TY - Generic T1 - Granite as a geothermal resource in the Northeast T2 - Abstracts with Programs - Geological Society of America Y1 - 2012 A1 - John Michael Rhodes A1 - Koteas, G. Christopher A1 - Stephen B Mabee KW - #StaffPubs KW - Cammenallis Pluton KW - Cornwall England KW - Eastern U.S. KW - Economic geology, geology of energy sources 29A KW - energy sources KW - England KW - Europe KW - geothermal energy KW - geothermal exploration KW - granites KW - Great Britain KW - heat flow KW - hydrothermal conditions KW - igneous rocks KW - intrusions KW - Northeastern U.S. KW - plutonic rocks KW - plutons KW - thermal conductivity KW - United Kingdom KW - United States KW - Western Europe AB - In the absence of volcano-derived hydrothermal activity and high heat flow, granitic plutons provide an alternative geothermal resource from which heat may be usefully extracted. Compared with other crustal rocks, granites contain higher concentrations of the heat producing elements (K, U, Th). Additionally, they are more homogeneous and have simpler fracture systems than surrounding country rock, allowing for stimulation through hydro-fracking of large (>1 km (super 3) ) geothermal reservoirs. However, not all granites are created equal! Those with heat production > 5 mu W/m (super 3) , or with deep batholithic roots, are the most promising. Estimated temperatures at a given depth are related to the heat production, thickness and thermal conductivity of the granite. For example, the Carnmenellis Pluton in Cornwall, England (which will be drilled in 2012) is estimated to have temperatures in excess of 170 degrees C at a depth of 5 km, which is sufficient for co-production of electricity and hot water for heating. More importantly, granite bodies that are buried beneath thick sequences of thermally insulating sediments are also potential geothermal targets. Most successful examples to date include the Soultz sur Foret project in France, with temperatures of 200 degrees C at a depth of 5 km. (and which is currently producing electricity), Innamincka, Australia, with temperatures of 250 degrees C at a depth of 4 km. (which will be producing in 2012), and the seismically ill-fated project in Basel, Switzerland. Surely, if such projects involving the geothermal potential of granites, can succeed elsewhere, they can succeed here in the granite-rich Northeast? The geothermal potential of the Conway Granite, NH has long been recognized. Other possibilities include the Fitchburg Pluton, MA, and granites buried beneath the Carboniferous sediments of the Narragansett Basin and the Triassic sediments of the Connecticut River valley. JF - Abstracts with Programs - Geological Society of America PB - Geological Society of America (GSA) : Boulder, CO, United States CY - United States VL - 44 SN - 00167592 UR - https://gsa.confex.com/gsa/2012NE/finalprogram/abstract_200603.htm IS - 22 N1 - Accession Number: 2012-090078; Conference Name: Geological Society of America, Northeastern Section, 47th annual meeting; Hartford, CT, United States; Conference Date: 20120318; Language: English; Coden: GAAPBC; Collation: 1; Collation: 76; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 201247; Monograph Title: Geological Society of America, Northeastern Section, 47th annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic JO - Abstracts with Programs - Geological Society of America ER - TY - Generic T1 - Identifying and examining potential geothermal resources in non-traditional regions, examples from the northeastern U.S. T2 - Abstracts with Programs - Geological Society of America Y1 - 2011 A1 - Koteas, G. Christopher A1 - John Michael Rhodes A1 - Stephen B Mabee A1 - Goodhue, Nathaniel A1 - Adams, Sharon A. KW - #StaffPubs KW - Andover Granite KW - Eastern U.S. KW - Economic geology, geology of energy sources 29A KW - exploitation KW - exploration KW - Fall River Granite KW - field studies KW - geochemistry KW - geothermal energy KW - identification KW - mapping KW - massachusetts KW - models KW - Northeastern U.S. KW - overburden KW - resources KW - sampling KW - southeastern Massachusetts KW - spectra KW - structural analysis KW - technology KW - temperature KW - United States KW - whole rock KW - X-ray fluorescence spectra AB - 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. JF - Abstracts with Programs - Geological Society of America PB - Geological Society of America (GSA) : Boulder, CO, United States CY - United States VL - 43 SN - 00167592 IS - 55 N1 - Accession Number: 2012-083486; Conference Name: Geological Society of America, 2011 annual meeting; Minneapolis, MN, United States; Conference Date: 20111009; Language: English; Coden: GAAPBC; Collation: 1; Collation: 40; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 201244; Monograph Title: Geological Society of America, 2011 annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic JO - Abstracts with Programs - Geological Society of America ER -