Stockmeyer, J.M., Shaw, J.H., Brown, N.D. et al. (5 more authors) (2017) Active thrust sheet deformation over multiple rupture cycles: A quantitative basis for relating terrace folds to fault slip rates. Geological Society of America bulletin. ISSN 0016-7606
Abstract
Many recent thrust fault earthquakes have involved coseismic surface faulting and folding, revealing the multifaceted nature of active thrust sheet deformation. We integrate records of surface deformation, subsurface structure and geochronology to investigate active surface deformation over multiple rupture cycles across the Southern Junggar Thrust (SJT) in the southern Junggar basin, NW China. Fluvial terrace geometries – extracted from a 1-m digital elevation model – reveal records of surface faulting across a prominent fault scarp. In addition, terraces exhibit progressive folding across fold scarps. Fault and fold scarps are spatially coincident with a surface-emergent SJT splay and subsurface fault bends along the SJT, respectively, constrained by seismic reflection data. We quantify the magnitude of fault slip at depth implied by fold scarps along Holocene-aged terraces. Our method yields results consistent with independent estimates of slip implied by fault scarp relief for the same terraces. Four late Quaternary terrace records are less continuous, preserved only as fold scarps that suggest folding kinematics involving a component of limb rotation. We develop a new method for quantifying fault slip at depth from terrace folds using a mechanical forward modeling approach. Our analysis yields quantitative relations between fold dip and fault slip, allowing us to quantify SJT fault slip from terrace folds from ~250 ka- present. SJT fault slip rate has decelerated from ~7.0 mm/yr in the Late Quaternary to ~1.3 mm/yr throughout the Holocene. These results provide new insight into the kinematics of fault-bend folding for natural structures and define new methods to accurately estimate fault slip and slip rates from terrace folds in active thrust sheets.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 Geological Society of America. This is an author produced version of a paper subsequently published in Geological Society of America Bulletin. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Social Sciences (Sheffield) > Department of Geography (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 13 Jun 2017 15:13 |
Last Modified: | 22 May 2018 00:39 |
Published Version: | http://doi.org/10.1130/B31590.1 |
Status: | Published |
Publisher: | Geological Society of America |
Refereed: | Yes |
Identification Number: | 10.1130/B31590.1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:117582 |