History of Sea-Floor Spreading West of Baja California

Abstract

Research Article| February 01, 1970 History of Sea-Floor Spreading West of Baja California C. G CHASE; C. G CHASE Scripps Institution of Oceanography, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar H. W MENARD; H. W MENARD Scripps Institution of Oceanography, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar R. L LARSON; R. L LARSON Scripps Institution of Oceanography, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar G. F SHARMAN, III; G. F SHARMAN, III Scripps Institution of Oceanography, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar S. M SMITH S. M SMITH Scripps Institution of Oceanography, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar Author and Article Information C. G CHASE Scripps Institution of Oceanography, La Jolla, California 92037 H. W MENARD Scripps Institution of Oceanography, La Jolla, California 92037 R. L LARSON Scripps Institution of Oceanography, La Jolla, California 92037 G. F SHARMAN, III Scripps Institution of Oceanography, La Jolla, California 92037 S. M SMITH Scripps Institution of Oceanography, La Jolla, California 92037 Publisher: Geological Society of America Received: 02 Jul 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 (2): 491–498. https://doi.org/10.1130/0016-7606(1970)81[491:HOSSWO]2.0.CO;2 Article history Received: 02 Jul 1969 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation C. G CHASE, H. W MENARD, R. L LARSON, G. F SHARMAN, S. M SMITH; History of Sea-Floor Spreading West of Baja California. GSA Bulletin 1970;; 81 (2): 491–498. doi: https://doi.org/10.1130/0016-7606(1970)81[491:HOSSWO]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 New SIO deep sea magnetic data from immediately west of southern Baja California are presented. Anomalies in the standard sequence of ages from 25 m.y. to 4 or 5 m.y.B.P. are correlated from north to south within the area. Interpreting the anomaly patterns in light of the assumptions of plate tectonics gives the following picture of evolution of the East Pacific Rise as it approached North America. Before 20 m.y.B.P., two Pacific Ocean plates were spreading east-west from each other, locally unaffected by approach of the continent. By 15m.y.B.P. the ridge had split into a “Y” of three ridges radiating from a point. Three Pacific blocks were present, the southern two still spreading east-west, while the northern one inside the arms of the “Y” had a northward relative component of motion presumably derived from coupling to the continent somewhere to the north. Soon after 12 m.y.B.P., the three-ridge system culminated, followed by reorganization into a single ridge spreading NW.—SE. Since 5 m.y. ago the present system has prevailed, with the remnants of the old Eastern Pacific block fused to the continent north of the Rivera Fracture Zone. The Western Pacific block has spread to the northwest, opening the Gulf of California, and carrying southwestern California and Baja California with it. 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.