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.