A simple numerical model of the Rio Grande Rift extension: implications on surface hydrology

Abstract

Tectonic extension of the Earth's crust significantly alters the surface hydrology in the region by disorganizing the established connections. On the contrary, the extension also promotes the development of a new hydrologic regime by opening basins and providing topographic relief to the basins. The Rio Grande Rift (RGR) is an excellent example of an east-west tectonic extension with a large, modern axial river flowing through multiple basins, retaining the history of long-term hydrologic changes associated with the complex tectonic activities in the past. Dozens of references on the development of the gross architecture of the RGR recognized the history of the succession of the Rio Grande and its subbasins. However, there is less consensus on how surface hydrologic systems have responded to the tectonic movement in the RGR. Thus, we focus on surface hydrologic changes associated with rift tectonics and river incision. This study put forth an overarching goal: to reconstruct the history of surface hydrologic connections among basins in RGR during rift evolution. We created simple rift opening scenarios that model the Oligocene to Miocene opening of the RGR to the present. Here, we demonstrate the preliminary results of our modeling practices, and they will be further developed to reconstruct the history of hydrologic connectivity during both syn-tectonic and post-tectonic periods of the RGR.