Geochemistry
Forty-two samples were collected in the field, of which thirty were
analyzed for elemental compositions. Whole rock powders were prepared
from fresh samples using an alumina ceramic shatter box and analyzed for
major and trace elements at the Peter Hooper GeoAnalytical Lab at
Washington State University. Major and minor elements were obtained
using a Thermo-ARL automated X-ray fluorescence spectrometer (XRF).
Trace elements were obtained using an Agilent inductively coupled plasma
mass spectrometer (ICP-MS). The sample locations are shown in Fig. 2 and
represented as circles in panel A. A full table summarizing the location
and chemistry of the samples can be found in the supplementary Tables 1,
2, and 3. Example thin sections of samples are shown in Fig. 3.