Origin of a rhyolite that intruded a geothermal well while drilling at the Krafla volcano, Iceland

Elders, W. A.; Friðleifsson, G. Ó.; Zierenberg, Robert A.; Pope, E. C.; Mortensen, Anette K.; Guðmundsson, Á.; Lowenstern, Jacob B.; Marks, Naomi; Owens, Lara; Bird, Dennis K.; Reed, Mark H.; Olsen, Nellie J.; Schiffman, P.

doi:10.1130/g31393.1

Cited by 97 publications

(57 citation statements)

References 20 publications

(12 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The rhyolite has high silica content (∼75 wt%, (Zierenberg et al, 2012;Elders et al, 2011). The rhyolite is compositionally and isotopically similar to rhyolites previously described from the Krafla caldera area (Jónasson, 1994;Swantesson and Kristmannsdóttir, 1978), and is interpreted to have formed by partial melting of hydrothermally altered basaltic rocks at depth within the Krafla rift zone (Jónasson, 1994;Elders et al, 2011;Zierenberg et al, 2012). Phenocrysts are typically present as less than 5 vol.% of the rock and include andesine plagioclase, augite, pigeonite, and titanomagnetite.…”

Section: The Rhyolite Magmasupporting

confidence: 55%

See 1 more Smart Citation

High temperature metamorphism in the conductive boundary layer adjacent to a rhyolite intrusion in the Krafla geothermal system, Iceland

Schiffman¹,

Zierenberg²,

Mortensen³

et al. 2014

Geothermics

Self Cite

View full text Add to dashboard Cite

A rhyolite magma body within the Krafla geothermal system that was encountered at a depth of 2.1 km during drilling of the IDDP-1 borehole is producing high temperature metamorphism within a conductive boundary layer (CBL) in adjacent host rocks. Cuttings recovered during drilling within a few meters of the intrusive contact in IDDP-1 are mainly comprised of granoblastic hornfelses, the rock type which confirms the presence of the CBL at the base of the IDDP-1 bore hole. The two pyroxenes in these hornfelses record temperatures that are in the range of 800-950• C. The minimum heat flow across the CBL is 23 W m −2 . Country rocks at distances beyond 30 m of the intrusive contact are essentially unaltered, implying that they have been emplaced very recently and/or as yet unaffected by hydrothermal fluid flow.

show abstract

Section: The Rhyolite Magmasupporting

confidence: 55%

“…1) was terminated at a depth of 2.1 km when the drill string penetrated a silicic magma body (Elders et al, 2011). In addition to quenched rhyolitic glass, cuttings returned included those of crystalline felsic and mafic lithologies.…”

Section: Introductionmentioning

confidence: 99%

High temperature metamorphism in the conductive boundary layer adjacent to a rhyolite intrusion in the Krafla geothermal system, Iceland

Schiffman¹,

Zierenberg²,

Mortensen³

et al. 2014

Geothermics

Self Cite

View full text Add to dashboard Cite

show abstract

“…The melt likely originated from partially molten and hydrothermally altered crust [Elders et al, 2011;Zierenberg et al, 2012]. Above the melt pocket at 1482-1527 m depth bsl, the most productive zone for fluid injections was located in felsic rock [Mortensen et al, 2014;Friðleifsson et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

Focal mechanisms and size distribution of earthquakes beneath the Krafla central volcano, NE Iceland

et al. 2016

View full text Add to dashboard Cite

Seismicity was monitored beneath the Krafla central volcano, NE Iceland, between 2009 and 2012 during a period of volcanic quiescence, when most earthquakes occurred within the shallow geothermal field. The highest concentration of earthquakes is located close to the rock‐melt transition zone as the Iceland Deep Drilling Project‐1 (IDDP‐1) wellbore suggests and decays quickly at greater depths. We recorded multiple swarms of microearthquakes, which coincide often with periods of changes in geothermal field operations, and found that about one third of the total number of earthquakes are repeating events. The event size distribution, evaluated within the central caldera, indicates average crustal values with b = 0.79 ± 0.04. No significant spatial b value contrasts are resolved within the geothermal field nor in the vicinity of the drilled melt. Besides the seismicity analysis, focal mechanisms are calculated for 342 events. Most of these short‐period events have source radiation patterns consistent with double‐couple (DC) mechanisms. A few events are attributed to non‐shear‐faulting mechanisms with geothermal fluids likely playing an important role in their source processes. Diverse faulting styles are inferred from DC events, but normal faulting prevails in the central caldera. The best fitting compressional and tensional axes of DC mechanisms are interpreted in terms of the principal stress or deformation rate orientations across the plate boundary rift. Maximum compressive stress directions are near‐vertically aligned in different study volumes, as expected in an extensional tectonic setting. Beneath the natural geothermal fields, the least compressive stress axis is found to align with the regional spreading direction. In the main geothermal field both horizontal stresses appear to have similar magnitudes causing a diversity of focal mechanisms.

show abstract

“…Much of our understanding of mantle plumes comes from plume tracks in oceanic lithosphere, but oceanic lithosphere is recycled back into the mantle by subduction, and evidence for mantle plumes in the oceanic realm is destroyed. Thus, if we are to understand plume-related volcanism prior to 200 Ma, we must learn how plume-derived magmas inter- Hotspot volcanism in oceanic lithosphere has been the subject of studies by the International Continental Drilling Program (ICDP)-e.g., the Hawaii Drilling Project and the Reykjanes Drilling Project-and by the Integrated Ocean Drilling Program (IODP) and its predecessors (Neal et al, 1997;DePaolo et al, 2001;Elders et al, 2011). A variety of geochemical evidence from oceanic hotspots suggests that the source of volcanism involves mantle that is distinct from the shallowest upper mantle (DePaolo and Manga, 2003).…”

Section: Introductionmentioning

confidence: 99%

First Results from HOTSPOT: The Snake River Plain Scientific Drilling Project, Idaho, U.S.A.

et al. 2013

View full text Add to dashboard Cite

HOTSPOT is an international collaborative effort to understand the volcanic history of the Snake River Plain (SRP). The SRP overlies a thermal anomaly, the Yellowstone-Snake River hotspot, that is thought to represent a deep-seated mantle plume under North America. The primary goal of this project is to document the volcanic and stratigraphic history of the SRP, which represents the surface expression of this hotspot, and to understand how it affected the evolution of continental crust and mantle. An additional goal is to evaluate the geothermal potential of southern Idaho.Project HOTSPOT has completed three drill holes.(1) The Kimama site is located along the central volcanic axis of the SRP; our goal here was to sample a long-term record of basaltic volcanism in the wake of the SRP hotspot.(2) The Kimberly site is located near the margin of the plain; our goal here was to sample a record of high-temperature rhyolite volcanism associated with the underlying plume. This site was chosen to form a nominally continuous record of volcanism when paired with the Kimama site. (3) The Mountain Home site is located in the western plain; our goal here was to sample the Pliocene-Pleistocene transition in lake sediments at this site and to sample older basalts that underlie the sediments.We report here on our initial results for each site, and on some of the geophysical logging studies carried out as part of this project.

show abstract

Origin of a rhyolite that intruded a geothermal well while drilling at the Krafla volcano, Iceland

Cited by 97 publications

References 20 publications

High temperature metamorphism in the conductive boundary layer adjacent to a rhyolite intrusion in the Krafla geothermal system, Iceland

High temperature metamorphism in the conductive boundary layer adjacent to a rhyolite intrusion in the Krafla geothermal system, Iceland

Focal mechanisms and size distribution of earthquakes beneath the Krafla central volcano, NE Iceland

First Results from HOTSPOT: The Snake River Plain Scientific Drilling Project, Idaho, U.S.A.

Contact Info

Product

Resources

About