Geothermal energy and ore-forming potential of 600 °C mid-ocean-ridge hydrothermal fluids

Bali, Enikő; Aradi, László E.; Zierenberg, Robert; Diamond, Larryn W.; Pettke, Thomas; Szabo, Ábel; Gudfinnsson, Guðmundur H.; Fridleifsson, Guðmundur Ó.; Szabo, Csaba (2020). Geothermal energy and ore-forming potential of 600 °C mid-ocean-ridge hydrothermal fluids. Geology, 48(12), pp. 1221-1225. Geological Society of America 10.1130/G47791.1

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The ~4500-m-deep Iceland Deep Drilling Project (IDDP) borehole IDDP-2 in Iceland penetrated the root of an active seawater-recharged hydrothermal system below the Mid-Atlantic Ridge. As direct sampling of pristine free fluid was impossible, we used fluid inclusions to constrain the in situ conditions and fluid composition at the bottom of the hydrothermal convection cell. The fluid temperature is ~600 °C, and its pressure is near-hydrostatic (~45 MPa). The fluid exists as two separate phases: an H2O-rich vapor (with an enthalpy of ~59.4 kJ/mol) and an Fe-K–rich brine containing 2000 μg/g Cu, 3.5 μg/g Ag, 1.4 μg/g U, and 0.14 μg/g Au. Occasionally, the fluid inclusions coexist with rhyolite melt inclusions. These findings indicate that the borehole intersected high-energy steam, which is valuable for energy production, and discovered a potentially ore-forming brine. We suggest that similar fluids circulate deep beneath mid-ocean ridges worldwide and form volcanogenic massive sulfide Cu-Zn-Au-Ag ore deposits.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Diamond, Larryn William and Pettke, Thomas

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0091-7613

Publisher:

Geological Society of America

Language:

English

Submitter:

Thomas Pettke

Date Deposited:

02 Nov 2020 10:34

Last Modified:

29 Nov 2020 02:44

Publisher DOI:

10.1130/G47791.1

BORIS DOI:

10.7892/boris.147110

URI:

https://boris.unibe.ch/id/eprint/147110

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