C-DEBI Newsletter – August 15, 2013

The National Ocean Sciences Bowl (NOSB) is looking for Washington D.C. metropolitan area ocean science professionals to join a NOSB Technical Advisory Panel (TAP).  The NOSB takes great pride in its challenging questions and each year asks scholars, scientists, and teachers to participate in the question review process.  TAPs are held each September and October to review the buzzer and Team Challenge Questions for the regional and national NOSB competitions.  If you have expertise in Biology, Chemistry, Physics, Geology, Marine Policy, Technology, Social Science or Geography, please help us ensure the competition questions are of the highest quality possible.  Please note that this is a volunteer opportunity.  If interested in volunteering by using your expertise in the marine sciences to help the next generation of ocean scientists and stewards succeed, contact Melissa Brodeur.

Publications

Hot Off the Press: Characterizing borehole fluid flow and formation permeability in the ocean crust using linked analytic models and Markov Chain Monte Carlo analysis (C-DEBI Contribution 173) in Geochemistry, Geophysics, Geosystems Online
Thermal records from boreholes in young oceanic crust, in which there is water flowing up or down, are used to assess formation and borehole flow properties using three analytic equations that describe the transient thermal and barometric influence of downhole or uphole flow. C-DEBI graduate student D.M. Winslow, Co-I A.T. Fisher and K. Becker link these calculations with an iterative model and apply Markov Chain Monte Carlo (MCMC) analysis to quantify ranges of possible values. The model is applied to two data sets interpreted in previous studies, from Deep Sea Drilling Project Hole 504B on the southern flank of the Costa Rica Rift and Ocean Drilling Program Hole 1026B on eastern flank of the Juan de Fuca Ridge, and to two new records collected in Integrated Ocean Drilling Program Holes U1301A and U1301B, also on the eastern flank of the Juan de Fuca Ridge. Their calculations indicate that fluid flow rates when thermal logs were collected were ~2 L/s in Holes 504B, 1026B, and U1301A, and >20 L/s in Hole U1301B. The median bulk permeabilities determined with MCMC analyses are 4 to 7 x 10^-12 m² around the uppermost parts of Holes 504B, 1026B, and U1301A, and 1.5 x 10^-11 m² around a deeper section of Hole U1301B, with a standard deviation of 0.2 to 0.3 log-cycles at each borehole. The consistency of permeability values inferred from these four holes is surprising, given the range of values determined globally and the tendency for permeability to be highly variable in fractured crystalline rock formations such as the upper oceanic crust.

Preliminary Report: Expedition 341S, Simple Cabled Instrument for Measuring Parameters In situ (SCIMPI) and Hole 858G CORK Replacement.
Integrated Ocean Drilling Program Expedition 341S was an engineering expedition dedicated to two separate projects. One was the first deployment of the Simple Cabled Instrument for Measuring Parameters In Situ (SCIMPI) on the Cascadia margin. The second was replacement of the CORK in Hole 858G for formation pressure monitoring in the Middle Valley axial rift of the Juan de Fuca Ridge. Both installations were targeted to be incorporated into the NEPTUNE observatory network. SCIMPI is a new observatory instrument designed to study dynamic processes in the subseabed based on a simple and low-cost approach. SCIMPI was successfully installed in Hole U1416A. The final tool string consisted of nine modules, with three of these including pressure sensors (modules 1, 5, and 9, at 8, 117, and 234 meters below seafloor, respectively). The second operation with SCIMPI was the deployment of a single module (with a seafloor connector and command module, dubbed SHRIMPI) in Hole U1416B. The new CORK that was to be installed in Hole 858G was constructed with a simplified seal system designed to survive the overpressures and high temperatures at this location. The new CORK was not installed because the old CORK could not be removed from Hole 858G.