Iceland GeoSurvey

Abstract: Carbon capture and storage (CCS) provides a solution toward decarbonization of the global economy. The success of this solution depends on the ability to safely and permanently store CO2. This study demonstrates for the first time the permanent disposal of CO2 as environmentally benign carbonate minerals in basaltic rocks. We find that over 95% of the CO2 injected into the CarbFix site in Iceland was mineralized to carbonate minerals in less than 2 years. This result contrasts with the common view that the immobilization of CO2 as carbonate minerals within geologic reservoirs takes several hundreds to thousands of years. Our results, therefore, demonstrate that the safe long-term storage of anthropogenic CO2 emissions through mineralization can be far faster than previously postulated.

Abstract: Natural hazard prediction and efficient crust exploration require dense seismic observations both in time and space. Seismological techniques provide ground-motion data, whose accuracy depends on sensor characteristics and spatial distribution. Here we demonstrate that dynamic strain determination is possible with conventional fibre-optic cables deployed for telecommunication. Extending recently distributed acoustic sensing (DAS) studies, we present high resolution spatially un-aliased broadband strain data. We recorded seismic signals from natural and man-made sources with 4-m spacing along a 15-km-long fibre-optic cable layout on Reykjanes Peninsula, SW-Iceland. We identify with unprecedented resolution structural features such as normal faults and volcanic dykes in the Reykjanes Oblique Rift, allowing us to infer new dynamic fault processes. Conventional seismometer recordings, acquired simultaneously, validate the spectral amplitude DAS response between 0.1 and 100 Hz bandwidth. We suggest that the networks of fibre-optic telecommunication lines worldwide could be used as seismometers opening a new window for Earth hazard assessment and exploration.

Abstract: The main goal of geothermal geochemistry research is to identify the origin of geothermal fluids and to quantify the processes that govern their compositions and the associated chemical and mineralogical transformations of the rocks with which the fluids interact. The subject has a strong applied component: Geothermal chemistry constitutes an important tool for the exploration of geothermal resources and in assessing the production characteristics of drilled geothermal reservoirs and their response to production. Geothermal fluids are also of interest as analogues to ore-forming fluids. Understanding of chemical processes within active geothermal systems has been advanced by thermodynamic and kinetic experiments and numerical modeling of fluid flow. Deep drillings for geothermal energy have provided important information on the sources and composition of geothermal fluids, their reaction with rock-forming minerals, migration of the fluids, and fluid phase separation and fluid mixing processes. Based on findings to date, geothermal fluids may be classified as primary or secondary. Primary fluids are those found in the roots of geothermal systems. They may constitute a mixture of two or more fluids, such as water of meteoric origin, seawater and magmatic volatiles. Several processes can lead to the formation of secondary fluids, such as the boiling of a primary fluid that separates it into liquid and vapor and the un-mixing of a very hot brine by its depressurization and cooling. Further, secondary geothermal fluids form by the mixing of deep fluids with shallow ground water or surface water. In this chapter we summarize the geo-hydrological and geochemical features of geothermal systems and delineate the processes that produce the observed chemical composition of the various types of geothermal fluids found in these systems. The main emphasis is, however, on gas chemistry and the assessment of fluid phase separation below hot springs and around discharging wells drilled into liquid-dominated …