The metal potential of a slow-spreading ridge segment : abstract OS12A-05

Petersen, Sven (2012) The metal potential of a slow-spreading ridge segment : abstract OS12A-05 [Invited talk] In: AGU Fall Meeting 2012, 02.12.2012, San Francisco, USA.

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Investigations of submarine massive sulfide deposits as a possible metal resource are lacking some fundamental data. First of all, we do not know how much of the metal that is released by high-temperature venting over a given length of a ridge axis and over a specific geological time frame is actually deposited as massive sulfides or occurs as geochemical anomaly within sediments or is related to altered rocks in the upflow zone. Additionally, exploration is usually performed by identifying chemical and physical tracers in the water column limiting the search to only active deposits within or close to the neovolcanic rift zone. We also lack the ability to identify buried deposits (beneath sediments or lava) thereby underestimating the resource potential of explored areas. Systematic surveys from the ridge axis to tens of kilometers away from the axis have never been performed limiting our interpretations to a small snapshot in time.

In a recent meeting at GEOMAR in Kiel, a number of researchers from various countries came together in order to discuss the necessary steps forward. We propose a regional high-resolution geological and geophysical exploration of a mid-ocean ridge segment in order to establish the metal potential of an entire slow-spreading ridge segment. Investigations will be targeted at the TAG segment (26°N, MAR) where active and inactive massive sulfide deposits are well known and were visual observation by submersibles suggests the presence of additional massive sulfide deposits further away from the ridge axis. The metal inventory of this ridge segment, however, is still unknown despite the numerous research cruises and the presence of the 4 mio tonnes TAG deposit. As a first step we want to perform segment-scale high-resolution mapping (AUV-based bathymetry, sidescan, photomosaicing) for identifying favorable locations as well as AUV-based magnetic and subbottom profiling surveys to locate buried deposits and possibly estimate their thickness. Due to the size of the working area the simultaneous use of a fleet of AUV’s seems necessary, which requires the combined efforts of several institutes. This survey would also allow for photo surveys of large parts of the seafloor to guide in structural interpretation and provide the opportunity for large-scale habitat mapping. At later stages active and passive seismicity as well as marine EM will be employed to image the upflow zones. This information will, together with the structural interpretation, water column and petrological information as well as the regional bathymetric datasets, feed into a 3-dimensional model of fluid flow in the crust along this ridge segment in order to constrain fluid pathways, the physicochemical conditions at depth and to ultimately budget the metal resource of this ridge segment over geological time scales. The entire project is at an early stage, however, proposals for shiptime and funding for the first surveys are being submitted this fall.

Document Type: Conference or Workshop Item (Invited talk)
Keywords: Marine geology; marine geophysics; hydrothermal systems; midocean ridge processes;submergence instruments: ROV, AUV, submersibles
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
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Date Deposited: 08 Mar 2013 09:48
Last Modified: 08 Mar 2013 09:49

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