琼东南盆地构造沉降的时空分布及裂后期异常沉降机制

J4 ›› 2012, Vol. 42 ›› Issue (1): 47-57.

琼东南盆地构造沉降的时空分布及裂后期异常沉降机制

李亚敏^{1, 2},施小斌¹,徐辉龙¹,何家雄³,刘兵⁴

1.中国科学院边缘海地质重点实验室/南海海洋研究所|广州510301；
2.中国科学院研究生院|北京100049；
3.中国科学院广州地球化学研究所|广州510640；
4.中海石油有限公司湛江分公司| 广东湛江524057

收稿日期:2011-05-04 出版日期:2012-01-26 发布日期:2012-01-26
作者简介:李亚敏(1979-)|女|博士研究生|主要从事盆地分析方面研究|E-mail:liyamin05@scsio.ac.cn
基金资助:
国家自然科学基金项目（40676041）；国家“973”计划项目（2007CB41170104，2007 CB41170401）

Temporal and Spatial Distribution of Tectonic Subsidence and Discussion on Formation Mechanism of Anomalous Post-Rift Tectonic Subsidence in the Qiongdongnan Basin

LI Ya-min^{1, 2}, SHI Xiao-bin¹, XU Hui-long¹, HE Jia-xiong³, LIU Bing⁴

1.CAS Key Laboratory of Marginal Sea Geology/South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou510301, China；
2.Graduate School, Chinese Academy of Science, Beijing100049, China；
3.Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou510640, China；
4.Zhanjiang Branch Company|China National Offshore Oil (China)Corporation Limited,Zhanjiang524057,Guangdong,China

Received:2011-05-04 Online:2012-01-26 Published:2012-01-26

摘要/Abstract

摘要：

为考察琼东南盆地构造沉降的时空分布及裂后期异常沉降机制，利用回剥技术计算了盆内68口井的构造沉降史，并选择15口代表井进行拉张应变速率反演及拉张因子计算。结果表明：琼东南盆地构造沉降空间上表现为中央凹陷带和南部凹陷带强于北部凹陷带；时间上在裂陷期出现局部快速沉降-整体慢速沉降－局部快速沉降的阶段特征，进入裂后期逐渐减缓并在15.5~10.5 Ma期间减至最低值，但自10.5~5.5 Ma以来又明显增大。裂后期异常沉降在盆地东西部都有明显表现，在北部凹陷带较小，在中央凹陷带内往东区有逐渐增大趋势；时间上裂后异常构造沉降随时间增大，增长过程具有快-慢-快的阶段性。分析认为:裂后阶段早期的快速沉降可能是裂陷期非均匀拉张的结果，而晚中新世以后的快速构造沉降主要与岩浆活动有关。

关键词: 构造沉降, 裂后期异常沉降, 应变速率反演, 拉张因子, 琼东南盆地

Abstract:

To investigate the temporal and spatial distribution of tectonic subsidence and the formation mechanism of anomalous post-rift tectonic subsidence in the Qiongdongnan basin, we calculated the tectonic subsidence history of sixty-eight wells by back stripping method. Then fifteen representative wells were chosen to estimate stretching strain rate using inverse theory and to calculate stretching factors. The results suggest that the extent of tectonic subsidence in the center and southern depressions is greater than that in northern depression. Tectonic subsidence rate that varied with time can be summarized as “locally quick-holisticly slow-locally quick”followed by gradually decreasing in the post-rift period and attained its minimum during 15.5-10.5 Ma, but it started to increase again since 10.5-5.5 Ma. Anomalous post-rift tectonic subsidence is more obvious in both east and west than in the north of the Qiongdongnan basin and the extent in center depressions increases from west to east. In time scale, the post-rift subsidence increases with time, and the process can be summarized as quick-slow-quick multiple stages. Our results suggest that the quick subsidence in the early post-rift stage likely resulted from the diversity of stretching during the rift period, and the quick tectonic subsidence since Later Miocene was likely caused by magmatic activities.

Key words: tectonic subsidence, anomalous post-rift subsidence, strain rate inversion, stretching factor, Qiongdongnan basin

中图分类号:

P548.265

李亚敏, 施小斌, 徐辉龙, 何家雄, 刘兵. 琼东南盆地构造沉降的时空分布及裂后期异常沉降机制[J]. J4, 2012, 42(1): 47-57.

LI Ya-min, SHI Xiao-bin, XU Hui-long, HE Jia-xiong, LIU Bing. Temporal and Spatial Distribution of Tectonic Subsidence and Discussion on Formation Mechanism of Anomalous Post-Rift Tectonic Subsidence in the Qiongdongnan Basin[J]. J4, 2012, 42(1): 47-57.

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