A New Zealand late Miocene magnetostratigraphy; glacioeustatic and biostratigraphic correlations

Author(s): Wright, I. C.; Vella, P. P.
Author Affiliation(s): Primary:
Victoria Univ. Wellington, Res. Sch. Earth Sci., Wellington, New Zealand
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 87(1-2), p.193-204. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 35 refs.; illus. incl. charts, sketch map
Summary: Magnetostratigraphy is described for a sequence of predominantly hemipelagic marine mudstone, 2200 m thick, representing the Late Miocene and earliest Pliocene from the Mangapoike River section, eastern North Island, New Zealand. Together with the early Pliocene magnetostratigraphy previously described from Mangapoike, it now provides a 3000 m thick magnetostratographic reference section for New Zealand, ranging in age from 10.5 Ma to 3.5 Ma. Thirteen magnetozones are recognised in the 2200 m described here and all but the highest are confidently correlated with the polarity timescale from the base of Chron 11 to Chron 7. Correlation of the highest (normal) magnetozone to the timescale is ambiguous, and two possible interpretations are presented, both of which imply a previously unrecognised latest Miocene unconformity. The inferred unconformity is supported by biostratigraphy. It is shown that the integration of biostratigraphy, lithostratigraphy and magnetostratigraphy can discern diastems of the order of 104 years. Magnetostratigraphy and δ13C data also indicates a diastem between 6.30 Ma to 5.41 Ma at the Miocene-Pliocene angular unconformity at Mangapoike. These two unconformities and a distinct lithological change at the base of the Late Miocene are synchronous with deep-sea benthic δ18O records and unconformities expected from postulated eustatic sea-level changes. A coherent correlation model for New Zealand on-shore magnetostratigraphic, biostratigraphic and isotopic data conflicts with the two magnetostratigraphic interpretations proposed for DSDP Site 594, 150 km east of New Zealand, both of which are probably incorrect.
Year of Publication: 1988
Research Program: DSDP Deep Sea Drilling Project
Key Words: 03 Geochronology; 24 Surficial Geology, Quaternary Geology; Australasia; Biostratigraphy; Cenozoic; Changes of level; Clastic rocks; Correlation; Foraminifera; Geochronology; Invertebrata; Magnetostratigraphy; Mangapoike River; Microfossils; Miocene; Mudstone; Neogene; New Zealand; North Island; Paleomagnetism; Protista; Radiolaria; Sedimentary rocks; Stratigraphy; Tertiary; Unconformities; Upper Miocene; Zoning
Coordinates: S385400 S385400 E1773600 E1773600
Record ID: 1988025302
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by Institute of Geological and Nuclear Sciences Limited (GNS Science), Lower Hutt, New Zealand