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Late Tertiary history of hydrothermal deposition at the East Pacific Rise, 19°S: Correlation to volcano‐tectonic events
Author(s) -
Lyle Mitchell,
Leinen Margaret,
Owen Robert M.,
Rea David K.
Publication year - 1987
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl014i006p00595
Subject(s) - hydrothermal circulation , geology , ridge , volcano , tectonics , mid ocean ridge , hydrothermal vent , seawater , deposition (geology) , crust , seafloor spreading , oceanic crust , drilling , deep sea , geochemistry , oceanography , paleontology , subduction , sediment , mechanical engineering , engineering
Commonly it is assumed that the intensity of mid‐ocean ridge hydrothermal activity should correlate with spreading rate, since high spreading rates are an indication of large subcrustal heat sources needed for intense hydrothermal activity. We have tested this hypothesis by modeling the deposition of hydrothermal precipitates from cores from Deep Sea Drilling Project Leg 92, taken on the west flank of the East Pacific Rise at 19°S. Although spreading rates at the East Pacific Rise and its predecessor, the Mendoza Rise, have varied by only 50% in the last 30 million years, we found certain episodes, at about 25, 18, 14, and 9 million years ago, of hydrothermal manganese deposition as much as a factor of 20 higher than equivalent Holocene accumulation. These eposides do not correlate with spreading rate changes and instead seem to occur at times of major tectonic reorganizations. We propose that ridge jumps and changes of ridge orientation may substantially increase hydrothermal activity by fracturing the ocean crust and providing seawater access to deep‐seated heat sources.