Heavy mineral suites of core samples from the McKee Formation (Eocene—Lower Oligocene), Taranaki: Implications for provenance and diagenesis

Sandstones from McKee Formation and near correlatives, are known only from cores in Taranaki, New Zealand, from depths >2130 m. Their heavy mineral suites consist dominantly of ilmenite, garnet, zircon, and tourmaline, with pyrite and barite of probable diagenetic origin. Hornblende, epidote, titanite, and kyanite are absent. Staurolite and garnet are absent through intrastratal solution below burial depths of about 3100 m and 3600 m respectively. This dissolution pattern is comparable to that observed in the North Sea Basin, although total dissolution of mineral species takes place somewhat deeper in the McKee Formation. The provenance, indicated particularly by staurolite and compositions of the garnet grains, consisted mainly of basement rocks such as those encountered in offshore boreholes or those now exposed in North Westland and northwest Nelson. A small component is probably from the Haast Schist.