Dynamics of orogenic wedges and the uplift of high-pressure metamorphic rocks

Abstract

Research Article| September 01, 1986 Dynamics of orogenic wedges and the uplift of high-pressure metamorphic rocks J. P. PLATT J. P. PLATT 1Department of Earth Sciences, Oxford University, Parks Road, Oxford 0X1 3PR, England Search for other works by this author on: GSW Google Scholar Author and Article Information J. P. PLATT 1Department of Earth Sciences, Oxford University, Parks Road, Oxford 0X1 3PR, England Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1986) 97 (9): 1037–1053. https://doi.org/10.1130/0016-7606(1986)97<1037:DOOWAT>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation J. P. PLATT; Dynamics of orogenic wedges and the uplift of high-pressure metamorphic rocks. GSA Bulletin 1986;; 97 (9): 1037–1053. doi: https://doi.org/10.1130/0016-7606(1986)97<1037:DOOWAT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Subduction-accretion complexes can be approximated as wedge-shaped continua with a rigid buttress behind and a subducting litho-spheric slab beneath. Thick wedges undergoing prograde metamorphism have a negligible long-term yield strength and are likely to exhibit a complex nonlinear viscous rheology. Such a wedge will tend to deform internally until it reaches a stable configuration, in which the gravitational forces generated by the wedge geometry balance the traction exerted on its underside by the subducting slab. Accretion of material at the wedge front will lengthen the wedge and cause it to shorten internally to regain the stable geometry. This shortening will be expressed as late (out-of-sequence) thrusting, backthrusting, and folding. Conversely, underplating of sediment or crustal slices will thicken the wedge, which may need to extend internally to regain stability. Extension will cause listric normal faults that may merge downward into zones of ductile extension. Continued underplating at depth and compensating extension above provides a mechanism for bringing high-P/low-T metamorphic rocks to upper levels in the rear of the wedge, where they are commonly observed. Many major tectonic boundaries in convergent orogens (such as the Coast Range thrust in the Franciscan Complex, major nappe contacts in the Alps, and the contact between the Nevado-Filabride and Higher Betic nappe complexes in the Betic Cordillera) show abrupt increases in metamorphic grade downward across them. This is consistent with their origin or reactivation as uplift-related, extensional structures. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.