中国大陆克拉通地体地壳密度结构特征

发布时间：2018-10-12 11:37

【摘要】：本文根据重力场小波变换的尺度—源深度转换律,进行地面重力异常场多尺度分解,取得了反映中国地壳不同埋藏深度的小波细节,揭示了克拉通地体地壳的密度结构。中国大陆克拉通地体地壳密度结构的总体特点是:地壳密度总体偏高,尤其是在经历了岩浆底垫作用后,下地壳形成了粗大的和高密度的壳根,而造山带的下地壳通常有低密度的山根。现今的克拉通地体有几个演化的阶段,由陆地核演化为一定规模的克拉通地体可能经历漫长的时间。不同演化的阶段地体的物理性质有明显的变化,要赋予大地构造单元以演化阶段的内涵,才能准确理解它们的行为和属性。同时,根据地壳密度结构成像的结果,可以了解克拉通地体的成熟度。中国大陆克拉通地体或者内部地块的地壳密度结构大致可以分为三类。上中下地壳密度都偏高的属于第一类,称为典型的克拉通,塔里木、阿拉善、华北东部、上中扬子等属于第一类。第二类克拉通地体上地壳密度偏低,而下地壳密度偏高,称为弱结晶基底的克拉通,鄂尔多斯和佳木斯属于第二类。第三类上中地壳密度偏高,而下地壳密度偏低,称为无壳根的克拉通残片,柴达木和准噶尔盆地属于此类,它们可能是古克拉通地体的残片。
[Abstract]:Based on the scale-source depth transformation law of gravity field wavelet transform, the multi-scale decomposition of ground gravity anomaly field is carried out in this paper. The wavelet details reflecting the different burial depths of the crust of China are obtained, and the density structure of the craton earth crust is revealed. The general characteristics of the crustal density structure of the cratonic terrane in the mainland of China are that the crustal density is generally high, especially after the magmatic underlay, the lower crust forms a thick and high density crust root. The lower crust of the orogenic belt usually has low-density mountain roots. There are several stages in the evolution of the cratonic terrane, and it may take a long time for the land core to evolve into a certain scale of cratonic terrane. The physical properties of terraces in different stages of evolution have obvious changes. Only by endowing tectonic units with the connotation of evolution stage can their behavior and properties be accurately understood. At the same time, according to the crustal density structure imaging results, we can understand the maturity of the craton. The crustal density structure of cratonic terrane or inner block in Chinese mainland can be divided into three types. The upper, middle and lower crust with high density belong to the first type, which is called the typical craton, Tarim, Alashan, East of North China, Upper and Middle Yangtze, and so on. The upper crust density of the second type craton is low, while the lower crust density is higher, which is called the craton of weak crystalline basement. Ordos and Jiamusi belong to the second kind. The density of the upper middle crust is higher than that of the lower crust, which is called craton fragments without shell roots. The Qaidam and Junggar basins belong to this type, which may be the remnants of the paleo-cratonic terrane.
【作者单位】：浙江大学地球科学学院;中国地质科学院地质研究所;贵州恒昊软件科技有限公司;
【基金】：国家自然科学基金资助项目(编号:41574111)的成果~~
【分类号】：P313

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