Genesis and Distribution of the Cambro-Ordovician Dolomite in Tarim Basin

The dolomites of Cambro-Ordovician in Tarim basin are of four geneses,corresponding with four kinds of dolomitization ones such as sabakha dolomite,seepage reflux dolomite,buried dolomite and hydrothermal dolomite,which can be properly identified from the lithologic characteristics and geochemical characteristics.This paper comprehensively analyzes the paleogeographic and paleoclimate data,concludes the vertical and lateral distributions of dolomites with different geneses in Tarim basin: the development of sabakha dolomite and seepage reflux dolomite are controlled by sedimentary facies and mainly developed in Lower-Middle Cambrian;the development of burial dolomite are controlled by diagenetic facies,but the reef and shoal with high porosity as well as open system connected with fracture passage are easy to dolomitize;hydrothermal dolomite mainly develops below unconformity and near the discordogenic fault.