Generalized lithology and lithogeochemical character of near-surface bedrock in the New England region

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Title:
Generalized lithology and lithogeochemical character of near-surface bedrock in the New England region
Abstract:
This geographic information system (GIS) data layer shows the dominant lithology and geochemical, termed lithogeochemical, character of near-surface bedrock in the New England region covering the states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. The bedrock units in the map are generalized into groups based on their lithological composition and, for granites, geochemistry. Geologic provinces are defined as time-stratigraphic groups that share common features of age of formation, geologic setting, tectonic history, and lithology.
This data set incorporates data from digital maps of two NAWQA study areas, the New England Coastal Basin (NECB) and the Connecticut, Housatonic, and Thames River Basins (CONN) areas and extends data to cover the states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. The result is a regional dataset for the lithogeochemical characterization of New England (the layer named NE_LITH). Polygons in the final coverage are attributed according to state, drainage area, geologic province, general rock type, lithogeochemical characteristics, and specific bedrock map unit.
Supplemental_Information:
The lithogeochemical classification scheme for the New England Lithology data set was first developed as part of the USGS's study of the CONN area (Robinson and others, 1999). The classification scheme is based on geochemical principles, previous studies of the relations among water-quality and ecosystem characteristics and rock type, and regional geology (Robinson, 1997 and references cited within). The classification scheme and data set are intended to provide a general, flexible framework to portray the lithologic character of mapped bedrock units in New England in relation to regional geochemical and water-quality data.
The data set is a lithologic map that has been coded to reflect the potential influence of bedrock geology on water quality and sediment chemistry. Information on the map unit identities portrayed on the source bedrock geologic maps for each state are retained in this digital dataset.
The bedrock units in New England have been mapped by time- stratigraphic and other geologic criteria that may not be directly relevant to variation in regional geochemistry and water quality. Bedrock units depicted on the state geologic maps are inconsistent across state boundaries in some areas. Thus, a regional coding scheme was developed to reclassify the geologic map units according to mineralogical and chemical characteristics that are relevant for analysis of regional variation in geochemistry and water-quality.
To provide a framework for geochemical investigations, the bedrock units were classified according to the chemical composition (based upon the geologic maps used in the creation of this data set) and the relative susceptibility to weathering of their constituent minerals. Although weathering rates may vary, the relative stability of different minerals during weathering in moist climates is generally consistent (Robinson, 1997). However, the degree to which a rock weathers reflects the proportions of its constituent mineral as well as many other factors such as degree of induration and relative amount of mineral surfaces exposed to water through primary and secondary porosity (Robinson, 1997 and references cited within). Thus, although largely based on the relative stability of rock constituent minerals, the classification scheme to group bedrock units according to effects on soil and sediment chemistry and water quality is more complex than mineral-stability sequences. Most common rock-forming minerals are only sparingly soluble, so small amounts of highly reactive minerals can have large effects on water quality (Robinson, 1997; Grady and Mullaney, 1998). For example, rocks containing significant amounts of carbonate minerals are more rapidly weathered and tend to produce higher solute concentrations in natural waters than many other rock types. In contrast, rock types such as granite, schist and quartzite are rich in quartz, muscovite, and alkali-feldspars; these minerals tend to produce low solute concentrations because they react to a lesser degree and at slower rates than other mineral types in humid temperate climates (Robinson, 1997). Further description of the lithogeochemical classification scheme and the expected water-quality and ecosystem characteristics associated with each lithogeochemical unit is explained in Robinson (1997).
The lithogeochemical classification scheme used in this data set incorporates mineralogical information derived from published descriptions of the bedrock geology map units with other information on geologic features, such as metamorphic grade and geologic setting. The attributes of lithology code ("Litho_code") and modifier code ("Lith_mod") are used to express this lithogeochemical coding of bedrock units. Thirty-seven lithogeochemical units (combinations of lithology and modifier codes) are defined for the New England study region based on the mineral and textural properties of the bedrock unit's constituent minerals, presence of carbonate and sulfide minerals, depositional setting (such as restricted deposition within fault bounded sedimentary basins of Mississipian or younger age), and for some of the granitic units, mineralogy and magma chemistry. The classification scheme used descriptions from state and regional geologic maps (Doll and others, 1961; Osberg and others, 1985; Lyons and others, 1997; Zen and others, 1983; Hermes and others, 1994; and Rogers, 1985; Smoot, 1991). For Rhode Island and Maine, source materials of the state geologic maps were available as digital data layers (Osberg and others, 1985, Maine; Hermes and others, 1994, 1:100,000 scale, Rhode Island).
Information from these sources included descriptions of the lithology, mineralogy, and weathering characteristics of the bedrock units. For example, "rusty-weathering" serves as an indicator of sulfidic-bearing bedrock units (Robinson, 1997). Carbonate and sulfide minerals predominate in the classification scheme because these highly reactive minerals have a disproportionately large effect on water chemistry compared to other minerals commonly found in the rocks of this region (Robinson, 1997). In the Maine data set, information about metamorphic grade was also used to classify bedrock units. A digital data layer of generalized regional metamorphic zones (Guidotti, 1985, shown in Osberg and others, 1985, was obtained from the Maine Geological Survey. This layer was intersected with the digital bedrock geology to determine the regional metamorphic grade of each polygon in the bedrock geology data layer. Polygons lying within two metamorphic zones were split at the metamorphic-zone boundary. Metamorphic grade and geochemical composition of the protolith (pre-metamorphism source rock) were used to classify polygons into lithogeochemical units. For example, bedrock units with protoliths of "limestone and (or) dolostone" were classified as "limestone, dolomite, and carbonate-rich clastic sediments" (lithogeochemical unit "11u") in areas of little or no regional metamorphism and as "marble, may include some calc-silicate rock" (lithogeochemical unit "12u") in areas of greenschist facies or high-grade metamorphism.
Bibliographic References:
Ayotte, J.P., Nielsen, M.G., Robinson, G.R., Jr., Moore, R,B., 1999, Relation of arsenic, iron, and manganese in ground water to aquifer type, bedrock lithogeochemistry, and land use in the New England Coastal Basins, U. S. Geological Survey Water-Resources Investigative Report 99-4162, 61 p.
Ayotte, J.D., Montgomery, D.L., Flanagan, S.M., and Robinson, K.W., 2003, Arsenic in ground water in eastern New England: Occurrence, controls, and human health implications: Environmental Science and Technology, v. 37, no.10, p.2075-2083.
Bailey, S.W. and Hornbeck, J.W., 1992, Lithologic composition and rock weathering potential of forested, glacial-till soils, Research paper NE-662, Radnor PA: United States Department of Agriculture, Forest Service, Northeastern Forest Experimental Station, 7 p.
Doll, C.G., Cady, W.M., and Thompson, J.B., Jr., and Billings, M.P., eds. and compilers, 1961, Centennial Geology Map of Vermont: Montpelier, VT, U.S. Geological Survey, 1:250,000, 1 sheet. (transverse mercator projection, based on best available information).
Grady, S.J. and Mullaney, J.R., 1998, Natural and human factors affecting shallow water quality in surficial aquifers in the Connecticut, Housatonic, and Thames River Basins: U.S. Geological Survey Water-Resources Investigations Report 98-4042, 81 p.
Guidotti, C.V., 1985, Generalized map of regional metamorphic zones:in Osberg, P.H., and others: Augusta, Maine, Maine Geological Survey, 1 map sheet, 1:1,600,000.
Hermes, O.D., Gromet, L.P., Murray, D.P., 1994, Bedrock geologic map of Rhode Island: Kingston, R.I., Office of the Rhode Island State Geologist, Rhode Island Map Series No 1, 1 map sheet, 1:100,000.
Lyons, J.B., Bothner, W.A., Moench, R.H., and Thompson, J.B., Jr., 1997, Bedrock geologic map of New Hampshire: Reston, Va., U.S. Geological Survey Special Map, 2 map sheets, 1:250,000.
McHone, J.G., and Butler, J.R. 1984. Mesozoic igneous provinces of New England and the opening of the North Atlantic Ocean: Geological Society of America Bulletin v.95, p. 757-765.
Osberg, P.H., Hussey, A.M. II, and Boone, G.M., 1985, Bedrock geologic map of Maine: Augusta, Maine, Maine Geological Survey, 1 map sheet, 1:500,000.
Robinson, G.R., Jr., 1997, Portraying chemical properties of bedrock for water quality and ecosystem analysis: an approach for the New England Region: U.S. Geological Survey Open-File Report 97-154, 17 p.
Robinson, G.R., Jr., Peper, J.D., Steeves, P.A., and DeSimone, L.A., 1999, Lithogeochemical character of near-surface bedrock in the Connecticut, Housatonic, and Thames River Basins: U.S. Geological Survey, Water-Resources Investigations Report 99-4000 digital.
Robinson, G.R., Jr., Ayotte, J.P., Montgomery, D.C., and DeSimone, L.A. 2002, Lithogeochemical Character of Near-Surface Bedrock in the New England Coastal Basins: U.S. Geological Survey Open-File Report, 02-00 digital.
Rogers, John (compiler), 1985, Bedrock geological map of Connecticut: Connecticut Geologic and Natural History Survey, Natural Resource Atlas Map Series, 2 map sheets, 1:125,000.
Soller, D.R., 1993, Map showing the thickness and character of Quaternary sediments in the glaciated United States east of the Rocky Mountains - Northeastern states, the Great Lakes, and parts of southern Ontario and the Atlantic offshore area (east of 80o 31' west longitude): U.S. Geological Survey Miscellaneous Invistigations Series Map I-1970-A.
Smoot, J.P., 1991, Sedimentary facies and depositional environments of early Mesozoic Newark Supergroup basins, eastern North America: Paleogeography, Paleoclimatology, Paleoecology, v. 84, p. 369-423.
Zen, E-an, Goldsmith, G.R., Ratcliffe, N.L., Robinson, P., and Stanley, R.S., 1983, Bedrock geologic map of Massachusetts: U.S. Geological Survey, Monograph Series, 3 map sheets, 1:250,000.
  1. How might this data set be cited?
    G. R. Robinson, Jr., and Kapo, K. E., 2003, Generalized lithology and lithogeochemical character of near-surface bedrock in the New England region: U.S. Geological Survey Open-File Report 03-225, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.73
    East_Bounding_Coordinate: -66.93
    North_Bounding_Coordinate: 47.42
    South_Bounding_Coordinate: 40.90
  3. What does it look like?
    http://pubs.usgs.gov/of/2003/of03-225/Fig_1.jpg (JPEG)
    The drainage basins covered by this dataset, 745x548 pixels, 34k bytes.
    http://pubs.usgs.gov/of/2003/of03-225/Fig_2.jpg (JPEG)
    The geologic provinces of New England, 745x567 pixels, 47k bytes.
    http://pubs.usgs.gov/of/2003/of03-225/Fig_3.jpg (JPEG)
    General lithology distribution in New England (symbolized with attribute Rock_GpA), 745x551 pixels, 66k bytes.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2003
    Currentness_Reference:
    publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Map
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set.
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    The thirty-seven lithogeochemical units are defined for the New England study region using an alpha-numeric identification: a lithology code ("Litho_code", numeric) with a modifier code ("Lith_mod", alphabetic).
    Example: Litho_code= "33" and Lith_mod= "cs" Lithogeochemical unit is expressed as "33cs"
    There are 20 lithology codes (including a code for water) that represent rock type, metamorphic grade, and geologic setting. Each bedrock unit is assigned one of 20 lithology codes based on the description of the bedrock unit from the state bedrock geologic maps. Nine lithological modifier codes are used to identify minor amounts of carbonate or sulfide minerals, and subdivide granitic units into subgroups based on their chemical and mineral characteristics.
    The 37 lithogeochemical units are generalized into major rock group categories (Rock_GpA and Rock_GpB). Each category under these headings shares similarities in overall geochemistry and lithology. Rock Group A ("Rock_gpA") has 8 categories (including one for freshwater).
    Bedrock lithology information was obtained from separate state source maps, and this results in some discrepancies in rock group categories between polygons that meet at state boundaries. For example, a bedrock polygon that is split into two polygons by a state border may be be categorized as "Metamorphic Rocks Undivided" in one state and "Carbonate Rocks" in the other state, based upon the different characterization methods used by the originators of each of the state geologic maps. However, these discrepancies are relatively few and do not interfere with the overall lithologic patterns of the New England study area.
    The eight major groups for Rock Group A are further divided into Rock Group B. Rock Group B ("Rock_GpB") has 19 categories (including one for freshwater). Each category has an ID code ("R_GpB_ID") that is used as a cross reference to other tabled information.
    Individual bedrock unit codes are designated by state from the original state geologic maps used to create the digital coverage (see references for source maps). Names and descriptions for each bedrock code were gathered from source maps and are provided in the associated file Bedrock.dbf. The "Bedrock_1" attribute describes the alphanumeric code given to bedrock units in the original state map sources (for example, "Trnh" or "Dw3A"). Some units have been combined (example "O-cr+O-cra") during the digitizing process. "Bedrock_2" may further designate a polygon as "water" if appropriate, but for polygons not water bodies "Bedrock_2" is the same as "Bedrock_1".
    The bedrock units shown on the individual state maps for the New England study region were classified according to a lithogeochemical scheme modified from Robinson and others (1999). Specifically, the modification included additional classification into broad rock groups and the subdivision of granitic bedrock units into subgroups based on age and magma chemistry, and the addition of modifying attributes to indicate relative age. However, this modification to the classification system is evident in the lithogeochemical units.
    Entity_and_Attribute_Detail_Citation:
    A detailed listing and descriptions of the 37 lithogeochemical units is provided in http://pubs.usgs.gov/of/2003/of03-225/unit-description.html
    Relationships among rock groups and between rock groups and lithogeochemical units are shown in http://pubs.usgs.gov/of/2003/of03-225/rock-groups.html
    More detailed descriptions of each bedrock unit (grouped by the state in which they occur) are provided in http://pubs.usgs.gov/of/2003/of03-225/bedrock.dbf
    ne_lith.dbf
    Polygonal map units define bedrock areas with similar lithologic and geochemical properties.
    State
    This item identifies the state locations of polygons. Because the lithogeochemical characterization was derived from information on the state geological map, the state is associated with each polygon to help identify of source of the geologic information.
    ValueDefinition
    CTConnecticut
    MAMassachusetts
    MEMaine
    NHNew Hampshire
    RIRhode Island
    VTVermont
    Hydro_Bsn
    The coverage is divided by drainage basins based on the USGS National Water Quality Assessment (NAWQA) study areas CONN and NECB. NAWQA program information can be accessed at
    http://water.usgs.gov/nawqa/studyu.html
    For purposes of focusing on the area of New England in this coverage, two new drainage areas have been added to the coverage: Northern Maine (N_MAINE) and St. Lawrence/Hudson River (STL_HUD) drainage areas. The N_MAINE drainage area covers the area in Maine not included in the NECB study area. The STL_HUD drainage area combines the small portion of the NAWQA Hudson River basin included in this coverage, and the area of northern Vermont not included in a NAWQA study area. (Source: National Water Quality Assessment Program)
    ValueDefinition
    NECBNew England Coastal Basin
    CONNConnecticut, Housatonic, and Thames River Basins
    STL_HUDSt. Lawrence-Hudson River Basins
    N_MAINENorthern Maine
    G_Province
    The bedrock units shown on the individual state maps for the New England study area have been grouped into 10 geologic provinces. The map units in each province group share common features of lithology, age of formation, geologic setting, and tectonic history. The province groups generally occur as northeast-trending belts that follow the structural fabric of the Appalachian foldbelt and faults in New England.
    The tectonic map features contained with the state-level bedrock geologic maps and the grouping of bedrock map units by geologic belts in the legends of the state-level bedrock geologic maps were used to define province attributes.
    ValueDefinition
    Avalon BeltAvalon Belt terrane, Avalon Province
    Localized in eastern Massachusetts, Rhode Island, and coastal Connecticut. Principally Precambrian Z granite and granitic gneiss and metasedimentary rocks of Precambrian Z to Ordovician age. Intruded by Ordovician to Devonian granites. Cretaceous sediments and thick areas of Quaternary glacial sediments occur in southern coastal areas.
    Bronson Hill SequenceBronson Hill Sequence terrane
    Triassic to Jurassic age sediments and basalt flows deposited in localized rift basins in from Connecticut to western New Hampshire and northern Maine. Principally Ordovician igneous and metavolcanic rocks overlain by Ordovician to Devonian metasedimentary rocks. Sulfidic schists and mafic rocks are common. Intruded by Devonian granites.
    Coastal MaineCoastal Maine terrane
    Localized along northeastern coastal Maine. Principally PreCambrian Z to Silurian metasedimentary and metavolcanic rocks intruded by Devonian granites.
    Eugeosyncline SequenceEugeosyncline Sequence terrane
    Includes slates and pelitic metamorphic rocks in the Taconic Range and schists east of the Grenville Belt. Principally Cambrian to Ordovician pelitic metasedimentary rocks, including metavolcanic layers and lenses of ultramafic rocks.
    Grenville BeltGrenville Belt terrane
    Includes areas of Grenville Basement (PreCambrian Y metamorphic rocks) in western Connecticut, Massachusetts, and Vermont. Principally granitic gneiss and metasedimentary rocks. Includes some Cambrian metasedimentary rocks deposited on Precambrian basement.
    Grenville Shelf SequenceGrenville Shelf Sequence terrane
    Principally carbonate rocks and other metasedimentary rocks deposited in a carbonate shelf sequence overlying Grenville basement in western Connecticut, Massachusetts, and Vermont.
    Mesozoic BasinMesozoic Basin terrane
    Triassic to Jurassic age sediments and basalt flows deposited in localized rift basins in central Connecticut and Massachusetts. Intruded by Jurassic diabase and basalt dikes.
    NH - Maine SequenceNH-ME terrane, New Hampshire-Maine Sequence
    Covers eastern Connecticut, central Massachusetts, eastern New Hampshire, and central Maine. Principally Silurodevonian metasedimentary rocks and Silurodevonian and younger igneous rocks, principally granite.
    Narragansett BasinNarragansett basin terrane
    Permian conglomerates and other sediments deposited in fault-bounded basins in Avalon province rocks in southeastern Massachusetts and Rhode Island.
    Waits River-Gile Mt. SWaits River Gile Mt. Sequence terrane
    Principally Devonian variably-calcareous metasedimentary rocks in eastern Vermont and the northern Connecticut valley in Massachusetts, intruded by Devonian granite.
    G_Prov_id
    A one- or two-letter abbreviation for the geologic provinces.
    ValueDefinition
    BBronson Hill Sequence
    CWaits River-Gile Mt. Sequence
    CMCoastal Maine
    HEugeosyncline Sequence
    MNH - Maine Sequence
    NMesozoic Basin
    NBNarragansett basin
    SGrenville Shelf Sequence
    YGrenville Belt
    ZAvalon Province
    Rock_GpA
    A broad categorization of lithogeochemical units. Each category under these headings shares similarities in overall geochemistry and lithology.
    ValueDefinition
    Basin SedimentarySediments deposited in fault-bounded basins of Permian and younger age.
    CalcpeliteCalcareous clastic and metaclastic rocks containing approximately 15-45% carbonate minerals.
    Carbonate RocksGeneral rock composition carbonate rock, includes limestone, dolomite, and marble with mixed calc-silicate rocks.
    GranitesGeneral rock composition granite.
    Mafic RocksGeneral rock composition mafic igneous rocks and their metamorphic equivalents.
    Metamorphic Rocks UndiviMetamorphic rocks other than carbonate rocks, calcpelite, or mafic rocks.
    Unconsolidated SedimentsUnconsolidated or poorly consolidated sediments of tertiary and younger age.
    WaterInland freshwater body
    Rock_GpB
    Further subdivides the broad categories of lithgeochemical units defined by Rock_GpA.
    ValueDefinition
    Alkali Granite (White Mt)Alkali granites associated with the White Mountain Plutonic-Volcanic suite (Lyons and others, 1997. Includes granitic rocks in the New England-Quebec and White Mountain igneous provinces of McHone and Butler (1984).
    Avalon GraniteGranite of Precambrian Z age in the Avalon province.
    BasaltsBasalts.
    CalcpeliteCalcareous clastic and metaclastic rocks containing Approximately 15-45% carbonate minerals.
    CalcgranofelsFine-grained calcareous clastic and metaclastic rocks containing calc-silicate minerals. May contain a small percentage of carbonate minerals.
    Carbonate rocksGeneral rock composition carbonate rock, includes limestone, dolomite, and marble with mixed calc-silicate rocks.
    Felsic VolcanicsFelsic volcanic rocks and mixed volcanic rocks where felsic volcanics predominate.
    Granite, otherGranite, other than types listed below.
    Grenville GraniteGranite of the Precambrian Y age in Grenville basement rocks.
    Mafic RocksMafic igneous rocks and their metamorphic equivalents.
    Mesozoic Basin SedimentsTriassic-Jurassic continental sediments deposited in rift basins of Mesozoic age.
    Metamorphic Rocks UndiviMetamorphic rocks other than carbonate rocks, calpelite, calcgranofels, pelitic rocks, sulfidic schists, or mafic rocks.
    Narragansett Basin SedimentPermian continental sediments deposited in fault-bounded Permian basin.
    Pelitic RocksPelitic rocks and interbedded pelitic and sandy sediments and their metamorphic equivalents.
    Peraluminous graniteGranite types containing primary muscovite, of Late Devonian to Carboniferous age.
    Sulfidic SchistsMetamorphosed pelitic rocks containing sufficient pyrite and(or) pyrrhotite to develop a rusty-weathering characteristic.
    Ultramafic RocksSerpentine, dunite, and other ultramafic rocks.
    Unconsolidated SedimentsUnconsolidated and poorly consolidated sediments of tertiary or younger age.
    WaterInland bodies of fresh water.
    R_GpB_id
    Numerical code for Rock_GpB values.
    ValueDefinition
    0Inland body of fresh water
    1Carbonate rocks
    10Calcpelite
    11Calcgranofels
    20Mesozoic basin sediments
    21Narragansett basin sediments
    3Metamorphic rocks, undivided
    30Pelitic rocks
    31Sulfidic schists
    4Mafic rocks
    41Basalts
    5Ultramafic rocks
    6Granite, other
    60Felsic volcanics
    61Grenville granites
    62Avalon granites
    63Peraluminous granites
    64Alkali granite (White Mt)
    7Unconsolidated sediments
    This includes both non-consolidated and poorly consolidated sediments, and encompasses areas in the south-coastal part of the New England study area where the bedrock is overlain by thick glacial sediments at the surface. These surficial glacial deposits are the primary aquifer for these areas.
    Litho_code
    Lithogeochemical classification code, developed for this data set. Field is defined as double (width 16, 3 digits to right of the decimal) but all values are integer.
    ValueDefinition
    -9999(surface water body)
    11limestone, dolomite, and carbonate-rich clastic rocks; may include fine-grained non-calcareous clastic rocks
    12marble; may include some calc-silicate rock
    13calcareous clastic and metaclastic rocks containing approximately 15 to 45% carbonate minerals
    21tan and red mudstone and shale; may include sandstone; locally contains minor carbonate or gypsum
    22interbedded mudstone, shale, and siltstone; may contain sandstone
    23sandstone and interbedded sandstone and conglomerate; may contain siltstone, shale, and mudstone
    31slate and graywacke
    32pelitic schist and phyllite, may include granofels
    33mixed schist, granofels; and gneiss
    34quartzose metasandstone, quartzite, quartz granofels, and quartzose gneiss
    41basalt
    42greenstone, lower greenschist facies metabasalt, and schistose mafic rock with minor dispersed carbonate (Mg-rich)
    43amphibolite and layered mafic gneiss; may be mixed with other lesser lithologies such as felsic volcanics and metaclastic rocks
    44massive mafic rocks; includes gabbro, diorite, monzodiorite, and diabase
    45mafic gneiss
    50ultramafic rocks; includes serpentinites, dunites, peridotites, and tremolite-talc schists associated with other ultramafic rocks
    61granitoid rocks; includes granite, quartz monzonite, granodiorite, trondhjemite, and equivalent gneiss
    62quartz-poor plutonic rocks; includes syenite, monzonite, quartz syenite, and anorthosite
    70nepheline syenite; includes feldspathoid-bearing syenitic rocks and volcanic rocks
    Lith_mod
    Lithogeochemical classification code, developed for this data set that further subdivides the lithogeochemial groups based on the presence of carbonate and(or) sulfide mineral or on the relative age of the bedrock unit.
    ValueDefinition
    uunit is undifferentiated
    cunit may contain small or variable amounts of carbonate minerals
    csunit may contain small or variable amounts of carbonate minerals and minor amounts of pyrite, pyrrhotite, or both
    gunit contains variable amounts of graphite or organic materials
    gcunit may contain variable amounts of carbonate minerals and organic materials
    gsunit may contain minor amounts of pyrite, pyrrhotite, or organic materials, sufficient to cause a rusty-weathering characteristic.
    sunit may contain minor amounts of pyrite, pyrrhotite, or both
    vfelsic volcanics associated within granite intrusions
    nnepheline-bearing syenite
    Bedrock_1
    Bedrock Unit label appearing on the state geologic map used as the source for the lithogeochemical categorization.
    Formal codeset
    Codeset Name:Lithologic units from state maps
    Codeset Source:File Bedrock.dbf in this data set
    Bedrock_2
    Bedrock unit codes characterized by state and including value for water bodies. Except for surface waters, this field is the same as Bedrock_1.
    ValueDefinition
    WaterInland freshwater body
    Formal codeset
    Codeset Name:Lithologic units from state maps
    Codeset Source:File Bedrock.dbf in this data set
    X_COORD
    X coordinate of polygon label point in Albers projection
    Range of values
    Minimum:-226338.73438
    Maximum:317584.70835
    Units:meters
    Y_COORD
    Y coordinate of polygon label point in Albers projection
    Range of values
    Minimum:2002056.5
    Maximum:2719492.875
    Units:meters

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • G. R. Robinson, Jr.
    • K. E. Kapo
  2. Who also contributed to the data set?
    Individuals involved in the creation of the final New England Lithology (NE_LITH), CONN, and NECB coverages are listed as follows:
    New England Lithology (final Coverage NE_LITH):
    Gilpin R. Robinson, Jr.: U.S. Geological Survey, Reston, Va. Primary developer of the classification scheme. Preparation of source materials and information for combining the coverages into a general representation of New England Lithology.
    Katherine E. Kapo: U.S. Geological Survey, Reston, Virginia. Assisted in editing the coverage linework and attributes, creation of the final "New England Lithology" version, and compilation of the final metadata.
    Joseph D. Ayotte: U.S. Geological Survey, Pembroke, New Hampshire. New England Coastal Basin NAWQA ground-water specialist; reviewed the construction of the combined coverage.
    Laura Hayes: U.S. Geological Survey, Pembroke, New Hampshire. Reviewed the finalized coverage and metadata and provided corrections for the metadata and attribute table.
    CONN Coverage:
    Gilpin R. Robinson, Jr: Preparation of source materials and compilation of lithogeochemical units for Connecticut and Massachusetts regions; primary development of lithogeochemical classification scheme.
    John D. Peper: Preparation of source materials and compilation of lithogeochemical units for Vermont and New Hampshire regions; additional development of lithogeochemical classification scheme.
    Peter A. Steeves: Construction, revision, quality-assurance, and documentation of the digital data layer and publication of the data layer as a digital map product.
    Leslie A. DeSimone: Quality assurance, revision, and documentation of the data layer and publication of the data layer as a digital map product.
    Stephen P. Garabedian: Connecticut River NAWQA chief; coordinating personnel and funding, planning, oversight, and review of the data layer
    Stephen J. Grady: Connecticut River NAWQA ground-water specialist; primary user of the resulting data; planning and definition of water quality issues of the NAWQA study unit for use in development of the data layer and oversight of the initial data-layer construction phases.
    Robert Sava, Jr: Digitizing and coding contributions in NH, MA, and VT
    Shanon Wappel: Digitizing and coding contributions in CT
    NECB Coverage:
    Gilpin R. Robinson, Jr.: U.S. Geological Survey, Reston, VA. Primary developer of the classification scheme. Preparation of source materials and compilation of lithogeochemical units for Maine, Massachusetts, and Rhode Island.
    John D. Peper: U.S. Geological Survey, Reston, VA. Preparation of source materials and compilation of lithogeochemical units for New Hampshire; secondary developer of the lithogeochemical classification scheme.
    John C. Rader: U.S. Geological Survey, Marlboro, Massachusetts. Construction, revision, quality-assurance, and documentation of the original digital data layer.
    Keith W. Robinson: U.S. Geological Survey, Pembroke, New Hampshire. New England Coastal Basin NAWQA Chief; Coordination of personnel and funding, planning, oversight, and review of the data layer.
    Joseph D. Ayotte: U.S. Geological Survey, Pembroke, New Hampshire. New England Coastal Basin NAWQA ground-water specialist; primary user of the resulting data; planning and definition of the water-quality issues of the NAWQA study unit for use in development of the data layer and oversight of the data layer construction phases.
    Leslie A. DeSimone: U.S. Geological Survey, Marlboro, Massachusetts. Technical reviewer of original digital data layer.
    Walt Bawiec: U.S. Geological Survey, Reston, Virginia. Colleague reviewer who performed technical reviews of the completed digital data set and metadata document.
    Curtis Price: U.S. Geological Survey, Rapid City, South Dakota. Colleague reviewer who performed technical reviews of the completed digital data set and metadata document.
    Sarah M. Flanagan: U.S. Geological Survey, Pembroke, New Hampshire. Edited the coverage and assisted in compilation and editing the metadata.
    Laura Hayes: U.S. Geological Survey, Pembroke, New Hampshire. Created plots of the CONN lithogeochemical coverage and the NECB lithogeochemical coverage so that consistency along the study-unit border could be checked. Corrected the shift in the Massachusetts portion of the coverage. Assisted in compilation and editing of the NECB metadata.
  3. To whom should users address questions about the data?
    Gilpin R Robinson
    U.S. Geological Survey, ER
    Mail Stop 954
    12201 Sunrise Valley Drive
    Reston, VA
    USA

    703-648-6113 (voice)
    703-648-6383 (FAX)
    grobinso@usgs.gov

Why was the data set created?

This geologic characterization provides a framework to interpret regional geochemistry and habitat characteristics in relation to bedrock lithology and geologic provinces that share common features. The lithogeochemical data layer combines and extends data previously compiled for the U.S. Geological Survey National Water Quality Assessment Program (NAWQA) study areas of the New England Coastal Basin (NECB), and the Connecticut, Housatonic, and Thames River Basins (CONN). The coverage provides digital geologic information that may be applied to the analysis of water-quality characteristics of surface water and shallow ground water, and soil and stream sediment characteristics based on bedrock lithogeochemistry.
The geologic characterization provided in this classification is intended to portray significant bedrock geologic features that influence stream sediment and soil chemistry and water quality.
"Near-surface bedrock" in this report refers to lithified materials covered by no more than about 60 feet of overlying unconsolidated surficial materials. The thickness of Quaternary sediments overlying bedrock is generally less than 60 feet in the New England states (Soller, 1993).
The bedrock units shown on the source maps were grouped and generalized for this compilation. Consequently this map will show fewer geologic units and less detail than the state geologic maps from which the information was drawn.
A few areas have been modified from those shown on the state maps, for example, additional units portrayed by Smoot (1991) are shown in the Hartford Basin area of Connecticut and Massachusetts and mismatched contacts have been adjusted along state borders.
Based on the geologic map compilation scales, mismatches of some unit contacts across state boundaries, and the positioneal uncertainty of the source digital files relative to the published geologic maps, the spatial accuracy of this compilation is estimated as 1.5 km.
To the degree that surficial materials are related to their proximal bedrock source, the variations in bedrock geology also provide guidelines to the expected variation in the properties and chemistry of surficial materials and surface waters. In glaciated areas, such as New England, the mineralogy of tills and some stratified drift is related to adjacent bedrock units, and bedrock geology has been used to help define their chemical character (Bailey and Hornbeck, 1992). A lithogeochemical framework similar to that provided in this report has been used to define correlations between groundwater chemistry and bedrock geology (Grady and Mullaney, 1988; Ayotte and others, 1999). Groundwater chemistry for alkalinity, pH, Ca, Mg, Na, silica, and radon in surficial aquifers sampled from wells up to 60 feet in depth in surficial aquifers have been shown to correlate with groups of lithology of the underlying bedrock (Grady and Mullaney, 1988). Groundwater chemistry for pH, iron, manganese, and arsenic in fractured crystalline bedrock aquifers sampled from wells up to 500 feet in depth differ by bedrock lithology groups (Ayotte and others, 1999; Ayotte and others, 2003).
The lithogeochemical characterization in these data have been put to use analyzing water-quality characteristics in studies by Grady and Mullaney (1998) and Ayotte and others (2003).

How was the data set created?

  1. From what previous works were the data drawn?
    NHBedrock (source 1 of 7)
    Lyons, John B., Bothner, Wallace A., Moench, Robert H., and Thompson, James B. Jr., (unpublished), Digital bedrock geologic map of New Hampshire.

    Source_Scale_Denominator: 250000
    Source_Contribution:
    Provided internal line work and initial polygon attribute data for New Hampshire.
    Digitizing was performed at the Complex Systems Research Center, University of New Hampshire, from the Bedrock geologic map of New Hampshire (Lyons and others, 1997).
    MEBedrock (source 2 of 7)
    Osberg, P.H., Hussey, A.M. II, and Boone, G.M., 1985, Bedrock geologic map of Maine: Maine Geological Survey, Augusta, Maine.

    Source_Scale_Denominator: 500000
    Source_Contribution:
    Provided internal line work and initial polygon attribute data for Maine.
    Digitized from the Bedrock Geologic Map of Maine (Osberg and others, 1985). This coverage contains statewide bedrock geology map units and major faults as mapped by the Maine Geologic Survey (MGS).
    Maine metamorphic data (source 3 of 7)
    Osberg, P.H., Hussey, A.M. II, and Boone, G.M., 1985, Bedrock geologic map of Maine: Generalized regional metamorphic zones: Maine Geological Survey, Augusta, Maine.

    Source_Scale_Denominator: 1600000
    Source_Contribution:
    Provided internal line work and initial polygon attribute data for metamorphic zones in Maine.
    Digitized from the Bedrock Geologic Map of Maine (Osberg and others, 1985). This coverage contains generalized regional metamorphic zones as mapped by the Maine Geologic Survey (MGS).
    CTBedrock (source 4 of 7)
    Rogers, John (compiler), 1985, Bedrock geological map of Connecticut: Natural Resource Atlas Map Series, Connecticut Geologic and Natural History Survey.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 125000
    Source_Contribution:
    Provided internal line work and initial polygon attribute data for Connecticut.
    MABedrock (source 5 of 7)
    Zen, E-an, Goldsmith, G. Richard, Ratcliffe, N.L., Robinson, Peter, Stanley, R.S., Hatch, N.L., Shride, A.F., Weed, E.G.A., and Wones, D.R., 1983, Bedrock geologic map of Massachusetts: U.S. Geological Survey, Reston, VA.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 250000
    Source_Contribution:
    Provided internal line work and initial polygon attribute data.
    Rudolph Hon digitized from the Bedrock geologic map of Massachusetts (Zen and others, 1983) under the direction of Rudolph Hon (Department of Geology, Boston College) as part of a project funded by the Massachusetts Highway Department.
    Rudolph Hon provided reference to correct registration problems in the bedrock polygon lines in MABedrock.
    RIBedrock (source 6 of 7)
    Hermes, O.D., Gromet, L.P., Murray, D.P, Hamidzada, N.A., Skehan, J.W., and Mosher, S., 1994, Bedrock geologic map of Rhode Island: Rhode Island map series 1, University of Rhode Island, Kingston, Rhode Island.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 100000
    Source_Contribution:
    Provided internal linework and initial polygon attribute data for Rhode Island.
    VTBedrock (source 7 of 7)
    Doll, G.C. (editor and compiler), Cady, W.M. (editor and compiler), Thompson, J.B. Jr. (editor and compiler), and Billings, M.P. (editor and compiler), Centennial geologic map of Vermont:, Montpelier, VT.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 250000
    Source_Contribution: Information about Vermont
  2. How were the data generated, processed, and modified?
    Date: 1997 (process 1 of 13)
    Digital versions of the state geologic maps were obtained from the originators or authors for Maine (Marc Loiselle, Maine Geological Survey, Augusta, ME), New Hampshire (U.S. Geological Survey), Rhode Island (N. Hamidzeda, University of Rhode Island, Department of Geology, Kingston, RI), and Massachusetts, (Rudolph Hon, Department of Geology, Boston College). The bedrock polylines of Connecticut were pieced together from two digital sources; the Bedrock Geologic map of Rhode Island (which shows a buffer of the adjacent state bedrock units) and the Bedrock Geologic map of Connecticut. Hence some of the bedrock line work and geologic names in Connecticut are from the Bedrock Geologic map of Rhode Island.
    Date: 1997 (process 2 of 13)
    The original digital state bedrock data layers were combined into one study-unit wide data layer using the ARC/INFO MAPJOIN command. The individual coverages did not match perfectly at the state borders, so the resulting sliver polygons had to be deleted.
    Date: 1997 (process 3 of 13)
    A lithogeochemical unit, lithology code, modifier code, major group code, and state abbreviation were added as attributes to each bedrock polygon present in the digital state geologic maps. The statewide data layers were then clipped and mapjoined to create a data layer for the NECB study unit. State boundaries were maintained in the combined data layer.
    Date: 2001 (process 4 of 13)
    The original source data (MABedrock) for the Massachusetts portion of this data layer contained some georeferencing problems, which caused the arcs to display generally southwest of their true locations, although the direction and distance of the shift was not uniform across the state. Rudolph Hon developed a method of re-registering the scanned image of the paper map (Zen and others, 1983) based on thousands of control points from USGS topographic maps, and digitized the bedrock polygons again. This updated digital version of the Massachusetts bedrock was obtained from the Eastern Mineral Resources Team (USGS - Reston, Virginia) and showed improved horizontal accuracy. Arcs from this updated bedrock coverage were used as locational reference for the Massachusetts linework in the NECB lithogeochemical coverage and the original lithogeochemical label points with attributes were retained and shifted to match the newly located polygons. Arcs near the state and study unit boundaries were edited exactly to meet the borders, and other minor corrections to linework and labels were made.
    Date: 2000 (process 5 of 13)
    NECB metadata created using FGDCMETA.AML ver. 1.35 08/02/2000 on ARC/INFO data set.
    Date: 2000 (process 6 of 13)
    The CONN and NECB data sets were combined using mapjoin functions in ARC/INFO. Attributes for the NECB coverage were edited to create a uniform attribute table (the CONN attribute format was edited to follow the NECB attribute format). The NECB data set used in the join was an earlier version without the corrected work done in Massachusetts, so the horizontal accuracy of the coverage was in need of improvement again in a section of Massachusetts.
    Date: 2002 (process 7 of 13)
    The georeferencing issue of Massachusetts was addressed for the combined CONN/NECB data set by replacing the shifted portion of the Massachussetts linework with the re-registered linework from the corrected NECB data set. Bedrock polygons of Massachusetts starting at and to the east of the western border of the Mesozoic Basin were deleted and replaced with the re- registered polygons of the NECB data set, using ARC/INFO map join and editing features. Original arcs that were shared boundaries between Massachusetts and other states were saved in the combined coverage.
    Date: 2002 (process 8 of 13)
    A small section of western Massachusetts and three small missing portions of western Connecticut (along the northwest border) that had been lost at some point in the combination of the data sets were added from the original CONN data set using ARC/INFO map join. Polygons located in Canada and New York were removed from the data set to limit the New England coverage to six states (Connecticut, Massachusetts, Maine, New Hampshire, Rhode Island, and Vermont).
    Date: 2002 (process 9 of 13)
    Additional edits were made to the attributes of the New England data set using the paper copies state geologic maps (those mentioned above as references for all digital CONN and NECB data sets) for lithological information. Additional attributes (such as province groups) were added based on research needs. All edits to attributes were reviewed by Gilpin R. Robinson, Jr., an originator of the data set.
    Date: 2002 (process 10 of 13)
    Metadata from the CONN and NECB data sets was combined and revised in html and .pdf format.
    Date: 2003 (process 11 of 13)
    State border polygon discrepancies that could be addressed were edited by correcting cross-border line shifts with new linework.
    Date: 2003 (process 12 of 13)
    The finalized coverage and metadata were reviewed by Laura Hayes (U.S. Geological Survey, Pembroke, New Hampshire); small edits to the metadata and attribute table were made.
    Date: 29-Jun-2009 (process 13 of 13)
    Creation of original metadata record Person who carried out this activity:
    Gilpin R Robinson
    U.S. Geological Survey, ER
    Mail Stop 954
    12201 Sunrise Valley Drive
    Reston, VA
    USA

    703-648-6113 (voice)
    703-648-6383 (FAX)
    grobinso@usgs.gov
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Potential errors associated with the polygon labels and line junctions were checked using the LABELERRORS and NODEERRORS command in ARC/INFO. The ARC/INFO FREQUENCY command was used to compare the assignments of the lithology code and modifier code attributes to the state bedrock codes. After the CONN and NECB data sets were combined, the lithological patterns and bedrock designations were checked using reference state geologic maps mentioned in the reference section, and corrections were made as needed to the digital data sets for the final combined data set.
    The scientific content of this digital data set underwent technical review by two USGS scientists who have knowledge of the regional geology, and GIS and spatial-data production. The data set was evaluated on positional accuracy, contextual accuracy, attribute accuracy, and topological consistency.
  2. How accurate are the geographic locations?
    The spatial accuracy of the geologic source information varies. The source geologic map scales range from 1:100,000 to 1:500,000. In addition, analysis near state boundaries may be limited by the geologic map interpretation differences across state boundaries. This New England Lithology coverage is limited by variances related to these differences in source materials used and interpretation of geologic information between the CONN and NECB lithochemical mapping.
    The spatial component of this data layer was compiled from five different digital sources and, therefore, incorporates any limitations associated with those individual state geologic data layers as well as their source paper maps. The digital sources were provided with minimal documentation, so it is unknown how or with what accuracy they were digitized. The scales of the original state bedrock maps range from 1:100,000 to 1:500,000. Based on the geologic map compilation scales, mismatches of some unit contacts across state boundaries, and the positioneal uncertainty of the source digital files relative to the published geologic maps, the spatial accuracy of this New England Lithology compilation is estimated as 1.5 km.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This data set contains bedrock unit boundaries, lithogeochemical boundaries, and rock group boundaries for the New England study area, which combines the CONN and NECB study units. The CONN NAWQA study unit includes most of Connecticut, western Massachusetts, eastern Vermont, western New Hampshire and small parts of Rhode Island, New York, and Quebec, Canada. The NECB NAWQA study area encompasses 23,000 square miles in western and central Maine, eastern Massachusetts, most of Rhode Island, and a small part of eastern Connecticut. Included in the NECB study area are the Kennebec, Androscogginn, Saco, Merrimack, Charles, and Blackstone River Basins as well as all of Cape Cod.
  5. How consistent are the relationships among the observations, including topology?
    Every polygon has a single label point and all polygons are closed. The same lithologic unit may extend across a state line but have different formation names in different states.
    Discrepancies at state borders. Compilation of the lithogeochemical data layer using state geologic maps also resulted in some discontinuities at state borders. The lithogeochemical unit assigned to a bedrock unit was based primarily on its description on the appropriate state geologic map. Because the information contained on the individual state maps was interpreted and assembled by different groups of geologists, the compiled data set is not always internally consistent. In addition, the state map descriptions have generalized the chemical and mineral-assemblage characteristics of the bedrock units and formations across the different states; thus, regional trends in lithology or metamorphic grade may have resulted in different generalized descriptions of the same geologic unit in adjacent states. Discrepancies across state borders in the lithogeochemical data layer reflect these and other inconsistencies among the state geologic maps that could not be resolved with the existing information. However, the lithogeochemical coding of geologic units is consistent in each state.
    Discrepancies at the Study Unit boundary: The classification scheme was first developed as part of the U.S. Geological Survey's NAWQA study of the Connecticut, Housatonic, and Thames River Basins (Robinson and others, 1999). When the CONN and NECB lithogeochemical data sets are plotted together, there are discrepancies along the study unit boundaries between bedrock lines, lithogeochemical units and major groups. These discrepancies are attributed to modifications in the lithogeochemical classfication scheme since the publication of Robinson and others (1999), specifically the granitic bedrock units, which were subdivided into additional lithogeochemical units with modifying attributes to indicate relative age. In addition, there are differences in digital source materials for the bedrock data layers in New Hampshire and Massachusetts and difference in the presence/occurrence of bedrock units between the different study areas. These discrepancies are more frequent when the data set is viewed with the lithogeochemical units showing, and less frequent when the data set is viewed with the major groups showing. Overall, the bedrock units within the two study units were classified in a consistent manner to create a regional product that can be used to evaluate bedrock geology affect on water-quality characteristics.
    Where surficial deposits are derived from the local bedrock, the data layer might also be used to describe the lithogeochemical character of these materials. However, chemical characteristics of natural waters associated with surficial deposits may differ from that suggested by the lithogeochemical character of the bedrock units to the extent that the surficial deposits consist of, or are mixed with, materials transported from source areas with differing lithogeochemical characteristics.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints: none
  1. Who distributes the data set? (Distributor 1 of 1)
    Katherine E Kapo
    U.S. Geological Survey, Eastern Minerals Resources Team
    Mail Stop 954
    12201 Sunrise Valley Drive
    Reston, VA
    USA

    703 648-6103 (voice)
    703 648-6252 (FAX)
    kkapo@usgs.gov
  2. What's the catalog number I need to order this data set? USGS Open-File Report 03-225
  3. What legal disclaimers am I supposed to read?
    Although these data have been used by the U.S. Department of the Interior, U.S. Geological Survey, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data.
    The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 04-Feb-2015
Metadata author:
Peter N Schweitzer
USGS Midwest Area
Collection manager, USGS Geoscience Data Clearinghouse, http://geo-nsdi.er.usgs.gov/
Mail Stop 954
12201 Sunrise Valley Dr
Reston, VA
USA

703-648-6533 (voice)
703-648-6252 (FAX)
pschweitzer@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://geo-nsdi.er.usgs.gov/metadata/open-file/03-225/metadata.faq.html>
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