Fracture analysis, hydrothermal mineralization and fluid pathways in the Neogene Geitafell central volcano: insights for the Krafla active geothermal system, Iceland

Liotta, Domenico; Brogi, Andrea; Ruggieri, Giovanni; Rimondi, Valentina; Zucchi, Martina; Helgadóttir, Helga Margrét; Montegrossi, Giordano; Friðleifsson, G. Ó.

doi:10.1016/j.jvolgeores.2018.11.023

Cited by 22 publications

(28 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Magma provides the heat in many hydrothermal systems. The intrusion and subsequent cooling of magma in host rock can (re)activate and/or modify hydrothermal systems (Cathles et al, ; Grant & Bixley, ; Liotta et al, ). An extreme example of this was documented at Krafla volcano, Iceland (Mortensen et al, ; Scott et al, ), where large changes in rock mass properties were encountered during drilling close to an active shallow rhyolite magma body, providing evidence of the thermal and chemical impact of the magma body on the surrounding host rock.…”

Section: Introductionmentioning

confidence: 99%

Increasing the Permeability of Hydrothermally Altered Andesite by Transitory Heating

Mordensky

Kennedy

Villeneuve

et al. 2019

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Changes in permeability can impact geological processes, geohazards, and geothermal energy production. In hydrothermal systems, high‐temperature heat sources drive fluid convection through the pore network of reservoir rocks. Additionally, thermal fluctuations may induce microfracturing and affect the mineralogical stability of the reservoir rock, thus modifying the fluid pathways and affecting permeability and strength. This study describes the results of thermal heating events lasting several hours on a “moderately altered” plagioclase‐clinochlore‐calcite‐quartz andesite and a “highly altered” plagioclase‐clinozoisite‐quartz‐clinochlore andesite from the Rotokawa Geothermal Field, New Zealand. We use a low thermal gradient (~1.2 °C/min) in an H2O‐saturated, 20‐MPa pressure environment to constrain changes in petrophysical properties associated with transitory thermal phenomena between 350 and 739 °C. As the treatment temperature increases, the mass reduces, while porosity and permeability increase. These effects were greater in the “moderately altered” andesite than in the “highly altered” andesite. Microfracturing is responsible for these changes at lower temperatures (e.g., ≤400 °C). At higher temperatures (e.g., >400 °C), microfracturing remains partially responsible for these rock property changes (e.g., higher permeability); however, these changes are also a product of clinochlore, quartz, and (when present) calcite reacting out of the altered andesite, and increasing porosity. We propose that at temperatures >400 °C, volumetric phase changes associated with heat‐driven reactions in a wet environment can contribute to microcracking and porosity/permeability changes. Our data support observations where high‐temperature conditions at the margins of magma bodies can be associated with substantial increased permeability and decreased strength.

show abstract

Section: Introductionmentioning

confidence: 99%

Increasing the Permeability of Hydrothermally Altered Andesite by Transitory Heating

Mordensky

Kennedy

Villeneuve

et al. 2019

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…This study is an example of geochemical and thermodynamic changes that might happen during metasomatic processes at a local scale. Many such studies explain how the breakdown or dissolution of carbonate assemblages occurs in skarn deposits, calcareous sandstones, and many hydrothermally altered rocks [15][16][17][61][62][63][64]68]. In this study, we have shown the importance of K activity in the infiltrating fluid, which could control the mineralogy of the metasomatized marble.…”

Section: Discussionmentioning

confidence: 65%

“…The intrusion of hot magma into country rocks is a common phenomenon, and is important in understanding the process of the exchange of heat and fluids between cooling magma and cold country rocks [16,17,[61][62][63]. Fluid infiltration and heating around the boundaries of a hot magmatic intrusion cause chemical and mineralogical alterations to nearby rocks [15][16][17]27].…”

Section: Discussionmentioning

confidence: 99%

“…Fluid infiltration and heating around the boundaries of a hot magmatic intrusion cause chemical and mineralogical alterations to nearby rocks [15][16][17]27]. Such altered rocks are typically called skarn [61][62][63][64][65][66]. Different types of rocks such as limestone, dolostone, marble, granite, basalt, conglomerate, tuff, and shale can be transformed into skarn by metasomatism [64][65][66].…”

Section: Discussionmentioning

confidence: 99%

“…Fluid expelled from the magma acts like a solvent that might have ability to dissolve and re-precipitate new minerals in the neighboring rocks [67,68]. Fluid released from the crystallizing intrusion infiltrates through interconnected fracture networks, pores, and along mineral grain boundaries [15,16,[61][62][63][64]68]. Equation (1) shows that the olivine and calcite-bearing metasomatized marble region could be formed by the infiltration of silica-saturated fluid that dissolved existing dolomite in the marble.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Fluid Infiltration and Mass Transfer along a Lamprophyre Dyke–Marble Contact: An Example from the South-Western Korean Peninsula

et al. 2020

View full text Add to dashboard Cite

In this contribution, we report the metasomatic characteristics of a lamprophyre dyke–marble contact zone from the Hongseong–Imjingang belt along the western Gyeonggi Massif, South Korea. The lamprophyre dyke intruded into the dolomitic marble, forming a serpentinized contact zone. The zone consists of olivine, serpentine, calcite, dolomite, biotite, spinel, and hematite. Minor F and Cl contents in the serpentine and biotite indicate the composition of the infiltrating H2O-CO2 fluid. SiO2 (12.42 wt %), FeO (1.83 wt %), K2O (0.03 wt %), Sr (89 ppm), U (0.7 ppm), Th (1.44 ppm), and rare earth elements (REEs) are highly mobile, while Zr, Cr, and Ba are moderately mobile in the fluid. Phase equilibria modelling suggests that the olivine, spinel, biotite, and calcite assemblage might be formed by the dissolution of dolomite at ~700 °C, 130 MPa. Such modelling requires stable diopside in the observed conditions in the presence of silica-saturated fluid. The lack of diopside in the metasomatized region is due to the high K activity of the fluid. Our log activity K2O (aK2O)–temperature pseudosection shows that at aK2O~−40, the olivine, spinel, biotite, and calcite assemblage is stable without diopside. Subsequently, at ~450 °C, 130 MPa, serpentine is formed due to the infiltration of H2O during the cooling of the lamprophyre dyke. This suggests that hot H2O-CO2 fluids with dissolved major and trace elements infiltrated through fractures, grain boundaries, and micron-scale porosity, which dissolved dolomite in the marble and precipitated the observed olivine-bearing peak metasomatic assemblage. During cooling, exsolved CO2 could increase the water activity to stabilize the serpentine. Our example implies that dissolution-reprecipitation is an important process, locally and regionally, that could impart important textural and geochemical variations in metasomatized rocks.

show abstract

Hydrothermally induced edifice destabilisation: The mechanical behaviour of rock mass surrounding a shallow intrusion in andesitic lavas, Pinnacle Ridge, Ruapehu, New Zealand

Mordensky

Villeneuve

Kennedy

et al. 2022

Engineering Geology

View full text Add to dashboard Cite

Fracture analysis, hydrothermal mineralization and fluid pathways in the Neogene Geitafell central volcano: insights for the Krafla active geothermal system, Iceland

Cited by 22 publications

References 61 publications

Increasing the Permeability of Hydrothermally Altered Andesite by Transitory Heating

Increasing the Permeability of Hydrothermally Altered Andesite by Transitory Heating

Fluid Infiltration and Mass Transfer along a Lamprophyre Dyke–Marble Contact: An Example from the South-Western Korean Peninsula

Hydrothermally induced edifice destabilisation: The mechanical behaviour of rock mass surrounding a shallow intrusion in andesitic lavas, Pinnacle Ridge, Ruapehu, New Zealand

Contact Info

Product

Resources

About