海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。

PALEOMAGNETIC STUDY AND TECTONIC EVOLUTION OF HAINAN TERRANE AND ITS VICINAL CONTINENTAL COAST THE LATE MESOZOIC TO CENOZOIC

In this paper, the authors describe in detail the process of paleomagnetic study on rocks of Hainan Island and vicinity from Cretaceous to Quaternary. By analysing the data of paleomagnetism, the authors give a tectonic evolutionary model of Hainan Island since Cretaceous: first, southward clockwise, and then northward counterclockwise. Combining the data of Geology with that of Geophysics about the proceeding, particularly about Beibu Gulf (i.e. The Gulf of Tonkin), the authors propose a preliminary idea on tectonic movement of Hainan Island as follows: In the early stage, there is an extentional process in Beibu Gulf, which makes evidently the crust of Beibu Gulf thin and extends and forms Beibu Gulf Basin, so as to result in the fore tectonic movement of Hainan Island, and the late tectonic movement of Hainan Island as an effect of the opening of the South China Sea. Elucidation of the law of movement of Hainan Terrane has great theoretical and practical significance for study on the formation and evolution of the oil and gas basins in Beibu Gulf.