U.S. Geological Survey 1999 tabular digital data http://mrdata.usgs.gov/akages/ http://mrdata.usgs.gov/services/akages-geo?request=getcapabilities&service=WMS&version=1.1.1& http://mrdata.usgs.gov/services/akages-geo?request=getcapabilities&service=WFS&version=1.0.0& 1999 Date on which data provided online was extracted from the database The Alaska Radiometric Age file is a database of radiometric ages of rocks or minerals sampled from Alaska. The data was collected from professional publications and/or received from researchers and used by permission. Database of radiometric ages is designed to aid in the research of geochronologic information of Alaska rocks and minerals. Users should always review the cited publications for more complete descriptions of the samples, analyses, and geologic interpretation. The radiometric dates in this data set were collected from published sources through 1990(approximately). The dates were compiled over many years and published as a map in the series Decade of North American Geology, by the Geological Society of America. In work As needed 172.0 -130.0 72.0 54.0 None geochronology radiometric age radiometric date geologic time potassium-argon uranium-lead ISO 19115 Topic Categories geoscientificInformation None Alaska None The U.S. Geological Survey makes no warranties related to the accuracy of the data and users are required to determine the usability for any particular purpose. U.S. Geological Survey Nora Shew mailing and physical

4200 University Drive

Anchorage AK 99508-4667 U.S.A. 907-561-1181 nshew@usgs.gov The radiometric age data base has been maintained since the mid-1970's. Compilers include: F.H. Wilson, Nora Shew, G.D. DuBois, and Shawn Dadisman. Generally, the radiometric ages in the database are as published. Some potassium-argon ages have been recalculated using the decay constants recommended by the IUGS Subcommission on Geochronology in 1976. Dates that have been recalculated are noted in the 'Comments' field. The radiometric age database does not include the analytical information which is often found in the published sources. Also, the database records do not contain the geologic interpretation of the analysis. Users of this database should always /refer to the publications listed in the 'Reference' field for detailed information about each analysis. The Alaska radiometric age file is a compilation of published and other released radiometric dates on rocks and minerals of Alaska. The precision of the analyses and the locations of the samples vary widely from the various sources. This compilation has not attempted to interpret the data. Users of this data should always refer to the published sources of the information. This database contains for each record: location, dating method, rock type, mineral/phase dated, age (in millions of years), comments, and references. The data was imported into Microsoft Access, brought into ArcView3.1 as an event theme, and then converted into a shape file. 1999 U.S. Geological Survey Nora Shew mailing and physical

4200 University Drive

Anchorage AK 99508-4667 USA 907-561-1181 nshew@usgs.gov Point 0.002 0.002 Decimal degrees North American Datum of 1927 Clarke 1866 6378206.4 294.98 points Characteristics of points in shape table. Quad Name of 1:250,000 scale quadrangle USGS Geographic Names Information System Name of 1:250,000 scale quadrangle. Latdeg Degree of latitude 50 70 degrees 1. Latmin Minute of latitude 0.0 59.9 minutes 0.1 Latdir Direction of latitude N North Londeg Degree of longitude 126 179 degrees 1. Lonmin Minute of longitude 0.0 59.9 minutes 0.1 londir Direction of longitude E East W West Sample Sample ID from published source. If none was given in the cited source, then a sample id was created for this database. free text Rock Rock name or type ADAM adamellite AGNS augen gneiss ALSK alaskite ALT altered AMPH amphibolite AND andesite APL aplite ASH ash BAS basalt BIOT biotitite BENT bentonite BSCH blueschist BREC breccia CG conglomerate DAC dacite DI diorite DIA diabase ECLG eclogite FELS felsite GAB gabbro GDI granodiorite GLASS glass GNLT granulite GNS gneiss GNST greenstone GR granite GRTD granitoid GSCH greenschist HBDT hornblendite HFLS hornfels INTR intrusive LAMP lamprophyre LAT latite LBAS leucobasalt LGAB leucogabbro MAF mafic MAR marble META metamorphic METB metabasite METP metapelite METV metavolcanic METW metawacke MIG migmatite MON monzonite MONDI monzodiorite MYLT mylonite OTHER other (rock identified in comments field) PEG pegmatite PHYL phyllite PORPH porphyry PYRX pyroxenite Q DI quartz diorite QMD quartz monzodiorite QMON quartz monzonite QS quartz sericite QTZT quartzite RHY rhyolite SBREC sedimentary breccia SCH schist SERP serpentinite SKARN skarn SS sandstone SY syenite TON tonalite TRCH trachyte TROND trondjemite TUFF tuff UMAF ultramafic VOL volcanic UNID unidentified XENO xenolith Method Isotopic dating method A Pb-alpha F Fission track K K-Ar P Pb methods R Rb-Sr S Sm-Nd Mineral Mineral or phase dated from sample; or denotes that date is calculated from an isochron. AC actinolite AM amphibole AP apatite AW anorthoclase BI biotite CH chlorite FD feldspar GL glass GP glaucophane HO hornblende IC isochron KF K-feldspar MI mica MU muscovite OT other (mineral identified in comments field) PA paragonite PH phengnite PL plagioclase PP phologopite PY pyroxene RI riebeckite SA sanidine SE sericite SP sphene TR tremolite UN unknown WR whole rock ZI zircon Age m.y. Age of sample in millions of years positive number Comment Field for free text. free text Ref Reference of data sample. free text U.S. Geological Survey Tom Kress mailing address

12201 Sunrise Valley Drive MS954

Reston VA 20192 USA 703-648-6328 thkress@usgs.gov akages.shp The U.S. Geological Survey (USGS) provides this point data "as is." The USGS make no guarantee or warranty concerning the accuracy of information contained in the dataset. Further, the USGS makes no warranties, either expressed or implied, as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although this data has bee processed successfully on computers at the USGS, no warranty, express or implied, is made by the USGS regarding the use of this data on any other system, nor does the fact of distribution constitute or imply any such warranty. OGC WMS 1.1.1 Sample locations, characteristics, and radiometric ages http://mrdata.usgs.gov/services/akages-geo?request=getcapabilities&service=WMS&version=1.1.1& OGC WFS 1.0.0 Sample locations, characteristics, and radiometric ages http://mrdata.usgs.gov/services/akages-geo?request=getcapabilities&service=WFS&version=1.0.0& none 20091118 U.S. Geological Survey Nora Shew mailing and physical address

4200 University Drive

Anchorage AK 99508-4667 USA 907-561-1181 nshew@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998