@proceedings {271, title = {Arsenic in central Massachusetts bedrock and groundwater}, volume = {42}, year = {2010}, note = {Accession Number: 2011-044094; Conference Name: Geological Society of America, 2010 annual meeting; Denver, CO, United States; Conference Date: 20101031; Language: English; Coden: GAAPBC; Collation: 2; Collation: 216-217; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 201125; Monograph Title: Geological Society of America, 2010 annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic}, month = {2010/11/01/}, pages = {216 - 217}, publisher = {Geological Society of America (GSA) : Boulder, CO, United States}, address = {United States}, abstract = {Across the New England "arsenic belt," groundwater arsenic (As) concentrations often exceed the EPA{\textquoteright}s 0.01-mg/L drinking water standard. In overburden groundwater at a site within this belt in north-central Massachusetts, As has been reported at levels up to 7.6 mg/L. Bedrock at the site consists of Silurian Central Maine Terrane metasediments intruded by the Devonian Ayer granodiorite and Chelmsford granite. Exchange of hydrothermal fluids between these lithologies during intrusion and later deformation, faulting, and metamorphism resulted in crystallization of arsenic-bearing minerals, including arsenopyrite. Quaternary deglaciation and unloading dilated joint systems in the bedrock, allowing increased exposure of the mineralogy to meteoric water. Several arsenopyrite alteration products (e.g., scorodite), of varying solubilities, precipitated on fracture surfaces and along grain boundaries between major phases. In the emerging conceptual model for this site, groundwater is recharged in bedrock uplands and moves downgradient through the fracture network, becoming increasingly reducing as it moves along a flow path. Arsenic dissolved from arsenopyrite and arsenic-bearing alteration phases in bedrock remains in solution until the groundwater discharges to lowland areas hydraulically downgradient. In these adjacent lowlands, glacial sand and gravel overburden lies above the bedrock. When the reducing water reaches more oxidizing conditions, As-sorbing hydrous ferric oxides (HFO) precipitate out on the aquifer solids, resulting in accumulation of As in the deep overburden aquifer. A large landfill at this site, now closed and capped, imposed reducing conditions, and As is mobilized into groundwater by reductive dissolution of the HFO. The presence of elevated As in groundwater is consistent with arsenic-bearing phases generated in granitoids at depth during regional metamorphism, which were subsequently altered, and are being solubilized at present by the circulation of shallow groundwater through varying redox environments. This scenario is supported by geochemical and petrographic studies of the granitoids and the occurrence of the highest groundwater and soil arsenic concentrations in the adjacent deep overburden.}, keywords = {$\#$StaffPubs, alteration, arsenic, arsenides, arsenopyrite, Ayer Granodiorite, BEDROCK, central Massachusetts, chelmsford granite, Devonian, dilation, discharge, dissolved materials, drinking water, Eh, fractures, General geochemistry 02A, geochemistry, granites, ground water, igneous rocks, joints, massachusetts, metals, metamorphism, meteoric water, overburden, Paleozoic, petrography, plutonic rocks, pollutants, reduction, solubility, solution, sulfides, theoretical models, United States}, isbn = {00167592}, url = {https://gsa.confex.com/gsa/2010AM/finalprogram/abstract_182430.htm}, author = {McTigue, David F. and Stein, Carol L. and Brandon, William C. and Joseph P Kopera and Keskula, Anna J. and Koteas, G. Christopher} } @proceedings {294, title = {Fracture characterization of crystalline bedrock for groundwater investigations; an example from the Marlborough Quadrangle, Massachusetts}, volume = {36}, year = {2004}, note = {Accession Number: 2005-077195; Conference Name: Geological Society of America, Northeastern Section, 38th annual meeting; Geological Society of America, Southeastern Section, 53rd annual meeting; Washington, DC, United States; Conference Date: 20040325; Language: English; Coordinates: N421800N421800W0713000W0713000; Coden: GAAPBC; Collation: 1; Collation: 113; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 200524; Monograph Title: Geological Society of America, Northeastern Section, 38th annual meeting; Geological Society of America, Southeastern Section, 53rd annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic}, month = {2004/03/01/}, pages = {113 - 113}, publisher = {Geological Society of America (GSA) : Boulder, CO, United States}, address = {United States}, abstract = {Integration of a wide array of structural data with well-field hydrologic testing is increasingly recognized as a critical step in understanding groundwater flow behavior and recharge in crystalline bedrock aquifers (Lyford et al., 2003, Walsh and Lyford, 2002). The Marlborough Quadrangle, about 40 km west of Boston, was selected as a test case of how a state geological survey can most effectively and efficiently collect and present such data in order to better constrain conceptual models of groundwater flow in general and to be of maximum use for hydrologists and consultants working on specific local problems. In this study, 3200 structural measurements were taken by a two-person team over a nine-week period at 68 stations distributed throughout the quadrangle and keyed into a GIS database. Specialized data sheets allowed efficient recording and digitization of orientations, lengths, spacing and mineralization, and separation of various classes of joints and veins. Fault data also included motion direction and sense. Summary maps in GIS format include standard geologic map bases overlain by typical rose diagrams and stereograms and maps such as fracture domains and trajectories, sheeting distribution, foliation trajectories, bedrock elevations, generalized piezometric surface configuration, and overburden type and thickness with separations into permeability class. Geology of the quadrangle can be separated into three zones: (a) north of the Assabet River Fault (ARF), (b) the area between the ARF and 1.5 km-wide Bloody Bluff Fault Zone (BBFZ), and (c) south of the BBFZ. Generalized foliations in the zones are: (a) 215, 50N, (b) 240, 65N, and (c) 270, 45N. Two pervasive, steeply-dipping (>60 degrees ) fracture sets occur throughout the quadrangle: an older 150 degrees set that includes sulfide-bearing veins and fracture surfaces along the ARF and a 015 degrees set of largely unmineralized common joints, macrojoints (>3 m length) and joint zones (av. 1.2 m width). Sheeting and unloading joints are generally coincident with shallow dipping foliation in (c) but cross-cut foliation in (a) and (b). We believe this approach will provide hydrologists and consultants with basic framework data that will expedite and improve the planning of subsurface investigations, construction activities and groundwater exploration.}, keywords = {$\#$StaffPubs, aquifers, Assabet River Fault, BEDROCK, characterization, controls, crystalline rocks, fractured materials, fractures, geographic information systems, ground water, Hydrogeology 21, hydrology, information systems, joints, Marlborough Quadrangle, massachusetts, Middlesex County Massachusetts, permeability, preferential flow, recharge, style, testing, theoretical models, United States}, isbn = {00167592}, url = {https://gsa.confex.com/gsa/2004NE/finalprogram/abstract_70321.htm}, author = {Scott A Salamoff and Stephen B Mabee and Joseph P Kopera and Donald U Wise} } @proceedings {296, title = {Fracture patterns across two terrane boundaries in eastern Massachusetts; implications for regional groundwater flow and recharge}, volume = {38}, year = {2006}, note = {Accession Number: 2010-054322; Conference Name: Geological Society of America, 2006 annual meeting; Philadelphia, PA, United States; Conference Date: 20061022; Language: English; Coden: GAAPBC; Collation: 1; Collation: 434; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 201030; Monograph Title: Geological Society of America, 2006 annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic}, month = {2006/10/01/}, pages = {434 - 434}, publisher = {Geological Society of America (GSA) : Boulder, CO, United States}, address = {United States}, abstract = {The integration of structural data and field-based observations is becoming increasingly critical in understanding groundwater flow behavior and recharge potential. Over the past 3 years, the Office of the Massachusetts State Geologist (OMSG) has collected 8225 fracture measurements from 187 stations across 3 adjacent quadrangles as part of its bedrock geologic mapping program. These data provide a north-south transect across the Nashoba Terrane and its boundaries with the Merrimack Belt and Avalon Terranes in eastern Massachusetts. Areas with similar fracture patterns can be grouped into "hydrostructural domains" with distinct hydrogeologic properties. Within the above transect, hydrostructural domains were observed to closely correspond with bedrock lithology and ductile structure, and therefore, tectonic history. Such domains are commonly bounded by faults or intrusive contacts. Common features observed across all domains include a NE-striking regional foliation with corresponding NW-striking, steeply-dipping cross-joints. Strongly layered metasedimentary and metavolcanic rocks of the Merrimack Belt and the Marlborough Formation in the Nashoba Terrane tend to have the most pervasive and closely-spaced foliation-parallel fractures (FPF). Foliation intensity and FPF generally increases towards shear zones and regional fault systems, especially within granites and gneisses. The moderate to steeply dipping, well-developed FPF in these rocks provides a potentially excellent conduit for vertical recharge and a strong NE-trending regional anistropy that may control groundwater flow. Granitoidal rocks have very consistent NS-EW orthogonal networks of vertical fractures and subhorizontal sheeting joints, providing excellent potential for vertical recharge and near-surface lateral flow. Features such as small brittle faults, fracture zones, fold axes, and fracture sets distinct to each domain may dominate local groundwater flow and recharge. Abstract 116563 modified by 72.70.224.253 on 7-12-2006}, keywords = {$\#$StaffPubs, Avalon Zone, BEDROCK, eastern Massachusetts, faults, foliation, fractures, ground water, Hydrogeology 21, joints, massachusetts, Merrimack Belt, movement, observations, patterns, properties, recharge, shear zones, style, terranes, United States}, isbn = {00167592}, url = {https://gsa.confex.com/gsa/2006AM/finalprogram/abstract_116563.htm}, author = {Stephen B Mabee and Joseph P Kopera} } @proceedings {351, title = {The influence of ductile structure and rheological heterogeneity on brittle structures as exhibited by Avalonian granites in southeastern Massachusetts}, volume = {40}, year = {2008}, month = {03/2008}, pages = {3}, publisher = {Geological Society of America (GSA) : Boulder, CO, United States}, edition = {2}, address = {Buffalo, NY}, abstract = {The orientation and geographic distribution of joints, veins, and brittle faults show a conspicuous correlation with the heterogeneous distribution of foliation and lineation intensity in Neo-Proterozoic granites and their deformed counterparts in southeastern Massachusetts. Field mapping and stereonet analysis of brittle and ductile structural data collected during 1:24,000-scale geologic mapping of the Milford quadrangle yielded the following general observations, which suggest that the ductile deformational history of this region appears to have strongly influenced the later development of brittle structures in the same rocks: The behavior of these fractures in relation to ductile structure have implications for rheological constraints on tectonic models of the post-Alleghenian core of the New England Appalachians, hydrogeologic models of regional fractured bedrock aquifers, and the interpretation of topographic lineaments.}, keywords = {$\#$StaffPubs, acadian, alleghenian, avalon, BEDROCK, dikes, foliation, fracture, fracture system, fracture trace, fractures, granite, granites, Hopkinton, joints, l-tectonites, lineaments, lineation, Milford, Upton}, url = {https://gsa.confex.com/gsa/2008NE/finalprogram/abstract_134899.htm}, author = {Joseph P Kopera} } @proceedings {267, title = {A new way of looking at, and mapping, bedrock; the hydrostructural domain map of the Ayer Quadrangle, northeastern Massachusetts}, volume = {38}, year = {2006}, note = {Accession Number: 2008-100620; Conference Name: Geological Society of America, 2006 annual meeting; Philadelphia, PA, United States; Conference Date: 20061022; Language: English; Coden: GAAPBC; Collation: 1; Collation: 166; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 200816; Monograph Title: Geological Society of America, 2006 annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic}, month = {2006/10/01/}, pages = {166 - 166}, publisher = {Geological Society of America (GSA) : Boulder, CO, United States}, address = {United States}, abstract = {While traditional bedrock geologic maps contain valuable information, they commonly lack data on fractures and physical properties of the rock. The increased need for better understanding of groundwater behavior in bedrock aquifers has made this data critical. Hydrostructural domain maps reclassify bedrock based on fracture systems and physical properties that may have implications for groundwater flow and recharge. These maps are constructed from detailed field observations and measurements of 2000-3000 fractures from 60-70 stations across a 7.5{\textquoteright} quadrangle. Hydrostructural domains are displayed on the map as traditional lithologic units would be, with detailed descriptions and photos of the fracture characteristics and physical properties of each hydrostructural "unit". In the Ayer Quadrangle, such domains closely correspond with bedrock lithology and ductile structural history. Steeply dipping metasedimentary rocks of the Merrimack Belt have pervasive, closely spaced, throughgoing fractures developed parallel to foliation, and therefore provide an excellent potential for vertical recharge. Where these rocks are intensely cut by a strong subhorizontal cleavage, a parallel fracture set dominates providing an opportunity for lateral flow. Massive granites generally have a well developed, widely-spaced orthogonal network of fracture zones which may provide excellent local recharge. High-grade gneisses of the Nashoba Terrane have poorly developed fracture sets except near regional shear zones, where foliation parallel fractures and cross-joints may provide good vertical recharge and provide a strong northeast trending flow anisotropy. These maps are intended to provide a regional-scale information to assist in site-specific groundwater investigations. We believe that such maps are an example of how new types of geologic maps can, and must, be developed to address changing societal needs.}, keywords = {$\#$StaffPubs, aquifers, Ayer Quadrangle, BEDROCK, faults, foliation, fracture zones, fractures, ground water, Hydrogeology 21, joints, mapping, massachusetts, measurement, Merrimack Belt, movement, Nashoba terrane, northeastern Massachusetts, observations, orientation, physical properties, recharge, shear zones, Structural geology 16, style, United States}, isbn = {00167592}, url = {https://gsa.confex.com/gsa/2006AM/finalprogram/abstract_116561.htm}, author = {Joseph P Kopera and Stephen B Mabee} } @Map {219, title = {Preliminary bedrock geologic Map of the Milford quadrangle}, year = {2007}, publisher = {Massachusetts Geological Survey}, edition = {OFR-07-01}, abstract = {

Fracture Characterization Map is included as sheets 2 and 3. Water Resources data included as sheet 4.

GIS and metadata forthcoming

}, keywords = {$\#$BedrockMaps, $\#$FractureMaps, $\#$MGSPub, acadian, alaskite, alleghenian, amphibolite, antiform, Ashland, avalon, bedrock map, blackstone, fracture, GEOLOGIC MAP, gneiss, granite, Holliston, hopedale quartzite, Hopkinton, ironstone diorite, joints, l-tectonite, Mendon, MGS Publication, Milford, neoproterozoic, Northbridge, proterozoic, quarries, quartzite, Upton, Westborough}, author = {Joseph P Kopera and Shaw, C.E. and Fernandez, M.} }