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U.S. Geological Survey, 1999, Alaska Radiometric Ages.
This is a Point data set.
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.002. Longitudes are given to the nearest 0.002. Latitude and longitude values are specified in Decimal degrees.
Name of 1:250,000 scale quadrangle.
| Range of values | |
|---|---|
| Minimum: | 50 |
| Maximum: | 70 |
| Units: | degrees |
| Resolution: | 1. |
| Range of values | |
|---|---|
| Minimum: | 0.0 |
| Maximum: | 59.9 |
| Units: | minutes |
| Resolution: | 0.1 |
| Value | Definition |
|---|---|
| N | North |
| Range of values | |
|---|---|
| Minimum: | 126 |
| Maximum: | 179 |
| Units: | degrees |
| Resolution: | 1. |
| Range of values | |
|---|---|
| Minimum: | 0.0 |
| Maximum: | 59.9 |
| Units: | minutes |
| Resolution: | 0.1 |
| Value | Definition |
|---|---|
| E | East |
| W | West |
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| Value | Definition |
|---|---|
| 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 |
| Value | Definition |
|---|---|
| A | Pb-alpha |
| F | Fission track |
| K | K-Ar |
| P | Pb methods |
| R | Rb-Sr |
| S | Sm-Nd |
| Value | Definition |
|---|---|
| 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 |
positive number
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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.
907-561-1181 (voice)
nshew@usgs.gov
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.
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.
Person who carried out this activity:
907-561-1181 (voice)
nshew@usgs.gov
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.
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.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- 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.
703-648-6328 (voice)
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.
907-561-1181 (voice)
nshew@usgs.gov
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://tin.er.usgs.gov/metadata/akages.faq.html
Page Contact Information: Peter Schweitzer
Page Last Modified: Thursday, 18-Oct-2007 13:17:58 EDT
