Tectonic subsidence characteristics of Qiongdongnan Basin in Cenozoic
Tectonic subsidence characteristics of Qiongdongnan Basin in Cenozoic
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发表时间：
2008
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通讯作者：
Sun Zhen;C. Key
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作者：
Sun Zhen;C. Key
利用回剥技术分析了琼东南盆地亚北、延安、乐东和华光凹陷的构造沉降史，计算了30口假定威尔斯井的一维构造沉降史，并对其中8口威尔斯井的构造沉降速率和总沉降速率进行了评价。(1)第一阶段为始新世-早渐新世的裂陷阶段，平均构造沉降速率为81 m·Ma-1，由中央坳陷向南部坳陷递减，沉降中心位于中央坳陷，受先存基底断裂控制，乐东坳陷平均构造沉降速率为105 m·Ma-1，南部坳陷带为74 m·Ma-1，崖北坳陷为59 m·Ma-1。(2)第二阶段，早中新世-中中新世，琼东南盆地结束裂陷，转入坳陷阶段，平均构造沉降速率减小到68 m·Ma-1。(3)中中新世以来，琼东南盆地经历了一个加速沉降阶段，所有推测的威尔斯井的平均构造沉降速率增加到84 m·Ma-1，其中与莺歌海盆地连接带推测的5口威尔斯井的平均构造沉降速率为90 m·Ma-1，盆地北方推测的3口威尔斯井的平均构造沉降速率为73 m·Ma-1。上新世以后，琼东南盆地的构造沉降速率明显加快，盆地的构造沉降速率明显加快，盆地的构造沉降速率明显加快，盆地的构造沉降速率明显加快。北方和中央凹陷带沉降速率较大，为110 m·Ma-1。
Tectonic subsidence histories of the Yabei,Yanan,Ledong and Huaguang sags in the Qiongdongnan Basin were analyzed by back-stripping technique.One-dimensional tectonic subsidence histories of 30 presumed wells were calculated,8 wells of which were appraised for their tectonic and total subsidence rates.The results show that the Qiongdongnan Basin experienced 3 main subsiding stages in Cenozoic.(1) The first stage was a rifting stage during Eocene and early Oligocene.The average tectonic subsidence rate was 81m·Ma-1 and it decreased from the central depression to the southern depression.The subsidence center was located at the central depression,which was supposed to be controlled by the pre-existing basal fault.The average tectonic subsidence rate was 105m·Ma-1 at the Ledong depression,74m·Ma-1 in the southern depression zone and 59m·Ma-1 at the Yabei depression.(2) In the second stage from early Miocene to middle Miocene,the Qiongdongnan Basin ended rifting and shifted to a depression stage.The average tectonic subsidence rate decreased to 68m·Ma-1.(3) Since middle Miocene,the Qiongdongnan Basin had experienced an accelerated subsidence stage.The average tectonic subsidence rate increased to 84m·Ma-1 in all the presumed wells.It was 90m·Ma-1 in the 5 presumed wells in the connection zone with the Yinggehai Basin,and 73m·Ma-1 in the 3 presumed wells in the northern part of the basin.After Pliocene,the subsidence rate was higher in the northern and central depression zones,with a value of 110m·Ma-1.