U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Bedrock Geologic Map of the Worcester South Quadrangle, Worcester County, Massachusetts [Scale 1:24,000] by Gregory J. Walsh (1) and Arthur J. Merschat (2) Scientific Investigations Map 3345 2015 version 1.0 Prepared in cooperation with the Commonwealth of Massachusetts, Massachusetts Geological Survey ________________________________ (1) U.S. Geological Survey Montpelier, Vermont 05601 (2) U.S. Geological Survey Reston, Virginia 20192 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Source of Geologic Data: Original data. Geology mapped by Walsh and Merschat, 2008-2010. Assisted by Jamie Kendall in 2009. Additonal data sources consulted included: Grew, E.S., 1970, The geology of Pennsylvanian and pre-Pennsylvanian rocks of the Worcester area, Massachusetts: Cambridge, Mass., Harvard University, Ph.D. thesis, 263 p., scale 1:24,000. and Unpublished data sources including provisional maps by P.J. Barosh by H.R. Dixon. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This report is available online from: http://dx.doi.org/10.3133/sim3345 OR U.S. Geological Survey Information Services Box 25286, Denver Federal Center Denver, CO 80225 1-888-ASK-USGS http://ask.usgs.gov/ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The map was compiled from the GIS database of this report. The GIS database was compiled in ArcGIS version 10.0. Topographic base is from the U.S. Geological Survey, Worcester South, MASS., 1973, except I-395 south of Route 20 from Worcester South, MASS. 2012. Digital cartography was compiled in Adobe Illustrator version CS5 or later. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Suggested Citation: Walsh, G.J., and Merschat, A.J., 2015, Bedrock geologic map of the Worcester South quadrangle, Worcester County, Massachusetts, U.S. Geological Survey Scientific Investigations Map 3345, 1 sheet, scale 1:24,000, http://dx.doi.org/10.3133/sim3345. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Directory layout: http://dx.doi.org/10.3133/sim3345 -SIM3345.PDF---Sheet 1 Geologic map (37.1" tall x 62.4" wide) -README.TXT---ASCII text description (this file) -METADATA---Metadata files in html, txt, and xml formats -SIM3345.ZIP---Compressed GIS database files -SIM3345_withoutphotos.ZIP---compressed database files without photographs | |Zip file contains ArcGIS shapefiles and basemap image files and worldfiles | |---GoogleEarth---Folder contains KMZ files of GIS data layers | |---PHOTOS---Folder contains 499 photographs of the geology and landscape | |---SYMBOLS---Supporting files for structure symbols; used in Arc/Info ArcPlot ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ A subset of the contents of this readme.txt file are also included in the metadata for this report. This readme.txt, however, contains greater detail than the metadata. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Description: The bedrock geology of the 7.5-minute Worcester South quadrangle, Massachusetts, consists of deformed Neoproterozoic to Paleozoic crystalline metamorphic and intrusive igneous rocks in three fault-bounded terranes, or zones, including the Avalon, Nashoba, and Merrimack zones (Zen and others, 1983). This quadrangle spans the easternmost occurrence of Ganderian margin arc-related rocks (Nashoba zone) in the southern New England part of the northern Appalachians, and coincides with the trailing edge of Ganderia (Merrimack and Nashoba zones) where it structurally overlies Avalonia (Hibbard and others, 2006; Pollock et al., 2012; van Staal and others, 2009, 2012). Neoproterozoic intrusive rocks and minor metasedimentary and metavolcanic rocks crop out in the Avalon zone and structurally underlie the rocks of the Nashoba zone along the Bluddy Bluff fault. Due to poor exposure, the position of the Bloody Bluff fault is not well-constrained and its location is partly extrapolated from mapping in adjacent areas (Barosh, 2005; Walsh and others, 2011a). Cambrian to Silurian intrusive, metasedimentary, and metavolcanic rocks crop out in the Nashoba zone, and are overlain by Silurian metasedimentary rocks of the Merrimack zone along the Clinton – Newbury fault. Silurian to Mississippian plutonic rocks intrude the Merrimack and Nashoba zone rocks. Paleozoic metamorphism in the Merrimack and Nashoba zones peaked during Salinic, Acadian, and Neoacadian orogenesis from Silurian to Mississippian times (for example, Wintsch and others, 2007; Stroud et al., 2009; Walsh et al., 2011a; Hepburn et al., 2014). Metamorphism in the Avalon zone peaked during Alleghanian orogenesis in the Mississippian to Permian (Wintsch and others, 1992, 1993, 2001; Attenoukon, 2008). Evidence for garnet-grade extensional Alleghanian mylonitization showing normal motion along the Clinton – Newbury fault occurred after presumed original terrane juxtaposition by left-lateral Acadian thrusting (for example, Goldstein, 1994). Subsequent post-peak metamorphic deformation produced outcrop-scale open folds and weak cleavage, local faults, veins, shear bands, and pegmatite dikes. Late Paleozoic to Mesozoic largely brittle normal motion, locally along re-activated ductile faults and along the Wekepeke fault, led to the current configuration of fault-bounded lithotectonic terranes (for example Goldstein, 1982, 1994, 1998; Goldstein, and Hepburn, 1999; Goldsmith, 1991; Attenoukon, 2008; Wintsch and others, 2012). The youngest deformation includes kink bands, brittle faults, and joints. The bedrock geology was mapped to study the tectonic history of the area and to provide a framework for ongoing hydrogeologic characterization of the fractured bedrock of Massachusetts. This report presents mapping by G.J. Walsh and A.J. Merschat from 2008-2010. The report consists of a map and GIS database. The map is available as a downloadable electronic file. The GIS database is available for download. The database includes contacts of bedrock geologic units, faults, outcrops, structural information, and photographs. The geology was mapped during 2009-2010 at a scale of 1:24,000. The bedrock geology was mapped using standard techniques. Location information was collected with a GPS receiver (GPS model: Garmin eTrex Venture) The line and polygon data were compiled in Adobe Illustrator over the topographic basemap. Field sheets were scanned and registered in Illustrator. Line and polygon data were exported from Illustrator in DXF format to Arc/Info version 10.0. Point data were collected with GPS receievrs. Point attribure data were entered into an Excel spreadsheet and imported to ArcGIS version 10.0 and joined with GPS point data to create shapefiles. The GPS data were collected in Latitude and Longitude in decimal degrees in WGS84 datum. GPS data were projected to the Massachusetts Stateplane coordinate system (FIPS Zone 2001) in NAD83 datum, with units in meters. GPS locations were compared to the topographic basemap of the area and repositioned to match the base. The original coordinates remain in the STRUCTURE database. After editing in Arc/Info, all arcs, polygons, and points were converted to shapefiles in ArcCatalog. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Direct questions or comments on this report to: Gregory J. Walsh U.S. Geological Survey P.O. Box 628 Montpelier, Vermont 05601 Tel: 802-828-4528 e-mail: gwalsh@usgs.gov ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Date of latest revision: January 07, 2015 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The GIS data associated with this report are provided in two common GIS formats: ArcGIS Shapefile and GoogleEarth KMZ The GIS data were created in ArcGIS version 10.0 on an Dell PC running Windows 7 OS. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Note on Metadata: FGDC compliant metadata for the report exist in several file formats. These metadata files were created with the mp metadata tool available from: http://geology.usgs.gov/tools/metadata/ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Digital data are in: Massachusetts State Plane Coordinate System (FIPS Zone 2001) in NAD83 datum units in meters ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Computer Files: Some files have been archived into "zip" files. Useful URL: http://www.7-zip.org/ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ******************************************************************** The following is a brief description of the geologic data layers, tables, and non-standard attributes used in this report. ******************************************************************** CONTX - Data layers for bedrock geologic map units and contacts. CONTX is divided into 4 shapefiles for polygons, labels, tic marks, and arcs: wo_contx_polygon.shp wo_contx_label.shp wo_contx_tic.shp wo_contx_arc.shp Polygons - wo_contx_polygon.shp Lookup table - wo_contx_lookup.xls Bedrock lithology attribute lookup table. The lookup has been joined in the polygon shapefile. Lookup items: CODE = map unit designator (same as LITH_UNIT) AGE_SORT = order to sort by age (1 = youngest) LITH_UNIT = map unit designator SURF_BED = surficial or bedrock unit LITHPRI = primary lithology in the map unit LITHSEC = secondary lithology in the map unit ZONE = Merrimack, Avalon or Nashoba zone (or terrane) FORMATION = formation name MEMBER = member name ROCKCLASS = rock type AGE = geologic age of the map unit FOSSIL = Yes means the unit contains fossils outside the map area Labels - wo_contx_label.shp Items: CODE - Bedrock geologic map unit code (polygon label) LITH_UNIT - same as CODE Tic marks - wo_contx_tic.shp 4 corner tic marks from Mass GIS: MassGIS is the Commonwealth's Office of Geographic and Environmental Information http://www.mass.gov/mgis/massgis.htm 1613 1614 + + + + 1513 1514 Corner tic marks from the statewide coverage of USGS 7.5-minute quadrangles. Arcs - wo_contx_arc.shp Line data layer of geologic contacts Items: TYPE - fault or contact NAME - names of faults LINETYPE - type of faults or contacts, entries used in this database: contact contact concealed fault normal fault normal fault concealed scratch thrust fault thrust fault concealed _________________________________________________________________ EXPOSURE - wo_exposure.shp Unattributed polygon data layer of bedrock outcrops examined during mapping _________________________________________________________________ STRUCTURE - wo_structure_point.shp & wo_ptscarto.e00 Note: wo_ptscarto.e00 is an ArcInfo coverage of the structural geology points, and represents a subset of the full data in the shapefile. The coverage was used for plotting structural symbols shown on the geologic map. Symbols were plotted in ArcPlot, ArcInfo Workstation 10.0. Point data layer of ductile and brittle structural geology Items: STATION - Number of field station TYPE - Refers to the general type of geologic feature. Valid entries include 'planar', 'linear', or 'other' SUB_TYPE - Refers to the specific geologic structure STRIKE - Angle measured from North in right-hand rule, units in degrees. DIP - Dip value (planar data) or plunge value (linear data), units in degrees DIPDIR - Direction of dip (planar data) or trend (linear data), units in degrees FRACTURE - 'Y' indicates feature is a fracture PARTING - 'Y' indicates the planar feature exhibits parting or fracturing parallel to the surface measured SYMBOL - Arc/Info symbol number THROUGHOI - 'Y' indicates the measured brittle feature is throughgoing and passes through the entire outcrop. REL_AGE - Refers to the relative age of ductile fabrics. Valid entries include: n = Relative age is the dominant fabric, S2 n+1 = maybe S2 or S3 n+2 = probably S3 FAULTMOV - movement sense of brittle fault Valid entries include: normal, reverse, left lateral, right lateral, thrust NO_MSMTS - Number of features with same orientation. Valid for SUB_TYPE = 'joint' and 'joint set'. TERMINATIO - Termination of joints where known valid entries include: 'blind', 'abutting', 'crossing' TOPOFEAT - Topographic feature parallel to a geologic structure. Valid entries include: 'canyon', 'cliff', 'slope', and 'stream' LITH_NOTE - Freeform text indicating the rock type in which the feature was measured. Used for rock type of dikes and sills, and locations where multiple rock types occur at one station SYMBOL - Refers to the symbol number from the GEOLOGY1.MRK markerset; used for plotting in ArcInfo Workstation ArcPlot. SYMBOL_ANG - Refers to a standard Cartesian angle measured from East; used for symbol rotation and plotting in ArcPlot, units in degrees Note -- The following three diagrams show an explanation of the geometry of STRIKE, DIPDIR, and SYMBOL_ANG: For STRIKE and DIPDIR: 0 North = 0 | East = 90 270 -----|----- 90 South = 180 | West = 270 180 For SYMBOL_ANG: 90 North = 90 | East = 0 180 -----|----- 0 South = 270 | West = 180 270 SYMBOL_ANG is used for symbol rotation. In ARC/INFO calculate pseudo item $angle = symbol_ang Planar symbols with symbol_ang = 0 look like this: __________ \/ Linear symbols with symbol_ang = 0 look like this: -----> ROTATION - Rotation sense of minor folds as viewed down plunge. Valid entries: 'cc' = counterclockwise and 'cw' = clockwise (not used in this report) SPACING - Spacing of joints in joint sets, units in meters (not used in this report) WIDTH - Width or thickness of dike or vein, units in meters MIN1 - Primary mineral MIN2 - Secondary mineral MIN3 - Tertiary mineral Note on MIN1, MIN2, and MIN3 -- The aforementioned 3 items are used to describe minerals in veins or mineral lineations. Coordinate information in LATitude and LONGitude: LAT - Raw GPS decimal degrees (WGS84 datum) LONG - Raw GPS decimal degrees (WGS84 datum) POINT_X - Edited location in meters (Massachusetts State Plane Coordinate System, FIPS Zone 2001, NAD83 datum) POINT_Y - Edited location in meters (Massachusetts State Plane Coordinate System, FIPS Zone 2001, NAD83 datum) ____________________________________________________________ FOLDS - wo_folds.shp Line coverage of axial traces of folds Items: FOLD_TYPE - Valid entries include: 'inferred overturned F1 anticline' 'inferred overturned F1 syncline' PLUNGE_DIR - cardinal direction of plunge of fold ____________________________________________________________ PHOTO - wo_photos.shp Point data layer of photographs; includes landscape and outcrop photos PHOTO.PAT items: STATION - Number of field station TYPE - Valid entries include 'other' SUB_TYPE - Refers to the specific geologic feature, in this case 'photo'. PHOTO_FILE - Filename of JPG format color photograph Used for hyperlinks Note - The PHOTO shapefile is designed for use with the ArcMap hyperlink tool. There are 499 digital photos located in the PHOTOS directory. Users can copy the photos to the same directory as the shapefile, or copy the photos to their own folder and then specify the path: In ArcMap 10.0 - File, Map Document Properties, Hyperlink Base ____________________________________________________________ ISOGRADS - Data layers for metamorphic iosgrads and metamorphic facies boundaries. The lines are depicted on the PDF sheet on the geologic map and the metamorphic map. The polygons are only depicted on the metamorphic map. Divided into 2 shapefiles for arcs and polygons: wo_isograds_arc.shp wo_isograds_polygon.shp wo_isograds_arc.shp: Lines of metamorphic isograds or bounadaries between different metamorphic facies. Some lines, such as faults, are metamorphic boundaries and not true isograds. Items: Linetype - specific line type biotite - biotite isograd garnet - garnet isograd normal fault - fault boundary between different metamorphic facies quadrangle border - limt of study retrograde greenschist - area of retrograde greenschist metamorphic overprint on amphibolite facies rocks of the Nashoba Formation in the footwall of the Clinton-Newbury fault. staurolite - staurolite isograd thrust fault - major thrust faults Type - general line type isograd - isograd fault - fault scratch - scratch boundary wo_isograds_polygon.shp: Polygons showing different metamorphic zones or facies: Items: Zone - Valid entries include: Biotite Chlorite Garnet Retrograde Sil-Kfs Sil-Kfs Staurolite ************************************************************************ The following is a description of the basemap in this report: The basemap consists of: Four files in TIFF format bitmaps with worldfiles wo_hypsography.tif - Hypsography - brown separate with elevation contours, 1973 wo_hydrology.tif - Surface water - blue separate, 1973 wo_culture.tif - Primary culture originally on black and red separates includes roads, buildings, etc., 1973 wo_I395.tif - I-395 south of U.S. Route 20, 2012 Three black and white bitmap images in uncompressed TIFF format are from the USGS 7.5-minute Worcester South, Mass., topographic map (1973). On the PDF map (sheet 1) I-395 south of Route 20 is from the Worcester South, Mass. map of 2012. For the geologic map, it was necessary to revise Interstate 395 south of Route 20 because the location shown on the 1973 map was listed as the proposed location of Route 52. The location shown on the 2012 map differs from the proposed route on the 1973 map All images are registered to the 4 corner tics. ___________________________________________________________________________ SYMBOLS - ---SYMBOLS---ArcPlot and ArcMap symbols used for plotting structure data and symbolizing the map. Includes a PDF file showing structure symbol defintions used in this project and a custom True Type Font (a glossary). The structural data included in wo_structure_points.shp was converted to an an ArcInfo coverage (see the wo_ptscarto.e00 interchange file). The coverage wo_ptscarto is a subset of the complete data in the shapefile and was used for creating the cartographic representation of the structural geology data on the geologic map (PDF). The structural geology symbols and their annotation dip values shown on Sheet 1 were plotted in ArcPlot using custom routines in ArcInfo workstation and custom geology markerset and IGL fonts. An ArcPlot .gra file was converted to an .eps file and imported to Adobe Illustrator. The ArcInfo markerset (geology1.mrk) and IGL fonts (fnt025 to fnt040) are included in the symbols folder. Also included, but not used on this map, is a custom True Type font (USGSGeoNAB-Regular.ttf) which can be added and used in conjunction with the published FGDC fonts in ArcMap. Arcmap layer (*.lyr) files are also provided for symbolizing polygons and arcs (see the GIS folder). The lead author developed these symbols and definitions during the process of converting data from ESRI ArcInfo workstation to ArcGIS shapefile formats. This is an ongoing process, and one that is currently necessary in the shift towards a standard data model. In the opinion of the lead author, the use of custom ArcInfo author-defined macros and symbols enables much faster plotting and editing of structural geology data than is currently possible in ArcGIS ArcMap. Users can contact the lead author with any questions or problems with the use of these symbols. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ END