大巴山陆内造山带高压古流体及其运移动力学机制研究

发布时间：2018-05-18 10:49

本文选题：方解石脉 + 流体包裹体　；参考：《地学前缘》2017年02期

【摘要】：陆内造山带普遍存在的高压流体与金属矿产与油气形成与分布关系十分密切。大巴山陆内造山带发育有大量同构造期方解石脉,碳氧同位素反映其为围岩碳酸盐岩成岩流体产物。通过对方解石脉中盐水包裹体分析测试,应用包裹体p-T-X相图确定的大巴山构造带同构造期古流体压力自北而南由高变低,即从大巴山逆冲构造带、大巴山前陆构造带到大巴山前陆坳陷古流体压力分别为240~270 MPa、220~240 MPa和170~190 MPa,而恢复的古流体压力梯度分别为2.2 MPa/100m、2.3 MPa/100m和2.0 MPa/100m,明显高于正常静水压力,表明大巴山陆内造山期古流体为典型异常高压流体。综合分析表明,大巴山陆内造山带和四川盆地自古至今普遍存在异常高压流体。结合区域地质研究认为,处于大巴山推覆体前缘、受志留系泥岩滑脱层和逆掩断层控制的高压体系具有压力封存箱特征。大巴山陆内造山带高压流体是在埋藏过程中形成的,其形成深度在2 800m左右,异常高压是大巴山构造带驱动流体迁移的主要动力之一。
[Abstract]:High pressure fluids and metal minerals are closely related to the formation and distribution of oil and gas in intracontinental orogenic belts. There are a large number of calcite veins in the Dabashan intracontinental orogenic belt. The carbon and oxygen isotopes reflect that they are the product of diagenetic fluid of the surrounding carbonate rocks. Based on the analysis and test of brine inclusions in calcite veins, the paleofluid pressure of the Dabashan tectonic belt in the same tectonic period has changed from high to low from north to south, that is, from the Dabashan thrusting tectonic belt, which is determined by the p-T-X phase diagram of inclusions. The paleofluid pressure in the Foreland depression of the Daba Mountains is 240 ~ 270MPA ~ 220240 MPa and 170 ~ 190MPA, respectively, and the restored paleofluid pressure gradient is 2.2 MPA / 100m-1 2.3 MPa/100m and 2.0 MPA / 100m respectively, which is obviously higher than that of the normal hydrostatic pressure. The results show that the paleofluids in the Dabashan intracontinental orogenic period are typical abnormal high pressure fluids. Comprehensive analysis shows that abnormal high pressure fluid exists in the Dabashan intracontinental orogenic belt and Sichuan basin since ancient times. Combined with regional geological study, it is considered that the high-pressure system controlled by Silurian mudstone slippage and thrust fault has the characteristics of pressure storage box at the front edge of the Dabashan nappe. The high-pressure fluid in the Dabashan intracontinental orogenic belt was formed during the burial process, and its formation depth is about 2800m. The abnormal high pressure is one of the main driving forces for the migration of fluid in the Dabashan tectonic belt.
【作者单位】：长安大学地球科学与资源学院;国土资源部岩浆作用成矿与找矿重点实验室;陕西省地质调查院;中国地质科学院;中国石油长庆油田分公司勘探部;
【基金】：国家自然科学基金项目(41173055,41602128) 中央高校基金项目(310827151062)
【分类号】：P618.13

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