The evolution of continental rifts revealed from the numerical modeling: A case study of the Baikal rift system, Siberia

Abstract

We present new results on the Late Cenozoic uplift rates at the flanks of the Baikal rift system (SE Siberia) based on the morphotectonic analysis of basin-adjacent steep-slope mountains and numerical modeling of landscape evolution. As the basic instrument of modeling, we used the CHILD software program by Dr. Greg Tucker (University of Colorado, USA) which allows reconstructing the relief evolution taking into account various orogenic processes. The model problem of the normal-fault movements was solved using the CHILD modification: adding a new tectonic option and developing some adaptations. The objects of modeling were steep normal fault escarpments with clearly defined triangular facets and without young tectonic steps. We assumed that these objects were formed at the fast-rifting stage and may thereby be considered as morphometric indicators of orogenic processes of the Late Cenozoic time. The experiment consisted of two stages. First, we determined a specific set of exogenous parameters which may be conditionally considered general for all similar escarpments of the BRS and for the Late Cenozoic era as a whole. As a reference object there was used one of segments of the Barguzin Ridge with the known uplift rate obtained by AFT. Next, we modeled some other objects from different mountains of the BRS. The results of modeling showed that the approximated Late Cenozoic uplift rate on the considered segments varies over a small range between 0.3 and 0.5 mm/yr. At the final stage, we performed morphotectonic analysis to determine probable uplift rates for steep rift shoulders.