Abstract The Song Hong Basin situated at the distal part of the Ailaoshan-Red River Shear Zone (ASRRSZ) holds important information on the role of extrusion tectonics in the marginal basin development in the South China Sea. Based on an extensive dataset of 2 and 3-D seismic and stratigraphic information from 27 exploration wells, the Paleogene structural evolution of the northern Song Hong Basin and adjacent areas has been studied in detail. This study proposes a new Paleogene structural development model of the study area. Eocene-Oligocene rifting in the northern Song Hong Basin was driven by left-lateral shearing from the ASRRSZ associated with a combined motion of clockwise rotation and translation of the Indochina Block, which allowed extension along the “restraining bend” geometry of the basin's eastern margin. A structural high separates the Song Hong Basin from the Beibuwan Basin, inhibiting significant strike-slip displacement transfer from the ASRRSZ into rifting in the Beibuwan Basin. Strike-slip displacement from the ASRRSZ is maintained further south to the East Vietnam Boundary Fault segment. Thus, extension of the Beibuwan, Qiongdongnan and Phu Khanh Basins were the result of the interplay between extrusion and slab-pull tectonics. During the end of the Oligocene, reduced extrusion of Indochina caused minimal rotation of the block, and the remaining left-lateral displacement along the ASRRSZ was absorbed into inversion around the junction between the Song Hong and Beibuwan basins.

中文翻译：

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宋洪盆地北部及邻区古近系构造发育：挤压构造在北部湾盆地形成中的作用的意义

摘要 位于哀牢山-红河剪切带（ASRRSZ）远端的松洪盆地拥有挤压构造在南海边缘盆地发育中的作用的重要信息。基于来自 27 口探井的 2 维和 3 维地震和地层信息的广泛数据集，详细研究了松红盆地北部及邻近地区的古近系构造演化。本研究提出了研究区古近系构造发育新模式。宋洪盆地北部始新世-渐新世裂谷受 ASRRSZ 左旋剪切驱动，与印度支那地块顺时针旋转和平移的联合运动相关，这使得沿盆地东缘的“限制弯曲”几何形状延伸. 一个构造高压将松红盆地与北部湾盆地分开，抑制了从 ASRRSZ 到北部湾盆地裂谷的显着走滑位移转移。来自 ASRRSZ 的走滑位移继续向南延伸至东越边界断层段。因此，北部湾盆地、琼东南盆地和富庆盆地的伸展是挤压和板片拉动相互作用的结果。在渐新世末期，印度支那的挤压减少导致地块旋转最小，剩余的沿 ASRRSZ 的左侧位移被吸收到松红盆地和北部湾盆地交界处周围的反演中。来自 ASRRSZ 的走滑位移继续向南延伸至东越边界断层段。因此，北部湾盆地、琼东南盆地和富庆盆地的伸展是挤压和板片拉动相互作用的结果。在渐新世末期，印度支那的挤压减少导致地块旋转最小，剩余的沿 ASRRSZ 的左侧位移被吸收到松红盆地和北部湾盆地之间的交界处周围的反演中。来自 ASRRSZ 的走滑位移继续向南延伸至东越边界断层段。因此，北部湾盆地、琼东南盆地和富庆盆地的伸展是挤压和板片拉动相互作用的结果。在渐新世末期，印度支那的挤压减少导致地块旋转最小，剩余的沿 ASRRSZ 的左侧位移被吸收到松红盆地和北部湾盆地交界处周围的反演中。