塔里木盆地上白垩统依格孜牙组碳酸盐岩沉积学特征及地质意义

The Carbonate Depositional Features of Yigeziya Formation of Upper Cretaceous in Tarim Basin and Their Geological Implication

塔里木盆地西南缘沿西昆仑山前白垩系上统依格孜牙组沉积巨厚的碳酸盐岩 ,分布范围西至喀什 ,东至叶城县克里阳地区 ,主要岩相有以生物碎屑灰岩为主的 8种岩相 ,碳酸盐岩主要由亮晶鲕粒灰岩和亮晶生物碎屑灰岩组成 ;沉积环境以台地边缘、开阔台地相、局限台地相为主 ;沉积环境自东向西由台地边缘—开阔台地相—局限台地相演变 ;厚度自西向东由 12 5m减薄至 10m ;巨厚的碳酸盐岩沉积可以划出 7个米级旋回 ,7个米级旋回的碳酸盐岩沉积组成了塔里木盆地西南缘白垩系新的油气勘探目的层系 ;丰富的牡蛎、蛤、螺等化石 ,稳定的台地相、礁滩相台地边缘相沉积 ,说明当时塔里木盆地西南缘为向西北开口的海域 ,古气候温暖 ,古盐度为半咸到咸水 ;海域古地理西边与塔吉克相通 ,东边至叶城县克里阳地区 。

The thick carbonate was deposited on the foreland of western Kunrin mountain in northwest margin of Tarim basin in Yigeziya Formation of the upper Cretaceous.The distribution of carbonate is from Kashi in the west to Keliyang of Yecheng county in the east.The bioclast limestone is one of the most important lithofacies of eight lithofacies.Oosparite and bioclast sparite are the main compositions of carbonate.The main sedimentary facies are carbonate plateform edge,open carbonate platform and limited carbonate platform.From the west to the east, the evolution of sedimentary environment is from carbonate plateform edge,open carbonate platform to limited carbonate platform.From the west to the east,the thickness of Yigeziya Formation changes from 125 meters to 20 meters.Seven meter scale sychles were recognized in thick carbonate deposition. They are new sequence of oil and gas survey in Cretaceous in Tarim basin. The rich fossils of oyster mactra and spiral shell,carbonate plateform and reef shore show that the north western Tarim basin was sea with the mouth open to the northwest,and the palaeoclimate was warm,the palaeosalinity was salt to semisalt.The palaeosea graphic shape was long narrow band from Tajike in the west to Keliyang of Yecheng county in the east.