RADIOLARIANS IN OFFSCRAPED SEAMOUNT FRAGMENTS, AORANGI RANGE, NEW-ZEALAND

Well-preserved radiolarians occur in coloured argillites at two locali ties in the Torlesse Terrane exposed in the Aorangi Range in the south ernmost part of the North Island, New Zealand. The coloured argillites which host the radiolarians are associated with metabasite, and toget her these rocks are interpreted as remnants of seamounts which were di smembered immediately before or during subduction and accretion. Recen t studies have shown that radiolarian faunas are highly useful for dat ing such oceanic deposits, and for constraining the depositional ages of adjacent turbidites in terranes which are typically sparsely fossil iferous. Radiolarians from the two Aorangi Range localities are consis tent with the Late Jurassic to Early Cretaceous age established by reg ional age constraints, although one genus previously considered to be exclusively Late Cretaceous is also present. This suggests that radiol arian biostratigraphic zones defined by Northern Hemisphere studies sh ould not be rigidly applied to rocks preserved in Southern Hemisphere terranes until radiolarian stratigraphic ranges for these terranes are adequately established.