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    珠江口盆地新生代沉降特征及其影响因素分析

    An analysis of subsidence characteristics and affecting factors in the Pearl River Mouth Basin in Cenozoic

    • 摘要: 为了研究珠江口盆地的沉降特征、沉降特征时空差异性以及影响因素,文章共选取了32口人工井进行沉降史计算,并进行综合分析,从中又特选出12口典型人工井进行对比分析,编绘和对比分析了3条典型沉降演化图。结果表明:盆地整体沉降可分为3幕,第一幕为始新世,平均总沉降速率为85 m/Ma;第二幕为渐新世至中中新世,平均总沉降速率为146 m/Ma;第三幕为晚中新世至第四纪,平均总沉降速率为104 m/Ma。同一时期不同构造单元之间及同一构造单元在不同时期,沉降与演化特征都存在差异性,各时期沉降速率平面分布表现出"分区"、"分带"的特征,沉降演化的差异性变化与盆地的演化阶段及其构造特征有关。盆地整体沉降特征受成盆动力学影响,而沉降特征差异性受盆地动力学和构造格局共同影响。珠江口盆地整体沉降表现为"幕式"特征,沉降及其演化特征表现出明显的时空差异性,盆地动力学特征和构造格局共同影响盆地的沉降特征。

       

      Abstract: In order to study the characteristics of subsidence and the difference between each tectonic unit and time as well as its affecting factors in Pearl River Mouth Basin, the authors chose 32 simulation wells to calculate the subsidence and to make comprehensive analysis, and selected 12 typical wells from 32 simulation wells to make contrastive analysis. In the meantime, 3 typically evolution sections were also analyzed comprehensively. According to the results obtained, the overall subsidence can be divided into three episodes:the first episode was Eocene, whose average overall subsidence rate was 85m/myr; the second episode was from Oligocene to Middle Miocene, whose average overall subsidence rate was 146m/myr; the third episode was from Late Miocene to Quaternary, whose average overall subsidence rate was 104m/myr. The subsidence and evolution characteristics of various tectonic units were different during the same period, and the characteristics of subsidence and evolution in the same unit were also varied during different periods. The subsidence rate on the same plane can be arranged into different zones. The diversity in the changes during the subsidence evolution was affected by tectonic evolution stages of the basin as well as the structural characteristics. The characteristics of overall subsidence were controlled by basin dynamics, whereas the differences of subsidence were controlled by dynamics and structural framework. The overall subsidence can be divided into several episodes in Pearl River Mouth Basin. The characteristics of subsidence and evolution were varied between different time and space spans. Both of the basin dynamics and structural framework controlled the features of subsidence.

       

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