摘要
在建立了统一的地层格架和生物地层序列的基础上,结合古生态及沉积特征综合分析了柴达木盆地石炭纪沉积相。柴达木盆地东北缘下石炭统富含珊瑚、腕足等化石。珊瑚由小型单体向大型单体和复体演化,化石属种由少变多、丰度明显增加,反映了沉积环境趋于稳定和水体加深的过程。同时,石炭系剖面岩性出现由砂砾岩或砂、页岩-灰岩组成的两个沉积旋回,表明沉积环境由滨岸向碳酸盐台坪演变。上石炭统生物群以蜓竽类为主,腕足类、珊瑚次之,下部植物化石丰富。腕足个体变小和珊瑚化石减少,与浅水和变冷的气候有关。岩性为砂、页岩-灰岩互层,沉积环境以滨岸潮坪为主,下部沼泽发育。西南缘下石炭统生物以珊瑚、腕足类为主,岩性和生物有与东北缘相似的旋回特征。上石炭统以竽蜓类为主,腕足次之,岩性以生物碎屑灰岩和鲕状灰岩为主。西南缘石炭纪沉积环境主要以浅海高能环境的台滩和能量较低的台坪交互发育为特征。分析表明,早石炭世两度海侵,晚石炭世持续海进;西南缘多发育有利于储油的碳酸盐台滩相,东北缘多发育有利于形成生储盖配套体系的海陆交互相。
The Carboniferous outcrops is mainly distributed in two areas of Northeastern and Southwestern margins of Qaidam basin. On the basis of uniform stratigraphic framework and correlated biostratigraphic sequences, comprehensive analysis of paleoecology and sedimentary feature provides convincing evidences for division of the sedimentary facies. The Lower Carboniferous is rich in fossil coral and brachiopod in the northeastern margin of Qaidam Basin. The coral evolved from small size of monomer toward big one, and the number of fossil genus and species varied frnm few to more with their abundance increasing, indicating that the sedimentary environment went stable and the water went deep. Meanwhile, two lithologic cycles of glutenite or inter-bedded sandstone and shale graded to limestone are developed,and the sedimentary environment evolved gradually from shoreland toward carbonate terrace. The biota of Upper Carboniferous is dominated by fusulinid and secondly by brachiopod and coral with flourished fossil plants in the lower part. Fossil brachiopod evolved toward smaller size and the abundance of coral is reduced, these changes are connected with shallow water and cold climate. The lithologies are dominated by alternating sandstones, shales and limestone, and the sedimentary environment based on shoreland tidal flat with swamp developed in the lower. The biota of Lower Carboniferous is dominantly composed of coral and brachiopod in southwestern margin of Qaidam basin. The biota of Upper Carboniferous is composed of dominantly fusulinid and secondly brachiopod, and the lithologies are mainly bioclastic limestone and oolitic limestone. Sedimentary environment of Carboniferous in southwestern margin based on alternating carbonate shoal of higher-energy environment and carbonate terrace of lower-energy environment. The analysis indicates that there existed transgressions twice in Early Carboniferous and continuous transgression in Late Carboniferous; the carbonate shoal facies favorable for oil accumulation is well dev
出处
《新疆石油地质》
CAS
CSCD
北大核心
2006年第3期280-284,共5页
Xinjiang Petroleum Geology
关键词
柴达木盆地
石炭系
化石
岩性
沉积环境
Qaidam basin
Carboniferous
fossil
lithology
sedimentary environment
