Northeastern Section - 47th Annual Meeting (1820 March 2012)
Paper No. 27-2
Presentation Time: 8:20 AM-8:40 AM

IMPLICATIONS FOR NON-TRADITIONAL GEOTHERMAL RESOURCES IN SOUTHERN NEW ENGLAND: VARIABILITY IN HEAT POTENTIAL BASED ON THERMAL CONDUCTIVITY AND GEOCHEMISTRY STUDIES

KOTEAS, G. Christopher1, RHODES, J. Michael1, MABEE, Stephen B.2, RYAN, Amy2, SCHMIDT, Joe2, LEAGUE, Corey2, GOODHUE, Nathaniel1, ADAMS, Sharon A.1, GAGNON, Teresa K.3, and THOMAS, Margaret A.4, (1) Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, 233 Morrill Science Center, Amherst, MA 01003, ckoteas@geo.umass.edu, (2) Massachusetts Geological Survey, Univ. Massachusetts, 611 North Pleasant Street, Amherst, MA 01003, (3) Department of Energy and Environmental Protection, Connecticut Geological Survey / Dinosaur State Park, 79 Elm St, Hartford, CT 06106, (4) Connecticut Geological Survey, Department of Energy and Environmental Protection, 79 Elm Street, Hartford, CT 06106

Estimating geothermal potential in southern New England in the absence of borehole heat flow data or geophysical studies has led to a focus on models based on thermal conductivity, geochemistry, and density-based heat production models. Preliminary estimates of geothermal potential generally match borehole-based heat flow data from similar tectonic environments. Nevertheless, microstructural and compositional heterogeneity with depth remain largely unconstrained. The extrapolation of regional structures based on detailed field mapping has helped to improve structural projections adjacent to major basins. However, an additional source of error in models of heat potential-with-depth are thermal conductivity estimates of igneous and meta-igneous rocks throughout Massachusetts (MA) and Connecticut (CT).

Over three hundred granitoid localities in MA and CT have been analyzed to date. The southern New England region can be simplified into four major litho-tectonic zones: the Taconic-Berkshire zone of western MA and northwestern CT, The Bronson Hill zone associated with the CT River Valley, the Nashoba zone of central MA and eastern CT, and the Milford-Dedham zone of eastern MA and eastern CT. Granitic rocks adjacent to the CT River Valley and the Narragansett Basin vary considerably in thermal conductivity. Granites adjacent to the Narragansett Basin vary from 2.9 to 3.7 W/m*K. Average thermal conductivity values, combined with modeled heat production values, produce temperatures at 3 km depth along the Narragansett Basin that approach 85-115°C. Values of meta-igneous rocks from the margin of the CT River Valley in MA and CT vary more considerably in thermal conductivity, from 1.8 to 3.9W/m*K. Modeled heat potentials at 3 km depths along the eastern margin of the CT River Valley vary between 74-122°C and appear to be largely related to compositional variation. However, local rock composition is also related to metamorphic grade and fabric development, suggesting that both fabric and composition are first order controls on thermal conductivity. Modeling based on this data set to date suggests that combining thermal conductivity, whole rock geochemistry data, and density measurements can produce accurate reconnaissance estimates of geothermal potential in southern New England.

Northeastern Section - 47th Annual Meeting (1820 March 2012)
General Information for this Meeting
Session No. 27
Geothermal Potential in the Northeast: A Quixotic Quest or Reality?
Hartford Marriott Downtown: Ballroom B
8:00 AM-12:00 PM, Monday, 19 March 2012

Geological Society of America Abstracts with Programs, Vol. 44, No. 2, p. 76

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