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Fig. 9.14 Photo of the base of
core 173-X030
16.5m
23m
FA4
24m
27m
34m
39m
40.5m
43.5m
Fish
49m
Dolerite Basement
DRC, which has the sedimentary cover sequences in this
area mapped as Early Cretaceous.
handpicked. Zircons were mounted in a 25 mm epoxy resin
puck, polished to expose their mid-sections, and imaged
using a Jeol JSM5410LV scanning electron microscope
with attached cathodoluminescence detector for identifica-
tion of zoning, cracks and impurities. All work was
conducted at the Advanced Analytical Centre at James
Cook University, using a Coherent GeolasPro 193 nm ArF
Excimer laser ablation system connected to a Bruker 820-
MS (formerly Varian 820-MS), following the methodology
described in Tucker et al. (2013). Fifty-eight zircon grains
were analyzed using a 24
9.5
Detrital Zircon Geochronology
9.5.1 Methods
A single pilot sample for detrital zircon geochronology was
acquired from core 173-X009. Sample 173-X009-3B was
collected at a depth of 65 m below surface (near the base
of the section) from lithofacies LF1A (Figs. 9.9 and 9.15 ).
The sample was crushed and the heavy minerals were then
separated using lithium polytungstate and a Frantz magnetic
separator,
m spot size. The primary standard
used was GJ-1 (609 Ma, Jackson et al. 2004 ) and the sec-
ondary standard used was an in-house zircon standard
(Temora-2 [TEM-2] 416.8 Ma, Black et al. 2003 ). NIST
612 was analyzed at the beginning and end of each session,
μ
and
then
the
non-magnetic
grains were
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