川西北地区下二叠统栖霞组白云岩分布与成因探讨

四川盆地川西北地区下二叠统栖霞组主要以灰—灰黑色灰岩及生物碎屑灰岩、白云岩为主,沉积相以深和浅缓坡相为主,局部发育浅水生屑滩体。该区内栖霞组白云岩集中发育于栖霞中上部。通过野外、钻井岩心及镜下观察,结合阴极发光、X衍射、碳氧同位素等分析,认为川西北地区下二叠统栖霞组白云岩主要经历了准同生期的混合水白云化过程,而后由于东吴运动的影响,叠加了成岩作用后期的混合水白云化过程和埋藏白云化作用。

An Approach to Distribution and Genesis of Dolomitite of the Lower Permian Qixia Formation in Northwest Sichuan

The Lower Permian Qixia Formation in the northwest Sichuan basin consists mainly of gray and grayish black limestone,bioclastic limestone and dolomitite of ramp platform facies with local organic shoal facies.The dolomitite is developed in the middle and upper parts of the Qixia Formation.Field and microscopic study in combination with cathodoluminescence,X-ray diffraction and δ18O and δ13C data indicates that the dolomitite resulted from penecontemporaneous dolomitization,late diagenetic dolomitization and burial dolomitization.