Identification_Information: Citation: Citation_Information: Originator: Joel E. Robinson Originator: Dillon R. Dutton Originator: David W. Ramsey Originator: Peter W. Lipman Originator: Tracey J. Felger Publication_Date: 2006 Title: Sheet 1 Geospatial_Data_Presentation_Form: vector digital data Series_Information: Series_Name: Geologic Investigations Series Map Issue_Identification: I-2799 Publication_Information: Publication_Place: Menlo Park, CA Publisher: U.S. Geological Survey Online_Linkage: http://pubs.usgs.gov/imap/i2799/ Larger_Work_Citation: Citation_Information: Originator: Peter W. Lipman Publication_Date: 2006 Title: Geologic Map of the central San Juan caldera cluster, southwestern Colorado Geospatial_Data_Presentation_Form: printed map Series_Information: Series_Name: Geologic Investigations Series Map Issue_Identification: I-2799 Publication_Information: Publication_Place: Menlo Park Publisher: United States Geological Survey Online_Linkage: http://pubs.usgs.gov/imap/i2799/ Description: Abstract: This digital publication contains all the geologic map information for the northern sheet of the Geologic Map of the San Juan caldera cluster, southwestern Colorado and is part of U.S. Geological Survey Geologic Investigations Map Series I-2799. The San Juan Mountains are the largest erosional remnant of a composite volcanic field that covered much of the southern Rocky Mountains in middle Tertiary time. The San Juan field consists mainly of intermediate-composition lavas and breccias, erupted about 35-30 Ma from scattered central volcanoes (Conejos Formation) and overlain by voluminous ash-flow sheets erupted from caldera sources. In the central San Juan Mountains, eruption of at least 8,800 km3 of dacitic-rhyolitic magma as nine major ash flow sheets (individually 150-5,000 km3) was accompanied by recurrent caldera subsidence between 28.3 Ma and about 26.5 Ma. Voluminous andesitic-dacitic lavas and breccias were erupted from central volcanoes prior to the ash-flow eruptions, and similar lava eruptions continued within and adjacent to the calderas during the period of more silicic explosive volcanism. Exposed calderas vary in size from 10 to 75 km in maximum dimension, the largest calderas being associated with the most voluminous eruptions. Purpose: This database was constructed in order to produce a geologic map as a basis for understanding processes involved in the eruptions that built the central San Juan caldera cluster. Supplemental_Information: All the geologic map information used to publish U.S. Geological Survey Geologic Investigations Series I-2799 is contained in this digital publication. These coverages show the distribution and relations of volcanic and bedrock units and contain the geologic units, contacts, structural measurements, radiometric age dates, caldera boundaries, and areas of geothermal alteration. This map sheet contains the following quadrangles: Baldy Cinco(bc), Cannibal Plateau(ca), Elk Park(ep), Half Moon Pass(hm), Mesa Mountain(me), Mineral Mountain(mi), Saguache Park(sa), Slimgulion(sg), San Luis Peak(sl), and Stewart Peak(sp). For each quadrangle geologic lines, polygons and structural points were mapped and labeled with the quad's abbreviation. Geologic sample locations, areas of alteration, and caldera boundaries were mapped by sheet rather than quad for cartographic reasons. This metadata file was written to generally describe all coverages used to create sheet 1. For more specific metadata, see the individual metadata files provided with each coverage contained in the data release. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2000 Currentness_Reference: The information in this report is the most up-to-date available at the time of publication. Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -107.255921 East_Bounding_Coordinate: -106.621207 North_Bounding_Coordinate: 38.132593 South_Bounding_Coordinate: 37.867381 Keywords: Theme: Theme_Keyword_Thesaurus: none Theme_Keyword: volcanoes Theme_Keyword: geology Theme_Keyword: caldera Theme_Keyword: explosive eruptions Theme_Keyword: lava flows Theme_Keyword: breccia Place: Place_Keyword_Thesaurus: none Place_Keyword: United States of America Place_Keyword: Colorado Place_Keyword: central San Juan mountains Place_Keyword: Gunnison, CO Stratum: Stratum_Keyword_Thesaurus: none Temporal: Temporal_Keyword_Thesaurus: none Temporal_Keyword: Quaternary Temporal_Keyword: Holocene Temporal_Keyword: Pleistocene Temporal_Keyword: Pliocene Temporal_Keyword: Tertiary Temporal_Keyword: Oligocene Temporal_Keyword: Miocene Access_Constraints: none Use_Constraints: Uses of this digital geologic map should not violate the spatial resolution of the data. Although the digital form of the data removes the constraint imposed by the scale of a paper map, the detail and accuracy inherent in map scale are also present in the digital data. The fact that this database was edited for a scale of 1:24,000 means that higher resolution information is not present in the dataset. Plotting at scales larger than 1:24,000 will not yield greater real detail, although it may reveal fine-scale irregularities below the intended resolution of the database. Similarly, where this database is used in combination with other data of higher resolution, the resolution of the combined output will be limited by the lower resolution of these data. Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from these data. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey, Volcano Hazards Team Contact_Person: Joel E Robinson Contact_Position: Geologist Contact_Address: Address_Type: mailing address Address: 345 Middlefield Road Address: MS 910 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: USA Contact_Electronic_Mail_Address: jrobins@usgs.gov Contact_Instructions: preferred contact by e-mail Data_Set_Credit: The database was compiled from original geologic mapping by Peter W. Lipman. Preparation of the database was done by Joel E. Robinson, David W. Ramsey, Dillon Dutton, Tracey Felgar, and Don Shamp. Security_Information: Security_Classification: Unclassified Native_Data_Set_Environment: Microsoft Windows 2000 Version 5.2 (Build 3790) Service Pack 1; ESRI ArcCatalog 9.1.0.722 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: See Entity_Attribute_Information Logical_Consistency_Report: Polygon and arc (chain-node) topology present in appropriate feature classes. Other feature classes are point, annotation or raster and do not require topologic relationships. Completeness_Report: The report is intended to describe completely the igneous and volcanic products, volcanic vent locations, structural features and structural measurements at 1:24,000 scale. Geological information appropriately mapped at larger scale has been omitted. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Well located data items are intended to have a horizontal positional accuracy better than 0.5 mm at 1:24,000 scale, or within 12 meters on the ground. The general positional accuracy of each line in the database is indicated qualitatively within the LTYPE field in the Arc Attribute Table (see Attribute_Domain_Values). Points in the database are generally well located. The position of each data item is derived from a USGS 1:24,000 topographic base map, and therefore additonal inaccuracies may also be encountered that are within National Map Accuracy Standards. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: No vertical positional data recorded Lineage: Process_Step: Process_Description: Geologic linework was compiled on USGS 1:24,000 topographic maps by Peter W. Lipman. The linework was then scanned at 400 dpi, georeferenced, converted to vector data using the ArcInfo command GRIDLINE , and edited on-screen to repair errors visible at map scale. Polygon topology was created and each arc and polygon tagged on-screen. Structural information was digitized by hand on-screen. Plotfiles were created in ArcPlot. Individual quadrangles were then plotted with topography and checked by Peter Lipman. Metadata was created. Process_Date: 2006 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey, Volcano Hazards Team Contact_Person: Joel E Robinson Contact_Position: Geologist Contact_Address: Address_Type: mailing address Address: 345 Middlefield Road Address: MS 910 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: USA Contact_Electronic_Mail_Address: jrobins@usgs.gov Spatial_Data_Organization_Information: Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: Lambert Conformal Conic Lambert_Conformal_Conic: Standard_Parallel: 37.233333 Standard_Parallel: 38.433333 Longitude_of_Central_Meridian: -105.500000 Latitude_of_Projection_Origin: 36.666667 False_Easting: 609601.219202 False_Northing: 0.000000 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: 0.000148 Ordinate_Resolution: 0.000148 Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1927 Ellipsoid_Name: Clarke 1866 Semi-major_Axis: 6378206.400000 Denominator_of_Flattening_Ratio: 294.978698 Vertical_Coordinate_System_Definition: Altitude_System_Definition: Altitude_Resolution: 0.000010 Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: This metadata is included to provide general information that is applicable to all of the geologic quadrangles and structural layers. We have tried to tailor specific aspects to better fit arcs versus points versus rasters, but this was kept to a minimum. See individual data files for more specific metadata information. Lines (arcs) in the database serve two functions: they represent boundaries to polygonal areas (e.g. line types of geologic contacts and faults), and they represent linear features (e.g. line types of faults, crater rims, and morain crests). This information on line type is described in the LTYPE field in the geology_arc table. Geologic units (polygons) are described in a geology_poly table. The unit symbol for each geologic map unit is recorded in the PTYPE field of the table. For a detailed description of the geologic map units please see the Description of Map Units in the pamphlet. Point features (e.g. sample locations, vents, strikes and dips) are described in the PTTYPE field in the geology_points table. Other fields in this table include STRIKE, DIP and RADIO_AGE, which are used to describe the orientation and attitude of structural symbols and radiometric ages of samples. Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Person: USGS Information Services Contact_Address: Address_Type: mailing address Address: Box 25286 Address: Denver Federal Center City: Denver State_or_Province: Colorado Postal_Code: 80225-0046 Country: USA Contact_Voice_Telephone: (303)202-4200 Contact_Voice_Telephone: 1-888-ASK-USGS Contact_Facsimile_Telephone: (303)202-4695 Contact_Electronic_Mail_Address: infoservices@usgs.gov Resource_Description: These files are integral to the U.S. Geological Survey I-2799. Distribution_Liability: This database, identified as I-2799, has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Transfer_Size: 0.646 Digital_Transfer_Option: Offline_Option: Offline_Media: CD-ROM Metadata_Reference_Information: Metadata_Date: 20060810 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Person: Joel E Robinson Contact_Position: Geologist Contact_Address: Address_Type: mailing address Address: 345 Middlefield Road Address: MS 910 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: USA Contact_Voice_Telephone: (650)329-5322 Contact_Facsimile_Telephone: (650)329-5203 Contact_Electronic_Mail_Address: jrobins@usgs.gov Contact_Instructions: prefered contact by e-mail Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time Metadata_Security_Information: Metadata_Security_Classification: Unclassified Metadata_Extensions: Online_Linkage: http://www.esri.com/metadata/esriprof80.html Profile_Name: ESRI Metadata Profile