%0 Conference Proceedings %B AGU Fall Conference, 2005 %D 2005 %T Field mapping and fracture characterization techniques predict groundwater preferential flow paths in fractured bedrock aquifers, Nashoba Terrane, MA %A Alex K Manda %A Stephen B Mabee %A Hubbs, S. A. %K #StaffPubs %K aquifers %K BEDROCK %K characterization %K fractured materials %K fractures %K ground water %K Hydrogeology 21 %K mapping %K massachusetts %K Middlesex County Massachusetts %K movement %K Nashoba terrane %K patterns %K preferential flow %K recharge %K reservoir properties %K substrates %K United States %X A study examining the relationship between fracture characteristics and groundwater was undertaken in the crystalline Nashoba Terrane of eastern Massachusetts. The Nashoba Terrane, a fault-bounded, highly deformed sliver of Paleozoic igneous and metamorphic rocks, covers an area of 600 sq km about 50 km northwest of Boston. Increasing industrial development coupled with population growth place significant pressure on developers to provide sufficient potable water for the population. To aid water development and management, this study examined fracture characteristics at regional, quadrangle and wellfield scales. The regional-scale work involved recording over 4000 structural measurements from 80 outcrops in the terrane. Fracture information recorded at each data station included strike and dip, trace length, spacing, termination, and fracture type. Preliminary results show that hydrostructural domains can be defined from combinations of fracture characterization and rock types. These domains are used to conceptualize general groundwater flow patterns in the subsurface: steeply dipping fractures, such as partings parallel to foliation enhance recharge potential and impose strong flow anisotropy. A different character is observed if steeply dipping joints intersect sheeting joints. In this instance, both recharge and lateral flow will be enhanced and flow anisotropy will be reduced. The distribution and intensity of particular fracture sets varies as a function of rock type, proximity to major features and local stress states. Partings parallel to foliation are prevalent in gneissic rocks whereas sheeting joints are more common in igneous rocks. Common joints are the most prevalent fractures, present in all rock types across the entire terrane. Quadrangle and wellfield scale data can be used to validate the regional-scale conceptual models. A comprehensive well-yield database was created to test the proposed models. Over 500 water wells in the terrane were evaluated to determine regions with high and low yield. The findings were evaluated in terms of location with respect to newly defined hydrostructural domain maps at both regional and quadrangle scales. Application of these hydrostructural domains in field studies can be useful not only in characterizing fracture intensity and distribution, but can shed more light on the potential of intersecting subsurface zones that could be exploited for economic gain. %B AGU Fall Conference, 2005 %7 Special supplement %I American Geophysical Union : Washington, DC, United States %C United States %V 86 %P 1477 %8 2005/12/01/ %@ 00963941 %G eng %N 52, Suppl.52, Suppl. %! Eos, Transactions, American Geophysical Union %0 Conference Proceedings %B Abstracts with Programs - Geological Society of America %D 2004 %T Fracture characterization of crystalline bedrock for groundwater investigations; an example from the Marlborough Quadrangle, Massachusetts %A Scott A Salamoff %A Stephen B Mabee %A Joseph P Kopera %A Donald U Wise %K #StaffPubs %K aquifers %K Assabet River Fault %K BEDROCK %K characterization %K controls %K crystalline rocks %K fractured materials %K fractures %K geographic information systems %K ground water %K Hydrogeology 21 %K hydrology %K information systems %K joints %K Marlborough Quadrangle %K massachusetts %K Middlesex County Massachusetts %K permeability %K preferential flow %K recharge %K style %K testing %K theoretical models %K United States %X 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. %B Abstracts with Programs - Geological Society of America %I Geological Society of America (GSA) : Boulder, CO, United States %C United States %V 36 %P 113 - 113 %8 2004/03/01/ %@ 00167592 %G eng %U https://gsa.confex.com/gsa/2004NE/finalprogram/abstract_70321.htm %N 22 %! Abstracts with Programs - Geological Society of America %0 Journal Article %J Ground Water %D 2002 %T Correlation of lineaments to ground water inflows in a bedrock tunnel %A Stephen B Mabee %A Curry, Patrick J. %A Hardcastle, Kenneth C. %K #StaffPubs %K aquifers %K BEDROCK %K construction %K eastern Massachusetts %K Engineering geology 30 %K Framingham Quadrangle %K ground water %K hydrodynamics %K Hydrogeology 21 %K lineaments %K massachusetts %K Middlesex County Massachusetts %K Natick Quadrangle %K tectonics %K tunnels %K United States %X Lineaments derived from three image types (1:80,000 black and white, 1:58,000 color infrared, and 1:250,000 side-looking airborne radar) were compared to water-bearing features within a 9.6 km section of tunnel being constructed through foliated crystalline metamorphic bedrock in a glaciated region of eastern Massachusetts. Lineaments drawn by three observers during two independent trials (N = 9137) were reduced to three sets (one per image type) of coincident lineaments (N = 794). Thirty-five coincident lineaments crossed the tunnel. Nineteen discrete flow zones, each producing ≥ 19 L/min, were identified in the tunnel and used to quantify the reliability of lineament analysis as a method of predicting water-bearing features in glaciated metamorphic rocks. Thirteen (68%) of the flow zones correlate with coincident lineaments, six zones correlate with more than one image type, and one zone correlates with all three image types. Overall, without additional corroborating evidence, it is difficult to interpret in advance which lineaments will result in a successful correlation with water-producing zones in the subsurface and which ones will not. Most of the observed flow (80%) correlates with northwest-trending coincident lineaments; however, the majority of the flow (67%) associated with these lineaments is produced from structures that strike to the north or northeast. In addition, only 15 of the 35 coincident lineaments correlate with the flow zones, indicating that 20 lineaments are not associated with any appreciable flow. Six flow zones are undetected by the lineament analysis. %B Ground Water %I National Ground Water Association : Urbana, IL, United States %C United States %V 40 %P 37 - 43 %8 2002/02/01/ %@ 0017467X %G eng %U http://onlinelibrary.wiley.com/doi/10.1111/j.1745-6584.2002.tb02489.x/abstract %N 11 %! Ground Water