沙垒田、庙西凸起前第三纪地层研究

PRETERTIARY STRATIGRAPHY OF SHALEITIAN AND MIAOXI UPLIFTS

长期以来,沙垒田凸起、庙西凸起前第三纪变质花岗岩被笼统地划归前寒武纪,对两凸起有代表性的4口井的变质花岗岩进行了锆石U-Pb同位素年龄测定,结果表明,变质花岗岩成岩年龄为2047～2483Ma,属新太古代-古元古代五台期-吕梁期的产物.对C1井井深1406～14 43m钻遇的灰岩地层进行了采样分析,首次获得了大量微体古生物化石,并证实灰岩地层属古生界下寒武统,从而为沙垒田凸起古生代地层划分提供了重要依据.

Pretertiary metamorphic granite in Shaleitian and Miaoxi uplift blocks has been generally designed to Precambrian for many years. Zircon U Pb isotopic dating in four typical wells has revealed that the metamorphic granite is as old as 2047~2483Ma, and produced during Wutai-Lüliang periods of Late Archaean-Early Proterozoic. A large number of microfossils are found from limestone strata in Well C1, which can confirm that the limstone is in Lower Cambrian. This provides a very important basis for Paleozoic stratigraphic division in Shaleitian uplift.