2025 CSDMS meeting-054
From CSDMS
(if you haven't already)
Log in (or create account for non-CSDMS members)
Forgot username? Search or email:CSDMSweb@colorado.edu
Browse abstracts
Exploring the role of normal faulting and strong lithological contrasts on landscape transience using Landlab.
Sarah Boulton,
(she/her),University of Plymouth Plymouth , United Kingdom. sarah.boulton@plymouth.ac.uk
The Gediz Fault, forming the southern margin of the Gediz (Alaşehir) Graben, has been the focus of a number of studies over the last decade that have highly constrained its structural and geomorphic evolution. Consequently, this region now forms an excellent natural laboratory for the investigation of the interplay of lithology and tectonics on long term landscape evolution. Located in the highly tectonically active and seismogenic region of Western Turkey, extension owing to regional geodynamic controls has resulted in a broadly three-phase evolution of the graben. Initial low-angle normal faulting between 16 - 2.6 Ma was followed by high-angle normal faulting along three fault strands that initiated ~ 2 Ma. Subsequent, fault linkage at ~ 0.8 Ma resulted in the present structural configuration. The long-term throw rate of the graben boundary fault, derived from geological piercing points, lies in the range 0.4 - 1.3 mm/yr, while river profile analysis suggests an increase from 0.6 to 2 mm/yr as a result of the linkage. Recent measurements of catchment averaged erosion rates (CAERs) from 10Be and 26Al cosmogenic nuclide analysis indicate that erosion rates within the transient reach of rivers crossing the fault vary from 16 to 1330 mMyr-1. However, CAERs only show weak relationships with unit stream power, steepness index and slip rate on the bounding fault and no clear relationships between erosion rate and relief or catchment slope. This is potentially the result of the strong lithological contrast in the footwall between strong metamorphic rocks and weak sediments, resulting in the sedimentary reaches behaving as gravel-bed or transport-limited channels. A landscape evolution model (LEM) built using Landlab components is used to further investigate the complex interplay between bedrock lithology, uplift, erosion and channel behaviour. First, a simple dipping fault model is used to validate the proposed evolution of the boundary fault. Second, a strong lithological boundary is introduced with and without sediment transport. While, the LEM does not explicitly address different mathematical models of river profile evolution, it confirms the significance of a strong lithological contrast on the geomorphic development of the Gediz region.
