Formation time and fluid source of calcite veins and geological signifi-cance:An example from the Triassic Qinglong Formation carbonate res-ervoirs in the Huangqiao area,Subei Basin
Formation time and fluid source of calcite veins and geological signifi-cance:An example from the Triassic Qinglong Formation carbonate res-ervoirs in the Huangqiao area,Subei Basin
[Objective]Calcite veins are the products of tectonic diagenesis.Information about fracture opening and fluid activity was recorded by calcite veins.[Methods]Multiple approaches,consisting of thin section obser-vation,cathodoluminescence,U-Pb isotope dating,and REE,C,O and Sr isotope analyses of calcite veins from the Triassic Qinglong carbonate reservoirs in the Huangqiao area,Subei Basin,are used to analyse the origin of vein-forming fluid.[Results]Four stages of calcite veins were identified in the Qinglong Formation and successive-ly formed at(115.30±0.42),(97.03±0.43),(85.29±0.25),(45.5±19.0)Ma.In the first stage,the calcite veins were derived from deep hydrothermal fluids.And in the second stage,the calcite veins were derived from mixed fluids of atmospheric fresh water and seawater.Formation water and deep shell-source hydrothermal fluid mixed in the vein-forming fluid of the third-stage calcite veins.In the fourth stage of calcite veins formation,deep mantle-source hydrothermal fluid mixed with the formation water,resulting in the precipitation of calcite veins.The formation timing of the four stages of calcite veins corresponds to multistage tectonic movements during different pe-riods,indicating that fluid evolution in the Triassic Qinglong carbonate reservoirs was controlled by multiple stages of tectonic movements.[Conclusion]Importantly,three stages of deep hydrothermal fluid injectionin the reservoir were the result of deep fault opening caused by tectonic movements,which possibly indicate multistage hydrocarbon accumulation in the Triassic Qinglong Formation in the Huangqiao area.
关键词
方解石脉体/碳酸盐岩储层/U-Pb同位素年龄/流体来源/流体活动/黄桥气田/苏北盆地
Key words
calcite vein/carbonate reservoir/U-Pb isotope age/fluid source/fluid activity/Huangqiao gas field/Subei Basin
维普
万方数据