Magnetic and Petrologic Variations along the Galapagos Spreading Center and Their Relation to the Galapagos Melting Anomaly

Research Article| May 01, 1975 Magnetic and Petrologic Variations along the Galapagos Spreading Center and Their Relation to the Galapagos Melting Anomaly ROGER N. ANDERSON; ROGER N. ANDERSON 1Marine Physical Laboratory of the Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 920374Present address: (Anderson) Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964; (Clague) U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025. Search for other works by this author on: GSW Google Scholar DAVID A. CLAGUE; DAVID A. CLAGUE 2Geological Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 920374Present address: (Anderson) Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964; (Clague) U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025. Search for other works by this author on: GSW Google Scholar KIM D. KLITGORD; KIM D. KLITGORD 1Marine Physical Laboratory of the Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar MONTE MARSHALL; MONTE MARSHALL 3U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar RICHARD K. NISHIMORI RICHARD K. NISHIMORI 2Geological Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1975) 86 (5): 683–694. https://doi.org/10.1130/0016-7606(1975)86<683:MAPVAT>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 ROGER N. ANDERSON, DAVID A. CLAGUE, KIM D. KLITGORD, MONTE MARSHALL, RICHARD K. NISHIMORI; Magnetic and Petrologic Variations along the Galapagos Spreading Center and Their Relation to the Galapagos Melting Anomaly. GSA Bulletin 1975;; 86 (5): 683–694. doi: https://doi.org/10.1130/0016-7606(1975)86<683:MAPVAT>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 Magnetic anomalies with unusually large amplitudes are found along the Galapagos spreading center near the Galapagos Islands from long. 85° to 95° W. On either end of the Galapagos spreading center, however, normal amplitudes occur. Modeling of these magnetic anomalies, which were measured by both surface and deep-tow methods, indicates that the amplitude differences are probably caused by variations in the magnetic intensity of the rocks in the area. Tholeiitic basalt samples that were recovered from the ridge crests involved showed the expected variation in magnetic intensity.Basalt samples from the ridge crests with normal-amplitude anomalies contained 9 percent total Fe (calculated as FeO) and 1 percent TiO2, whereas basalt samples from the ridge crests with large-magnetic amplitude contained 14 percent total Fe and 2 percent TiO2. Variations in MgO, CaO, P2O5, K2O, and Al2O3, as well as in FeO and TiO2, are consistent with the theory of Fe enrichment by fractional crystallization as a mechanism for the formation along ridge crests of tholeiite with high magnetic intensity. This phenomenon may be related to the proximity of those ridge segments with large magnetic amplitudes to the Galapagos melting anomaly.Furthermore, the transition from large magnetic amplitudes at the ridge crest near the Galapagos Islands to normal magnetic amplitudes on the flanks suggests that the Galapagos melting anomaly may have formed 3 to 4 m.y. ago. 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.