High-precision U–Pb geochronology of Phanerozoic large igneous provinces - Volcanism and Global Environmental Change - page 50

(a) (b)

(c)

Figure 4.1 Photographs of a doloritic intrusion from the Siberian LIP. (a) View
of sill thickness and columnar jointing. (b) View of coarse-grained segregation
and finer-grained matrix. (c) View of plagioclase and pyroxene-rich coarse-

grained segregation from which zircon crystals were isolated. Photo credit Dougal
Jerram. A black and white version of this figure will appear in some formats. For

the colour version, please refer to the plate section .

350

300

250

200

150

100

50

0

0 500 1000 100 200 300

[Zr] (ppm)

0 2 4 6 8

Crystal size (um) Th/U

Figure 4.2 Crystal size, Zr concentration and Th/U for vertical transect through
Palisades sill, New Jersey, USA. Data from Shirley, 1987 . Sample NB08

13,
which contained zircon crystals, was dated by Blackburn et al ., 2013 , and was
sampled at a stratigraphic height of

-

~ 300 m.