Identification_Information: Citation: Citation_Information: Originator: Anna Burack Wilson Originator: Bruce Bryant Publication_Date: 2006 Title: Isotopic ages of rocks in the northern Front Range, Colorado Series_Information: Series_Name: Open-File Report Issue_Identification: OFR-2006-1051 Publication_Information: Publication_Place: Denver, Colorado Publisher: U.S. Geological Survey Online_Linkage: http://pubs.usgs.gov/of/2006/ Description: Abstract: These maps, and the tables that accompany them, are a compilation of isotopic age determinations of rocks and minerals in four 1:100,000 quadrangles in the northern and central Front Range, Colorado. Phanerozoic (primarily Tertiary and Cretaceous) age data are shown on one map; Proterozoic data are on the other. A sample location map is included for ease of matching specific localities and data in the tables to the maps. Several records in the tables were not included in the maps because either there were ambiguous dates or lack of location precluded accurate plotting. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2005 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: None planned. Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -106.00 East_Bounding_Coordinate: -105.00 North_Bounding_Coordinate: 41.00 South_Bounding_Coordinate: 39.00 Keywords: Theme: Theme_Keyword_Thesaurus: none Theme_Keyword: Isotope Theme_Keyword: Isotopic Theme_Keyword: Age Theme_Keyword: Date Theme_Keyword: Fort Collins Theme_Keyword: Estes Park Theme_Keyword: Denver West Theme_Keyword: Bailey Theme_Keyword: Denver Theme_Keyword: Greeley Place: Place_Keyword_Thesaurus: none Place_Keyword: USA Place_Keyword: Colorado Place_Keyword: Larimer County Place_Keyword: Jackson County Place_Keyword: Grand County Place_Keyword: Boulder County Place_Keyword: Gilpin County Place_Keyword: Jefferson County Place_Keyword: Clear Creek County Place_Keyword: Summit County Place_Keyword: Park County Place_Keyword: Douglas Access_Constraints: none Use_Constraints: Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data. Browse_Graphic: Browse_Graphic_File_Name: http://pubs.usgs.gov/of/2006/ Browse_Graphic_File_Description: graphic representation of map layout Browse_Graphic_File_Type: PDF Data_Set_Credit: Anna B. Wilson and Bruce Bryant Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Isotopic age data was compiled and entered into Microsoft Word tables by Bruce Bryant. Anna Wilson translated the Word tables into a Microsoft Office 2003 Excel spreadsheet and imported the spreadsheet into MapInfo Professional v. 8.0, a GIS. The plates were made by printing directly from MapInfo Pro 8.0 to pdf files using Adobe Acrobat Distiller. Many revisions were made to the GIS database. If any discepancies are found between the tables and the GIS data, the location information in the GIS supersedes that in the tables, whereas comments and references in the tables supersede comments and references in the GIS datasets. Phanerozoic and Proterozoic intrusive rocks are shown only as an illustrative aid. These bodies were selected and modified by Anna Wilson from the Geologic Map of Colorado (Green, 1992 after Tweto, 1979) with several modifications by Anna Wilson and Bruce Bryant. Specifically, the Mt. Evans pluton, mapped by Tweto as Early Proterozoic (Xg), was later demonstrated to be Middle Proterozoic and is therefore shown as Yg on this map. Although portrayed at 1:250,000 scale for illustration purposes, the geologic layer is not accurate at scales more detailed than 1:500,000. This map has not been thoroughly reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Logical_Consistency_Report: The map was reviewed by two other scientists for consistency with basic geologic principles and general conformity to USGS mapping standards. Completeness_Report: Data is complete: Most features on Tweto's 1979 geologic map were eliminated or generalized. The age of the Mt. Evans pluton has been revised to Middle Proterozoic. On the Phanerozoic plate, TKi of Tweto is equivalent to TKi on this map, Tmi on this map includes units Tmi, Tui, and locally may include Tbr, of Tweto. Units are described in Tweto (1979) and in Green (1992). In addition, intrusive bodies at Mt. Richthofen/Mt. Cumulus, Jamestown/Porphyry Mtn., Sunset/Bald Mtn., Caribou/Eldora-Bryan (north), have been subdivided by Wilson based on more detailed maps. These subdivisions are for illustrative purposes only, and are not accurate even at 1:500,000-scale. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Accuracy of the sample locations is varied and rarely stated in the source literature. In most cases, if the user were to plot the location given on a 1:24,000-scale topographic map and then visit the site, it would be fairly easy to determine the likely source of the sample within a hundred meters. Locations marked as approximate (either with an "x" in the "approx" field in the tables or database, or indicated as an open (unfilled) symbol on the maps, are estimated to be within 1/4 mi of the sample site. Sites we deemed beyond that distance are included in the Word tables but not in the GIS datasets. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Tweto, Ogden Publication_Date: 1979 Title: Geologic Map of Colorado Type_of_Source_Media: paper Source_Citation_Abbreviation: Tweto (1979) Source_Contribution: This data was used to compile the geologic units on the maps. Source_Information: Source_Citation: Citation_Information: Originator: Green, G.N. Publication_Date: 1992 Title: The Digital Geologic Map of Colorado in ARC/INFO Format: U.S. Geological Survey Open-File Report OF-92-0507. http://pubs.usgs.gov/of/1992/ofr-92-0507/ Type_of_Source_Media: digital Source_Time_Period_of_Content: Source_Currentness_Reference: 1992 Source_Citation_Abbreviation: Green (1992) Source_Contribution: Selected data was used from this source to compile part of the simplified geologic maps. Process_Step: Process_Description: ArcInfo datasets were imported into MapInfo and the intrusive rock units within the four quadrangles of interest were selected by Anna Wilson. Process_Date: 2003 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Planar: Grid_Coordinate_System: Geographic: Geographic_Coordinate_Units: decimal degrees (latitude/longitude) Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: The maps can be created from the files 4QuadMask_Tplutons, 4QuadMask_pCplutons, and IsotopicAgeDates. The first two files contain a subset of polygons for the Tertiary and Cretaceous intrusions and the Proterozoic intrusions at 1:500,000-scale. The last file contains the location and age information for each of the samples. Entity_and_Attribute_Detail_Citation: The data is supplied in ARC shape file (.shp) and export (.e00) formats. DATABASE STRUCTURE - ARC==================================== The databases used to construct the map consist of the following root-name shape files: 4QuadMask_Tplutons (Phanerozoic polygons, mostly Tertiary and Cretaceous, intrusive rocks) NAME-5 character label based on Tweto (1979) or Wilson (2005, unpub. data). unit_name-up to 254 character name based on Tweto (1979) or Wilson (2005, unpub. data). PLUT_ID-7 character ID number of no concern to the user (Wilson, 2005, unpub. database). PLUT_NAME-40 character name assigned by Wilson and Bryant to each pluton. UNIT_REF-80 character simplified reference for additional information. STMAP_SYM-5 character symbol used on Tweto's State map (same as NAME) 4QuadMask_pCplutons (Proterozoic polygons, intrusive rocks) CONTACT_Integer, links to Green (1992) but serves no other purpose. CONTACT_ID-Integer, links to Green (1992) but serves no other purpose. NAME-5 character symbol used on Tweto's State map. Mt. Evans pluton was coded Xg by Tweto (1979) but changed to Yg on this map. IsotopicAgeDates (point locations for age date samples) QuadID-7 character identification number where the first two letters indicate BA, Bailey; DW, Denver West; EP, Estes Park; or FC, Fort Collins 1:100,000-scale quadrangle. The last 3 digits identify each site within each quadrangle. A lower case letter follows the number if there is more than one sample at the same location. Unit_name-map unit name on Tweto (1979) Sample_No_-Sample number in original publication, if given. Latitude_N_, Longitude_W_-Latitude and longitude in degrees, minutes, seconds, as given in original publication. May be obsolete. Superseded by the decimal degree field. approx.-very important field, an "X" indicates the location is approximate. LatDD, LongDD-Latitude and longitude in decimal degrees. This field was populated by querying the location in the GIS and supersedes any discrepancies in the degrees, minutes, and seconds. _71_2_minute_quadrangle-Name of 1:24,000-scale quadrangle. Method-Isotopic dating method used. tracklength-if determined for FT (fission-track) samples. Mineral-mineral dated, or whole-rock analysis. Age_Ma-age in millions of years. uncertainty-analytical uncertainty in millions of years, if given in original publication. recalc-an 'x' indicates the age given was recalculated by Bryant for this publication. Date_as_Published-for recalculated ages, the date as originally published. Reference-source of the date or sample data. Comment-any comments about the sample or data. Superseded by any comments in the Word tables. additionalcomment-any additional comments. Superseded by any comments in the Word tables. type-general rock type, if known: P, pluton; M, metamorphic; Vol, volcanic; Vdis, volcanics, disturbed ; Vn, vein. indexmapID-sample ID on index map. Same as QuadID. Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: Central Publications Group Address: U.S. Geological Survey Address: MS 902, Box 25046 DFC City: Lakewood State_or_Province: CO Postal_Code: 80225-0046 Contact_Voice_Telephone: 303-236-7431 Distribution_Liability: 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. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: SHP, PDF Format_Version_Number: v. 1.0 Format_Version_Date: 2006 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://pubs.usgs.gov/OF/2006/ Fees: none Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: USGS Information Services Address: Box 25286 City: Denver State_or_Province: CO Postal_Code: 80225 Country: United States Contact_Voice_Telephone: 1-888-ASK-USGS Resource_Description: I-2760 Distribution_Liability: None Standard_Order_Process: Non-digital_Form: Available as two printed map sheets plus one pamphlet, all inserted in an envelope. Order from USGS at the address listed above or see http://rockyweb.cr.usgs.gov/mod/index.html for more ordering information. Fees: For current charges see http//rockyweb.cr.usgs.gov/mod/order.html Metadata_Reference_Information: Metadata_Date: 20060130 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Anna Wilson Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: U.S. Geological Survey Address: MS 905, Box 25046 DFC City: Lakewood State_or_Province: CO Postal_Code: 80225-0046 Contact_Voice_Telephone: 303-236-5593 Contact_email: awilson@usgs.gov Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998