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
Description
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.