Jones III, J.V. (ORCID: 0000-0002-6602-5935)
Box, S.E. (ORCID: 0000-0002-5268-8375)
Todd, E. (ORCID: 0000-0002-4871-9730)
Bradley, D.C. (ORCID: 0000-0001-9116-5289)
Karl, S. (ORCID: 0000-0003-1559-7826)
Miller, M.L. (ORCID: 0000-0003-0285-4942)
O'Sullivan, P. (ORCID: 0000-0002-7247-5107)
Friedman, R.
20200721
U-Pb Isotopic Data and Ages of Zircon and Titanite from Rocks
from the Western Alaska Range, Northern Aleutian Range, Taylor
Mountains, and Tikchik Mountains Regions, Alaska
tabular digital data
Anchorage, Alaska
U.S. Geological Survey, Alaska Science Center
Suggested citation: Jones III, J.V., Box, S.E., Todd, E., Bradley,
D.C., Karl, S., Miller, M.L., O'Sullivan, P., and Friedman, R.,
2020, U-Pb isotopic data and ages of zircon, titanite, and detrital
zircon from selected rocks from the western Alaska Range,
northern Aleutian Range, Taylor Mountains, and Tikchik Mountains
regions, Alaska: U.S. Geological Survey data release,
https://doi.org/10.5066/P9K5NFKN.
https://doi.org/10.5066/P9K5NFKN
This data set contains U-Pb isotopic data and ages of zircon
and titanite from igneous and metamorphic rocks collected
from the western Alaska and northern Aleutian Range of
south-central Alaska. The data sets also contain U-Pb isotopic
data and ages of detrital zircon from sedimentary and
metasedimentary rocks collected in the same region but also
from the Taylor and Wood River Mountains of southwestern
Alaska. The entire sample suite was collected as part of
geological mapping and supporting geochemical and
geochronological analysis conducted from 2004 to 2019 and
funded by the Mineral Resources Program of the U.S. Geological
Survey (USGS). Zircon and (or) titanite were obtained from
igneous and metamorphic rocks to determine the crystallization
age and (or) age of metamorphism for the bedrock samples. Bulk
rock samples were processed into concentrated mineral separates
in USGS laboratories in Denver, Colorado, or by Apatite to
Zircon, Inc. (A2Z) and analyzed by USGS research scientists at
the Stanford-USGS Sensitive High Resolution Ion Microprobe with
Reverse-Geometry (SHRIMP-RG) at Stanford University. Detrital
zircon grains were obtained from samples of sedimentary and
metasedimentary rocks to determine depositional age and
sediment sources. Detrital zircon grains were separated from
bulk bedrock samples and analyzed at one of three different
laboratories [University of British Columbia (UBC,
2004 to 2006), at A2Z (2006 to 2009), and GeoSep Services
(GSS, 2015 to 2019)] using
laser-ablation-inductively-coupled-plasma-mass spectrometry
(LA-ICP-MS) techniques. The data tables accompanying this
data release report the isotopic composition of uranium (U)
and thorium (Th) measured in each grain, ratios of two
isotopes of lead (207Pb and 206Pb) and two isotopes of
uranium (235U and 238U), and the age of each grain. The
SHRIMP-RG data table also reports concentrations of selected
trace elements measured in each grain.
U-Pb zircon and titanite dates from igneous and metamorphic
rocks aid in the interpretation of the age of original
formation (e.g. crystallization age) and/or the timing of
metamorphism of rocks with variety of compositions. U-Pb ages
of detrital zircon grains aid in the interpretation of where
the zircons in the rocks may have originated. The youngest
detrital zircon date from any single sample also provides
information about the maximum possible depositional age of the
host sediment and, therefore, the geologic unit that contains
it. Comparison of detrital zircon age populations from
different samples test local to regional correlations of
geologic units and aids in the reconstruction of geologic
histories of large regions. In this study, detrital zircon
U-Pb dates were used to understand the geologic history of
large regions of southcentral and southwestern Alaska. These
data will be used in support of multiple geological maps,
reports, and papers that describe the geological framework
and mineral resource potential of the region.
2020
publication date
None planned
-159.2
-150.7
62.6
59.6
USGS Metadata Identifier
USGS:ASC282
ISO 19115 Topic Category
geoscientificInformation
USGS Thesaurus
geology
geochronology
uranium-lead analysis
igneous rocks
sedimentary rocks
NASA GCMD Earth Science Keywords Thesaurus
earth science
GeoRef Thesaurus
U/Pb
SHRIMP data
trace elements
USGS Geographic Names Information System (GNIS)
Alaska
Alaska Range
Taylor Mountains
Wood River Mountains
Lake Clark National Preserve
Lake Clark National Park
Wood-Tikchik State Park
Nushagak Hills
Bonanza Hills
Chigmit Mountains
Jack Rabbit Hills
None
None. Users are advised to read the metadata thoroughly to
understand appropriate use and data limitations.
U.S. Geological Survey, Alaska Science Center
James V. Jones
Geologist
mailing and physical address
4210 University Drive
Anchorage
Alaska
99508-4626
U.S.A.
907-786-7000
ascweb@usgs.gov
Jones III, J.V. (ORCID: 0000-0002-6602-5935)
2009
Western Alaska Range Metallogeny and Tectonics
Anchorage, Alaska
U.S. Geological Survey, Alaska Science Center
https://alaska.usgs.gov/portal/project.php?project_id=302
Zircon crystals were run with zircon reference materials
(R33, Temora2, MADDER), and the titanite samples were run with
titanite reference materials (BLR1, MMS). The reference
materials were analyzed until isotopic fractionation was stable
and the variance in the measured 206Pb/238U and 207Pb/206Pb
ratios was at or near 1 percent. Reference materials were
subsequently analyzed together with unknowns at a regular
interval to monitor fractionation throughout the analytical
session. All measured isotopic ratios are reported with
associated analytical uncertainty.
No unexpected values are found in these data. Blank cells
in the data tables indicate values were either not provided,
not measured, or not calculated.
This data set is complete; no data were omitted.
Horizontal position was measured using hand-held GPS units with
positional accuracy of 3 meters or less.
Apatite to Zircon, Inc.
2018
Detrital Zircon Analytical Methods
Moscow, Idaho
Apatite to Zircon, Inc. GeoSep Services
This is a supplemental PDF document included in this data
release. The file name is
Supplemental_Info_Analytical_Methods_A2Z_GSS.pdf.
pdf file
2018
publication date
Supplemental Info Analytical Methods A2Z GSS
Provides detailed description of laboratory methods and data
modeling for U-Pb geochronology.
Stanford-USGS SHRIMP-RG Laboratory
2019
Titanite U-Pb geochronology and trace element analytical
methods using Stanford-USGS SHRIMP-RG
Palo Alto, California
Stanford-USGS SHRIMP-RG laboratory
This is a supplemental document included in this data release. The
file name is
Supplemental_Info_Analytical_Methods_StanfordUSGSSHRIMPRG.pdf.
pdf file
2019
publication date
SHRIMP-RG Methods
Provides detailed descriptions of laboratory methods and data
modeling for titanite U-Pb geochronology.
Detrital zircons were separated from bulk sample using lithium
polytungstate and a centrifuge. Zircon grains were mounted in
epoxy wafers and then ground down to expose the grain interior,
and then polished. Isotopic analyses were performed with
either a new Wave UP-213 or New Wave YAG 213 laser ablation
system in line with Finnigan Element2 magnetic sector,
inductively coupled plasma, mass spectrometer (ICP-MS) at
Washington State University Geoanalytical Laboratory in
Pullman, Washington. Detailed analytical procedures are
described in the accompanying document,
Supplemental_Info_Analytical_Methods_A2Z.pdf.
2019
Titanite and zircon grains were separated from crushed and
ground samples using standard magnetic and heavy liquid
techniques, hand-picked under binocular microscope, and mounted
in epoxy discs. The mounts were ground to expose the grain
interior, further polished, and imaged using back-scattered
electron (BSE) imaging on a JEOL 5600 SEM to identify internal
grain zonation patterns and to identify any inclusions or other
features such as cracks to be avoided during analysis.
Titanite U-Pb ages were obtained with the Stanford-U.S.
Geological (USGS) Sensitive High Resolution Ion Microprobe
with Reverse-Geometry (SHRIMP-RG) at Stanford University.
Detailed analytical procedures are described in the
accompanying document,
Supplemental_Info_Analytical_Methods_StanfordUSGSSHRIMPRG.pdf.
2019
Point
0.0001
0.0001
Decimal degrees
North American Datum of 1983
GRS 1980
6378137
298.257222101
geology_detritalZircon_westernAKRange_Jones.csv
Table of U-Pb detrital zircon
laser-ablation-inductively-coupled-plasma-mass-spectrometry
(LA-ICP-MS) data, reporting concentration and isotopic
composition of uranium (U) and thorium (Th) measured in each
grain, isotopic ratios of lead (Pb) and uranium (U), and the
age of each grain calculated from isotope ratios. The table is
presented in comma separated value (CSV) format and holds 8930
records.
Author defined
Sample
Sample identifier as collected in the field.
Author defined
Unique sample identifier; most labels consisting of the last two
digits of the year collected, an abbreviation identifying the
collector, and a number and possible suffix.
Analysis_Lab
Identifies the lab where analysis was done. Analyses were
performed at University of British Columbia from 2004 to 2006,
at Apatite to Zircon, Inc. from 2006 to 2009, and at GSS from
2015 to 2019.
Author defined
A2Z
Apatite to Zircon, Inc., Moscow, Idaho
Author defined
GSS
GeoSep Services, Moscow, Idaho
Author defined
UBC
University of British Columbia, Vancouver, B.C. Canada
Author defined
Lab_Sample
Laboratory sample identifier assigned by A2Z or GSS. There is
a one to one correspondence to the field sample identifier,
Sample. Blanks cells indicate that the laboratory did not
assign a different sample identifier.
Author defined
Hyphenated numeric code assigned by the A2Z or GSS laboratory.
Mineral
Material analyzed.
Author defined
DZ
detrital zircon
Author defined
Analysis_Name
A unique identification assigned by the laboratory for an
individual analysis.
Author defined
For samples run at UBC, the Analysis_Name is a numeric or
alpha-numeric code, and often the concatenation of field
Sample with a numeric suffix. For samples run at A2Z,
the name is an alpha-numeric code including a variation of the
Lab_Sample.
U_conc_ppm
Concentration of uranium (U) in parts per million (ppm). Value
-9999 denotes value not reported.
Author defined
4.0
7930.9
parts per million (ppm)
Th_conc_ppm
Concentration of thorium (Th) in parts per million (ppm). Value
-9999 denotes value not reported.
Author defined
0.1
9620.8
parts per million (ppm)
U_Th_Ratio
The ratio of the concentration of uranium (U) to the
concentration of thorium (Th). Value -9999 denotes ratio not
calculated due to absence of reported U_conc_ppm and Th_conc_ppm.
Author defined
0.2
488
unit-less value
207Pb_235U_Ratio
Total ratio of 207Pb to 235U.
Author defined
0.009
120.333
unit-less value
207Pb_235U_Ratio_Unc_1sig_abs
Uncertainty (1-sigma) for the ratio of 207Pb to 235U.
Author defined
0.00059
28.52288
unit-less value
206Pb_238U_Ratio
Total ratio of 206Pb to 238U.
Author defined
0.0007
1.4709
unit-less value
206Pb_238U_Ratio_Unc_1sig_abs
Uncertainty (1-sigma) for the ratio of 206Pb to 238U.
Value -9999 denotes value not reported.
Author defined
0.00005
0.27402
unit-less value
Error_Correlation
Error correlation of the 207Pb/235U and 206Pb/238U ratios.
Author defined
0.01
1.00
unit-less value
207Pb_206Pb_Ratio
Total ratio of 207Pb to 206Pb. Value -9999 denotes value
not reported.
Author defined
0.0059
0.783
unit-less value
207Pb_206Pb_Ratio_Unc_1sig_abs
Uncertainty (1-sigma) of the ratio of 207Pb to 206Pb. Value
-9999 denotes value not reported.
Author defined
0.00030
0.14192
unit-less value
207Pb_235U_Age
Age in millions of years (Ma) calculated from the 207Pb/235U
ratio.
Author defined
9.1
4872.3
millions of years (Ma)
207Pb_235U_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years (Ma) for the
age calculated from the 207Pb/235U ratio.
Author defined
0.6
1154.9
millions of years (Ma)
206Pb_238U_Age
Age in millions of years (Ma) calculated from the 206Pb/238U
ratio.
Author defined
4.7
5831.3
millions of years (Ma)
206Pb_238U_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years (Ma) for the
age calculated from the 206Pb/238U ratio.
Author defined
0.3
1429.7
millions of years (Ma)
207Pb_206Pb_Age
Age in millions of years (Ma) calculated from the 207Pb/206Pb
ratio. Value -9999 denotes value not reported.
Author defined
0.1
4560
millions of years (Ma)
207Pb_206Pb_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years (Ma) for the
age calculated from the 207Pb/206Pb ratio. Value -9999
denotes value not reported.
Author defined
1.1
2298.9
millions of years (Ma)
Preferred_Age
Preferred age in millions of years (Ma) selected from
one of the three following fields containing calculated ages for
each grain: 207Pb_235U_Age or 206Pb_238U_Age or 207Pb_206Pb_Age.
Zero values indicate an analysis that failed to yield an age.
This may occur when the concentration of uranium (U) in a zircon
or detrital zircon is zero parts per million (ppm). In such
cases, U is not available to decay to lead (Pb).
Author defined
4.7
4558.0
millions of years (Ma)
Preferred_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years (Ma) for the
preferred age. Zero values indicate an analysis that failed
to yield an age.
Author defined
0.3
1379.1
millions of years (Ma)
Preferred_Age_Type
Method used to calculate the value in Preferred_Age field for
each individual analysis that yielded a valid result. Refer to
the description of analytical methods, file
Supplemental_Info_Analytical_Methods_A2Z.pdf, for more details.
Author defined
The following values are used: 206Pb_238U_Age and 207Pb_206Pb_Age
Percent_Discordant
Discordance of 206Pb/238U age versus 207Pb/206Pb age, in
percent. Blank cells are present.
Author defined
-98.1
99.7
percent
geology_SHRIMPRGData_westernAKRange_Jones.csv
Table of U-Pb titanite and zircon SHRIMP-RG data, reporting
the isotopic concentration of uranium (U) and thorium (Th)
measured in individual grains, isotopic ratios of lead and
uranium, and the age of each grain calculated from
the isotope ratios. The table also reports concentrations of
selected trace elements measured in the same grains. The
table contains 1344 records and is presented in comma
separated value (CSV) format.
Author defined
Sample
Sample number attributed when collected in the field. The
value is unique for each sample but is repeated many times
in this table because many individual grains from a single
sample are analyzed. Descriptive and locational information
about the sample is in table
geology_sampleSummary_westernAKRange_Jones.csv, and may
be linked through attribute Sample.
Author defined
Unique sample identifier; most labels consisting of the last two
digits of the year collected, an abbreviation identifying the
collector, and a number and possible suffix.
Mineral
Mineral analyzed
Author defined
The following values are used in this data set: titanite and zircon.
Mount
Internal laboratory ID number for sample mount
Author defined
Alphanumeric code assigned by the laboratory
Standard
Age reference material used on mount
Author defined
BLR1
Bear Lake diggings titanite standard
Aleinikoff, J.A., Wintsch, R.P., Tollo, R.P., Unruh, D.M.,
Fanning, C.M., and Schmitz, M.D., 2007, Ages and origins of
rocks of the Killingworth Dome, south-central Connecticut:
Implications for the tectonic evolution of southern New
England: American Journal of Science, v. 307, p. 63-118,
https://doi.org/10.2475/01.2007.04.
Mazdab, F.K., 2009, Characterization of flux-grown
trace-element-doped titanite using the high-mass-resolution
ion microprobe (SHRIMP-RG): The Canadian Mineralogist,
v. 47, p. 813-831, https://doi.org/10.3749/canmin.47.4.813.
MMS
McClure Mountain syenite titanite standard
Schoene, B., and Bowring, S.A., 2006, U-Pb systematics of the
McClure Mountain syenite: thermochronological constraints on
the age of the 40Ar/39Ar standard MMhb: Contributions to
Mineralogy and Petrology, v. 151, p. 615-630,
https://doi.org/10.1007/s00410-006-0077-4.
R33
Braintree Complex monzodiorite zircon standard
Black, L.P., Kamo, S.L., Allen, C.M., Davis, D.W., Aleinikoff,
J.N., Valley, J.W., Mundil, R., Campbell, I.H., Korsch, R.J.,
Williams, I.S., and Foudoulis, C. 2004, Improved 206Pb/238U
microprobe geochronology by the monitoring of
trace-element-related matrix effect; SHRIMP, ID-TIMS,
ELA-ICP-MS and oxygen isotope documentation for a series of
zircon standards. Chemical Geology, 205, p.115-140,
https://doi.org/10.1016/j.chemgeo.2004.01.003.
TEM2
Middledale gabbroic diorite zircon standard
Black, L.P., Kamo, S.L., Allen, C.M., Davis, D.W., Aleinikoff,
J.N., Valley, J.W., Mundil, R., Campbell, I.H., Korsch, R.J.,
Williams, I.S., and Foudoulis, C. 2004, Improved 206Pb/238U
microprobe geochronology by the monitoring of
trace-element-related matrix effect; SHRIMP, ID-TIMS,
ELA-ICP-MS and oxygen isotope documentation for a series of
zircon standards: Chemical Geology, 205, p.115-140,
https://doi.org/10.1016/j.chemgeo.2004.01.003.
Standard_Age
Assumed age of age reference material for data reduction, in
millions of years before present (Ma, mega-annum).
Author defined
The assumed ages for the standards are: BLR1 (1047 Ma), MMS (524 Ma),
R33 (419 Ma), and TEM2 (416.8 Ma).
Conc_Std
Concentration standard used to calibrate trace element
concentrations in unknowns.
Author defined
BLR1
Bear Lake diggings titanite standard
Aleinikoff, J.A., Wintsch, R.P., Tollo, R.P., Unruh, D.M.,
Fanning, C.M., and Schmitz, M.D., 2007, Ages and origins of
rocks of the Killingworth Dome, south-central Connecticut:
Implications for the tectonic evolution of southern New
England: American Journal of Science, v. 307, p. 63-118,
https://doi.org/10.2475/01.2007.04.
Mazdab, F.K., 2009, Characterization of flux-grown
trace-element-doped titanite using the high-mass-resolution
ion microprobe (SHRIMP-RG): The Canadian Mineralogist,
v. 47, p. 813-831, https://doi.org/10.3749/canmin.47.4.813.
MAD
zircon reference material
Barth, A.P., and Wooden, J.L., 2010, Coupled elemental and
isotopic analyses of polygenetic zircons from granitic rocks
by ion microprobe, with implications for melt evolution and
the sources of granitic magmas: Chemical Geology, v. 277,
p. 149-159, https://doi.org/10.1016/j.chemgeo.2010.07.017.
MAD559
zircon reference material
Coble, M.A., Vazquez, J.A., Barth, A.P., Wooden, J., Burns, D.,
Kylander-Clark, A., Jackson, S., and Vennari, C.E., 2018,
Trace element characterization of MAD-559 zircon
reference material of ion microprobe analysis: Geostandards
and Geoanalytical Research, v. 42, p. 481-497,
https://doi.org/10.1111/ggr.12238.
Analysis_Spot
Internal ID number of individual analysis spot on this Mount.
Author defined
Alphanumeric code assigned by the analyst. In general, the
first number after the sample name indicates the unique
grain from an individual sample. The second number indicates
the unique spot for each individual grain.
AnalysisSpot_Mount
Concatenation of Analysis_Spot and Mount attributes. This is
a unique identifier in this table.
Author defined
Concatenation of Analysis_Spot and Mount attributes separated
by and underscore (_).
Analysis_Date_Time
The calendar date and time of the analysis.
Author defined
Data formatted yyyy-mm-dd, hh:mm
U_conc_ppm
Uranium concentration, in parts per million (ppm)
Author defined
0.3
18232.7
parts per million (ppm)
Th_conc_ppm
Thorium concentration, in parts per million (ppm)
Author defined
0
8390.5
parts per million (ppm)
comm_206Pb
207Pb corrected common 206Pb, in percent
Author defined
0.00
475.78
percent
238U_206Pb_Ratio
Total ratio of 238U to 206Pb
Author defined
2.2
11225.4
238U_206Pb_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on total ratio of 238U to 206Pb, in
percent
Author defined
0.5
73.6
percent
207Pb_206Pb_Ratio
Total ratio of 207Pb to 206Pb
Author defined
0.025
3.574
207Pb_206Pb_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on total ratio of 207Pb to 206Pb, in
percent
Author defined
0.1
71.2
percent
204Pbcorr_238U_206Pb_Ratio
204Pb-corrected ratio of 238U to 206Pb
Author defined
-157.8
4638.8
204Pbcorr_238U_206Pb_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on 204Pb-corrected ratio of 238U to
206Pb, in percent
Author defined
0.6
270.3
percent
204Pbcorr_207Pb_206Pb_Ratio
204Pb-corrected ratio of 207Pb to 206Pb
Author defined
0.000
4.012
204Pbcorr_207Pb_206Pb_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on 204Pb-corrected ratio of 207Pb to 206Pb,
in percent
Author defined
0.0
18230.8
percent
204Pbcorr_207Pb_235U_Ratio
204Pb-corrected ratio of 207Pb to 235U
Author defined
-4.884
133.595
204Pbcorr_207Pb_235U_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on 204Pb-corrected ratio of 207Pb to
235U, in percent
Author defined
0.0
18230.8
percent
204Pbcorr_206Pb_238U_Ratio
204Pb-corrected ratio of 206Pb to 238U
Author defined
-0.048
133.655
204Pbcorr_206Pb_238U_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on 204Pb-corrected ratio of 206Pb/238U,
in percent
Author defined
0.0
270.3
percent
Error_Correlation
Error correlation of 207Pb/235U and 206Pb/238U ratios
Author defined
0.00
4.01
207Pbcorr_206Pb_238U_Age
207Pb-corrected 206Pb/238U age, in millions of years
before present (mega-annum)
Author defined
-42.4
2230.1
millions of years (Ma)
207Pbcorr_206Pb_238U_Age_Unc_1sig
Uncertainty (1-sigma) on 207Pb-corrected 206Pb/238U age,
in millions of years before present (mega-annum)
Author defined
0.0
113.1
millions of years (Ma)
204Pbcorr_207Pb_206Pb_Age
204Pb-corrected 207Pb/206Pb age, in millions of years before
present (mega-annum). Blank cells are present.
Author defined
12.9
5977.3
millions of years (Ma)
204Pbcorr_207Pb_206Pb_Age_Unc_1sig
Uncertainty (1-sigma) on 204Pb-corrected 207Pb/206Pb age, in
millions of years before present (mega-annum). Blank cells are
present.
Author defined
11.0
12605.3
millions of years (Ma)
Preferred_SHRIMP_Age
Preferred grain age for calculation of sample age
(in millions of years, Ma) selected from one of the two
following fields containing calculated ages:
207Pbcorr_206Pb_238U_Age or 204Pbcorr_207Pb_206Pb_Age.
Author defined
-42.4
2679.9
millions of years (Ma)
Preferred_SHRIMP_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years (Ma) on
preferred grain age
Author defined
0.0
113.1
millions of years (Ma)
Preferred_SHRIMP_Age_Type
Method used to calculate the values in Preferred_SHRIMP_Age
field for each individual analysis that yielded a valid
result.
Author defined
The only attributes in this data set are
204Pbcorr_207Pb_206Pb_Age and 207Pbcorr_206Pb_238U_Age.
Interpreted_Age_Included
Indication of whether or not analysis was used in the
calculation of field UPb_Age_Ma in table
geology_sampleSummary_westernAKRange_Jones.csv
Author defined
Y
yes
Author defined
N
no
Author defined
Percent_Discordant
Discordance of 206Pb/238U age versus 207Pb/206Pb age, in
percent. Blank cells are present.
Author defined
-742.0
104.0
percent
Y_ppm
Yttrium concentration in parts per million. Value -9999
indicates not reported.
Author defined
0
10419
parts per million (ppm)
Nb_ppm
Niobium concentration in parts per million. Value -9999
indicates not reported.
Author defined
19.8
2251.3
parts per million (ppm)
La_ppm
Lanthanum concentration in parts per million. Value -9999
indicates not reported.
Author defined
0
3536.233
parts per million (ppm)
Ce_ppm
Cerium concentration in parts per million. Value -9999
indicates not reported.
Author defined
0
11648.6
parts per million (ppm)
Pr_ppm
Praseodymium concentration in parts per million. Value -9999
indicates not reported.
Author defined
1.09
1458.71
parts per million (ppm)
Nd_ppm
Neodymium concentration in parts per million. Value -9999
indicates not reported.
Author defined
0
7344.48
parts per million (ppm)
Sm_ppm
Samarium concentration in parts per million. Value -9999
indicates not reported.
Author defined
0
2769.00
parts per million (ppm)
Eu_ppm
Europium concentration in parts per million. Value -9999
indicates not reported.
Author defined
0.00
2853.75
parts per million (ppm)
Gd_ppm
Gadolinium concentration in parts per million. Value -9999
indicates not reported.
Author defined
0
20176.22
parts per million (ppm)
Dy_ppm
Dysprosium concentration in parts per million
Author defined
0.09
2386.69
parts per million (ppm)
Er_ppm
Erbium concentration in parts per million. Value -9999
indicates not reported.
Author defined
0
1903.57
parts per million (ppm)
Yb_ppm
Ytterbium concentration in parts per million. Value -9999
indicates not reported.
Author defined
0
3929.21
parts per million (ppm)
Hf_ppm
Hafnium concentration in parts per million. Value -9999
indicates not reported.
Author defined
0.09
23601.22
parts per million (ppm)
48Ti_ppm
Titanium (from mass 48) concentration in parts per million.
Value -9999 indicates not reported.
Author defined
0.03
5300.15
parts per million (ppm)
49Ti_ppm
Titanium (from mass 49) concentration in parts per million.
Value -9999 indicates not reported.
Author defined
0
18439.16
parts per million (ppm)
Fe_ppm
Iron concentration in parts per million. Value -9999
indicates not reported.
Author defined
0
10468.39
parts per million (ppm)
geology_sampleSummary_westernAKRange_Jones.csv
Table with sample information, including location, rock
description, and summary of geochronology analyses. This
table contains 190 entries.
Author defined
Sample
Sample number assigned when sample was collected in the
field. This attribute links to field Sample in tables
geology_detritalZircon_westernAKRange_Jones.csv and
geology_SHRIMPRGData_westernAKRange_Jones.csv.
Author defined
Unique sample identifier; most labels consisting of the last two
digits of the year collected, an abbreviation identifying the
collector, and a number and possible suffix.
Lab_Sample
Laboratory sample identifier assigned by A2Z or GSS. Same as
field Lab_Sample in table
geology_detritalZircon_westernAKRange_Jones.csv.
Author defined
Hyphenated numeric code assigned by the A2Z or GSS laboratory.
Latitude
Latitude given in decimal degrees; datum NAD83
Author defined
59.6773
62.5143
decimal degree
Longitude
Longitude given in decimal degrees; datum NAD83.
Author defined
-159.1764
-150.7431
decimal degree
Rock_Class
Basic rock classification of the sample
Author defined
Attributes in this dataset are igneous, metamorphic, and sedimentary.
Rock_Type
Sample rock type
Author defined
General rock description.
Rock_Comment
Additional sample description which may include more detailed
rock description, location, geologic map unit. Blank cells are
present.
Author defined
Additional sample description which may include more detailed
rock description, location, geologic map unit.
Analysis_Type
Type of geochronologic analysis
Author defined
U-Pb detrital zircon
Uranium-lead analysis on detrital zircon
Author defined
U-Pb titanite
Uranium-lead analysis on titanite
Author defined
U-Pb zircon
Uranium-lead analysis on zircon
Author defined
Analysis_Lab
Laboratory or contractor responsible for the analysis
Author defined
A2Z
Apatite to Zircon, Inc., Moscow, Idaho
Author defined
GSS
GeoSep Services, Moscow, Idaho
Author defined
Stanford-USGS SHRIMP-RG
Stanford-USGS Sensitive High Resolution Ion Microprobe with
Reverse Geometry
Author defined
UBC
University of British Columbia, Vancouver, B.C., Canada
Author defined
Analysis_Method
Laboratory equipment and methodology used to collect data.
Author defined
LA-ICP-MS U-Pb
Laser ablation inductively coupled plasma mass spectrometry
techniques for U-Pb
Author defined
SHRIMP U-Pb
Sensitive high resolution ion microprobe with reverse geometry
for U-Pb
Author defined
UPb_Age_N_Grains_Total
Total number of grains analyzed. Blank cells are present.
Author defined
3
34
UPb_Age_Ma
Weighted average age calculated for sample in millions of
years (Ma). Blanks cells are present.
Author defined
28.5
585.9
millions of years (Ma)
UPb_Age_Unc_Ma
Uncertainty (2-sigma) of weighted average age calculated
for sample, in millions of years (Ma). Blank cells
are present.
Author defined
0.3
6.9
millions of years (Ma)
UPb_Age_Method
Method used to calculate the value in UPb_Age_Ma. Blank cells
are present.
Author defined
The only attribute in this data set is 'weighted average
206Pb/238U age'
UPb_Age_N_Grains
Number of analyses used to calculate the value in UPb_Age_Ma.
Blanks cells are present.
Author defined
2
32
UPb_Age_MSWD
Mean square of weighted deviates for calculated value in
UPb_Age_Ma. Blank cells are present.
Author defined
0.22
2.58
UPb_Age_Comment
Comments on the sample age or analytical observations. Blank
cells are present.
Author defined
Comments on the sample age or analytical observations.
UPb_Age_Interpretation
Geological significance of the interpreted age. Blank cells
are present.
Author defined
Includes interpretations such as, cooling, crystallization,
metamorphism, and detrital.
geology_dataDictionary_westernAKRange_Jones.csv
Table listing the name of all fields in each table, with a brief
description of the field and the data units, if applicable.
Author defined
Table
Name of the data table the field is found in.
Author defined
The data tables in this data set include
geology_detritalZircon_westernAKRange_Jones.csv,
geology_SHRIMPData_westernAKRange_Jones.csv, and
geology_sampleSummary_westernAKRange_Jones.csv.
Field
Field name found in data table listed in field Table
Author defined
The field names are single words or concatenated abbreviations that
describe the contents of the field.
Description
Brief description of the contents of the field
Author defined
Brief description of the contents of the field
Units
The unit of measurement for applicable data fields
Author defined
%
percent
Author defined
degrees
unit of angle measurement
Author defined
Ma
mega-annum or million years
Author defined
n/a
not applicable
Author defined
ppm
parts per million
Author defined
U.S. Geological Survey, Alaska Science Center
mailing and physical
4210 University Drive
Anchorage
Alaska
99508-4626
U.S.A.
907-786-7000
ascweb@usgs.gov
Authoritative source for the data.
Unless otherwise stated, all data, metadata and related materials are
considered to satisfy the quality standards relative to the purpose
for which the data were collected. Although these data and
associated metadata have been reviewed for accuracy and
completeness and approved for release by the U.S. Geological
Survey (USGS), no warranty expressed or implied is made regarding
the display or utility of the data on any other system or for
general or scientific purposes, nor shall the act of distribution
constitute any such warranty.
CSV
Data are distributed in a Zip package containing data in CSV format and FGDC metadata in XML and HTML formats. Supplementary information about laboratory
methods are provided in PDF format.
Compression applied by the 7-Zip utility using default compression (5). The file can be decompressed and unpacked by open source or commercially available unzip tools.
2.20
https://doi.org/10.5066/P9K5NFKN
None
20201125
20200707
U.S. Geological Survey, Alaska Science Center
mailing and physical address
4210 University Drive
Anchorage
Alaska
99508-4626
U.S.A.
907-786-7000
ascweb@usgs.gov
FGDC Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998