Linking proximal ignimbrites and coeval distal tephra deposits to establish a record of voluminous Early Quaternary (2.4–1.9 Ma) volcanism of the Tauranga Volcanic Centre, New Zealand

Abstract

The Tauranga Volcanic Centre (TgaVC) of the North Island, New Zealand, was active from 2.95 to 1.9 Ma. It lies temporally and spatially between the currently active Taupō Volcanic Zone, one of the most productive regions of Quaternary silicic volcanism globally, and its predecessor, the Coromandel Volcanic Zone. This study provides an enhanced chronology for pyroclastic volcanism of the TgaVC with four locally widespread units named and defined as follows: Welcome Bay and Wharo ignimbrites (together formerly known as Lower Pāpāmoa Ignimbrite); Otawera Ignimbrite; and Arateka Ignimbrite (formerly known as Upper Pāpāmoa Ignimbrite). These eruptives were followed by the eruption of the large-volume Waiteariki Ignimbrite at 2.1 Ma. In northern Hawke’s Bay (150-170 km southeast of TgaVC), several distal tephra-fall horizons and an ignimbrite (Hikuroa Pumice Member) are preserved in marine-hosted sediments and are stratigraphically equivalent to the five ignimbrites of the TgaVC. Using new major- and trace-element data on glass in conjunction with new zircon-derived U-Pb ages, a correlation between the Hawke’s Bay tephras and the TgaVC ignimbrites is established and the Hikuroa Pumice Member is confirmed as the distal deposit of the Waiteariki Ignimbrite. The integrated proximal and distal records show that at least eight eruptions occurred in the TgaVC between 2.4 and 1.9 Ma and provide a maximum repose period between explosive eruptions of ca. 50 kyrs.