Ancient marine carbonates experienced complex modifications, making it difficult to identify reservoir genesis and effective porosity before hydrocarbon migration. To solve these issues, we used element mapping and carbonate mineral laser U-Pb radiometric dating techniques to study the diagenetic environments based on geochemistry and diagenesis-porosity evolution based on geochronology of the dolomite reservoir of the Sinian Qigebrak Formation, northwest Tarim Basin. Two major understandings were obtained as follows: (1) Supported by petrographic observations, the element mapping, stable isotopes, strontium isotope, and cathodoluminescence tests were performed on different phases of dolomite cements precipitated in vugs and dissolved fissures. The results show that the dolomite reservoirs of the Qigebrak Formation went through freshwater, marine, extremely shallow burial, burial and hydrothermal diagenetic environments after synsedimentary dolomitization; the reservoir spaces were mainly formed in the synsedimentary period (primary pores) and freshwater environment (supergene dissolution pores) before burial; whereas the marine, burial and hydrothermal environments caused the gradual filling of reservoir space by dolomite cements. (2) Based on the above understandings, each phase of dolomite cement precipitated in the reservoir space was dated by the U-Pb radiometric dating technique, and the diagenesis-porosity evolution curves constrained by geochronology were established. The loss of reservoir porosity mainly occurred in the early Caledonian, and during the peak period of hydrocarbon generation of Yuertusi Formation source rock, the reservoirs still maintained at a porosity of 6%–10%. The above understandings provide a certain basis for the evaluation of accumulation effectiveness of the Sinian Qigebrak Formation, northwestern Tarim Basin, and provide a case for the application of mapping and dating techniques in the study of ancient carbonate reservoirs.

古代海相碳酸盐经历了复杂的改造，因此在烃运移之前很难确定储层成因和有效孔隙度。为了解决这些问题，我们使用元素测绘和碳酸盐矿物激光U-Pb放射性测年技术，基于塔里木盆地西北部震旦纪奇布拉克组白云岩储层的地球化学和成岩-孔隙度演化，基于地球化学研究了成岩环境。得出以下两个主要理解：（1）在岩石学观测的支持下，对在孔洞和溶解裂缝中沉淀的白云石胶结物的不同相进行了元素映射，稳定同位素，锶同位素和阴极发光测试。结果表明，奇格布拉克组白云岩储层经历了淡水，海洋，沉积白云石化后的极浅埋葬，埋葬和热液成岩环境; 储层空间主要形成在埋藏前的沉积期（初级孔隙）和淡水环境（表生溶解孔隙）中。而海洋，埋葬和热液环境导致白云石水泥逐渐填充了储层空间。（2）根据以上认识，利用U-Pb放射性测年技术对储集空间中白云岩胶结物的各相进行了测年，并建立了受年代学约束的成岩-孔隙演化曲线。储层孔隙度的损失主要发生在加里东期早期，在于尔图斯组烃源岩生烃高峰期，储层仍保持在6％〜10％的孔隙度。