Cu-Rich Scales in the Reykjanes Geothermal System, Iceland

Hardardóttir, Vigdís; Hannington, Mark D.; Hedenquist, Jeffrey W.; Kjarsgaard, I M; Hoal, Karin O.

doi:10.2113/econgeo.105.6.1143

Cited by 28 publications

(23 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1S in 495 Supporting information). This is in agreement with mineralogical observations of alteration 496 and well scales in Iceland (Steinthórsson and Sveinbjörnsdóttir, 1981;Hardardóttir et al, 2009Hardardóttir et al, , 2010; however, most of these studies have focused on the 498 Reykjanes system containing saline fluids although the majority of geothermal systems in 499 Iceland have dilute fluids. For several elements such as Cd, Ni, Cr, and Co, the exact 500 secondary phases and/or the concentrations in the major alteration minerals are unknown.…”

supporting

confidence: 86%

The geochemistry of trace elements in geothermal fluids, Iceland

Kaasalainen

Stefánsson

Giroud

et al. 2015

Applied Geochemistry

View full text Add to dashboard Cite

supporting

confidence: 86%

The geochemistry of trace elements in geothermal fluids, Iceland

Kaasalainen

Stefánsson

Giroud

et al. 2015

Applied Geochemistry

View full text Add to dashboard Cite

“…While hydrothermal fluids collected from in situ wells at 1,350-1,500 m depth contained sub-millimolar order of Fe, Cu and Zn, samples collected at the surface of the same wells had orders of magnitude lower metal concentrations. This significant difference was attributed to precipitation caused by boiling during depressurization, which was confirmed by occurrence of Cu-rich scales deposit at the orifice of the well (Hardartóttir et al 2010). Based on this result, they proposed that subseafloor mineralization associated with phase separation may occur in some submarine hydrothermal systems where boiling of fluids occur before discharging from seafloor vents.…”

Section: Diverse Range Of Mineralization and Fluid Chemistrymentioning

confidence: 92%

Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization

Ishibashi

Ikegami

Tsuji

et al. 2014

Subseafloor Biosphere Linked to Hydrothermal Systems

View full text Add to dashboard Cite

The Okinawa Trough is a back-arc basin behind the Ryukyu trench-arc system and located along the eastern margin of the Eurasian continent. Sulfide and sulfate mineralization associated with hydrothermal activity has been recognized in ten hydrothermal fields in the Okinawa Trough. Hydrothermal mineralization recognized in these fields is commonly represented by coexisting occurrence of zinc-and lead-enriched polymetallic sulfides and abundant sulfate minerals. The mineralogy and geochemical signatures present has led researchers to suggest these areas may be a modern analogue for the formation of ancient Kuroko-type volcanogenic massive sulfide (VMS) deposits. Recent seafloor drilling during IODP (Integrated Ocean Drilling Program) Expedition 331 documented the subseafloor structure of a hydrothermal system at the Iheya North Knoll. Mineral textures and hydrothermal assemblages present in the drilled cores obtained from a hydrothermal mound in the proximal area are consistent with Kuroko-type mineralization. Based on geochemical studies, the intra-field diversity of mineralization commonly recognized in the Okinawa Trough can be explained by subseafloor phase separation of the hydrothermal fluid, which reflects shallow water depth (from 700 to 1,600 m). The subseafloor phase separation may. play an important role to accumulate metal elements beneath the seafloor. Based on geophysical and geological studies, the Okinawa Trough is considered a back-arc basin in the rifting stage. Such a tectonic setting is characterized by development of normal faulting in brittle continental crust and frequent intrusion of a magma, which can be expected to provide favorable environment for development of a hydrothermal system Keywords

show abstract

“…These are regions of frequent volcanic eruption, high heat flow, and submarine hot springs. Base-metal sulfide scales that form in drill holes and production pipes are similar to seafloor massive sulfide deposits (Hardardóttir et al, 2012). The IDDP-2 is a unique opportunity to examine the roots of a black smoker.…”

Section: Significance Of the Iddp-2mentioning

confidence: 99%

The Iceland Deep Drilling Project 4.5 km deep well, IDDP-2, in the seawater-recharged Reykjanes geothermal field in SW Iceland has successfully reached its supercritical target

Friðleifsson¹,

Elders

Zierenberg

et al. 2017

Sci. Dril.

View full text Add to dashboard Cite

Abstract. The Iceland Deep Drilling Project research well RN-15/IDDP-2 at Reykjanes, Iceland, reached its target of supercritical conditions at a depth of 4.5 km in January 2017. After only 6 days of heating, the measured bottom hole temperature was 426 °C, and the fluid pressure was 34 MPa. The southern tip of the Reykjanes peninsula is the landward extension of the Mid-Atlantic Ridge in Iceland. Reykjanes is unique among Icelandic geothermal systems in that it is recharged by seawater, which has a critical point of 406 °C at 29.8 MPa. The geologic setting and fluid characteristics at Reykjanes provide a geochemical analog that allows us to investigate the roots of a mid-ocean ridge submarine black smoker hydrothermal system. Drilling began with deepening an existing 2.5 km deep vertical production well (RN-15) to 3 km depth, followed by inclined drilling directed towards the main upflow zone of the system, for a total slant depth of 4659 m ( ∼  4.5 km vertical depth). Total circulation losses of drilling fluid were encountered below 2.5 km, which could not be cured using lost circulation blocking materials or multiple cement jobs. Accordingly, drilling continued to the total depth without return of drill cuttings. Thirteen spot coring attempts were made below 3 km depth. Rocks in the cores are basalts and dolerites with alteration ranging from upper greenschist facies to amphibolite facies, suggesting that formation temperatures at depth exceed 450 °C. High-permeability circulation-fluid loss zones (feed points or feed zones) were detected at multiple depth levels below 3 km depth to bottom. The largest circulation losses (most permeable zones) occurred between the bottom of the casing and 3.4 km depth. Permeable zones encountered below 3.4 km accepted less than 5 % of the injected water. Currently, the project is attempting soft stimulation to increase deep permeability. While it is too early to speculate on the energy potential of this well and its economics, the IDDP-2 is a milestone in the development of geothermal resources and the study of hydrothermal systems. It is the first well that successfully encountered supercritical hydrothermal conditions, with potential high-power output, and in which on-going hydrothermal metamorphism at amphibolite facies conditions can be observed. The next step will be to carry out flow testing and fluid sampling to determine the chemical and thermodynamic properties of the formation fluids.

show abstract

Cu-Rich Scales in the Reykjanes Geothermal System, Iceland

Cited by 28 publications

References 48 publications

The geochemistry of trace elements in geothermal fluids, Iceland

The geochemistry of trace elements in geothermal fluids, Iceland

Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization

The Iceland Deep Drilling Project 4.5 km deep well, IDDP-2, in the seawater-recharged Reykjanes geothermal field in SW Iceland has successfully reached its supercritical target

Contact Info

Product

Resources

About

Cu-Rich Scales in the Reykjanes Geothermal System, Iceland

Cited by 28 publications

References 48 publications

The geochemistry of trace elements in geothermal fluids, Iceland

The geochemistry of trace elements in geothermal fluids, Iceland

Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization

The Iceland Deep Drilling Project 4.5 km deep well, IDDP-2, in the seawater-recharged Reykjanes geothermal field in SW Iceland has successfully reached its supercritical target

Contact Info

Product

Resources

About

The Iceland Deep Drilling Project 4.5 km deep well, IDDP-2, in the seawater-recharged Reykjanes geothermal field in SW Iceland has successfully reached its supercritical target