中国大陆造山带地壳密度结构特征

发布时间：2018-06-15 05:30

本文选题：大陆动力学 + 中国大陆　；参考：《地质论评》2017年03期

【摘要】：本文探讨中国大陆造山带地壳介质密度的变化特征和不同类型,并用大陆动力学机制解释这些特征产生的原因。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,揭示了造山带地壳的密度结构。和克拉通地体不同,中国大陆的造山带下地壳密度都偏低,只有古生代块体弱碰撞形成的摺皱山脉是例外。这些造山带大都与古大洋封闭和俯冲碰撞作用有关。古大洋封闭后在地壳中留下的裂隙和海水,会造成地壳密度降低。中国大陆造山带地壳密度结构大致可以分四类。上中下地壳密度都偏低的属于第一类造山带。第二类造山带上中地壳密度偏低,而下地壳密度偏高。第三类造山带上中地壳密度偏高,而下地壳密度偏低。第四类造山带上中下地壳密度都偏高。通过板块构造原理和岩石物理规律对青藏高原造山带地壳密度结构分类的解释可见,青藏高原南部,中部和北部地壳密度结构分属三类不同的造山带,体现印度次大陆和欧亚板块碰撞不同阶段作用造成的结果。根据地壳密度变低和厚度是否加大,还可以识别板沿和板内造山带。
[Abstract]:In this paper, the variation characteristics and different types of crustal media density in the Chinese continental orogenic belt are discussed, and the causes of these characteristics are explained by the continental dynamics mechanism. According to the scale-source depth transformation law of gravity field wavelet transform, the multi-scale decomposition of the ground gravity anomaly field is carried out, and the wavelet details reflecting the different burial depths of the crust of China are obtained, and the density structure of the crust of the orogenic belt is revealed. In contrast to cratonic terrains, the density of the lower crust of the orogenic belts in China is low, except for the crinkled mountains formed by the weak collision of Paleozoic blocks. Most of these orogenic belts are related to the paleo-oceanic closure and subduction collision. The cracks and sea water left in the crust after the closure of the ancient ocean will reduce the crustal density. The crustal density structure of the Chinese continental orogenic belt can be roughly divided into four categories. The upper, middle and lower crust belong to the first type orogenic belt with low density. The density of the upper and middle crust of the second type orogenic belt is low, while the density of the lower crust is higher. The density of the upper and middle crust of the third type orogenic belt is higher than that of the lower crust. The density of the upper, middle and lower crust of the fourth type of orogenic belt is on the high side. Based on the interpretation of plate tectonics and petrophysical laws to the classification of crustal density structure of the Qinghai-Tibet Plateau orogenic belt, it can be seen that the crustal density structure of the southern, central and northern Qinghai-Xizang Plateau belong to three different orogenic belts. The results of different stages of collision between Indian subcontinent and Eurasian plate are reflected. The plate edge and intraplate orogenic belt can also be identified according to the lower density and greater thickness of the crust.
【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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