),
except Rb, Sr, and Zr, which are 5%.Major elements were mostly
obtained by X-ray fluorescence (XRF) analysis on glass discs from fused fluxed
samples on a Philips PW1606 instrument. Na was analyzed by flame photometry, Fe2+
by titration, and loss on ignition by heating of dried samples in an oven to
>1000°C in the rock-analytical laboratory of the Geological Survey of
Denmark and Greenland. Reproducibility of the major elements was <0.5
relative percent for Si, Al, Fe, Ca, and Mg and better than 1 relative percent
for the rest, including Fe2+. A suite of trace elements was analyzed
by standard XRF techniques on pressed powder pellets on a Philips 1400
instrument at the Geological Institute. The detection limits were as follows: Rb
= 0.1, Ba = 1, Pb = 2, Sr = 0.1, La = 0.5, Ce = 1, Nd = 1, Y = 1, Zr = 1, Nb =
0.1, Zn = 1, Cu = 2, Co = 1, Ni = 1, Sc = 1, V = 3, Cr = 3, and Ga = 1 ppm. Long
counting times were applied to ensure detection. Other trace elements were
analyzed by instrumental neutron activation analysis (INAA) by "Tracechem"
at the Geological Institute, University of Copenhagen. The results appear in
Table T1, and
the dectection limits were as follows: La = 0.1, Ce = 0.2, Nd = 3, Sm = 0.05, Eu
= 0.006, Tb = 0.03, Yb = 0.04, Lu = 0.02, Hf = 0.02, Ta = 0.02, and Th = 0.02
ppm. Uncertainties are comparable to the detection limits for samples at low
concentrations. For higher concentrations, reproducibilities are ~10% (2 ),
except Rb, Sr, and Zr, which are 5%.
