TY - Generic T1 - Age-constraints on fabric reactivation in the Tusas Range, northern New Mexico, using electron-microprobe monazite geochronology; implications for the nature of regional approximately 1400 Ga deformation T2 - Abstracts with Programs - Geological Society of America Y1 - 2002 A1 - Joseph P Kopera A1 - Williams, Michael L. A1 - Jercinovic, Michael J. KW - #StaffPubs KW - dates KW - deformation KW - electron probe data KW - fabric KW - folds KW - geochronology KW - Geochronology 03 KW - geometry KW - in situ KW - Laurentia KW - Mesoproterozoic KW - metamorphism KW - monazite KW - New Mexico KW - northern New Mexico KW - orogeny KW - Ortega Group KW - overgrowths KW - phosphates KW - Precambrian KW - preferred orientation KW - proterozoic KW - reactivation KW - Southwestern U.S. KW - strain KW - structural analysis KW - Structural geology 16 KW - synclines KW - tectonics KW - Tusas Mountains KW - United States KW - upper Precambrian KW - zoning AB - A key issue in constructing models for the southward growth of Laurentia during the Proterozoic is distinguishing the effects of approximately 1650 Ma and approximately 1400 Ma tectonism. These events share similar styles of deformation and metamorphism, making it difficult to assign structures, fabrics, and metamorphic phases to a particular event. The fundamental geometry of this orogen in the southwestern United States is defined in many areas by fold-fault pairs and isolated synclines of thick approximately 1700 Ma quartzite. In-situ EMP chemical dating of monazite, combined with detailed structural analysis, indicates that such synclines within the Tusas Range of northern New Mexico (locally F (sub 3) ) were substantially modified, if not developed, during approximately 1400 Ma tectonism. Monazite grains from the Ortega quartzite in the central Tusas Range display a shape preferred orientation parallel to the axial-planar fabric of these folds (S (sub 3) ), with overgrowth rims preferentially developed in the X direction of strain. These monazite grains have either >1700 Ma cores or approximately 1650 Ma cores with approximately 1400 Ma overgrowth rims, or are entirely approximately 1400 Ma in age. Field and microstructural observations show that the upright, east-west trending F (sub 3) and S (sub 3) are reactivations of older, northwest-trending fabrics and structures. The presence of approximately 1650 Ma overgrowth rims on monazite grains from the central and northern Tusas Range implies that these folds and fabrics may have nucleated prior to approximately 1400 Ma tectonism. Previous studies have shown an increase in approximately 1400 Ma monazite ages from north to south within the range, consistent with a similar increase in metamorphic grade. This gradient suggests that the central and northern Tusas may have been at progressively shallower crustal levels during approximately 1400 Ma tectonism, thus increasing the preservation of older fabrics, structures, and metamorphic monazite from south to north within the range. These observations support the hypothesis that approximately 1400 Ma tectonism locally reactivated and utilized pre-existing structures and fabrics, but had also profoundly shaped the geometry and metamorphic character of the orogen. JF - Abstracts with Programs - Geological Society of America PB - Geological Society of America (GSA) : Boulder, CO, United States CY - United States VL - 34 SN - 00167592 UR - http://silk.library.umass.edu/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=geh&AN=2004-044516&site=ehost-live&scope=site IS - 66 N1 - Accession Number: 2004-044516; Conference Name: Geological Society of America, 2002 annual meeting; Denver, CO, United States; Conference Date: 20021027; Language: English; Coden: GAAPBC; Collation: 1; Collation: 180; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 200413; Monograph Title: Geological Society of America, 2002 annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic JO - Abstracts with Programs - Geological Society of America ER - TY - Generic T1 - Ground truth? Relationship between lineaments and bedrock fabric T2 - Abstracts with Programs - Geological Society of America Y1 - 1989 A1 - Stephen B Mabee A1 - Hardcastle, Kenneth C. A1 - Donald U Wise KW - #StaffPubs KW - aerial photography KW - BEDROCK KW - fabric KW - faults KW - fractures KW - granites KW - ground truth KW - igneous rocks KW - joints KW - lineaments KW - Maine KW - orientation KW - pegmatite KW - plutonic rocks KW - quartz veins KW - SLAR KW - structural analysis KW - Structural geology KW - Structural geology 16 KW - United States KW - veins JF - Abstracts with Programs - Geological Society of America PB - Geological Society of America (GSA) : Boulder, CO, United States CY - United States VL - 21 SN - 00167592 IS - 66 N1 - Accession Number: 1991-043915; Conference Name: Geological Society of America, 1989 annual meeting; St. Louis, MO, United States; Conference Date: 19891106; Language: English; Coden: GAAPBC; Collation: 1; Collation: A68; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 1991; Monograph Title: Geological Society of America, 1989 annual meeting; Monograph Author(s): Dymek, Robert F. [chairperson]; Shelton, Kevin L. [chairperson]; 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 - JOUR T1 - Influence of rock fabric on fracture attribute distribution and implications for groundwater flow in the Nashoba Terrane, eastern Massachusetts JF - Journal of Structural Geology Y1 - 2008 A1 - Alex K Manda A1 - Stephen B Mabee A1 - Donald U Wise KW - #StaffPubs KW - foliation KW - fractures KW - ground water KW - Hydrogeology 21 KW - joints KW - massachusetts KW - movement KW - Nashoba terrane KW - preferred orientation KW - statistical distribution KW - structural analysis KW - Structural geology KW - style KW - terranes KW - United States AB - Attributes (i.e. trace-length, spacing, termination and orientation) of joints and foliation-parallel fractures (FPFs) are used to assess the influence of lithology and fabric on fracture type and distribution in metamorphic and igneous rocks of the Nashoba terrane, Massachusetts. Orientations of NE-SW and NW-SE trending joints are consistent throughout the region, whereas FPFs are sub-parallel to the axis of the terrane. Joint spacing generally decreases to the northeast across the terrane reflecting lithologic changes from metamorphic to igneous rock types. Although trace-length and spacing frequency distributions of both joints and FPFs are best described by lognormal functions, FPFs possess narrower fracture spacing than joints. Median fracture trace-lengths of all FPFs are comparable to those of all steep joints, but the median fracture spacing is half that of all steep joints. Trace-lengths of FPFs vary as a function of the degree of development of foliation. Fracture attributes and groundwater flow models suggest that FPFs may significantly increase fracture connectivity and potential for groundwater recharge. FPFs may account for as much as 30% of flow in fracture networks suggesting that in addition to joints, FPFs play a significant role in groundwater hydraulics that may include imparting flow anisotropy on the groundwater system. PB - Elsevier : Oxford, International CY - International VL - 30 SN - 01918141 UR - http://www.sciencedirect.com/science/article/pii/S0191814107002362 IS - 44 N1 - Accession Number: 2009-050694; Language: English; Coden: JSGEDY; Collation: 14; Publication Types: Serial; Updated Code: 200928; Reviewed Item: Analytic JO - Journal of Structural Geology ER -