白云深水区新生代沉降及岩石圈伸展变形  

Baiyun deepwater cenozoic subsidence and lithospheric stretching deformation

作　　者：赵中贤[1,2] 孙珍[1] 谢辉[1,2] 颜承志 李元平 

机构地区：[1]中国科学院边缘海地质重点实验室,中国科学院南海海洋研究所,广州510301 [2]中国科学院研究生院,北京100049 [3]中海石油中国有限公司深圳分公司研究院,广州510240

出　　处：《地球物理学报》2011年第12期3336-3343,共8页Chinese Journal of Geophysics

基　　金：国家重点基础研究发展计划(973计划)(2007CB41170404,2009CB219401);国家科技重大专项(2008ZX05025-006-001)资助

摘　　要：为认识白云深水区新生代构造沉降和岩石圈伸展变形特征,本文对过研究区的两条测线进行了回剥分析和伸展系数计算,结果表明:白云深水区新生代构造沉降具有幕式特点,由快到慢共分4幕:①65～24.4 Ma;②24.4～18.5 Ma;③18.5～13.8 Ma;④13.8～0 Ma,在裂后存在3期快速沉降(24.4～21 Ma,18.5～16.5 Ma,13.8～10.5 Ma)和4期慢速沉降(或隆升)(30～24.4 Ma,21～18.5 Ma,16.5～13.8 Ma,10.5～0 Ma).白云深水区裂陷期和裂后期沉降受基底形态影响,总体向洋陆边界增加,裂陷期的沉降量为200～2100 m,裂后沉降量为1000～1500 m,由裂陷期沉降反演的岩石圈伸展系数为1～7,与全地壳的伸展系数变化趋势一致,在基底隆起处伸展系数小,凹陷处伸展系数大;白云深水区裂后存在异常沉降,约300～700 m,它的分布与基底形态负相关,在隆起处异常沉降量大,为600 m左右,凹陷处异常沉降量小,约300 m,可能与岩石圈破裂引起洋陆过渡带不同构造单元的差异沉降相关.Through backstripping and stretching factor calculating of two profiles across Baiyun Deepwater, the characteristics of Cenozoic subsidence and lithospheric stretching deformation are revealed. Baiyun deepwater is characterized by four episodes of tectonic subsidence during Cenozoic,（1） 65-24.4 Ma;（2） 24.4-18.5 Ma;（3） 18.5-13.8 Ma;（4） 13.8-0 Ma. There exist three fast subsidence periods （24.4-21 Ma,18.5-16.5 Ma,13.8-10.5 Ma） and four slow or uplift periods （30-24.4 Ma,21-18.5 Ma,16.5-13.8 Ma,10.5-0 Ma）. Syn-rift subsidence varies from 200-2100 m and that of post-rift from 1000 - 1500 m, which are all related to basement topography. Stretching factor of lithosphere calculated from syn-rift subsidence changes from 1 to 7 and has the same trend as crust stretching factor. Anomalous subsidence of about 300 700 m generated during post-rift which is inversely proportional to basement topography, about 600 m anomalous subsidence in the uplift and 300 m in the sag which is probably related to the differential subsidence of uplift and sag induced by lithosphere breakup.

关 键 词：沉降 伸展系数 岩石圈 白云深水区 

分 类 号：P541[天文地球—构造地质学]