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

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 condition...

Full description

Bibliographic Details
Published in:Geology
Main Authors: Bali, Enikő, Aradi, László E., Zierenberg, Robert, Diamond, Larryn W., Pettke, Thomas, Szabo, Ábel, Gudfinnsson, Guðmundur H., Fridleifsson, Guðmundur Ó., Szabo, Csaba
Format: Article in Journal/Newspaper
Language:English
Published: Geological Society of America 2020
Subjects:
550 Earth sciences & geology
Mid-Atlantic Ridge
Iceland
Online Access:https://boris.unibe.ch/147110/1/g47791.pdf
https://boris.unibe.ch/147110/
Description
Summary: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.

Similar Items