南海北部白云凹陷及其邻区的岩石圈强度分析

摘要

Using flexural backstripping and gravity anomaly modeling techniques and Process-Oriented Gravity Modelling (POGM), we calculated variable effective elastic thickness (Te) of a long cable, multi-channel seismic reflection profile across the northern margin of the South China Sea and analyzed the lithospheric strength distribution during rifting and post rifting. Results show that the lithospheric strength is weak during rifting and that the post-rifting Te is different for different tectonic units. The lithospheric strengths of the Panyu Low Rise and Lower Slope are larger, with Te of about 15 km; the Te of the Northern Depression is about 7 km, and the Baiyun Sag is the weakest in strength, whose Te is only about 5 km. Lithospheric strength can help to understand the distribution of the basin and the process of lithospheric evolution in the northern continental margin of the South China Sea.%选取纵穿南海北部陆缘的长排列多道地震剖面,利用挠曲回剥和重力异常模拟相结合的过程导向法(process-oriented gravity modelling, POGM),计算了研究区内不同构造单元同张裂及裂后阶段的岩石圈有效弹性厚度(effective elastic thickness, Te),并对其分布特征进行了详细分析。计算结果显示：张裂过程中岩石圈强度很弱；而裂后阶段岩石圈强度在不同构造单元并不相同,其中番禺低隆起和下陆坡区强度较高, Te约为15km,而在北部坳陷带为7km左右,白云凹陷地区强度最低,仅为5km左右。获得的岩石圈强度结果,加深了对南海北部大陆边缘盆地特征和岩石圈构造演化过程的认识,具有重要的意义。