Publication Date:
2022-10-26
Description:
© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Zhang, F., Lin, J., Zhou, Z., Yang, H., & Morgan, J. P. Mechanism of progressive broad deformation from oceanic transform valley to off-transform faulting and rifting. Innovation, 3(1), (2022): 100193, https://doi.org/10.1016/j.xinn.2021.100193.
Description:
Oceanic transform faults (TFs) are commonly viewed as single, narrow strike-slip seismic faults that offset two mid-ocean ridge segments. However, broad zones of complex deformation are ubiquitous at TFs. Here, we propose a new conceptual model for the progressive deformation within broad zones at oceanic TFs through detailed morphological, seismic, and stress analyses. We argue that, under across-transform extension due to a change in plate motion, plate deformation occurs first along high-angle transtensional faults (TTFs) within the transform valleys. Off-transform normal faults (ONFs) form when across-transform deviatoric extensional stresses exceed the yield strength of the adjacent oceanic lithosphere. With further extension, these normal faults can develop into off-transform rift zones (ORZs), some of which can further develop into transform plate boundaries. We illustrate that such progressive complex deformation is an inherent feature of oceanic TFs. The new conceptual model provides a unifying theory to explain the observed broad deformation at global transform systems.
Description:
We benefited from discussions with Drs. Tao Zhang, Huihui Weng, Yen Joe Tan, the SCSIO Deep Ocean Geodynamics Group, the CUHK Seismology Group, and the participants of the InterRidge transform fault workshop in France, 2018. This work was supported by the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (GML2019ZD0205), NSFC grants (41976064, 41890813, 41976066, 91628301, and 91858207), CAS grants (Y4SL021001, QYZDY-SSW-DQC005, 133244KYSB20180029, 131551KYSB20200021, and ISEE2021PY03), National Key R&D Program of China grants (2018YFC0309800 and 2018YFC0310105), the Guangdong Basic and Applied Basic Research Foundation (2021A1515012227), and Hong Kong Research Grant Council grants (14304820 and 14306119).
Keywords:
Transform fault deformation
;
Off-transform faulting and rifting
;
Plate rotation
;
Transtensional fault
;
Ridge-transform interaction
Repository Name:
Woods Hole Open Access Server
Type:
Article
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