by Ilmo Tapio Kukkonen

The Geological Survey of Finland (GTK) is currently running a deep drilling research project at Outokumpu, in eastern Finland, the aim of which is to drill to a depth of 2,500 m within a Palaeoproterozoic metasedimentary and ophiolite sequence. Drilling is completed in January-February, 2005. We propose that the Outokumpu Deep Drilling Project will be included in the current group of ICDP projects. The 2,500 m deep, continuously cored Outokumpu Deep Drill Hole, eastern Finland, aims at (1) improved understanding of the deep structure of a classical Palaeoproterozoic Cu-Co-Zn ore province in a metasedimentary and ophiolitic assemblage, (2) understanding the composition and origin of deep saline fluids, and investigating the deep biosphere, (3) investigating the vertical variation of different geological and geophysical parameters and correlating geological, geophysical and petrophysical data sets, and (4) using the Outokumpu hole as a deep geolaboratory for various in situ experiments, fluid sampling and monitoring programmes. The basic drilling program funded by GTK includes continuous coring of the hole, carrying out borehole geophysics with 20 different methods, as well as fluid sampling and hydraulic conductivity measurements. GTK has already actively encouraged national and international co-operation in the Outokumpu Deep Drilling Project to maximize the scientific benefit from this drill hole. In this application we ask ICDP support for an international workshop in 2005, as well as operational ICDP-OSG support and economic support for the first operations in the drill hole in 2005-2006. Project web site: http://www.gsf.fi/projects/o_k_deepdrilling/index.htm .

• The scientific objectives of the Outokumpu Deep Drilling Project are as follows: · Deep structural investigations of crystalline bedrock in a classical ore province · Improved understanding of saline fluids and gas in crystalline bedrock · Forms of life in crystalline bedrock · Improved understanding of heat and fluid flow in the crystalline bedrock · Ground temperature history during the Weichselian glaciation and Holocene inverted from geothermal data · Vertical variation of several petrophysical and geological parameters · Virgin state of stress and stress perturbation caused by a geological structure · Microseismic activity in a shield area · Improved exploration techniques · Improved understanding of apatite fission track thermochronology and (U-Th)/He age dating methods in Precambrian terrain · Use of Outokumpu Deep Hole as a calibration and test hole facility The Outokumpu deep drill hole, its core samples, geophysical logging data and hydrogeological results provide a unique possibility for a multidisciplinary research project. Several fields of interest as well as interested research teams have been already identified. The preliminary titles of research include geothermal studies, active and passive seismic experiments, hydrogeology, hydro-geochemistry, deep biosphere, physical properties of rocks, borehole geophysics, apatite fission track thermochronology, U-Pb geochronology, stress field studies, petrological, metamorphic, geochemical and structural studies, as well as Deep Geolaboratory activities and monitoring. We believe that the Outokumpu deep hole has good potential to become a reference site in deep drilling studies of Precambrian crystalline crust.

Finland, ICDP-2005/07, Ophiolites, OUTOKUMPU, Precambrian, Saline Fluids, Thermal Regimes

Latitude: 62.717807, Longitude: 29.061993