Digital geologic map of the Thirsty Canyon NW quadrangle, Nye County, Nevada

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What does this data set describe?

Digital geologic map of the Thirsty Canyon NW quadrangle, Nye County, Nevada
This digital geologic map compilation presents new polygon (i.e., geologic map unit contacts), line (i.e., fault, fold axis, dike, and caldera wall), and point (i.e., structural attitude) vector data for the Thirsty Canyon NW 7 1/2' quadrangle in southern Nevada. The map database, which is at 1:24,000-scale resolution, provides geologic coverage of an area of current hydrogeologic and tectonic interest. The Thirsty Canyon NW quadrangle is located in southern Nye County about 20 km west of the Nevada Test Site (NTS) and 30 km north of the town of Beatty. The map area is underlain by extensive layers of Neogene (about 14 to 4.5 million years old [Ma]) mafic and silicic volcanic rocks that are temporally and spatially associated with transtensional tectonic deformation. Mapped volcanic features include part of a late Miocene (about 9.2 Ma) collapse caldera, a Pliocene (about 4.5 Ma) shield volcano, and two Pleistocene (about 0.3 Ma) cinder cones. Also documented are numerous normal, oblique-slip, and strike-slip faults that reflect regional transtensional deformation along the southern part of the Walker Lane belt. The Thirsty Canyon NW map provides new geologic information for modeling groundwater flow paths that may enter the map area from underground nuclear testing areas located in the NTS about 25 km to the east. The geologic map database comprises six component ArcINFO map coverages that can be accessed after decompressing and unbundling the data archive file (tcnw.tar.gz). These six coverages (tcnwpoly, tcnwflt, tcnwfold, tcnwdike, tcnwcald, and tcnwatt) are formatted here in ArcINFO EXPORT format. Bundled with this database are two PDF files for readily viewing and printing the map, accessory graphics, and a description of map units and compilation methods.
The current map database incorporates geologic data from: (1) early geologic mapping (1965-1969) by P.P. Orkild and K.A. Sargent of chiefly flat-lying volcanic rocks in the eastern part of the mapped area; (2) more recent field mapping (1991-1995) by S.A. Minor of older, more deformed bedrock terrane (i.e., pre-~12-Ma rocks) in the western part of the mapped area; (3) recent (1994) mapping by S.A. Minor and D.A. Sawyer of part of the Thirsty Mountain shield volcano in the southern part of the mapped area; (4) recent mapping (at 1:100,000-scale detail) of surficial deposits mainly in the southwestern part of the mapped area (Wahl and others, 1997); and (5) new detailed petrographic and geochemical data of Tertiary volcanic units of the southwest Nevada volcanic field obtained by R.G. Warren and D.A. Sawyer (written commun., 1998).
  1. How might this data set be cited?
    Minor, Scott A., 1998, Digital geologic map of the Thirsty Canyon NW quadrangle, Nye County, Nevada: U.S. Geological Survey Open-File Report 98-623, U.S. Geological Survey, Denver, Colorado.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -116.75
    East_Bounding_Coordinate: -116.625
    North_Bounding_Coordinate: 37.25
    South_Bounding_Coordinate: 37.125
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 05-Nov-1998
    Publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: map vector digital data
  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. It contains the following vector data types (SDTS terminology):
      • Point (614)
      • String (2008)
      • GT-polygon composed of chains (613)
      • String (576)
      • String (15)
      • String (34)
      • String (11)
      • Point (187)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      UTM_Zone_Number: 11
      Scale_Factor_at_Central_Meridian: .9996
      Longitude_of_Central_Meridian: -117
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1.390341
      Ordinates (y-coordinates) are specified to the nearest 1.390341
      Planar coordinates are specified in Meters
      The horizontal datum used is NAS_B.
      The ellipsoid used is Clarke 1866.
      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?
    The geologic map database comprises six component ArcINFO map coverages (tcnwpoly, tcnwflt, tcnwfold, tcnwdike, tcnwcald, and tcnwatt). The tcnwpoly coverage contains all contact lines and labelpoints for each of the map polygons. The database includes four line coverages that depict faults (tcnwflt), fold axes (tcnwfold), dikes (tcnwdike), and caldera-wall segments (tcnwcald). Faults that are contacts also appear in the tcnwpo
    Listed below are definitions of alpha and numeric attribute codes that are embedded in the various INFO files (i.e., TCNW*.PAT and TCNW*.AAT files) associated with the geologic Arc coverages. The name of the INFO file containing the listed attribute codes is present above each list, and those column headings in each list with capitalized letters correspond to custom ITEMS in the INFO files that contain the listed codes.
    (Numeric codes associated with the item COLOR in the TCNWPOLY.PAT file refer to map-unit polygon colors defined in the Arc shadeset file color524.shd.)
    UNIT#	LABEL	Definition
    1	Qay	Young alluvium (Holocene and late Pleistocene)
    2	QTc	Colluvium (Quaternary and Pliocene)
    3	Qam	Middle alluvium (middle Pleistocene)
    		Basalt of Little Black Peak (middle Pleistocene)
    4	Qbbc		Cinder cone
    5	Qbbl		Lava flow
    		Basalt of Hidden Cone (middle Pleistocene)
    6	Qbhc		Cinder cone
    7	Qbhl3		Upper lava flow
    8	Qbhl2		Middle lava flow
    9	Qbhl1		Lower lava flow
    10	QTa	Old alluvium (early Pleistocene and Pliocene?)
    11	Typ	Basalt of Thirsty Mountain (Pliocene)
    12	Typv	Vent-facies scoria deposits
    13	Tgo	Gravel of Oasis Valley (Pliocene and Miocene)
    14	Ttb	Thirsty Canyon and younger basalts (Miocene)
    		Thirsty Canyon Group (Miocene)
    15	Ttg		Gold Flat Tuff
    16	Tts		Trachytic lavas of Pillar Spring
    17	Ttf		Black Mountain caldera moat-filling sediments
    18	Ttt		Trail Ridge Tuff
    19	Ttp		Pahute Mesa Tuff
    20	Ttr		Rocket Wash Tuff
    21	Ttc		Comendite of Ribbon Cliff
    22	Tte	Pre-Thirsty Canyon basaltic rocks (Miocene)
    23	Tbd	Basalt dikes (Miocene)
    24	Tfu	Tuff and tuffaceous sedimentary rocks, undivided (Miocene)
    25	Txmr	Gravity-slide breccia of Rainier Mesa Tuff (Miocene)
    		Timber Mountain Group (Miocene)
    26	Tma		Ammonia Tanks Tuff
    27	Tmt		Basalts in Timber Mountain Group
    28	Tmr		Rainier Mesa Tuff
    		Paintbrush Group (Miocene)
    29	Tpc		Tiva Canyon Tuff
    30	Txbg	Gravity-slide breccia of Grouse Canyon Tuff (Miocene)
    		Belted Range Group (Miocene)
    31	Tbg		Grouse Canyon Tuff
    32	Tbgb		Bedded Grouse Canyon Tuff
    33	Tob	Older basalt (Miocene)
    		Volcanic rocks of Quartz Mountain (Miocene)
    34	Tqg		Crystal-poor rhyolite lava
    36	Txqs		Gravity-slide breccia of tuff of Sleeping Butte
    37	Txqh		Gravity-slide breccia of hornblende rhyolite lava
    			Tuff of Sleeping Butte
    38	Tqsu			Upper nonwelded tuff
    				Lower welded tuff
    39	Tqsp				Upper partly welded facies
    40	Tqsm				Middle welded facies
    41	Tqsl				Lower crystal-poor welded facies
    42	Tqp		Pyroxene rhyolite lava
    43	Tqpb		Pyroxene rhyolite pyroclastic rocks
    44	Tqh		Hornblende rhyolite lava
    45	Tqhb		Hornblende rhyolite pyroclastic rocks
    46	Tqht		Partly welded tuff
    47	Tqt?		Tuff of Tolicha Peak?
    48	Tqhs		Sedimentary rocks
    49	Typd	Feeder dikes (Basalt of Thirsty Mountain) (Pliocene)
    FAULT_SLIP		Definition
    und			fault slip not determined
    Lbb			normal fault; down-to-left (with respect to origin of digital fault line) apparent offset
    Rbb			normal fault; down-to-right apparent offset
    Rss			strike-slip fault; right-lateral sense of movement
    Lss			strike-slip fault; left-lateral sense of movement
    Lro			oblique-slip fault; down-to-left / right-lateral sense of movement
    Llo			oblique-slip fault; down-to-left / left-lateral sense of movement
    Rro			oblique-slip fault; down-to-right / right-lateral sense of movement
    Rlo			oblique-slip fault; down-to-right / left-lateral sense of movement
    vent			concealed linear vent of basalt of Thristy Mountain inferred from geophysical data
    FAULT_TRACE	        Definition
    well			well located fault
    inf			approximately located/inferred fault
    con			concealed fault
    geophys			concealed structure; location constrained by geophysical expression
    (Each record in TCNW.PAT includes a strike AZIMUTH and a DIP value, where the strike azimuth is measured clockwise with respect to north and the dip direction is 90o clockwise relative to the azimuth (i.e., "right hand rule").  In the case of fault plane measurements, TREND and PLUNGE indicate the orientation of slickenside striations or lineations.)
    TYPE		Definition
    BED		inclined bedding
    FOL		compaction or flow foliation
    FLT		fault plane
    MES		mesoscale fault plane

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Scott A. Minor
  2. Who also contributed to the data set?
    Funding for map project was provided by the U.S. Department of Energy. Permission for field access was granted by, and a field escort was provided by, the Nellis Air Force Range. T.R. Brandt and J.B. Workman assisted in compiling the digital database and in preparing the digital cartographic output.
  3. To whom should users address questions about the data?
    Scott A. Minor
    U.S. Geological Survey, Geologic Division, National Cooperative Geologic Mapping Team
    research geologist
    Box 25046, MS 913
    Denver, CO

    303-236-0303 (voice)
    303-236-0214 (FAX)

Why was the data set created?

To provide a digital geologic map database of the quadrangle that improves understanding of the regional geologic framework and its influence on the regional groundwater flow system.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 19691231 (process 1 of 10)
    Original geologic mapping by P.P. Orkild and K.A. Sargent of chiefly flat-lying volcanic rocks in the eastern part of the mapped area.
    Date: 03-Oct-1991 (process 2 of 10)
    Hand-drafted stable-base layers of the early, original mapping were scanned and vectorized and then edited using AutoCAD software.
    Date: 31-Dec-1994 (process 3 of 10)
    Recent mapping by S.A. Minor and D.A. Sawyer of part of the Thirsty Mountain shield volcano in the southern part of the mapped area.
    Date: 31-Dec-1995 (process 4 of 10)
    Recent field mapping by S.A. Minor of older, more deformed bedrock terrane (i.e., pre-~12-Ma rocks) in the western part of the mapped area.
    Date: 31-Dec-1996 (process 5 of 10)
    Recent mapping (at 1:100,000-scale detail) of surficial deposits mainly in the southwestern part of the mapped area.
    Date: 31-Dec-1996 (process 6 of 10)
    New geologic field data, which were mapped on aerial photographs of about 1:24,000 scale, were mainly digitized directly from the photographs using a Kern PG-2 stereographic plotter interfaced with CADMAP digital capturing software. The new map data were also imported into AutoCAD for editing.
    Date: 19-Aug-1997 (process 7 of 10)
    Geographic Resource Analysis Support System (GRASS), a public-domain GIS, was used to transform the component map files to Universal Transverse Mercator (UTM) projection and coordinate system. The various map data layers were then converted to ArcINFO coverages.
    Date: 10-Jul-1998 (process 8 of 10)
    ArcINFO was used to conduct final editing and modification of map elements, build and tag polygons, assign attributes to map elements, and generate a plot file of the final geologic compilation.
    Date: 01-Sep-1999 (process 9 of 10)
    First draft of metadata created by sminor using FGDCMETA.AML ver. 1.2 05/14/98 on ARC/INFO data set /data_2/data/sminor/tcnw/tcnwpoly
    Date: 01-Sep-1999 (process 10 of 10)
    Creation of original metadata record Person who carried out this activity:
    U.S. Geological Survey, National Cooperative Geologic Mapping Team
    Attn: Scott A. Minor
    research geologist
    MS 913, Box 25046 DFC
    Denver, CO

    303-236-0303 (voice)
    303-236-0214 (FAX)
  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?
    Original data was entered and checked by the principal geologist/author, who also made a majority of the field observations. Map compilation was subjected to technical review by coauthors and by other USGS geologist.
  2. How accurate are the geographic locations?
    Original, scale-stable, geologic map data were scanned at a resolution of 300 dpi (dots per inch). New geologic data mapped on ~1:24,000-scale aerial photos were digitized photogrammetrically with a horizontal positional accuracy of ~10 m (ground meters). Most digitized positions on the final map compilation are estimated to have an horizontal accuracy of 10-20 m.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Data is complete: no features were eliminated or generalized. Unit properties are described in the text explanation. A digital base map coverage is not included but is available separately.
  5. How consistent are the relationships among the observations, including topology?
    Polygon and chain-node topology present. Map elements were visually checked by the author for overshoots, undershoots, duplicate features, and other errors.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
none--Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data. These data are not to be used at scales larger than 1:24,000.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey, National Cooperative Geologic Mapping Team
    research geologist
    Scott A. Minor
    Denver, CO

    303-236-0303 (voice)
    Contact_Instructions: Contact via email
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Although this digital spatial data has been subjected to rigorous review and is substantially complete, it is released on the condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 05-Feb-2016
Last Reviewed: 15-Sep-1999
Metadata author:
Peter N Schweitzer
USGS Midwest Area
Collection manager, USGS Geoscience Data Clearinghouse,
Mail Stop 954
12201 Sunrise Valley Dr
Reston, VA

703-648-6533 (voice)
703-648-6252 (FAX)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

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