关键词: 川东北地区, 下三叠统, 飞仙关组, 白云岩储层, 锶微量元素, 锶同位素, 成岩流体, 海源地层水

Abstract: Based on the rock structure, strontium trace element and strontium isotope geochemistry characteristics, the genesis of high quality dolostone reservoir of Feixianguan Formation were analyzed in the Lower Triassic of northeast Sichuan Basin. The result indicates that the rock structure of the deep burial dolostone is quite different from that of penecontemporaneous dolostone. The ⁸⁷Sr to ⁸⁶Sr ratios of carbonate rocks in Feixianguan Formation cover the range of that of global seawater in the early Triassic. The average value is consistent with that of the global in the early Triassic. The ⁸⁷Sr to ⁸⁶Sr ratio of the burial dolostone in Feixianguan Formation contains the changing range of that of global seawater in the early Triassic and can well approximate to that of seawater in the early Triassic of northeast Sichuan Basin. The average value of ⁸⁷Sr to ⁸⁶Sr ratio is closer to that of seawater in the global early Triassic, which shows that dolostone diagenesis fluids have much strontium isotope composition characteristics in Triassic seawater. The dolostone of Feixianguan Formation is the product of diagenesis in multi-period replacement-burial, and the dolostone diagenesis fluids come from condensed sea source water in sabkha, which is rich in Mg, Sr and high salinity.

Key words: Northeast Sichuan Basin, Lower Triassic, Feixianguan Formation, dolostone reservoir, strontium trace element, strontium isotope, diagenesis fluids, formation water of sea source