Nukumaruan records of the subantarctic scallopChlamys delicatulaand crabJacquinotia edwardsiiin Central Hawke's Bay

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Abstract
Two new localities for early Nukumaruan (Hautawan) Chlamys delicatula, at Mt Miroroa, near the Napier-Taihape Road, and at Mangleton Road between the Wakarara and Ruahine Ranges, are much further north than previous localities. The large subantarctic crab Jacquinotia edwardsii occurs with C. delicatula as far north as Mangleton Road, and known fossil localities for Jacquinotia are listed by Yaldwyn and Beu in Appendix 1. Early Nukumaruan sea-bottom temperatures in central Hawke's Bay were at least as low as they are today around southern Stewart Island. However, beech-podocarp palynofloras described by Mildenhall in Appendix 2 and dominantly dextral populations of Globorotalia pachyderma at Mangleton Road indicate that sea-surface and land temperatures were not more than 4°c colder than at present. The migration of Jacquinotia and Chlamys delicatula in the mobile larval stage was probably brought about by a bottom current flowing northwards up a trough beneath warmer surface water, aided by tidal currents to and from Wanganui Basin. For the first time, Globorotalia truncatulinoides is recorded in sequence below Chlamys delicatula, at Mangleton Road. Rocks of early Nukumaruan age that were deposited in water depths of at least 100 m have been uplifted to 1000 m at Mt Miroroa. If the age is taken as 1 · 8 m.y. the mean rate of uplift at Mt Miroroa is 0 · 6 mm/year.

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