昌宁—孟连带沧源糯良—孟来地区深色薄层灰岩层系牙形石生物地层学及沉积学特征

CONODONT BIOSTRATIGRAPHY AND SEDIMENTOLOGY OF THE DARK-COLORED THIN-BEDDED LIMESTONE STRATA IN THE NUOLIANG-MENGLAI AREA, CANGYUAN COUNTY, CHANGNING-MENGLIAN BELT

滇西昌宁—孟连带沧源县附近糯良—孟来一带发育一套以深色薄层灰岩为主的石炭纪—二叠纪地层。通过研究糯良、龙洞和孟来三条剖面的牙形石生物地层学和沉积地层学,在糯良剖面建立了Sweetognathus whitei带、Neostreptognathodus prayi带和S.guizhouensis带,在龙洞剖面建立了S.guizhouensis-N.pequopensis带。与北美、乌拉尔山南部、保山、华南和日本等地区牙形石带对比,证明本次研究所测糯良剖面和龙洞剖面的地层均为亚丁斯克阶一空谷阶。所测孟来剖面的牙形石Clarkina longicuspidata和C.transcaucasica指示该段地层为吴家坪阶。三条剖面识别出20种碳酸盐岩微相类型,可归为4个微相组合,分别对应浅潮下带、深潮下带上部、深潮下带下部和盆地四种沉积环境。

The Carboniferous-Permian strata near the Nuoliang-Menglai area, Cangyuan County, Changning-Menglian Belt, western Yunnan are characterized by a set of dark-colored thin-bedded limestones. Detailed studies on conodont biostratigraphy and sedimentary stratigraphy were carried out in the Nuoliang, Longdong and Menglai sections. The Sweetognathus whitei, Neostreptognathodus prayi, and S. guizhouensis zones were recognized at the Nuoliang section;the S. guizhouensis-N. pequopensis zone was recognized at the Longdong section. Correlation those conodont zones with that of Southern Ural, North America, Baoshan, South China, and Japan, strata of the Nuoliang and Longdong sections are assigned to the Artinskian and Kungurian stages. The conodonts Clarkina longicuspidata and C. transcaucasica at the Menglai section indicates that the conodont-bearing strata in this section should be the Wuchiapingian stage. Twenty carbonate microfacies types from the Nuoliang, Longdong and Menglai sections are classified into four microfacies assemblages, which correspond to four sedimentary environments: the shallow subtidal zone, the upper part of the deep subtidal zone, the lower part of the deep subtidal zone, and the basin.