substage(Late Triassic). The Carnian sedimentary facies groups are composed of neritic and littoral, slope and abyssal facies groups, constructing a complete sedimentary cycle sequence from transgression to regression. The sea water covered a maximum area during this period.
4. Norian substage(Late Triassic). The sedimentary sequences in the basin represent an overall regression sequence dominated by slope, littoral and neritic facies groups.
5. Rhaetic substage(Late Triassic). The continental and marine-terrestrial transitional facies groups have been recognized in the basin. -
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