准噶尔盆地深、浅部构造关系及其岩石圈结构动力学模型

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准噶尔盆地,岩石圈,动力学,构造,模型
准噶尔盆地深、浅部构造关系及其岩石圈结构动力学模型

摘要：准噶尔盆地是一个油气资源十分丰富的含油气盆地。其基底属“陆壳性质”；存在“双层基底结构”；具“南北拼贴特点”；盆地东西部结晶基底结构存在差异。准噶尔盆地深部构造对浅部构造活动的制约作用主要是通过力、物质和热三种形式完成。力的作用首先，盆地周缘褶皱山系中的逆冲断层使盆地周边的海西期地层发生拆离、位移、冲断、推覆和褶皱等作用；其次，全盆地结晶地壳和岩石圈的整体挠曲作用控制和影响了盆地沉积盖层的构造和活动；再次，盆地深部断裂把盆地结晶基底分割成数个大小不一的块体，并影响和作用到盆地腹部的盖层构造。南北向岩石圈规模的“张性”断裂与盆地形成初期的南北向挤压力有关，同时也是深部物质(可能来自上地幔顶部)上涌并侧向侵位，从而成为盆地深部物质高速度、高密度、高磁化强度的根源；最后，盆地周缘山系的地震活动与具较强深部背景的断层有密切联系。物质作用准噶尔盆地“陆壳”基底有酸性、基性岩存在，这些基性、酸性深成岩有幔源物质的特点，推测其可能来自岩石圈地幔，上涌后对盆地的基底进行改造。热的作用准噶尔盆地内部的热状态据火山岩资料可划分出5个火山活动时间序列；大地热流表明准噶尔盆地的热流值从晚古生代中期急剧下降，现今准噶尔盆地是一个“冷盆”；温泉分布和地震层析成像资料也揭示了盆地深部热作用的存在。从盆地周缘构造演化特征、盆地腹部构造特征、成盆后构造特征等三个方面构建和论述了准噶尔盆地岩石圈结构动力学模型。论文最后讨论了准噶尔盆地内油气资源的形成、分布及其与盆地基底结构、属性以及深浅部构造关系。

Abstract：It is well known that the Junggar Basin（JB）is a basin rich in petroleum. It has not only a

continental crustal basement but also a two-layer basement structure. The basement of the JB has a character of collage and has an obvious difference between the east and west. The deep structures have a close affiliation with the shallow structures by the processes of the force, substance and heat. As to the force, Firstly, the thrust faults in the margin of the JB make a series of structure processes, including decoupling, displacement, overthrust, nappe and fold, happen in the Hercynian stratum around the JB. Secondly, the bending of the whole crystalline basement and lithosphere in the JB has a close relation with the structure in the cover strata. Thirdly, the faults in the basement and the deep crust of the JB cut the crystalline basement of the JB into many unequal blocks, these blocks have a process of decoupling, displacement and overthrust in the deep lithosphere. The S-N trending extrusion stress is the main cause to the formation of the S-N trending tensional faults, which are the channels for the deep substance moving upwardly. And the deep substance possibly comes from the top of the upper mantle. This is an explanation for the high velocity, high density and high magnetization of the deep substance in the JB. Finally, the earthquakes occurred in the margin of the JB are induced by the faults, most of which have an obvious structural background in the deep crust. As to the substance, there are some acidic rocks and basic rocks in the continental crustal basement of the JB. These rocks have some characters of substance in the mantle. They possibly come from the mantle lithosphere and reconstruct the basement of the JB after moving upwardly. As to the heat, this study gets 5 time sequences of the volcanic activities in the JB. The terrestrial heat flow data shows that the heat flow descends suddenly since the middle late Paleozoic. Now, the JB is a cool basin. Moreover, the distribution of the hot wells and the seismic tomography also show that there are heat processes in the deep. Integrating all the above data, a geodynamic model of the lithospheric structure in the JB was constructed in this study. From the structural characteristics in the margin, hinterland and structures after the formation of the basin, this study also gives a commentary to this model. In the end, this paper also indicated that the distribution of the oil and gas has an intimate relationship with the basement, shallow and deep structure in the JB.