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Thermal Structure of Island Arcs

1970; Geological Society of America; Volume: 81; Issue: 6 Linguagem: Inglês

10.1130/0016-7606(1970)81[1665

1943-2674

E. R. Oxburgh, Donald L. Turcotte,

Railway Systems and Materials Science

Research Article| June 01, 1970 Thermal Structure of Island Arcs E. R OXBURGH; E. R OXBURGH Graduate School of Aerospace Engineering, Cornell University, Ithaca, New York 14850 PRESENT ADDRESS (OXBURGH): DEPARTMENT OF GEOLOGY AND MINERALOGY, UNIVERSITY OF OXFORD, OXFORD, ENGLAND Search for other works by this author on: GSW Google Scholar D. L TURCOTTE D. L TURCOTTE Graduate School of Aerospace Engineering, Cornell University, Ithaca, New York 14850 Search for other works by this author on: GSW Google Scholar Author and Article Information E. R OXBURGH PRESENT ADDRESS (OXBURGH): DEPARTMENT OF GEOLOGY AND MINERALOGY, UNIVERSITY OF OXFORD, OXFORD, ENGLAND Graduate School of Aerospace Engineering, Cornell University, Ithaca, New York 14850 D. L TURCOTTE Graduate School of Aerospace Engineering, Cornell University, Ithaca, New York 14850 Publisher: Geological Society of America Received: 07 Nov 1969 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1970, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1970) 81 (6): 1665–1688. https://doi.org/10.1130/0016-7606(1970)81[1665:TSOIA]2.0.CO;2 Article history Received: 07 Nov 1969 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation E. R OXBURGH, D. L TURCOTTE; Thermal Structure of Island Arcs. GSA Bulletin 1970;; 81 (6): 1665–1688. doi: https://doi.org/10.1130/0016-7606(1970)81[1665:TSOIA]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 The ocean-floor spreading hypothesis requires that island arc areas be loci of descending mass transport and destruction of oceanic crust. All island arc areas are characterized by volcanic activity and in some, unusually high heat flow values have been measured for hundreds of kilometers behind the arc. Downward mass motion is associated presumably with the sinking of cool and thus relatively denser matter, and high temperature phenomena normally would not be expected where this was occurring. The only feasible means of generating heat in such areas appears to be by frictional dissipation along the seismically active zone of movement (the Benioff zone) between the moving oceanic crust and upper mantle, and the relatively stationary material that it underrides. It has been shown elsewhere that dissipative heating is of the right order of magnitude to explain the observations, but the required shear stresses are rather high; in this paper a detailed thermal structure for the Benioff zone and the regions on either side is presented. The cold descending material heats very slowly and should form a thin cold slab extending to depths of more than 500 km. Within the zone of movement, temperatures are buffered by the melting temperatures of the various components of the oceanic crust that partially fuse to give the main members of the calc-alkaline igneous suite. The thermal structure of the region above the Benioff zone is subject to uncertainty because processes other than lattice conduction (for instance, magmatic activity) are probably involved in the transfer of heat to the surface.Observed rates of magmatic activity in island arcs require a relatively small degree of fusion of the descending material and probably only the oceanic crust is involved. The siliceous and presumably water-bearing sedimentary material of the oceanic crust is the most important source of material added to island arcs; growth occurs either by physical addition of sedimentary material, which, for mechanical reasons, may not be carried down, or by partial fusion of sedimentary material along the fault zone and by rise of the resultant magmas to the surface. Rates of growth suggested by these processes are compatible with the known ages of arcs. Older arcs should have larger crustal cross-sectional areas than younger ones, if both have been continuously active at similar rates. 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.