Coupling volcanism and tectonics along divergent plate boundaries: Collapsed rifts from central Afar, Ethiopia

Abstract

Research Article| September 01, 2010 Coupling volcanism and tectonics along divergent plate boundaries: Collapsed rifts from central Afar, Ethiopia Valerio Acocella Valerio Acocella † Dipartimento Scienze Geologiche Università Roma Tre Largo San Leonardo Murialdo, 1, Roma, 00146, Italy †E-mail: acocella@uniroma3.it Search for other works by this author on: GSW Google Scholar GSA Bulletin (2010) 122 (9-10): 1717–1728. https://doi.org/10.1130/B30105.1 Article history received: 08 Jun 2009 rev-recd: 25 Oct 2009 accepted: 27 Oct 2009 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Valerio Acocella; Coupling volcanism and tectonics along divergent plate boundaries: Collapsed rifts from central Afar, Ethiopia. GSA Bulletin 2010;; 122 (9-10): 1717–1728. doi: https://doi.org/10.1130/B30105.1 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 Magma along divergent plate boundaries is erupted from fissures or vents from central volcanoes, with limited impact on rift architecture. Here I summarize the geological and structural features accompanying the eruption of part of a km-thick volcanic sequence (“stratoids”) along the Red Sea divergent boundary in central Afar, in the area of Tendaho and Dobi grabens. More than 4700 km3/Ma (per 100 km of rift length) of magma have been produced by repeated fissure eruptions from within Tendaho graben. The graben sides show distinctive structural features, as steep topographic gradients, coinciding with inward-tilted blocks forming dominoes coeval to the emplacement of the km-thick volcanic sequence. Similar features are observed also in the Dobi graben. This allows proposing an original mechanism, where the distinctive structure of the grabens results from the collapse at the surface induced by magma withdrawal during the emplacement of the volcanic sequence. This portion of Afar shows how rift architecture is shaped by voluminous fissure eruptions, forming collapsed rifts. These occur in continental domains, during the breakup stage (central Afar) and in oceanic domains, where rifts narrow (East Pacific Rise). Collapsed rifts represent an end-member type of volcano-tectonic activity, where the width of the erupting reservoir balances that of the active rift zone. Along divergent boundaries, the width of the reservoir influences the style of surface deformation: a progressively higher ratio of the width of the reservoir emptied (Re) to that of the active rift zone (Ri) generates, in sequence, axial grabens, calderas, and collapsed rifts. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.