Revision of the Piripauan and Haumurian local stages and correlation of the Santonian-Maastrichtian (Late Cretaceous) in New Zealand

The uppermost Cretaceous in New Zealand is represented by the local Mata Se ries, composed of the Piripauan and overlying Haumurian Stages. The existin g definitions and subdivision of these stages, and the type section at Haum uri Bluff, southeastern Marlborough, are wholly inadequate. To address thes e problems, three key sections in southeastern Marlborough have been studie d in detail: a tributary of Ben More Stream, the headwaters of Kekerengu Ri ver, and a railway cutting at the mouth of Conway River. All three sections have yielded rich palynomorph assemblages and the first two contain inocer amid bivalves and foraminiferal faunas. In addition, magnetostratigraphic d ata have been obtained from the Ben More Stream section. We propose to revise the Piripauan and Haumurian Stages from new boundary s tratotypes in the Ben More Stream section. The Piripauan is defined at the lowest occurrence of the inoceramid I. pacificus. The base of the Haumurian Stage is defined at the lowest occurrence of the dinoflagellate Nelsoniell a aceras. In addition, we propose to subdivide the Haumurian into formal Lo wer and Upper substages; the base of the Upper Haumurian is defined at the lowest occurrence of the dinoflagellate Isabelidinium pellucidum in a bound ary stratotype in the Conway River railway cutting. These boundary criteria can be correlated widely within New Zealand across a broad range of marine facies. The Piripauan contains two inoceramid and three dinoflagellate zon es. The Haumurian contains six dinoflagellate zones and five subzones. Base d on biostratigraphic and magnetostratigraphic data, the Piripauan/Haumuria n boundary is correlated with the C34-C33 magnetochron boundary and with th e middle-upper Santonian boundary. The Piripauan and Haumurian Stages thus have durations of c. 1.7 and 19.5 m.y., respectively. In terms of content, these revisions largely preserve the stages as used pr eviously in New Zealand and require no significant changes to existing geol ogical maps.