The Iceland Deep Drilling Project (IDDP) will study the interaction of high-temperature (~ 450oC) hydrothermal fluids with oceanic crust on the Reykjanes Peninsula, at the southwestern tip of Iceland, where the Mid-Atlantic Ridge emerges from the ocean. The requested funds would be highly leveraged because most of the cost of drilling a 5km deep borehole will be borne by industry and the Icelandic government, with participation from the International Continental Scientific Drilling Program. An Icelandic geothermal power company is providing an existing ~ 3 km deep well for deepening to 5 km depth. This project will provide the first opportunity worldwide to investigate the deep, high temperature reaction zone of a mid-ocean ridge hydrothermal system, which has been a long-standing goal of the Ocean Drilling Program. This drill site is ideally situated for a broad array of scientific studies involving reactions between basalt and seawater at high temperatures, reaching supercritical conditions. Such active processes in the deep, high temperature reaction zones that control fluid compositions of black smokers have never before been available for comprehensive direct study and sampling. Ocean drilling has penetrated only 2 km into 5 Ma old ocean crust. where temperatures were ~ 180 oC. In contrast, the IDDP collaboration with industry in Iceland will produce fluid samples from the flow tests at 3, 4, and 5 km, drill cuttings and spot cores down to 4.0 km depth, and 1.0 km of continuous drill core from 4.0 to 5.0 km depth. These samples will reveal the integrated record of basalt-seawater interactions at >400oC. The study of these materials will permit a quantum leap in our understanding of active hydrothermal processes that are important on a global scale,
The funds provided will be used for: (1) coring for scientific purposes; (2) support for the scientific program at the well site, for fluid sampling, for core handling, and for basic petrologic characterization of the cores, and distribution of sub-samples and data to an approved list of international scientists; and (3) support for a coordinated group of US Co-PI's investigating hydrothermal water/rock interactions and geochemical modeling. The core and fluids that will be retrieved may characterize the lower boundary of a major hydrothermal system and thus provide important evidence about what controls the upper temperature limits of hydrothermal systems.
The goal of this collaborative research is to investigate the interaction of high-temperature supercritical (400-600°C) geothermal fluids with oceanic crust in Iceland, where the Mid-Atlantic Ridge is exposed above sea level, and to evaluate the feasibility of using supercritical geothermal fluids for energy production. Ultimately, if this drilling program proves successful, it will lead to major improvements in the development of geothermal resources worldwide using high-enthalpy supercritical fluids. This research is being carried out in collaboration with our colleagues at the University of California at Riverside and Davis, the University of Oregon, and our colleagues at various institutions in Iceland. The contribution of the Stanford University group to this collaborative research focuses on 1) the evolution and origin of the geothermal fluids (based on stable isotopic properties of fluids and minerals); 2) the evolution, origin, and flux of CO2 in the geothermal fluids (based on mineralogic phase relations, fluid rock interactions and thermodynamic calculations); and 3) the distribution and mobility of arsenic in geothermal systems of Iceland (based on mineralogic, and fluid and rock compositions). These specific research topics were evaluated using samples from existing and new geothermal drillholes in the Reykjanes and Krafla geothermal systems of Iceland, and from field investigations of fossil geothermal systems exposed by glacial erosion in Eastern Iceland. The results of our findings supported by NSF Grant 0506882 has been presented in publications in Geochimica et Cosomochimica Acta, the Journal Geology and the American Journal of Science, in three manuscripts published by the World Geothermal Congress, and one by the Geothermal Resources Council. In addition, our research has been presented at national and international meetings (14 published abstracts). This project has contributed to the education and training of undergraduate and graduate students (Emile Pope, Nellie Olsen, and Adam Freedman) in the fundamental techniques of mineral, isotopic and chemical analyses, thermodynamic analysis of there data, and techniques and experience of oral, poster, and written communication of the scientific findings. The research has lead to the completion of one undergraduate honors thesis (Adam Freedman), one Masters of Science Thesis (Nellie Olsen), and one PhD dissertation (Emily Pope). The research conducted in this project has made significant progress on the understanding of the evolution and origin of geothermal fluids, evolution and transport of CO2 in geothermal fluids, and the distribution and migration of arsenic in geothermal systems. Furthermore, we have analyzed the glass formed from the rhyolite melt intersected by drillhole IDDP-1 at the Krafla geothermal system and have presented evidence that it was formed my melting of hydrothermally altered basalts deep within the Krafla caldera. Collectively these studies present new insights into the interaction of geothermal fluids in oceanic rifting environments and on the geochemical and hydrologic conditions prevailing in geothermal environments approaching supercritical conditions.
