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世界上许多张性沉积盆地存在远大于McKenzie模型理论值的裂后异常沉降,南海北部陆缘的沉积盆地也是如此;确定裂后异常沉降的特征和分布是认识其成因机制和对油气成藏影响的前提.介绍了估算裂后异常沉降的3种方法:古水深比较法、应变速率反演法和沉降过程二维正反演法,并指出了各方法的应用前提和优缺点.对于由作者提出的后一种方法还结合在珠江口盆地的应用实例进行了较详细的讨论,表明这种方法能在考虑岩石圈挠曲强度的基础上正演模拟出单幕或多幕盆地沉降及相应的岩石圈伸展系数,从而计算出盆地理论热沉降,与通过回剥反演得到的实测构造沉降进行对比;还指出了该方法存在的问题和需进一步研究之处.
There are many post-fault anomalous subsidences in many tens of sedimentary basins in the world, which are much larger than the theoretical value of McKenzie model, as well as in the sedimentary basins on the northern continental margin of the South China Sea. Determine the characteristics and distribution of post-fault anomalous subsidence is to understand its genetic mechanism and influence on hydrocarbon accumulation The paper introduces three methods to estimate the anomalous subsidence after fracturing: the paleo-water depth comparison method, the strain rate inversion method and the two-dimensional forward and inverse method of settlement process, and points out the application prerequisites, advantages and disadvantages of each method. The latter method is also discussed in detail in the application of the Pearl River Mouth Basin. It shows that this method can simulate the subsidence and corresponding settlement of the single-curtain or multi-curtain basins on the basis of the flexural strength of the lithosphere Of the lithospheric extension coefficient, so as to calculate the theoretical thermal settlement of the basin, compared with the measured settlement by back-stripping inversion. The problems existing in this method and the points for further study are also pointed out.