Near-Bottom Geologic Studies of the East Pacific Rise Crest

Research Article| April 01, 1971 Near-Bottom Geologic Studies of the East Pacific Rise Crest ROGER L LARSON ROGER L LARSON University of California, San Diego, Marine Physical Laboratory of the Scripps Institution of Oceanography, La Jolla, California 92037 AUTHOR'S PRESENT ADDRESS: LAMONT-DOHERTY GEOLOGICAL OBSERVATORY OF COLUMBIA UNIVERSITY, PALISADES, NEW YORK 10964 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1971) 82 (4): 823–842. https://doi.org/10.1130/0016-7606(1971)82[823:NGSOTE]2.0.CO;2 Article history received: 08 Jun 1970 rev-recd: 07 Dec 1970 first online: 02 Mar 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 L LARSON; Near-Bottom Geologic Studies of the East Pacific Rise Crest. GSA Bulletin 1971;; 82 (4): 823–842. doi: https://doi.org/10.1130/0016-7606(1971)82[823:NGSOTE]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 A survey with near-bottom instruments was made over a 15 km by 25 km area of the East Pacific Rise crest at the mouth of the Gulf of California. The survey lines were positioned to an accuracy of about 10 m relative to three acoustic transponders on the sea floor. The abyssal hills that compose the rise crest are approximately 5 km wide, 200 m high, and are elongate parallel to the northeast trend of the rise. They have been formed by a combination of faulting and volcanism at the rise crest. In addition to producing relief, volcanism is also a means of smoothing relief in this region.A zone 22 km wide at the rise crest is essentially barren of sediment. Sediment is present on both sides of this bare zone and was measured to increase in thickness away from the rise crest on the western side. The sediment has been preferentially concentrated in local topographic lows by redistribution processes near the sea floor.The boundary between the Pacific and American plates at the rise crest is a very precise and narrow feature that lends itself to two definitions. The first is the center of intrusion which was about 100m wide during the last three magnetic field reversals and probably has been similarly as narrow for at least the past 1.2 m.y. The second definition of the plate boundary is a rift-defined zone of crustal extension at the axis of the rise crest. The plates behave rigidly beyond this zone that is presently about 5 km wide. 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.