40 Micro to Macro: Linking Structural Geology, Petrology, Geochronology, and Tectonics Across Scales (Posters)

Tuesday, 19 March 2024
9:00 AM - 1:00 PM
Armory Ballroom

INCIPIENT RIFT FAULTING AND SCALING RELATIONSHIPS IN THE OKAVANGO-MAKGADIKGADI RIFT ZONE, BOTSWANA

Paper number: 40-14
Program: Theme Sessions
Time: 9:00 AM – 1:00 PM

Authors

Abstract

Many studies assert that continental rifts transition from power-law fault length distribution during the early stages of extension, to exponential distribution during the transition to continental break-up. However, fault scaling relationships during rift initiation remain largely unknown. To fill this knowledge gap, we explore the incipient Okavango-Makgadikgadi Rift Zone, Northern Botswana, consisting of the amagmatic Okavango Rift Basin and Makgadikgadi Rift Basin. We utilize high-resolution satellite topography data (TanDEM-X) and aeromagnetic data to image and map faults across the rift zones and generate a new robust fault map for the rift zone. Then, we analyze the length-frequency distribution of faults using a two-sample Kolmogorov-Smirnov test. The results show that the Makgadikgadi Rift Basin exhibits an exponential distribution associated with a nucleating rift as it features diffuse faulting and lacks a border-fault, whereas the Okavango Rift Basin exhibits a power-law distribution that is consistent with its relatively more evolved rift structure with established border faults. Our findings imply that continental divergent plate boundaries nucleate with an initial exponential distribution of fault lengths which subsequently transition into a power-law distribution as the rift evolves, and again evolving into an exponential distribution as break-up initializes.

Geological Society of America Abstracts with Programs. Vol. 56, No. 1

doi: 10.1130/abs/2024NE-397577

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