3D Structure of the Mesozoic Tan-Lu FaultZone and Its Impact on Basin Evolution: Insights from the Southern Bohai Bay Basin, NE China

The Cenozoic Tan-Lu Fault Zone, as the largest strike-slip fault system in eastern China, features complex deformation patterns and mechanisms and a tectonic evolution that has been investigated by previous studies.Here, we present high-resolution seismic profiles across the whole southern Bohai Bay basin, where the Tan-Lu Fault Zonetraverses, enabling the identification oftwo types of Mesozoic normal fault systems: an E-W trending fault set, and a NNE trending fault set. Considering the tectonic events that have happened since the Mesozoic and the intersection relationshipbetween the two fault systems, we propose that the E-W trending normalfaults originated fromthe Triassic collision between the South China Block and the North China craton. The NNE trending normalfaults were derived fromstrike-slip faults formed under transpression, due to multiple phases of subduction of the Pacific plate during Jurassic to Late Cretaceous. Both fault systems were subsequently reactivated and transformed into normal faults during the Early Cretaceous rifting, leading to the formation of a cross-graben rift. The widespread Early Cretaceous extension promoted volcanic activity, allowing significant volumes of deep-seated magmatic material to rise along these two sets of faults and to erupt onto the surface. The spatial distribution of the volcanic products was structurally controlled by fault boundaries, leading to the formation of a large-scale, quadrangular Mesozoic volcanic basin.新生代郯庐断裂带（Cenozoic Tan-Lu Fault Zone）作为中国东部规模最大的走滑断裂系统，其变形样式与形成机制复杂，构造演化历程已为诸多前期研究深入探讨。本研究依托横跨整个渤海湾盆地（Bohai Bay Basin）南部的高分辨率地震剖面——该区域为郯庐断裂带的穿经区域——成功识别出两类中生代正断裂系统：近东西向断裂组与北北东向断裂组。结合中生代以来的构造事件与两类断裂系统的交切关系，本研究提出：近东西向正断裂起源于华南地块（South China Block）与华北克拉通（North China craton）的三叠纪碰撞事件；北北东向正断裂则源自侏罗纪至晚白垩世太平洋板块多阶段俯冲作用下，走滑断裂在压扭环境下形成的构造形迹。两类断裂系统后续均在早白垩世裂谷作用期间发生活化并改造为正断裂，最终形成交叉地堑型裂谷构造。广泛发育的早白垩世伸展作用推动了火山活动，使得大量深部岩浆物质沿这两组断裂向上运移并喷溢至地表。火山产物的空间分布受断裂边界构造控制，最终形成了大型的四边形中生代火山岩盆地。