The geological setting of the ultramafic-hosted Logatchev hydrothermal field (14°45′N, Mid-Atlantic Ridge) and its influence on massive sulfide formation

Petersen, Sven, Kuhn, K., Kuhn, Thomas, Augustin, Nico, Hékinian, R., Franz, L. and Borowski, C. (2009) The geological setting of the ultramafic-hosted Logatchev hydrothermal field (14°45′N, Mid-Atlantic Ridge) and its influence on massive sulfide formation Lithos, 112 . pp. 40-56. DOI 10.1016/j.lithos.2009.02.008.

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Abstract

The Logatchev hydrothermal field (14 degrees 45'N on the MAR) is one of a few submarine hydrothermal systems associated with ultramafic rocks. It is situated on the eastern inner flank of the rift valley wall, 7 km away from the spreading axis and its formation has previously been linked to detachment faulting and core complex formation. Geological mapping during various ROV dives, geological sampling, and shallow drilling reveal a structural control of hydrothermal activity as well as its location in a debris flow consisting of heterogeneous ultramafic and mafic intrusive rocks. The mixed mafic/ultramafic host rock lithology is in agreement with published vent fluid and gas chemical data showing characteristics for interaction with mafic as well as with ultramafic rocks. Massive sulfide formation is more focused than previously thought and likely limited to a thin veneer at the seafloor. The Logatchev hydrothermal field shows a number of peculiarities that are unusual for most other hydrothermal systems. One of these are so-called,smoking craters", seafloor depressions that are several meters wide, characterized by an elevated crater rim made up partly of sulfide talus but also of abundant wall rock material. At these smoking craters hydrothermal venting occurs directly from holes within the craters and from small, cm to dm high, Cu-rich chimneys occurring at the crater rim. Based on geological mapping and sampling we suggest that these smoking craters are the product of processes related to the regional and local geological setting in an ultramafic-hosted, off-axis location with abundant landslides, as well as off-axis gabbroic intrusions providing the heat for the hydrothermal convection cell. (C) 2009 Elsevier B.V. All rights reserved.

Document Type: Article
Keywords: ultramafic-hosted hydrothermal systems, Mid-Atlantic Ridge, massive sulfides, petrology; slow-spreading ridges vent fluids mantle heterogeneity detachment faults core complexes fracture-zone mar geochemistry accretion rocks
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
DOI etc.: 10.1016/j.lithos.2009.02.008
ISSN: 0024-4937
Projects: Future Ocean
Date Deposited: 27 Aug 2009 10:29
Last Modified: 06 Jul 2012 15:02
URI: http://eprints.uni-kiel.de/id/eprint/2042

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