关键词: 岩浆热液, 成岩作用, 鞍状白云石, 硅质岩, 塔里木盆地

Abstract: Through the petrographic studies, it is found that the carbonate rocks in Northern Tarim Basin have developed a diagenetic paragenetic sequence of silicification → hydrothermal dolomitization → calcitization. Many lines of evidences, such as the quartz fluid inclusion with a high salinity and homogenization temperature, the positive Eu anomaly in REE pattern of the saddle dolomite, and the calculated δ¹⁸O_SMOW (+5.5‰ ? +12‰) of the fluid which precipitated the calcite crystals, all indicate that there exist magmatic hydrothermal fluids. It is also found that the hydrothermal diagenetic fluids have been mixed with organic carbon, meteoric water or the ⁸⁷Sr rich formation water in different degree. The carbonate rocks in the research area have a corresponding diagenetic response to the “magmatic hydrothermal fluids-formation water compound fluid system”. The magmatic hydrothermal fluids is an important source of Si and REE to the diagenetic fluid flow and is also a heat source that drives the magmatic hydrothermal fluids and formation water cycle underground. The acid dissolution mechanism indicates that the open fault area is a promising target for the petroleum reservoir exploration in the future.

Key words: magmatic hydrothermal fluids, diagenesis, saddle dolomite, silicolites, Tarim Basin