准噶尔盆地成藏动力学系统划分

Pool-Forming Dynamic System Division in Junggar Basin

本文在对成藏动力学系统的概念重新描述的基础上,选择经历了多旋回构造与沉积演化的准噶尔盆地进行成藏动力学系统划分。准噶尔盆地发育6套烃源岩、多套储集层、2套区域性盖层和数个局部盖层,它们构成6套生、储、盖组合。同时,钻井揭示盆地超压发育,结合测井与地震资料,将地层压力在垂向上划分为2个常压系统和3个超压系统。该盆地垂向通道众多,构造活动期流体上下连通性好,整体可划为一个复杂的成藏动力学系统。然而,断裂活动具幕式特征,相对盆地演化史,大部分时期处于静止封闭状态。因此,进一步将准噶尔盆地划分为6个成藏动力学子系统:①二叠系自源超压半封闭型成藏动力学子系统;②三叠系他源超压半封闭型成藏动力学子系统;③侏罗系混源超压半封闭型成藏动力学子系统;④白垩系—侏罗系混源常压开放型成藏动力学子系统;⑤古近系—白垩系混源超压封闭型成藏动力学子系统;⑥新近系他源常压开放型成藏动力学子系统。不同的子系统,成藏条件、成藏动力和成藏规律不同。

On the basis of the new description for the concept of pool-forming dynamic system, the Junggar basin invol- ving the polycyclic structural and sedimentary evolution has been selected to divide this system. There are six main source rocks, several reservoir rocks, two regionalized cap rocks and several local cap rocks in the Junggar basin. They formed six sets of source--reservoir--cap rock association. The drilling practice revealed that there was ap- parent overpressure in the Junggar basin. The formation pressure can be divided vertically into two normal pressure systems and three overpressure systems, according as logging and seismic data. This basin developed numerous ver- tical migration pathways with good connectivity in fluids hold during tectonic activity, so the Junggar basin can be taken as a complex pool-forming dynamic system. But, the fault activities are provided with the episodic charac- ters. At motionless stage, the fault sealing properties are strong. Therefore, the Junggar basin can be divided into six pool-forming dynamic sub-systems, including： ①Permian self-sourced and semi-sealed overpressure sub-sys- tem, ②Triassic outward-sourced and semi-sealed overpressure sub-system, ③Jurassic mixed-sourced and semi- sealed overpressure sub-system, ④Cretaceous--Jurassic mixed-sourced and open normal pressure sub-system, Early Tertiary-- Cretaceous mixed-sourced and sealed overpressure sub-system, ⑤open normal pressure sub-system. The different pool-forming dynamic sub-systems conditions, dynamics and rules. ⑥Quaternary outward-sourced and bear the different pool-formingconditions, dynamics and rules.