Construction of the Galapagos platform by large submarine volcanic terraces
Geist, Dennis J.
Diefenbach, Bridget A.
Fornari, Daniel J.
Kurz, Mark D.
Harpp, Karen S.
Blusztajn, Jerzy S.
MetadataShow full item record
New multibeam bathymetric and side-scan sonar data from the southwestern edge of the Galápagos platform reveal the presence of ∼60 large, stepped submarine terraces between depths of 800 m and 3500 m. These terraces are unique features, as none are known from any other archipelago that share this geomorphic form or size. The terraces slope seaward at <2° and are surrounded by escarpments that average ∼300 m in height with average slopes of 24°. The stepped morphology, fine-scale features, and sinuous planform continuity of terrace edges indicate that each terrace results from a sequence of major submarine volcanic eruptions, similar in extent to young deep-water (>3000 m) lava flow fields west of Fernandina and Isabela Islands. The terraces are formed of thick sequences of lava flows that coalesce to form the foundation of the Galápagos platform, on which the subaerial central volcanoes are built. The compositions of basalts dredged from the submarine terraces indicate that most lavas are chemically similar to subaerial lavas erupted from Sierra Negra volcano on southern Isabela Island. There are no regular major element, trace element, or isotopic variations in the submarine lavas as a function of depth, relative stratigraphic position, or geographic location along the southwest margin of the platform. We hypothesize that magma supply at the western edge of the Galápagos hot spot, which is influenced by both plume and mid-ocean ridge magmatic processes, leads to episodic eruption of large lava flows. These large lava flows coalesce to form the archipelagic apron upon which the island volcanoes are built.
Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 9 (2008): Q03015, doi:10.1029/2007GC001795.
Showing items related by title, author, creator and subject.
Submarine volcanic morphology of the western Galapagos based on EM300 bathymetry and MR1 side-scan sonar Glass, Jennifer B.; Fornari, Daniel J.; Hall, Hillary F.; Cougan, Allison A.; Berkenbosch, Heidi A.; Holmes, Mark L.; White, Scott M.; De La Torre, Giorgio (American Geophysical Union, 2007-03-21)A compilation of high-resolution EM300 multibeam bathymetric and existing MR1 side-scan sonar data was used to investigate the volcanic morphology of the flanks of the western Galápagos Islands. The data portray an assortment ...
Distribution of melt along the East Pacific Rise from 9°30′ to 10°N from an amplitude variation with angle of incidence (AVA) technique Marjanovic, Milena; Carton, Helene; Carbotte, Suzanne M.; Nedimovic, Mladen R.; Mutter, John C.; Canales, J. Pablo (Oxford University Press, 2015-06)We examine along-axis variations in melt content of the axial magma lens (AML) beneath the fast-spreading East Pacific Rise (EPR) using an amplitude variation with angle of incidence (AVA) crossplotting method applied to ...
Effects of variable magma supply on mid-ocean ridge eruptions : constraints from mapped lava flow fields along the Galápagos Spreading Center Colman, Alice; Sinton, John M.; White, Scott M.; McClinton, J. Timothy; Bowles, Julie A.; Rubin, Kenneth H.; Behn, Mark D.; Cushman, Buffy; Eason, Deborah E.; Gregg, Tracy K. P.; Gronvold, Karl; Hidalgo, Silvana; Howell, Julia; Neill, Owen; Russo, Chris (American Geophysical Union, 2012-08-25)Mapping and sampling of 18 eruptive units in two study areas along the Galápagos Spreading Center (GSC) provide insight into how magma supply affects mid-ocean ridge (MOR) volcanic eruptions. The two study areas have similar ...