南海海盆擴(kuò)張機(jī)制的動(dòng)力學(xué)模擬
發(fā)布時(shí)間：2018-12-28 07:24
【摘要】：南海處于印度—澳大利亞、歐亞和太平洋三大板塊匯聚中心,地理位置獨(dú)特,地質(zhì)作用復(fù)雜,經(jīng)歷了拉張、張裂到海底擴(kuò)張的演化過(guò)程,是水平拉張和地幔上涌共同作用下的被動(dòng)擴(kuò)張結(jié)構(gòu)。以南海中央海盆的地質(zhì)構(gòu)造為背景建立二維有限元模型,對(duì)具有先存薄弱帶情況下巖石圈在水平拉張力和上涌力共同作用下的減薄擴(kuò)張情況進(jìn)行動(dòng)力學(xué)模擬。計(jì)算結(jié)果表明:(1)巖石圈在受到拉張作用時(shí),薄弱帶和斷層的存在會(huì)使該區(qū)域發(fā)生應(yīng)力集中,優(yōu)先減薄破壞;(2)巖石圈在單純的拉張力條件下很難發(fā)生破壞,如果同時(shí)施加一個(gè)較小地幔上涌力反而能引起較大的變形,說(shuō)明地幔上涌力在海盆擴(kuò)張中起著重要的作用;(3)由于下地殼的流變性,下地殼比上地殼發(fā)生了更大程度的減薄,而且下地殼的流變特性比薄弱帶的存在更有助于海盆的擴(kuò)張。
[Abstract]:The South China Sea is located in the three major convergence centers of Indo-Australian, Eurasian and Pacific plates. It has a unique geographical location and complex geological processes, and has undergone an evolutionary process of stretching and fracture to undersea expansion. It is a passive spreading structure under the action of mantle upwelling. Based on the geological structure of the central basin of the South China Sea, a two-dimensional finite element model is established to simulate the thinning and spreading of the lithosphere under the combined action of horizontal tension and upwelling force in the case of pre-existing weak zone. The results show that: (1) when the lithosphere is subjected to tension, the existence of weak zones and faults will lead to stress concentration in the area and preferential thinning and failure; (2) it is difficult to destroy the lithosphere under the condition of simple tension. If a small mantle upwelling force is applied at the same time, it can cause a large deformation, which indicates that the mantle upwelling force plays an important role in the expansion of the ocean basin. (3) because of the rheological variation of the lower crust, the lower crust is thinned more than the upper crust, and the rheological characteristics of the lower crust are more helpful to the expansion of the basin than the existence of the weak zone.
【作者單位】： 中國(guó)科學(xué)院邊緣海地質(zhì)重點(diǎn)實(shí)驗(yàn)室南海海洋研究所;中國(guó)科學(xué)院大學(xué);
【基金】：國(guó)家自然科學(xué)基金項(xiàng)目(41376061;91428205)
【分類號(hào)】：P736.1
本文編號(hào)：2393669
[Abstract]:The South China Sea is located in the three major convergence centers of Indo-Australian, Eurasian and Pacific plates. It has a unique geographical location and complex geological processes, and has undergone an evolutionary process of stretching and fracture to undersea expansion. It is a passive spreading structure under the action of mantle upwelling. Based on the geological structure of the central basin of the South China Sea, a two-dimensional finite element model is established to simulate the thinning and spreading of the lithosphere under the combined action of horizontal tension and upwelling force in the case of pre-existing weak zone. The results show that: (1) when the lithosphere is subjected to tension, the existence of weak zones and faults will lead to stress concentration in the area and preferential thinning and failure; (2) it is difficult to destroy the lithosphere under the condition of simple tension. If a small mantle upwelling force is applied at the same time, it can cause a large deformation, which indicates that the mantle upwelling force plays an important role in the expansion of the ocean basin. (3) because of the rheological variation of the lower crust, the lower crust is thinned more than the upper crust, and the rheological characteristics of the lower crust are more helpful to the expansion of the basin than the existence of the weak zone.
【作者單位】： 中國(guó)科學(xué)院邊緣海地質(zhì)重點(diǎn)實(shí)驗(yàn)室南海海洋研究所;中國(guó)科學(xué)院大學(xué);
【基金】：國(guó)家自然科學(xué)基金項(xiàng)目(41376061;91428205)
【分類號(hào)】：P736.1
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