Phyllonite and metaquartzite clasts occur in early Pliocene or possibly Mio
cene sediment at the base of the University of Wisconsin Arctic Ocean core
F1-380. Single-crystal Ar-40/Ar-39 laser-probe ages derived from feldspars
in sediment enclosing the clasts range from Middle and Late Proterozoic to
Paleozoic. The clasts occur in sediment deposited 1-2 m.y. earlier than any
previously reported central Arctic Ocean ice-rafted debris, and although a
n ice-rafted origin may be possible, a local source such as adjacent Alpha
Ridge bedrock should also be considered.