Two-Dimensional Numerical Modeling Of Intracontinental Extension: A Case Study Of the Baikal Rift Formation

Abstract:

The Baikal Rift zone (BRZ) is a narrow (< 80 km) and deep (> 10 km) active intra-continental basin, located at the boundary between the Amurian and Eurasian Plates. Although the BRZ is one of the major tectonically active rift zones in the world andit has been a subject of numerous geological and geophysical studies, the geodynamic origin and evolution of the BRZ is still debated. We applytwo-dimensional finite difference code to model the lithosphere–scale de-formation in several locations across the strike of the Baikal Rift zone. The model se-tup takes an advantage of regional geophysical models on topography,basin depth, the structure of the crust, lithosphere thickness, and the location of major tectonic faults. Our goal is to determine the physical models that reproduce reasonably well the ob-served deformation patterns of the BRZ.We perform a systematic analysis of the pa-rameter space in order to determinethe set of parameters that may define regional li-thosphere evolution towards the present lithosphere structure, which we further con-trol by gravity data, regional volcanism, and the age of the BRZ formation. We dem-onstrate the roleof pre-existing faults on the BRZ evolution and on formation of “off-rift” basins.