An Early Jurassic age for chert within the Early Cretaceous Oponae Melange (Torlesse Supergroup), Raukumara Peninsula, New Zealand

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Abstract
Re-examination of a radiolarian fauna from an allochthonous chert block within the Oponae Melange shows the chert to be of Ururoan (Pliensbachian-Toarcian) age. The Oponae Melange occurs near the top of a thick sequence of Torlesse Supergroup flysch-type sedimentary rocks. Macrofossils indicate a Motuan (Albian) age of emplacement for the melange, and for the uppermost Torlesse Supergroup strata. This radiolarian fauna provides an opportunity to demonstrate clearly the considerable age difference (c. 80 m.y.) between older probable oceanic basement cover rocks characteristically occurring in Torlesse Supergroup melange zones and the enclosing younger clastic submarine fan-type strata.