TY - Generic T1 - Fracture characterization; valuable inputs for modeling groundwater flow in fractured bedrock T2 - Abstracts with Programs - Geological Society of America Y1 - 1996 A1 - Stephen B Mabee A1 - Hardcastle, Kenneth C. KW - #StaffPubs KW - BEDROCK KW - boreholes KW - California KW - discontinuities KW - experimental studies KW - field studies KW - fractured materials KW - fractures KW - ground water KW - Hydrogeology 21 KW - Madera County California KW - models KW - movement KW - observation wells KW - Raymond California KW - site exploration KW - spatial distribution KW - transmissivity KW - United States KW - wells JF - Abstracts with Programs - Geological Society of America PB - Geological Society of America (GSA) : Boulder, CO, United States CY - United States VL - 28 SN - 00167592 IS - 33 N1 - Accession Number: 1996-065028; Conference Name: Geological Society of America, Northeastern Section, 31st annual meeting; Buffalo, NY, United States; Conference Date: 19960321; Language: English; Coordinates: N364500N374500W1190100W1203800; Coden: GAAPBC; Collation: 1; Collation: 77; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 199620; Monograph Title: Geological Society of America, Northeastern Section, 31st 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 - TY - Generic T1 - Implications for non-traditional geothermal resources in southern New England; variability in heat potential based on thermal conductivity and geochemistry studies T2 - Abstracts with Programs - Geological Society of America Y1 - 2012 A1 - Koteas, G. Christopher A1 - John Michael Rhodes A1 - Stephen B Mabee A1 - Ryan, Amy A1 - Schmidt, Joe A1 - League, Corey A1 - Goodhue, Nathaniel A1 - Adams, Sharon A. A1 - Gagnon, Teresa K. A1 - Thomas, Margaret A. KW - #StaffPubs KW - chemical composition KW - Connecticut KW - Economic geology, geology of energy sources 29A KW - energy sources KW - geothermal energy KW - geothermal exploration KW - granites KW - heat flow KW - igneous rocks KW - massachusetts KW - models KW - New England KW - plutonic rocks KW - thermal conductivity KW - United States AB - 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. 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_200837.htm IS - 22 N1 - Accession Number: 2012-090079; Conference Name: Geological Society of America, Northeastern Section, 47th annual meeting; Hartford, CT, United States; Conference Date: 20120318; Language: English; Coordinates: N420000N473000W0670000W0733000; Coden: GAAPBC; Collation: 2; Collation: 76-77; 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 - Implications of diurnal river fluctuations on mass transport in a valley-fill aquifer T2 - Abstracts with Programs - Geological Society of America Y1 - 2006 A1 - Brandon J Fleming A1 - David F Boutt A1 - Stephen B Mabee KW - #StaffPubs KW - aquifers KW - BEDROCK KW - clastic sediments KW - controls KW - diffusion KW - diurnal variations KW - drainage KW - drift KW - Eastern U.S. KW - Environmental geology 22 KW - floods KW - fluctuations KW - geochemical cycle KW - geologic hazards KW - ground water KW - measurement KW - mixing KW - models KW - Northeastern U.S. KW - numerical models KW - nutrients KW - pollution KW - processes KW - pumping KW - quantitative analysis KW - residence time KW - sediments KW - shallow aquifers KW - surface water KW - three-dimensional models KW - tracers KW - transport KW - United States KW - valleys KW - water pollution KW - water resources KW - water wells AB - Aquifers located in isolated stratified drift deposits in the northeastern portion of the US are extremely fragile and important groundwater resources. These aquifers, when restricted to bedrock valleys, are often strongly coupled to significant surface water drainage systems. In northwestern Massachusetts, surface water associated with the Deerfield River watershed is highly regulated by dams to protect against flooding and to generate hydroelectric power. Regular releases of water from these dams cause diurnal fluctuations in river stage. In a previous study performed by the USGS, measurements from two clusters of wells show a significant response to river stage fluctuations in the aquifer. Fluctuations in river stage and resulting changes in head levels in the aquifer cause a switch from a losing to a gaining stream. The flow reversals have implications for mass transport and nutrient cycling within the hyporheic zone. In this paper we investigate the physical hydrologic controls on mass transport in the shallow aquifer. Using a coupled groundwater flow and transport code, we built a quasi three dimensional transient numerical model to approximate the head changes in the aquifer caused by the stage fluctuations in the river. Flow velocities and residence times were estimated in the aquifer for a variety of flow conditions. The mixing process driven by the aquifer head changes were quantified in the proximity of the hyporheic zone and shown to significantly influence both vertical and horizontal flow velocities in a region close to the stream-aquifer boundary. The diurnal river stage changes also appear to influence farfield hydrologic conditions and potentially hydrologically isolate the river and hyporheic zone. To further investigate these mixing processes we applied a mass transport code with conservative tracers to the aquifer. Fluctuation of the river stage combined with the heterogeneous nature of the aquifer creates a pumping mechanism that creates excess mixing within shallow portions of the aquifer. Aquifer dispersivity and molecular diffusion both contribute to the anomalous mixing modeled in the shallow aquifer. Mixing driven by stream stage changes has important implications for nutrient cycling as well as contaminant transport in the shallow aquifer. JF - Abstracts with Programs - Geological Society of America PB - Geological Society of America (GSA) : Boulder, CO, United States CY - United States VL - 38 SN - 00167592 UR - https://gsa.confex.com/gsa/2006AM/finalprogram/abstract_115285.htm IS - 77 N1 - Accession Number: 2010-061334; Conference Name: Geological Society of America, 2006 annual meeting; Philadelphia, PA, United States; Conference Date: 20061022; Language: English; Coden: GAAPBC; Collation: 1; Collation: 468; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 201034; Monograph Title: Geological Society of America, 2006 annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic JO - Abstracts with Programs - Geological Society of America ER -