%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 Conference Proceedings %B Abstracts with Programs - Geological Society of America %D 2006 %T Fracture patterns across two terrane boundaries in eastern Massachusetts; implications for regional groundwater flow and recharge %A Stephen B Mabee %A Joseph P Kopera %K #StaffPubs %K Avalon Zone %K BEDROCK %K eastern Massachusetts %K faults %K foliation %K fractures %K ground water %K Hydrogeology 21 %K joints %K massachusetts %K Merrimack Belt %K movement %K observations %K patterns %K properties %K recharge %K shear zones %K style %K terranes %K United States %X 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 %B Abstracts with Programs - Geological Society of America %I Geological Society of America (GSA) : Boulder, CO, United States %C United States %V 38 %P 434 - 434 %8 2006/10/01/ %@ 00167592 %G eng %U https://gsa.confex.com/gsa/2006AM/finalprogram/abstract_116563.htm %N 77 %! Abstracts with Programs - Geological Society of America %0 Conference Proceedings %B Abstracts with Programs - Geological Society of America %D 2006 %T A new way of looking at, and mapping, bedrock; the hydrostructural domain map of the Ayer Quadrangle, northeastern Massachusetts %A Joseph P Kopera %A Stephen B Mabee %K #StaffPubs %K aquifers %K Ayer Quadrangle %K BEDROCK %K faults %K foliation %K fracture zones %K fractures %K ground water %K Hydrogeology 21 %K joints %K mapping %K massachusetts %K measurement %K Merrimack Belt %K movement %K Nashoba terrane %K northeastern Massachusetts %K observations %K orientation %K physical properties %K recharge %K shear zones %K Structural geology 16 %K style %K United States %X 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' 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. %B Abstracts with Programs - Geological Society of America %I Geological Society of America (GSA) : Boulder, CO, United States %C United States %V 38 %P 166 - 166 %8 2006/10/01/ %@ 00167592 %G eng %U https://gsa.confex.com/gsa/2006AM/finalprogram/abstract_116561.htm %N 77 %! Abstracts with Programs - Geological Society of America %0 Journal Article %J International Journal of Rock Mechanics and Mining Sciences [1997] %D 2010 %T Comparison of three fracture sampling methods for layered rocks %A Alex K Manda %A Stephen B Mabee %K #StaffPubs %K Big Quarry %K carbonates %K case studies %K data acquisition %K data processing %K dolomite %K Door Peninsula %K fractures %K geographic information systems %K ground water %K information systems %K joints %K layered materials %K mapping %K methods %K movement %K multiple scanline method %K northeastern Wisconsin %K numerical models %K permeability %K sampling %K selection method %K simulation %K single scanline method %K statistical analysis %K Structural geology 16 %K style %K three-dimensional models %K United States %K Wisconsin %X Three methods of fracture data collection are tested against each other in layered dolomitic rocks to evaluate the effectiveness of each method in sampling fracture properties. The methods tested are the single scanline method (SSM), selection method (SM), and multiple scanline method (MSM). Finite element techniques were first used to build a base model with the exact locations, sizes and orientations of each fracture observed in the natural fracture network. Then, a second set of models were stochastically generated using statistics from each sampling technique. For each network, the overall fracture intensity was used to assess the effectiveness of each sampling technique in capturing the real fracture properties. Fracture network permeability was also calculated for each of two directions to evaluate the transmissive properties of the networks. Although all three methods produced good matches of relative intensity and permeability between natural and synthetic fractures, the results reveal that a well-placed scanline performed the best at recreating natural fractures. However, the results from one variation of the SSM were only slightly better than the results from both versions of the SM. In general, the SSM provides the best results but possibly at heavy costs in time and labor, whereas the SM gives comparable results with less expenditure of energy and time. Thus, the SM is an adequate technique and recommended for use at large outcrops or where time, access or budget constraints are a concern. %B International Journal of Rock Mechanics and Mining Sciences [1997] %I Elsevier : Oxford-New York, International %C International %V 47 %P 218 - 226 %8 2010/02/01/ %@ 13651609 %G eng %U http://www.sciencedirect.com/science/article/pii/S1365160909001804 %N 22 %! International Journal of Rock Mechanics and Mining Sciences [1997] %0 Journal Article %J Journal of Structural Geology %D 2008 %T Influence of rock fabric on fracture attribute distribution and implications for groundwater flow in the Nashoba Terrane, eastern Massachusetts %A Alex K Manda %A Stephen B Mabee %A Donald U Wise %K #StaffPubs %K foliation %K fractures %K ground water %K Hydrogeology 21 %K joints %K massachusetts %K movement %K Nashoba terrane %K preferred orientation %K statistical distribution %K structural analysis %K Structural geology %K style %K terranes %K United States %X 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. %B Journal of Structural Geology %I Elsevier : Oxford, International %C International %V 30 %P 464 - 477 %8 2008/04/01/ %@ 01918141 %G eng %U http://www.sciencedirect.com/science/article/pii/S0191814107002362 %N 44 %! Journal of Structural Geology