Abstract
AbstractTectonic extension of continental lithosphere creates accommodation space in which sediments are deposited. Climate‐driven processes provide the mechanism by which mass is detached from hillslopes and sediments are transported into this accommodation space. These two forcings, climate and tectonics, act together to create either endorheic (internally drained) or exorheic (externally drained) rift basins. Here we use a large‐scale dynamic landscape evolution‐tectonics model to understand the contribution of tectonic processes in endorheic‐exorheic transitions. In the model, extension results in opening of an asymmetric half‐graben along a listric normal fault. Rift opening occurs in the models in wet, temperate, or semiarid climates where runoff and evapotranspiration are varied. Our numerical experiments show that slow rift‐opening rates, a slowing‐down of rift opening, or increase of headwater topography (e.g., upstream epeirogenic uplift), are tectonic situations that can cause a transition from an endorheic to an exorheic drainage state in a rift basin. Our results also show that wet climate conditions lead to a permanent exorheism that persists regardless of rift‐opening rates. In semiarid climates, endorheic conditions are favored and may last for the duration of rifting except for when rift opening is very slow. These results form an interpretive framework to study endorheic and exorheic drainage systems in natural continental rifts. In the slow‐opening Rio Grande rift, the endorheic‐exorheic transition may have occurred without dramatic climate changes. Lake‐level variations in East African rift basins are predicted by our models to result from variations in climate.
Highlights
The important role of surface processes in continental rift evolution is widely recognized (e.g., Burov & Cloetingh, 1997; Cowie et al, 2006; Geurts et al, 2018; Olive et al, 2014)
Our results show that tectonic processes play an important role in the endorheic-exorheic transition of narrow continental rifts
The rift intersects several climate zones and has presently both endorheic and exorheic basins. In this discussion we focus on the western branch because its topography and structure are minimally perturbed by magmatism, allowing us to focus on climate and tectonic controls
Summary
The important role of surface processes in continental rift evolution is widely recognized (e.g., Burov & Cloetingh, 1997; Cowie et al, 2006; Geurts et al, 2018; Olive et al, 2014). This study focuses on an understanding of one of these contributing factors: tectonics (i.e., rift opening rate) in three different climate scenarios (wet, temperate, and semi-arid) Both wide and narrow continental rift zones are structurally divided into rift basins that form separate sediment depocenters during some or all stages of evolution. We use a landscape-evolution model to examine whether tectonic drivers may cause an endorheic-exorheic change in an asymmetric half-graben The structure of such grabens is complex, but can be described in its simplest form by (1) a border fault along which most slip occurs, bounding the deepest portion of the sedimentary package, (2) a series of antithetical normal faults accommodating extension on the hanging wall side of the basin (Ebinger et al, 1999; Gawthorpe & Leeder, 2000; Scholz & Contreras, 1998), and (3) transfer or accommodation zones bounding the strike-ends of the rift. Regional-scale landscape models, including TISC, have been successfully used in modeling tectonic events (i.e., Braun et al, 2012; Cowie et al, 2006; Duvall & Tucker, 2015; García-Castellanos & Jiménez-Munt, 2015; Whipple, 2009; and many others); here we apply this modeling approach to the endorheic-exorheic transition of continental rift basins
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
