Identification_Information: Citation: Citation_Information: Originator: Mitchell W. Reynolds Originator: William H. Hayes Originator: D. Paco VanSistine Publication_Date: 2002 Title: Geologic Map of the Nelson 7.5' Quadrangle, Lewis and Clark County, Montana Edition: (Version 1.0, February 22, 2001) Geospatial_Data_Presentation_Form: Map Series_Information: Series_Name: USGS Geologic Investigations Series Issue_Identification: I-2774 Publication_Information: Publication_Place: Denver, Colorado Publisher: U.S. Geological Survey Online_Linkage: http://pubs.usgs.gov/imap/i-2774/ Description: Abstract: The geologic map of the Nelson quadrangle, scale 1:24,000, was prepared as part of the Montana Investigations Project to provide new information on the stratigraphy, structure, and geologic history of an area in the geologically complex southern part of the Montana disturbed belt. In the Nelson area, rocks ranging in age from Middle Proterozoic through Cretaceous are exposed on three major thrust plates in which rocks have been telescoped eastward. Rocks within the thrust plates are folded and broken by thrust faults of smaller displacement than the major bounding thrust faults. Middle and Late Tertiary sedimentary and volcaniclastic rocks unconformably overlie the pre-Tertiary rocks. A major normal fault displaces rocks of the western half of the quadrangle down on the west with respect to strata of the eastern part. Alluvial and terrace gravels and local landslide deposits are present in valley bottoms and on canyon walls in the deeply dissected terrain. Different stratigraphic successions are exposed at different structural levels across the quadrangle. In the northeastern part, strata of the Middle Cambrian Flathead Sandstone, Wolsey Shale, and Meagher Limestone, the Middle and Upper Cambrian Pilgrim Formation and Park Shale undivided, the Devonian Maywood, Jefferson, and lower part of the Three Forks Formation, and Lower and Upper Mississippian rocks assigned to the upper part of the Three Forks Formation and the overlying Lodgepole and Mission Canyon Limestones are complexly folded and faulted. These deformed strata are overlain structurally in the east-central part of the quadrangle by a succession of strata including the Middle Proterozoic Greyson Formation and the Paleozoic succession from the Flathead Sandstone upward through the Lodgepole Limestone. In the east-central area, the Flathead Sandstone rests unconformably on the middle part of the Greyson Formation. The north edge, northwest quarter, and south half of the quadrangle are underlain by a succession of rocks that includes not only strata equivalent to those of the remainder of the quadrangle, but also the Middle Proterozoic Newland, Greyson, and Spokane Formations, Pennsylvanian and Upper Mississippian Amsden Formation and Big Snowy Group undivided, the Permian and Pennsylvanian Phosphoria and Quadrant Formations undivided, the Jurassic Ellis Group and Lower Cretaceous Kootenai Formation. Hornblende diorite sills and irregular bodies of probable Late Cretaceous age intrude Middle Proterozoic, Cambrian and Devonian strata. No equivalent intrusive rocks are present in structurally underlying successions of strata. In this main part of the quadrangle, the Flathead Sandstone cuts unconformably downward from south to north across the Spokane Formation into the upper middle part of the Greyson Formation. Tertiary (Miocene?) strata including sandstone, pebble and cobble conglomerate, and vitric crystal tuff underlie, but are poorly exposed, in the southeastern part of the quadrangle where they are overlain by late Tertiary and Quaternary gravel. The structural complexity of the quadrangle decreases from northeast to southwest across the quadrangle. At the lowest structural level (Avalanche Butte thrust plate) exposed in the canyon of Beaver Creek, lower and middle Paleozoic rocks are folded in northwest-trending east-inclined disharmonic anticlines and synclines that are overlain by recumbently folded and thrust faulted Devonian and Mississippian rocks. The Mississippian strata are imbricated adjacent to the recumbent folds. In the east-central part of the quadrangle, a structurally overlying thrust plate, likely equivalent to the Hogback Mountain thrust plate of the Hogback Mountain quadrangle adjacent to the east (Reynolds, 20xx), juxtaposes recumbently folded Middle Proterozoic and unconformably overlying lower Paleozoic rocks on the complexly folded and faulted rocks of the Avalanche Butte thrust plate. The highest structural plate, bounded below by the Moors Mountain thrust fault superposes a gently folded plate of Middle Proterozoic and Phanerozoic rocks on the complexly folded and faulted underlying plates. From the center of the east edge to the north edge of the quadrangle, the Moors Mountain thrust fault ramps steeply upward through the Newland formation to the middle part of the Greyson Formation across a structural culmination in the underlying thrust plates. Thrust faults with small stratigraphic separation displace upper Paleozoic strata in the southwest part of the quadrangle. A major normal fault, the Soup Creek fault, displaces rocks of the Moors Mountain thrust plate downward to the west across the quadrangle. The normal fault is likely listric to the Moors Mountain thrust fault. Movement on the fault has been younger than, and might also predate, the Miocene? strata that dip eastward into the fault. In the western part of the quadrangle, west-northwest-trending faults with components of strike-slip and normal movement are continuous westward with late Cenozoic faults that bound Hilger Valley (Robinson, McCallum, and Hays, 1969). Purpose: The geologic map of the Nelson quadrangle provides geologic information for land use planning, including assessment of natural resources, natural hazards, and recreational potential, and for land use management. The map provides interpretation of geology and scenic terrain for recreationalists using the Gates of the Mountains Wilderness. The map provides data for scientific interpretation of the geology of part of the south end of the Montana disturbed belt. Supplemental_Information: Map_Political_Location: Lewis and Clark County, Montana Map_Scale: 1:24,000 Geology mapped in 1967, 1976, 1977, 1988 Geospatial datafiles and other files included in this data set: nelson_geol: geologic units nelson_lines: faults, sills, folds nelson_pts: bedding, foliation nelson_xsect: cross section lines Data sources used for this map--- Billingsley, P.R., and Locke, Augustus, 1939, Structure of ore deposits in the continental framework: New York, American Institute of Mining and Metallurgical Engineers, 51 p. Folk, R.L., 1962, Spectral subdivision of limestone types, in Ham, W. E., ed., Classification of carbonate rocks-A symposium: American Association of Petroleum Geologists Memoir 1, p. 62-84. Harrison, J.E., and Reynolds, M.W., 1976, Western U.S. continental margin-A stable platform dominated by vertical tectonics in the late Precambrian: Geological Society of America Abstracts with Programs, v. 8, no. 6, p. 905. Hobbs, S.W., Griggs, A.B., Wallace, R.E., and Campbell, A.B., 1965, Geology of the Coeur d'Alene District, Shoshone County, Idaho: U.S. Geological Survey Professional Paper 478, 139 p. Reynolds, M.W., 1977, Character and significance of deformation at the east end of the Lewis and Clark line, Montana: Geological Society of America Abstracts with Programs, v. 9, no. 6, p. 758-759. Reynolds, M.W., 1979, Character and extent of basin-range faulting, western Montana and east-central Idaho, in Newman, G.W., and Goode, H.D., eds., RMAG and UGA 1979 Basin and Range Symposium: Denver, Colo., Rocky Mountain Association of Geologists, p. 185-193. Reynolds, Mitchell W., 2002, Geologic map of the Hogback Mountain quadrangle, Lewis and Clark and Meagher Counties, Montana: U.S. Geological Survey Geologic Investigations Map I-2773, Scale 1:24,000. Reynolds, M.W., and Close, T.J., 1984, Gates of the Mountains Wilderness and additions, Montana, in Marsh, S.P., Kropschot, S.J., and Dickinson, R.G., eds., Wilderness Mineral Potential: U.S. Geological Survey Professional Paper 1300, volume 2, p. 705-708. Reynolds, M.W., and Kleinkopf, M.D., 1977, The Lewis and Clark line, Montana-Idaho: A major intraplate tectonic boundary: Geological Society of America Abstracts with Programs, v. 9, no. 7, p. 1140-1141. Robinson, G.D., and McCallum, M.E., 1991, Preliminary geologic map of the Beartooth Mountain quadrangle, Lewis and Clark County, Montana: U.S. Geological Survey Open-File Report 991-113, scale 1:24,000. Robinson, G.D., McCallum, M.E., and Hays, W.H., 1969, Geologic map of the Upper Holder Lake quadrangle, Lewis and Clark County, Montana: U.S. Geological Survey Geologic Quadrangle Map GQ-840, scale 1:24,000. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2002 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: None Planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -111.875 East_Bounding_Coordinate: -111.75 North_Bounding_Coordinate: 46.875 South_Bounding_Coordinate: 46.75 Keywords: Theme: Theme_Keyword_Thesaurus: American Geologic Institute (AGI) Glossary of Geology Theme_Keyword: Montana disturbed belt Theme_Keyword: Lewis and Clark line Theme_Keyword: thrust fault Theme_Keyword: thrust plate Theme_Keyword: recumbent fold Theme_Keyword: strike-slip fault Theme_Keyword: Moors Mountain thrust fault Theme_Keyword: Moors Mountain thrust plate Theme_Keyword: Hogback Mountain thrust fault Theme_Keyword: Hogback Mountain thrust plate Theme_Keyword: Avalanche butte thrust plate Theme_Keyword: Soup Creek fault Place: Place_Keyword_Thesaurus: U.S. Board of Geographic Names (BGN) Geographic Names Information System (GNIS) Place_Keyword: USA Place_Keyword: Montana Place_Keyword: Lewis and Clark County Place_Keyword: Big Belt Mountains Place_Keyword: Gates of the Mountains Wilderness Place_Keyword: Nelson Place_Keyword: Beaver Creek Big Belt Mountains Place_Keyword: Soup Creek Big Belt Mountains Place_Keyword: Favorite Gulch Big Belt Mountains Access_Constraints: none Use_Constraints: None. However, citation of publication reference and acknowledgement of the U.S. Geological would be appreciated in all products that use or are derived from these data. These data are not intended to be used at a scale greater than 1:24,000. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Mitchell W. Reynolds Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: (mailing and physical address) Address: P.O. Box 25045, Federal Center, MS-913 City: Denver State_or_Province: CO Postal_Code: 80225-0046 Country: USA Contact_Voice_Telephone: 303-236-8007 Contact_Facsimile_Telephone: 303-236-5349 Contact_Electronic_Mail_Address: mwreynol@usgs.gov Data_Set_Credit: Technical reviews by Bradley S. VanGosen and William J. Perry, U.S. Geological Survey, helped improve the quality of the geologic map, illustrations and text. Paco VanSistine translated the original map data into digital files and provided ready counsel on issues related to the digital cartography. Native_Data_Set_Environment: SunOS, 5.7, sun4d UNIX ARC/INFO version 8.0.2 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Geologic data were entered in the field directly on the Nelson topographic base map at a scale of 1:24,000. Location of control and data points was made by instrument resection and by inspection where topographic contours were distinct. Data point in the southwest quarter of the quadrangle were located by inspection on aerial photographs and transferred by Kelsh plotter to the topographic base. Elevations were checked in the field using an altimeter calibrated at base stations and at surveyed elevations from the topographic map. Data were transferred from field sheets to a scale-stable mylar base map, and separate scale-stable registered overlays were constructed for polygons, lines, symbols, and tags. Color check test plots were compared carefully to the original geology map, and corrections were made as needed. The map has been thoroughly reviewed for conformity with U.S. Geological Survey stratigraphic nomenclature and editorial standards. Logical_Consistency_Report: Map elements were visually checked for overshoots, undershoots, duplicate features, polygon closure, and other errors by the author and by the GIS technician(s) that created the digital database. Automated (Arc Info) routines were also used to check the databases for polygon label errors, line or point attribution errors, sliver polygons, dangling arcs, intersection errors, and projection information. Check plots of the map were reviewed by at least two other geologists for consistency with basic geologic principles and general conformity to USGS mapping standards. Completeness_Report: Data are complete. No features that could be accurately represented at the compilation scale of 1:24,000 were eliminated or generalized. Data is complete: no features were eliminated or generalized. The smallest area represented is about 485 square meters. All geospatial database elements are attributed. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Location of control and data points was made by instrument resection and by inspection where topographic contours were distinct. Elevations were checked in the field using an altimeter calibrated at base stations and at surveyed elevations from the topographic map. Thus line and points on original field maps generally were located with a vertical position accuracy of less than one contour interval and with a horizontal position accuracy of about 15 m (50 ft) Lines and points were digitized from the scale-stable geologic base map with a resolution of 0.001 inch. Information is added in accordance to U.S. National Map Accuracy Standards, Revised June 17, 1947. 95 % of points plotted on mylar matched the source map within 1/50 inch. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Various authors; see complete references in Supplemental Information section of this metadata file. Title: Various titles; see complete references in Supplemental Information section of this metadata file. Publication_Date: 1939-2002; see complete references in Supplemental Information section of this metadata file. Type_of_Source_Media: paper; Reynolds (2002) also available as digital files. Source_Time_Period_of_Content: Source_Currentness_Reference: 1939-2002; see complete references in Supplemental Information section of this metadata file. Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1939 Ending_Date: 2002 Source_Citation_Abbreviation: Arbogast and others (2002) Source_Contribution: These data references were used to compile the main map; see complete references in Supplemental Information section of this metadata file. Process_Step: Process_Description: Part of the database was compiled from these references; see complete references in Supplemental Information section of this metadata file. Process_Date: 2001 Process_Step: Process_Description: A scale-stable greenline mylar containing the drafted geologic map compilation was scanned on an Image large-format scanner and the resultant image geo-registered. Process_Date: 2001 Process_Step: Process_Description: The geo-registered image was color separated using Autographics trainer software. The resulting image was converted to ArcInfo GRID and vectorized using ArcScan. Process_Date: 2001 Process_Step: Process_Description: Coverages were created using the ArcInfo GENERATE command with the FISHNET option. Coverages were captured and attributed in ArcEdit with the geo-registered image displayed in the background for reference. Process_Date: 2001 Process_Step: Process_Description: Attributes for linecode, name, source and symbol were added to the .AAT files of the polygon and line coverages. Attributes for unit, source, label, and desc(ription) were added to the .PAT of the polygon coverage. Attributes for pttype, symbol, strike, dip, calcang, sym$angle, and source were added to the .PAT file of the point coverage. Process_Date: 2001 Process_Step: Process_Description: ArcInfo attribute tables were created and updated containing full descriptive text for each rock unit, as well as additional structural information concerning line features and source identification for all objects in the GIS database. Process_Date: 2001 Process_Step: Process_Description: Check plots of the coverages were printed and checked against source materials for accuracy and completeness. The database information was checked visually and using various routines in ArcInfo for accuracy and consistency. Process_Date: 2001 Process_Step: Process_Description: Metadata created using FGDCMETA.AML ver. 1.2 05/14/98 and TKME version 2.8.10 Process_Date: 2002 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Point Point_and_Vector_Object_Count: 261 SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: String Point_and_Vector_Object_Count: 1083 SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains Point_and_Vector_Object_Count: 262 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: Polyconic Polyconic: Longitude_of_Central_Meridian: -111 48 45 Latitude_of_Projection_Origin: 46 45 00 False_Easting: 0.00000 False_Northing: 0.00000 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: 1.390722934541 Ordinate_Resolution: 1.390722934541 Planar_Distance_Units: Meters Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1927 Ellipsoid_Name: Clarke 1866 Semi-major_Axis: 6378206.4 Denominator_of_Flattening_Ratio: 294.98 Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: >NELSON_GEOL.PAT: > >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 AREA 8 18 F 5 > 9 PERIMETER 8 18 F 5 > 17 NELSON_GEOL# 4 5 B - > 21 NELSON_GEOL-ID 4 5 B - > 25 UNIT 10 10 C - > 35 LABEL 10 10 C - > 45 DESCRIPTION 100 100 C - > 145 SHADESYM 5 5 N 0 > 150 PATTERN 10 10 I - UNIT SHADESYM DESCRIPTION Cf 264 Flathead Sandstone (Middle Cambrian) Cm 164 Meagher Limestone (Middle Cambrian) Cpp 274 Pilgrim Formation and Park Shale, undivided (Upper and Middle Cambrian) Cw 143 Wolsey Shale (Middle Cambrian) DCm 346 Maywood Formation (Upper and Middle Devonian) Dj 102 Jefferson Formation (Devonian) Djb 325 Jefferson Formation (Devonian) Jme 530 Morrison Formation and Ellis Group, undivided (Jurassic) Khd 4 Hornblende diorite (Upper Cretaceous) Kk 261 Kootenai Formation (Lower Cretaceous) MDt 304 Three Forks Formation (Mississippian and Devonian) Ml 100 Lodgepole Limestone (Lower Mississippian) Mm 300 Mission Canyon Limestone (Upper and Lower Mississippian) PMab 432 Amsden Formation and Big Snowy Group, undivided (Pennsylvanian and Upper Mississippian) PPpq 533 Phosphoria and Quadrant Formations, undivided (Permian and Pennsylvanian) QTg 52 Older gravel (Pleistocene and Pliocene) Qa 30 Alluvium (Holocene) Ql 60 Landslide deposits (Holocene and Pleistocene) Qog 71 Old gravel (Holocene and Pleistocene) Ts 73 Sandstone, conglomerate, and tuff (Miocene?) Yg 453 Greyson Formation (Belt Supergroup, Middle Proterozoic) Yn 263 Newland Formation (Belt Supergroup, Middle Proterozoic) Ys 144 Spokane Formation (Belt Supergroup, Middle Proterozoic) > >NELSON_GEOL.AAT: > >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 FNODE# 4 5 B - > 5 TNODE# 4 5 B - > 9 LPOLY# 4 5 B - > 13 RPOLY# 4 5 B - > 17 LENGTH 8 18 F 5 > 25 NELSON_GEOL# 4 5 B - > 29 NELSON_GEOL-ID 4 5 B - > 33 LINECODE 3 3 I - > 36 DESCRIPTION 100 100 C - LINECODE DESCRIPTION 0 fault contact 1 contact certain 2 contact approximately located 3 contact inferred 4 contact concealed 173 border > >NELSON_LINES.AAT: > >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME INDEXED? > 1 FNODE# 4 5 B - - > 5 TNODE# 4 5 B - - > 9 LPOLY# 4 5 B - - > 13 RPOLY# 4 5 B - - > 17 LENGTH 8 18 F 5 - > 25 NELSON_LINES# 4 5 B - - > 29 NELSON_LINES-ID 4 5 B - - > 33 LINECODE 10 10 I - - > 43 DESCRIPTION 100 100 C - - LINECODE DESCRIPTION 14 thrust fault, first generation certain 15 thrust fault, first generation certain 20 thrust fault, first generation approximately located 21 thrust fault, first generation approximately located 22 thrust fault, first generation inferred 23 thrust fault, first generation inferred 24 thrust fault, first generation concealed 25 thrust fault, first generation concealed 33 overturned thrust fault, first generation approximately located 50 normal fault certain 51 normal fault certain 60 anticline certain 60 asymmetric anticline certain 61 anticline approximately located 61 asymmetric anticline approximately located 80 overturned anticline certain 81 overturned anticline approximately located 82 overturned anticline inferred 92 syncline certain 112 overturned syncline certain 113 overturned syncline approximately located 114 overturned syncline inferred 121 inverted syncline approximately located 122 inverted syncline inferred 173 fault certain 176 fault concealed 183 normal fault inferred 184 normal fault concealed 187 strike-slip fault, left-lateral offset inferred 216 fault approximately located 217 fault inferred 221 anticline certain 222 hornblende diorite sill certain 223 hornblende diorite sill approximately located 224 hornblende diorite sill inferred 231 hornblende diorite sill concealed 231 inverted anticline certain 233 fold axes concealed > >NELSON_PTS.PAT > >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME INDEXED? >1 AREA 8 18 F 5 - >9 PERIMETER 8 18 F 5 - >17 NELSON_PTS# 4 5 B - - >21 NELSON_PTS-ID 4 5 B - - >25 SYMBOL 3 3 I - - >28 ROTATION 3 3 I - AZIMUTH - >31 INCLINATION 3 3 I - DIP - >34 DESCRIPTION 100 100 C - - SYMBOL DESCRIPTION 2 inclined bedding 2 overturned bedding 3 inclined bedding - top direction of beds known from local features 4 vertical bedding 6 overturned bedding 92 inclined crinkled or deformed foliation in metamorphic rock 103 inclined tunnel or adit 109 prospect(pit or small open cut) 114 inclined cleavage 116 vertical or near-vertical cleavage 121 vertical mine shaft 153 minor anticline 180 lineation 241 spring 742 quartz vein 743 rock data site - Ts > >NELSON_XSECT.AAT > >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME INDEXED? > 1 FNODE# 4 5 B - - > 5 TNODE# 4 5 B - - > 9 LPOLY# 4 5 B - - > 13 RPOLY# 4 5 B - - > 17 LENGTH 8 18 F 5 - > 25 NELSON_XSECT# 4 5 B - - > 29 NELSON_XSECT-ID 4 5 B - - > 33 LINECODE 10 10 I - - > 43 DESCRIPTION 100 100 C - - DESCRIPTION section line A section line B section line C section line D Entity_and_Attribute_Detail_Citation: none Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Position: Water Webserver Team Contact_Address: Address_Type: mailing and physical address Address: Central Publications Group Address: P.O. Box 25046, Federal Center, MS 902 City: Denver State_or_Province: CO Postal_Code: 80225-0046 Country: USA Contact_Voice_Telephone: 303-236-5486 Distribution_Liability: Although these data have been subjected to rigorous review and are substantially complete, they are released on the condition that neither the U.S. Geological Survey nor the United States Government may be held liable for any damages resulting from their authorized or unauthorized use. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ARCE, SHP Format_Version_Number: created with ArcInfo v. 8.0.2 File_Decompression_Technique: .tar.gz - UNIX gzip-compressed TAR file(ARCE files) use GNU zip and TAR.EXE - self-extracting Window ZIP archive (SHP files_ - execute the file to extract Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: <