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Subduction zone infancy: Examples from the Eocene Izu-Bonin-Mariana and Jurassic California arcs

1992; Geological Society of America; Volume: 104; Issue: 12 Linguagem: Inglês

10.1130/0016-7606(1992)104 2.3.co;2

1943-2674

Robert J. Stern, Sherman H. Bloomer,

Geochemistry and Geologic Mapping

Research Article| December 01, 1992 Subduction zone infancy: Examples from the Eocene Izu-Bonin-Mariana and Jurassic California arcs ROBERT J. STERN; ROBERT J. STERN 1Center for Lithospheric Studies, University of Texas at Dallas, Box 830688, Richardson, Texas 75083-0688 Search for other works by this author on: GSW Google Scholar SHERMAN H. BLOOMER SHERMAN H. BLOOMER 2Department of Geology, Boston University, 675 Commonwealth Avenue, Boston, Massachusetts 02215 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1992) 104 (12): 1621–1636. https://doi.org/10.1130/0016-7606(1992)104 2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation ROBERT J. STERN, SHERMAN H. BLOOMER; Subduction zone infancy: Examples from the Eocene Izu-Bonin-Mariana and Jurassic California arcs. GSA Bulletin 1992;; 104 (12): 1621–1636. doi: https://doi.org/10.1130/0016-7606(1992)104 2.3.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 A new model for the earliest stages in the evolution of subduction zones is developed from recent geologic studies of the Izu-Bonin-Mariana (IBM) arc system and then applied to Late Jurassic ophiolites of Cailfornia. The model accounts for several key observations about the earliest stages in the evolution of the IBM system: (1) subduction nucleated along an active transform boundary, which separated younger, less-dense lithosphere in the west from older, more-dense lithosphere to the east; (2) initial arc magmatic activity occupied a much broader zone than existed later; (3) initial magmatism extended up to the modern trench, over a region now characterized by subnormal heat flow; (4) early are magmatism was characterized by depleted (tholeiitic) and ultra-depleted (boninitic) magmas, indicating that melting was more extensive and involved more depleted mantle than is found anywhere else on earth; (5) early arc magmatism was strongly extensional, with crust forming in a manner similar to slow-spreading ridges; and (6) crust production rates were 120 to 180 km3/km-Ma, several times greater than for mature arc systems. These observations require that the earliest stages of subduction involve rapid retreat of the trench; we infer that this resulted from continuous subsidence of denser lithosphere along the transform fault. This resulted in strong extension and thinning of younger, more buoyant lithosphere to the west. This extension was accompanied by the flow of water from the sinking oceanic lithosphere to the base of the extending lithosphere and the underlying asthenosphere. Addition of water and asthenospheric upwelling led to catastrophic melting, which continued until lithosphere subsidence was replaced by lithospheric subduction. Application of the subduction-zone infancy model to the Late Jurassic ophiolites of California provides a framework in which to understand the rapid formation of oceanic crust with strong arc affinities between the younger Sierran magmatic arc and the Franciscan subduction complex, provides a mechanism for the formation and subsidence of the Great Valley forearc basin, and explains the limited duration of high-T, high-P metamorphism experienced by Franciscan mélanges. 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.