EGU2020-1187
https://doi.org/10.5194/egusphere-egu2020-1187
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The temporal evolution of syn-sedimentary normal faults and the possible role of tip retreat

Bailey Lathrop1, Christopher Jackson1, Rebecca Bell1, and Atle Rotevatn2
Bailey Lathrop et al.
  • 1Imperial College London, Earth Science and Engineering, London, United Kingdom of Great Britain and Northern Ireland (b.lathrop17@imperial.ac.uk)
  • 2University of Bergen, Department of Earth Science, Bergen, Norway

We need to understand how normal faults grow in order to better determine the tectono-stratigraphic evolution of rifts, and the distribution and size of potentially hazardous earthquakes. The growth of normal faults is commonly described by two models: 1) the propagating fault model (isolated growth model), and 2) the constant-length model. The propagating fault model envisages a sympathetic increase between fault lengthening (L) and displacement (D), whereas the constant-length model states that faults reach their near-final length before accumulating significant displacement (Walsh et al., 2002). Several relatively recent studies agree that faults generally follow a constant-length model, or a “hybrid model” of the two, where most faults reach their near final length within the first 20-30% of their lives, and accrue displacement throughout. Furthermore, in the past 20 years, much research has focused on how faults grow; relatively few studies have questioned what happens to the fault geometry as it becomes inactive, i.e. do faults abruptly die, or do they more gradually become inactive by so-called tip retreat. We here use a 3D seismic reflection dataset from the Exmouth Plateau, offshore Australia to support a hybrid fault growth model for normal faults, and to also determine the relationship between length and displacement as a fault dies. We show that the studied faults grew in three distinct stages: a lengthening stage (<30% of the faults life), a displacement accrual stage (30-75%), and a possible tip retreat stage (75%-end). This work has important implications in our understanding of the temporal evolution of normal faults, both how they grow and how they die.

How to cite: Lathrop, B., Jackson, C., Bell, R., and Rotevatn, A.: The temporal evolution of syn-sedimentary normal faults and the possible role of tip retreat, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1187, https://doi.org/10.5194/egusphere-egu2020-1187, 2019

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Presentation version 1 – uploaded on 01 May 2020
  • CC1: Comment on EGU2020-1187, Zoe Mildon, 04 May 2020

    Picking up on Craig Magee's comment in the live session about why don't the dead parts/tips slip

    Maybe the recurrence interval (thinking about it on the timescale of earthquakes) becomes so long for the tips that these sections of the fault are able to heal/seal themselves and become strong enough to not re-rupture in the low strain region at the fault tips. I doubt you would be able to see this on seismic reflection data though.