Plagiogranites occur locally in the interface between the sheeted dike
complex and the uppermost level of gabbros, containing a high proport
ion of sulfate with a delta(34)S value of 13.0 parts per thousand on a
verage. Strontium and sulfur isotopic compositions of the plagiogranit
es suggest that magmatic or magmatic-hydrothermal sulfate constitutes
the major fraction of the sulfate in the plagiogranites with high delt
a(34)S values and that seawater-derived Sr might have been incorporate
d in the latest stage of crystallization.