通过详细的野外观测,结合岩石学和地球化学等方法,对塔里木盆地东北缘乌里格孜塔格中-下奥陶统巨斑状白云岩特征及成因进行研究。野外观测表明,黄灰色粉-细晶白云岩呈巨斑状(巨斑直径可超过10m)发育于灰黑色薄层泥晶灰岩中,界面形态不规则,且不受沉积控制。显微镜下观察,白云石粒径多在100μm左右,直面为主,半自形-自形。巨斑状白云岩具有独特的地球化学特征:碳同位素(δ13CPDB:-1.34‰~-0.62‰)位于早奥陶世海水值范围内,氧同位素(δ~(18)OPDB:-8.01‰~-4.79‰)比同期海水值高;87Sr/86Sr比值(0.711000~0.711535,AVG=0.710863)远大于泥晶灰岩与同期海水比值;Fe(2001.32μg/g)和Mn(601.73μg/g)含量高于泥晶灰岩,Sr(33.14μg/g)和Ba(8.27μg/g)含量相对较低;稀土元素组成及配分特征与泥晶灰岩相似,弱的Eu负异常;有序度(AVG=0.6)较低。综合研究认为,白云岩化发生于早-中奥陶世浅埋藏、较低温环境,属于构造-断裂相关的局部白云岩化。白云岩化流体主要来源于巷古勒塔格组中下段及突尔沙克塔格群封存的地层流体,准稳定碳酸盐矿物稳定化提供主要的Mg2+,灰岩地层中泥质沉积中的黏土矿物转化不仅提供少量Mg~(2+),更提供放射性87Sr。兴地同沉积断裂相关的伴生断裂富集自源白云岩化流体,充当其运移通道,使断裂系统附近灰岩优先白云岩化,形成巨斑状构造。 Through the detailed field observation and the combination of petrology and geochemistry, the characteristics and genesis of the Mesopannular and Holocene macrophyllous Dolomites in the northern part of the Tarim Basin are studied. Field observations show that the yellowish-gray fine-grained dolomite is a giant macula (giant spot diameter can exceed 10m) developed in a gray-black thin-bedded micrite-lacustrine limestone with an irregular interface morphology and is uncontrolled by sedimentation. Under the microscope, Dolomite more than 100μm in particle size, face-oriented, semi-self-shaped - self-shaped. Porphyritic dolomites have unique geochemical characteristics: the δ13CPDB: -1.34 ‰ ~ -0.62 ‰ is located in the seawater range of the Early Ordovician, the oxygen isotope (δ ~ (18) OPDB: -8.01 ‰ -4.79 ‰) was higher than that of seawater at the same period. The ratio of 87Sr / 86Sr (0.711000 ~ 0.711535, AVG = 0.710863) was much larger than that of montmorillonite and seawater at the same period. The content of Fe (2001.32μg / g) and Mn (601.73μg / g) The contents of Sr (33.14μg / g) and Ba (8.27μg / g) are relatively low. The REE composition and distribution characteristics are similar to that of micrite limestone and weak Eu negative anomaly. The orderliness (AVG = 0.6) is lower. Comprehensive studies suggest that dolomitization occurs in the early-middle Ordovician shallow-burial and lower-temperature environment and belongs to the tectonic-fracture-related local dolomitization. The dolomitization fluids mainly originate from the stratigraphic fluids sealed in the middle and lower parts of the alluvial grid and the Tulsa-Taktag group, and the stabilization of quasi-stable carbonate minerals provides the major Mg2 + Clay mineral transformation not only provides a small amount of Mg 2+, but also provides radioactive 87Sr. Xing associated with the sedimentary fault-related fault enrichment enrichment from the source dolomitization fluid, as its migration channel, the limestone near the fault system preferentially dolomitization, the formation of macular-shaped structure.