Jones III, J.V. (ORCID: 0000-0002-6602-5935)
O'Sullivan, P. (ORCID: 0000-0002-7247-5107)
20200826
U-Pb Isotopic Data and Ages of Zircon and Titanite from Rocks from the Yukon-Tanana Upland, Alaska
tabular digital data
Anchorage, Alaska
U.S. Geological Survey, Alaska Science Center
Suggested citation: Jones III, J.V., and O'Sullivan, P., 2020, U-Pb isotopic data and ages of zircon, titanite, and detrital zircon from rocks from the Yukon-Tanana Upland, Alaska: U.S. Geological Survey data release, https://doi.org/10.5066/P9WWV93S.
https://doi.org/10.5066/P9WWV93S
This data set contains 3 tables containing uranium-lead (U-Pb) isotopic data and crystallization ages of zircon and titanite from igneous, metamorphic, and sedimentary rocks collected from the Yukon-Tanana upland of eastern interior Alaska between 2013 and 2019. Bulk samples of igneous and metamorphic rocks were processed into concentrated mineral separates of zircon and (or) titanite 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. Bulk samples of sedimentary and metasedimentary rocks were processed into concentrated mineral separates of detrital zircon and analyzed by Apatite to Zircon, Inc. and GeoSep Services (GSS) using laser-ablation-inductively-coupled-plasma-mass spectrometry (LA-ICP-MS) techniques. The 2 data tables (geology_detritalZircon_easternAK_Jones.csv; geology_SHRIMPRGData_easternAK_Jones.csv) 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. A third table (geology_sampleSummary_easternAK_Jones.csv) reports sample locations, rock characteristics, and interpreted ages. The SHRIMP-RG data table (geology_SHRIMPRGData_easternAK_Jones.csv) also reports concentrations of selected trace elements measured in each grain.
This data set was developed from samples collected during geological mapping and research conducted from 2013 to 2019 and funded by the Mineral Resource Program of the U.S. Geological Survey (USGS). 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. These data are used to understand the geologic history of the Yukon-Tanana upland in eastern 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
-147.4
-140.5
65.6
63.0
USGS Metadata Identifier
USGS:ASC307
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
Fortymile River
Sixty Mile River
Ladue River
Chatanika River
Tok
Chicken
Eagle
Fairbanks
White Mountains
Divide Mountain
Taylor Mountain
None
Yukon-Tanana upland
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)
2015
Tectonic and metallogenic evolution of the eastern
Yukon-Tanana upland, Alaska
web page
Science Portal
389
Anchorage, Alaska
U.S. Geological Survey, Alaska Science Center
This is a link to the broader USGS Alaska Science Center research project supported by these data. Users will find a description of the research project and links to associated reports, publications, and data products.
https://alaska.usgs.gov/portal/project.php?project_id=389
Zircon crystals were run with zircon reference materials (Temora2, MAD, 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 at the 1 sigma range. Detailed analytical methods are described in two supplemental files included in this data release (Supplemental_Info_Analytical_Methods_StanfordUSGSSHRIMP.pdf; Supplemental_Info_Analytical_Methods_A2Z_GSS.pdf).
No unexpected values are found in these data. Blank cells and cells with value -9999 in the data tables indicate values were either notprovided, 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_easternAK_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 1491 records.
Author defined
Sample
Sample identifier as collected in the field. Descriptive
and locational information about the sample is provided in
table geology_sampleSummary_easternAK_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.
Analysis_Lab
Identifies the lab where analysis was done.
Author defined
A2Z
Apatite to Zircon, Inc., Moscow, Idaho
Author defined
GSS
GeoSep Services, Moscow, Idaho
Author defined
Lab_Sample
Laboratory sample identifier assigned by A2Z or GSS. Each
sample analyzed by A2Z or GSS has a single, unique lab
sample identifier that corresponds to the unique field 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. Each analysis represents a single
grain from the whole rock sample.
Author defined
An alpha-numeric code including a variation of the attribute
Lab_Sample.
U_conc_ppm
Concentration of uranium (U) in parts per million (ppm). Value
-9999 denotes not measured or not reported.
Author defined
10.0
8081.2
parts per million (ppm)
Th_conc_ppm
Concentration of thorium (Th) in parts per million (ppm). Value
-9999 denotes not measured or not reported.
Author defined
0.2
2591.0
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
0.33
503.75
207Pb_235U_Ratio
Total ratio of 207Pb to 235U.
Author defined
0.0520
23.8949
207Pb_235U_Ratio_Unc_1sig_abs
Uncertainty (1-sigma) for the ratio of 207Pb to 235U.
Author defined
0.0021
2.3522
206Pb_238U_Ratio
Total ratio of 206Pb to 238U.
Author defined
0.0079
0.6196
206Pb_238U_Ratio_Unc_1sig_abs
Uncertainty (1-sigma) for the ratio of 206Pb to 238U.
Author defined
0.0001
0.1024
Error_Correlation
Error correlation of the 207Pb/235U and 206Pb/238U ratios.
Author defined
0.01
0.84
207Pb_206Pb_Ratio
Total ratio of 207Pb to 206Pb.
Author defined
0.04610
0.29654
207Pb_206Pb_Ratio_Unc_1sig_abs
Uncertainty (1-sigma) of the ratio of 207Pb to 206Pb.
Author defined
0.00069
0.22340
207Pb_235U_Age
Age in millions of years calculated from the 207Pb/235U
ratio.
Author defined
51.4
3264.1
millions of years
207Pb_235U_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years for the
age calculated from the 207Pb/235U ratio.
Author defined
2.0
479.4
millions of years
206Pb_238U_Age
Age in millions of years calculated from the 206Pb/238U
ratio.
Author defined
51.0
3108.6
millions of years
206Pb_238U_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years for the
age calculated from the 206Pb/238U ratio.
Author defined
0.7
489.3
millions of years
207Pb_206Pb_Age
Age in millions of years calculated from the 207Pb/206Pb
ratio.
Author defined
3.4
3452.2
millions of years
207Pb_206Pb_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years for the
age calculated from the 207Pb/206Pb ratio.
Author defined
15.6
1998.8
millions of years
Preferred_Age
Preferred age in millions of years 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.
Author defined
51.0
3452.2
millions of years
Preferred_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years for the
preferred age. Zero values indicate an analysis that failed
to yield an age.
Author defined
0.8
513.2
millions of years
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.
Author defined
-1450.1
93.8
percent
geology_SHRIMPRGData_easternAK_Jones.csv
Table of U-Pb titanite and zircon SHRIMP-RG data, reporting
the isotopic concentration of uranium (U), lead (Pb), and
thorium (Th) measured in individual grains, isotopic ratios
of Pb and U, 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 1635 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_easternAK_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,
zircon, and zircon exterior (zircon surfaces).
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.
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 (Ma).
Author defined
The assumed ages for the standards are: BLR1 (1047 Ma),
MMS (524 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., 20010, Coupled elemental and isotopic
analyses of polygenetic zircons from granitic rocks and 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.
MADDER
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 for
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.
Author defined
Concatenation of Analysis_Spot and Mount attributes separated
by an underscore (_).
Analysis_Date_Time
The calendar date and time of the analysis; formatted yyyy-mm-dd, hh:mm.
Author defined
2013-11-22, 19:14
2020-01-10, 19:00
yyyy-mm-dd, hh:mm
U_conc_ppm
Uranium concentration, in parts per million (ppm). Value
-9999 denotes not measured or not reported.
Author defined
0.065
4487.114
parts per million (ppm)
Th_conc_ppm
Thorium concentration, in parts per million (ppm). Value
-9999 denotes not measured or not reported.
Author defined
0.000
15570.182
parts per million (ppm)
comm_206Pb
207Pb corrected common 206Pb, in percent. Value -9999 denotes
no data.
Author defined
-0.002
182.815
percent
238U_206Pb_Ratio
Total ratio of 238U to 206Pb
Author defined
0.09
292.26
238U_206Pb_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on total ratio of 238U to 206Pb, in
percent
Author defined
0.55
203.33
percent
207Pb_206Pb_Ratio
Total ratio of 207Pb to 206Pb
Author defined
-0.018
0.840
207Pb_206Pb_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on total ratio of 207Pb to 206Pb, in
percent
Author defined
0.339
100.354
percent
204Pbcorr_238U_206Pb_Ratio
204Pb-corrected ratio of 238U to 206Pb
Author defined
-14.997
294.379
204Pbcorr_238U_206Pb_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on 204Pb-corrected ratio of 238U to
206Pb, in percent
Author defined
0.576
762.705
percent
204Pbcorr_207Pb_206Pb_Ratio
204Pb-corrected ratio of 207Pb to 206Pb
Author defined
0.001
2.232
204Pbcorr_207Pb_206Pb_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on 204Pb-corrected ratio of 207Pb to 206Pb,
in percent
Author defined
0.468
2226.998
percent
204Pbcorr_207Pb_235U_Ratio
204Pb-corrected ratio of 207Pb to 235U
Author defined
-85.391
195.528
204Pbcorr_207Pb_235U_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on 204Pb-corrected ratio of 207Pb to
235U, in percent
Author defined
1.118
2227.002
percent
204Pbcorr_206Pb_238U_Ratio
204Pb-corrected ratio of 206Pb to 238U
Author defined
-0.679
2.871
204Pbcorr_206Pb_238U_Ratio_Unc_1sig_perc
Uncertainty (1-sigma) on 204Pb-corrected ratio of 206Pb/238U,
in percent
Author defined
0.576
762.705
percent
Error_Correlation
Error correlation of 207Pb/235U and 206Pb/238U ratios
Author defined
0.001
0.99
207Pbcorr_206Pb_238U_Age
207Pb-corrected 206Pb/238U age, in millions of years
before present (mega-annum)
Author defined
-216.33
3142.76
millions of years
207Pbcorr_206Pb_238U_Age_Unc_1sig
Uncertainty (1-sigma) on 207Pb-corrected 206Pb/238U age,
in millions of years
Author defined
0.00
4458.16
millions of years
204Pbcorr_207Pb_206Pb_Age
204Pb-corrected 207Pb/206Pb age, in millions of years. Blank
cells are present when a calculated age cannot be reported, possibly
due to a technical issue or the concentration of 207Pb is low.
Author defined
-1141.68
6342.95
millions of years
204Pbcorr_207Pb_206Pb_Age_Unc_1sig
Uncertainty (1-sigma) on 204Pb-corrected 207Pb/206Pb age, in
millions of years. Blank cells are present.
Author defined
8.45
31814.00
millions of years
Preferred_SHRIMP_Age
Preferred grain age for calculation of sample age
(in millions of years) selected from one of the two
following fields containing calculated ages:
207Pbcorr_206Pb_238U_Age or 204Pbcorr_207Pb_206Pb_Age.
Author defined
-216.33
3142.76
millions of years
Preferred_SHRIMP_Age_Unc_1sig
Uncertainty (1-sigma) in millions of years on
preferred grain age
Author defined
0.00
4458.16
millions of years
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_easternAK_Jones.csv. Blanks
cells are present; see UPb_Age_Comment in
geology_SampleSummary_easternAK_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
-99.41
99.35
percent
Y_ppm
Yttrium concentration in parts per million. Value -9999
indicates no data.
Author defined
9.2
10939.0
parts per million (ppm)
Nb_ppm
Niobium concentration in parts per million. Value -9999
indicates no data.
Author defined
232.9
736.4
parts per million (ppm)
La_ppm
Lanthanum concentration in parts per million. Value -9999
indicates no data.
Author defined
0.000
2471.888
parts per million (ppm)
Ce_ppm
Cerium concentration in parts per million. Value -9999
indicates no data.
Author defined
0.01
11301.54
parts per million (ppm)
Pr_ppm
Praseodymium concentration in parts per million. Value -9999
indicates no data.
Author defined
0.20
82.70
parts per million (ppm)
Nd_ppm
Neodymium concentration in parts per million. Value -9999
indicates no data.
Author defined
0.00
1226.01
parts per million (ppm)
Sm_ppm
Samarium concentration in parts per million. Value -9999
indicates no data.
Author defined
0.00
315.80
parts per million (ppm)
Eu_ppm
Europium concentration in parts per million. Value -9999
indicates no data.
Author defined
0.00
52.92
parts per million (ppm)
Gd_ppm
Gadolinium concentration in parts per million. Value -9999
indicates no data.
Author defined
0.00
553.56
parts per million (ppm)
Dy_ppm
Dysprosium concentration in parts per million. Value -9999
indicates no data.
Author defined
0.00
1150.59
parts per million (ppm)
Er_ppm
Erbium concentration in parts per million. Value -9999
indicates no data.
Author defined
0.00
2107.16
parts per million (ppm)
Yb_ppm
Ytterbium concentration in parts per million. Value -9999
indicates no data.
Author defined
2.46
4493.25
parts per million (ppm)
Hf_ppm
Hafnium concentration in parts per million. Value -9999
indicates no data.
Author defined
4443.76
43080.49
parts per million (ppm)
48Ti_ppm
Titanium (from mass 48) concentration in parts per million.
Value -9999 indicates no data.
Author defined
0.00
6668.21
parts per million (ppm)
49Ti_ppm
Titanium (from mass 49) concentration in parts per million.
Value -9999 indicates no data.
Author defined
0.00
6075.55
parts per million (ppm)
Fe_ppm
Iron concentration in parts per million. Value -9999
indicates no data.
Author defined
0.00
10394.30
parts per million (ppm)
geology_sampleSummary_easternAK_Jones.csv
Table with descriptive sample information, including location,
rock description, and summary of geochronology analyses. This
table contains 95 records and is presented in comma separated
value (CSV) format.
Author defined
Sample
Sample number assigned when sample was collected in the
field. This attribute links to field Sample in tables
geology_detritalZircon_easternAK_Jones.csv and
geology_SHRIMPRGData_easternAK_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_easternAK_Jones.csv. Blank cells are present.
Author defined
Hyphenated numeric code assigned by the A2Z or GSS laboratory.
Latitude
Latitude given in decimal degrees; datum NAD83
Author defined
63.0070
65.5770
decimal degree
Longitude
Longitude given in decimal degrees; datum NAD83.
Author defined
-147.3836
-140.5432
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.
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
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
70
UPb_Age_Ma
Weighted average age calculated for sample in millions of
years. Blanks cells are present.
Author defined
79.4
375.7
millions of years
UPb_Age_Unc_Ma
Uncertainty (2-sigma) of weighted average age calculated
for sample, in millions of years. Blank cells
are present.
Author defined
1.1
16.0
millions of years
UPb_Age_Method
Method used to calculate the value in UPb_Age_Ma. Blank cells
are present.
Author defined
The only attributes in this data set are 'weighted average of
206Pb/238U age' and 'isochron intercept'.
UPb_Age_N_Grains
Number of analyses used to calculate the value in UPb_Age_Ma.
Blanks cells are present.
Author defined
4
44
UPb_Age_MSWD
Mean square of weighted deviates for calculated value in
UPb_Age_Ma. Blank cells are present.
Author defined
0.14
2.50
UPb_Age_Comment
Comments on the sample age or analytical observations.
Author defined
Comments on the sample age or analytical observations.
UPb_Age_Interpretation
Geological significance of the interpreted age. Blank cells
when there is no age determination.
Author defined
crystallization
A crystallization age indicates growth of the dated
mineral grains during original formation of the rock.
Author defined
metamorphism
A metamorphic age indicates growth and (or) recrystallization
of the dated mineral grains during metamorphism.
Author defined
detrital
Indicates that all of the dated grains are detrital in
nature and formed prior to incorporation into the rock.
Author defined
geology_dataDictionary_easternAK_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_easternAK_Jones.csv, geology_SHRIMPData_easternAK_Jones.csv, and geology_sampleSummary_easternAK_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
degree
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
The USGS ASC Repository is the Authoritative source for this 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, FGDC metadata in XML and HTML formats and supplementary information about laboratory methods 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.
1.00
https://doi.org/10.5066/P9WWV93S
None
20201125
20200727
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