%0 Conference Proceedings %B Abstracts with Programs - Geological Society of America %D 2011 %T Identifying and examining potential geothermal resources in non-traditional regions, examples from the northeastern U.S. %A Koteas, G. Christopher %A John Michael Rhodes %A Stephen B Mabee %A Goodhue, Nathaniel %A Adams, Sharon A. %K #StaffPubs %K Andover Granite %K Eastern U.S. %K Economic geology, geology of energy sources 29A %K exploitation %K exploration %K Fall River Granite %K field studies %K geochemistry %K geothermal energy %K identification %K mapping %K massachusetts %K models %K Northeastern U.S. %K overburden %K resources %K sampling %K southeastern Massachusetts %K spectra %K structural analysis %K technology %K temperature %K United States %K whole rock %K X-ray fluorescence spectra %X The search for geothermal resources is rapidly expanding into tectonic regions that have not been previously considered to be suitable for exploitation. Many of these regions, such as the northeastern U.S., have never been the site of extensive geophysical investigations and have few deep borehole temperature measurements. Nevertheless, large portions of the northeastern U.S. are underlain by granitic bedrock that may be a productive energy source by applying enhanced geothermal technologies. In the absence of traditional reconnaissance data, we utilize field studies and sampling together with geochemical analysis to develop models of geothermal resources that can be tested against data from deep boreholes. Heat production is calculated from the measured density of the samples, the concentrations of K, U, and Th from whole-rock geochemical analysis via X-ray fluorescence, and established radiogenic heat production values. Models for a particular area can then be generated by calculating depth-specific temperatures using heat production, measured thermal conductivity for each sample, and assumptions related to local stratigraphy and regional heat flow. Mapping and structural extrapolation are used to establish the subsurface characteristics at a study site and are combined with the thermal and chemical characteristics of contact rocks and overburden materials. Two examples of the application of this technique are the Fall River granite at the margin of the Narragansett Basin in southeastern Massachusetts and the Andover Granite in northeastern Massachusetts. Thermal models of the Fall River Pluton indicate average temperatures of 71 degrees C at depths of 4 km and 97 degrees C at 6 km. Average temperatures increase to 107 degrees C and 132 degrees C, respectively, when a 2 km thick sediment package is modeled overlying the granite. The Andover Granite, which is not associated with a sedimentary basin and is in a more structurally complex configuration, yields an average temperature of 74 degrees C at a depth of 4 km and 101 degrees C at 6 km. While this approach to modeling temperature-depth profiles requires some regional heat flow assumptions, the application of mapping and structural analysis with geochemistry and thermal conductivity studies can be an important reconnaissance tool for identifying non-traditional geothermal resources. %B Abstracts with Programs - Geological Society of America %I Geological Society of America (GSA) : Boulder, CO, United States %C United States %V 43 %P 40 - 40 %8 2011/10/01/ %@ 00167592 %G eng %N 55 %! Abstracts with Programs - Geological Society of America %0 Conference Proceedings %B Abstracts with Programs - Geological Society of America %D 2012 %T Implications for non-traditional geothermal resources in southern New England; variability in heat potential based on thermal conductivity and geochemistry studies %A Koteas, G. Christopher %A John Michael Rhodes %A Stephen B Mabee %A Ryan, Amy %A Schmidt, Joe %A League, Corey %A Goodhue, Nathaniel %A Adams, Sharon A. %A Gagnon, Teresa K. %A Thomas, Margaret A. %K #StaffPubs %K chemical composition %K Connecticut %K Economic geology, geology of energy sources 29A %K energy sources %K geothermal energy %K geothermal exploration %K granites %K heat flow %K igneous rocks %K massachusetts %K models %K New England %K plutonic rocks %K thermal conductivity %K United States %X 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 degrees 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 degrees 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 these 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. %B Abstracts with Programs - Geological Society of America %I Geological Society of America (GSA) : Boulder, CO, United States %C United States %V 44 %P 76 - 77 %8 2012/02/01/ %@ 00167592 %G eng %U https://gsa.confex.com/gsa/2012NE/finalprogram/abstract_200837.htm %N 22 %! Abstracts with Programs - Geological Society of America %0 Map %D 2009 %T Preliminary bedrock geologic map of the Westford quadrangle, Massachusetts %A Joseph P Kopera %A D.C. Alvord %A Richard H Jahns %A M.E. Willard %A W.S. White %K #BedrockMaps %K #MGSPub %K Acton %K amphibolite %K ayer granite %K Berwick formation %K Boxborough %K calc-silicates %K Carlisle %K Chelmsford %K chelmsford granite %K Clinton-Newbury Fault %K Concord %K diorite %K gneiss %K Groton %K LITTLETON %K magnetite %K marble %K migmatite %K Nashoba Formation %K phyllonite %K tadmuck brook schist %K Tyngsborough %K Westford %X Bedrock Geologic Map contains brittle fracture data Mapping still in progress. For interim fracture database, please contact Joe Kopera %B Open-File Report %7 OFR-09-01 %I Massachusetts Geological Survey %G eng %2

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%0 Generic %D 0 %T Boston Rocks! %A Deb Allen %A Mark Goldner %K #EducationalResources %K #Fieldtrips %K #MassGeology %K Boston %K Boston geology %X An exploration into the geology, land use and engineering of the Boston area by teachers at the Brookline Public Schools %G eng %U http://bostongeology.com/index.htm