Tectonic evolution of the FAMOUS area of the Mid-Atlantic Ridge, lat 35°50′ to 37°20′N

Research Article| May 01, 1977 Tectonic evolution of the FAMOUS area of the Mid-Atlantic Ridge, lat 35°50′ to 37°20′N IVAR B. RAMBERG; IVAR B. RAMBERG 1Department of Geology, Stanford University, Stanford, California 94305 Search for other works by this author on: GSW Google Scholar DALE F. GRAY; DALE F. GRAY 2Department of Geophysics, Stanford University, Stanford, California 94305 Search for other works by this author on: GSW Google Scholar ROBERT G. H. RAYNOLDS ROBERT G. H. RAYNOLDS 3Department of Applied Earth Sciences, Stanford University, Stanford, California 94305 Search for other works by this author on: GSW Google Scholar Author and Article Information IVAR B. RAMBERG 1Department of Geology, Stanford University, Stanford, California 94305 DALE F. GRAY 2Department of Geophysics, Stanford University, Stanford, California 94305 ROBERT G. H. RAYNOLDS 3Department of Applied Earth Sciences, Stanford University, Stanford, California 94305 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1977) 88 (5): 609–620. https://doi.org/10.1130/0016-7606(1977)88<609:TEOTFA>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 Email Permissions Search Site Citation IVAR B. RAMBERG, DALE F. GRAY, ROBERT G. H. RAYNOLDS; Tectonic evolution of the FAMOUS area of the Mid-Atlantic Ridge, lat 35°50′ to 37°20′N. GSA Bulletin 1977;; 88 (5): 609–620. doi: https://doi.org/10.1130/0016-7606(1977)88<609:TEOTFA>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 The FAMOUS area, which straddles the Mid-Atlantic Ridge on the southwest extension of the Azores Plateau in the Atlantic Ocean, has been studied by means of morphotectonic and magnetic anomaly analysis. Major morphologic elements are (1) the rift valleys and associated fault blocks, (2) the transform faults, and (3) diagonal linear trends intersecting the azimuths of the rift valleys and transform faults. Within the past 6 m.y. the area has been characterized by a reorientation of the spreading axis, from an oblique trend toward an orthogonal pattern relative to the transform faults. The long and nearly continuous early spreading axis, with a strike of N50 °E, broke up into smaller rift segments, which progressively rotated to their present strike (about N23 °E) and now appear to be recombining through asymmetric spreading to form the continuous axis it now has. The process involved complex migrations of the larger rift segments through asymmetric spreading, as well as jumping of shorter rift segments and migration of transform faults, the latter mechanism leading to the diagonal troughs. The presence of parallel spreading axes and the propagation of rift axes may be due to coupling across transform plate boundaries. These boundaries are complex shear zones with tension cracks and en echelon fault scarps deviating from the overall trend of the zone; this implies that the fracture zones might be leaky. The reorientation of the spreading axis in the FAMOUS area seems not to be a unique event but a phenomenon that has been repeated periodically. It has tentatively been correlated with recurrent plume activity below the Azores Plateau. 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.