Observation of manganese deposits on the East Pacific Rise during the CYAMEX-RITA expedition, supplement to: Cyamex Scientific Team; Francheteau, Jean; Needham, H D; Choukroune, P; Juteau, Thierry; Séguret, Marie J M; Ballard, R D; Fox, P J; Normark, William R; Carranza, A; Cordoba, D; Guerrero, Gerardo; Rangin, Claude (1981): First manned submersible dives on the East Pacific Rise at 21�N (project RITA): General results. Marine Geophysical Research, 4(4), 345-379

DOI

A submersible study has been conducted in February - March 1978 at the axis of the East Pacific Rise near 21°N. The expedition CYAMEX, the first submersible program to be conducted on the East Pacific Rise, is part of the French-American-Mexican project RITA (Rivera - Tamayo), a 3-year study devoted to detailed geological and geophysical investigations of the East Pacific Rise Crest. On the basis of the 15 dives made by CYANA in the axial area of the Rise, a morphological and tectonic zonation can be established for this moderately-fast spreading center. A narrow, 0.6 to 1.2 km wide zone of extrusion (zone 1), dominated by young lava flows, is flanked by a highly fissured and faulted zone of extension (zone 2) with a width of 1 to 2 km. Further out, zone 3 is dominated by outward tilted blocks bounded by inward-facing fault scarps. Active or recent faults extend up to 12 km from the axis of extrusion of the East Pacific Rise. This represents the first determination from direct field evidence of the width of active tectonism associated with an accreting plate boundary. Massive sulfide deposits, made principally of zinc, copper and iron, were found close to the axis of the Rise. Other signs of the intense hydrothermal activity included the discovery of benthic fauna of giant size similar to that found at the axis of the Galapagos Rift. We emphasize the cyclic character of the volcanicity. The main characteristics of the geology of this segment of the East Pacific Rise can be explained by the thermal structure at depth below this moderately-fast spreading center. The geological observations are compatible with the existence of a shallow magma reservoir centered at the axis of the Rise with a half-width of the order of 10 km.

Identifier
DOI https://doi.org/10.1594/PANGAEA.873543
Related Identifier https://doi.org/10.1007/BF00286034
Related Identifier https://doi.org/10.7289/V52Z13FT
Related Identifier https://doi.org/10.7289/V53X84KN
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.873543
Provenance
Creator Cyamex Scientific Team; Francheteau, Jean; Needham, H D; Choukroune, P; Juteau, Thierry; Séguret, Marie J M; Ballard, R D; Fox, P J; Normark, William R; Carranza, A; Cordoba, D; Guerrero, Gerardo; Rangin, Claude
Publisher PANGAEA - Data Publisher for Earth & Environmental Science
Publication Year 1981
Rights Creative Commons Attribution 3.0 Unported
OpenAccess true
Representation
Language English
Resource Type Supplementary Dataset
Format text/tab-separated-values
Size 21 data points
Discipline Earth System Research
Spatial Coverage (-109.292W, 20.867S, -109.067E, 20.950N); East Pacific Rise