The samples were cut from quater-core sections that were cleaned in an ultrasonic bath and oven-dried at 80°C. The samples were precrushed by being wrapped in thick plastic sheeting and struck repeatedly with a 2.5-kg mechanic's hammer. Chips of fresh material with only broken surfaces of a total of 50-100 g were selected for further crushing, and the rest were put aside for future mineral separation. In this way surface contamination from drilling fluids and saw marks can be avoided in the whole-rock powder. The chips were then further crushed using an agate shatterbox and recrushed as necessary to obtain a fine powder without detectable graininess.
Major and trace elements were measured in the samples at the Universität Mainz using a Philips PW 1404 X-ray fluorescence spectrometer (Groschopf, 1997). Major elements were measured on LiBO4-fused glass disks, and trace elements were measured on pressed powder pellets. USGS reference standard BCR-1 was measured as an external control on the trace elements. The data are listed in Table T1.