DCO Project Summary

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Project Title
Deep Life Investigations That Support the ICDP Collisional Orogeny in the Scandinavian Caledonides (COSC) Drilling Project
Start DateEnd Date
2014-05-01 2014-11-01
NameRoleInstitutionDCO ID
Related GrantsDCO ID
11121/3468-1369-5510-9075-CC
Description

The Collisional Orogeny in the Scandinavian Caledonides (COSC) Project is a drilling effort sponsored by the International Continental Drilling Program (ICDP), the Swedish Deep Drilling Program, and the Swedish Science Research Council (Swedish NSF), which funded the purchase of the drill rig.  The main theme of the project is to understand the role of an ancient (400 Ma) thrust zone in the formation of the mountains of central Sweden and also as a model of other mountain-building processes, such as those that formed the Himalayas.  The DCO Deep Life Community provided funds ($24k + $1K for DNA sequencing) to add a geomicrobiological component to this ICDP project.  Funds were awarded to Kieft, Onstott, and Schrenk; they are collaborating with Karsten Pedersen of Chalmers University in Sweden, who is the lead microbiologist on the COSC project.  They are also collaborating with geologists from Uppsala University and geophysicists from Lund University.  The main emphases of the geomicrobiological efforts are to characterize the biodiversity and metabolic activities of microbes living within fractures, and to determine the importance of rock-water interactions in generating H2 and CH4 to support microbial activities.

 

The plan for the DCO-funded geomicrobiology is to collect samples of drill core at various depth intervals along the planned 2500-meter planned depth of the drilling and to collect a larger number of samples within the main thrust zone.  Three types of tracers will be deployed to quantify contamination from drilling fluids.  These tracers are (1) fluorescein dye, which has been added to the drilling mud, (2) a perfluorinated hydrocarbon, to be added to the drilling mud immediately before it’s pumped down the borehole, and (3) fluorescent microspheres to be added in a plastic bag attached to the bottom of a polycarbonate liner immediately before sampling. The polycarbonate liner serves as the third, or inner, tube, of a triple tube coring tool to minimize contamination of the rock core from drilling mud and handling. Cores to be used for geomicrobiology analyses will be removed from the polycarbonate liner and subcored by removing the outer portions of the core (“parings”), leaving an inner subcore.  Tracers will be quantified in the subcore, parings, and drilling muds. 

 

Cores will also be collected by Pedersen and Onstott for chemical and isotopic analyses of gases and pore fluids within the rock matrix and for 35S autoradiography.  Cores will be sealed in canisters and then incubated for several months, during which time the gases will diffuse from the rock into the atmosphere of the canister. Swabs of fractures for DNA and ATP analyses are also being collected for analyses in Pedersen’s lab.  Whole round cores and drilling mud samples have also been collected and archived in a freezer for later analyses.

 

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Reporting Year 2014 Click to expand


  • RY2014-1 - submitted on Aug 31, 2014

    Update Details:

    Kieft spent two weeks in late June to early July setting up the tracer delivery system and preparing materials for coring.  Onstott will be onsite during coring of the thrust zone in August. The current status of the drilling is that a depth of ~1800 m has been reached.  The first 1600 m were drilled with HQ size (~63-mm diam) drill pipe; the remainder is being drilled using NQ size (~47-mm diam).  The polycarbonate tubing is sized for NQ drilling, as the deep part of the borehole is the most important target of the geomicrobiological study.  Drilling delays have caused a switch to a double tube system, which speeds drilling but prevents use of the polycarbonate tubes.  The current plan is to switch back to triple-tube drilling for the thrust zone at ~2200- 2300 m in order to facilitate geomicrobiological sampling. 

    The ICDP has deployed an on-line gas analyzer (OLGA) to analyze gases released from the mud during drilling.  OLGA has shown peaks of H2, CH4, and associated with the drilling.  This may indicate release of hydrogen and CH4 that has been generated by rock-water interactions, e.g., oxidation of ultramafic rocks and/or radiolysis of water along with Fischer-Tropsch-type synthesis of CH4. Helium peaks suggest past radioactive decay with potential formation of H2 by radiolysis of water.  This bodes well for subsurface lithoautotrophic microbial ecosystems (SLiMEs), but we still await coring of the thrust zone to get the samples that we need.  The anticipated timing for this is now mid- to late August.

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