Kapitean Stage Research Articles

Magnetostratigraphic chronology of late Miocene to early Pliocene biostratigraphic and oceanographic events in New Zealand

Successions of uplifted shallow marine sediments in New Zealand were among the first to provide evidence of latest Miocene climatic deterioration and were also among the first onshore successions where late Miocene to early Pliocene magnetostratigraphic records were established. A revised chronology of late Miocene to early Pliocene events has been determined from new magnetostratiigraphic results from two important successions at Blind River and Upton Brook, South Island, New Zealand (lat. 41°45′S, long. 174°05′E). Magnetostratigraphic results from Upton Brook are the fast from strata containing the Kapitean index mollusks and provide the first reliable estimate of the age of the Tongaporutuan-Kapitean boundary. A coherent chronology from Blind River and Upton Brook indicates that two synchronous low sea level and cool paleoclimatic events occurred in the late Miocene Kapitean Stage. This inference is supported from other well-known coeval successions in the New Zealand region. The revised New Zealand chronology supports recent determinations from the Mediterranean that indicate a two-stage Messinian salinity crisis and a 5.2-Ma age for the Miocene-Pliocene boundary. Data from New Zealand, the Mediterranean, and ocean cores around the world suggest that these latest Miocene events are related to glacio-eustatic sea level fluctuations. A 6.05-Ma age for the first occurrence datum of Globorotalia conomiozea indicates that significant diachroneity exists in the placement of this datum between the Southwest Pacific and the Mediterranean, confirming the observation that G. conomiazea is unsuitable for correlation between ocean basins.

Pacific neogene stratigraphy

The Fourth International Congress of Pacific Neogene Stratigraphy, was held July 29–31, 1987, at the University of California, Berkeley. This very successful congress was organized by the Regional Committee on Pacific Neogene Stratigraphy (RCPNS) of the International Union of Geological Sciences (IUGS) and the International Geological Correlation Program (IGCP) Project 246 “Pacific Neogene Events in Time and Space.” The meeting was attended by 180 scientists from 16 different countries, and more than 90 presentations were made, on topics ranging from paleoclimatology, biostratigraphy, regional stratigraphy and geologic history, new techniques in stratigraphy, evolutionary studies, and modern biofacies and sediment relationships.A. R. Edwards of the New Zealand Geological Survey (Lower Hutt, New Zealand) spoke on climatic events that he recognizes in the late Neogene strata of New Zealand. The carbon isotope shift during chron 6 (6.3–6.5 Ma) is identified in the sequence at Blind River (Marlborough, New Zealand). The extinction of ∼25% of New Zealand molluscan genera during the latest Micoene (Kapitean Stage) accompanied the greatly accelerated diversification of planktonic foraminifera lineages at this time. The New Zealand events are also coeval with the Messinian “salinity crisis” in the Mediterranean. A series of events (extinctions of Mollusca, appearance of glacial rock types, foraminifera speciation, and nannofossil appearances) in New Zealand late Pliocene rocks reflect the climatic deterioration. One type of sub‐Antarctic molluscan fauna abruptly appeared in central North Island at 2.4 m.y., coeval with the onset of major Northern Hemisphere glaciation.

Late Miocene–Early Pliocene stratigraphy and paleoceanography of the South Atlantic and southwest Pacific oceans: A synthesis

The stratigraphy and paleoceanography of the late Miocene and early Pliocene have been examined at six sites in the South Atlantic and southwest Pacific oceans: Deep Sea Drilling Project (DSDP) sites 284, 516A, 519, 588, and 590 and two piston cores from Chain cruise 115. A consistent stratigraphy was developed among sites using graphic correlation, which resulted in age models for all sites that are tied to the revised paleomagnetic time scale of Berggren et al. (1985). Applying these chronologies, we assessed latitudinal and interocean contrasts in the stratigraphic ranges of late Miocene‐early Pliocene planktonic foraminiferal and nanno ‐ fossil datums. Salient stratigraphic results include (1) The last appearance datum (LAD) of Globoquadrina dehiscens is a late Miocene (∼6.4 Ma) event in the subtropics and is not useful for the placement of the Miocene/Pliocene (M/P) boundary in this biogeographic province. (2) The first appearance datum (FAD) of Globorotalia crassaformis occurred at ∼5.1 Ma in the South Atlantic near the M/P boundary, suggesting that Gr. crassaformis may have first evolved in the South Atlantic and later migrated to other regions. (3) In the southwest Pacific, the FADs of Gr. margaritae (5.97 Ma), Gr. puncticulata (5.09 Ma), and Gr. crassaformis (4.87 Ma) are significantly time transgressive between temperate and warm subtropical regions. Time lags of ∼1.0 m.y. were required for these species to adapt to physical and/or biotic conditions peripheral to their endemic biogeographic provinces. (4) Between the subtropics of the South Atlantic and southwest Pacific, many planktonic foraminiferal datums (FAD of Dentogloboquadrina altispira, Gr. cibaoensis, Gr. conomiozea, Gr. margaritae, and Gq. dehiscens and LAD of Gr. cibaoensis) markedly depart from the correlation suggested by magnetostratigraphy, indicating that these datum levels are unreliable for correlation between these ocean basins. (5) In contrast, available calcareous nannofossil datum levels fall on or near the paleomagnetic correlation line, indicating synchroneity of events within the subtropics. (6) Biostratigraphic, magnetic, and 87Sr/86Sr correlation between sites 588 and 519 and the M/P neostratotype at Capo Rossello, Sicily, suggests that the base of the Zanclean stratotype occurs at 5.1–5.0 Ma in the lower reversed subchron of the Gilbert, about 2–3 × 105 years above the Gilbert/Chron 5 boundary. Oxygen isotopic results from DSDP sites 284, 519, and CH115 piston cores confirm a prolonged benthic ∂18O increase in the latest Miocene between ∼5.6 and 5.0 Ma, as originally proposed by Shackleton and Kennett (1975). At DSDP site 588, the benthic ∂18O record in the latest Miocene is marked by high‐frequency fluctuations with amplitude variations of ∼0.5‰, and a long‐period wavelength component of ∼400,000 years. Maximum ∂18O values, however, occurred during the late Miocene (Kapitean Stage) between 5.5 and 5.1 Ma. The late Miocene ∂18O changes resulted from mid‐ and high‐latitude cooling and pulses of ice sheet expansion and contraction. Glacial events were most intense during the latest Miocene (Kapitean Stage), and occurred at 5.50–5.35 Ma and at 5.10 Ma. Glacial events are estimated to have lowered sea level by ∼40 to 60 m and contributed to the isolation and desiccation of the Mediterranean Basin during the late Messinian. Interglacial conditions prevailed at 5.2 Ma and between 5.0 and 4.1 Ma ihe early Pliocene. The beginning of the Pliocene was marked by changes in many proxy climatic indicators at all sites, suggesting a prolonged interval of warm, interglacial conditions between 5.0 and 4.1 Ma during the earliest Pliocene.Supplementary tables are available with entire article onmicrofiche. Order from American Geophysical Union, 2000Florida Avenue, N.W., Washington, DC 20009. DocumentP86‐001; $2.50. Payment must accompany order.

Application of Carbon Isotope Stratigraphy to Late Miocene Shallow Marine Sediments, New Zealand

A distinct (0.5 per mil) carbon-13/carbon-12 isotopic shift in the light direction has been identified in a shallow marine sedimentary sequence of Late Miocene age at Blind River, New Zealand, and correlated with a similar shift in Late Miocene Deep Sea Drilling Project sequences throughout the Indo-Pacific. A dated piston core provides an age for the shift of 6.2 +/- 0.1 million years. Correlations based on the carbon isotopic change require a revision of the previously established magnetostratigraphy at Blind River. The carbon shift at Blind River occurs between 6.2 and 6.3 +/- 0.1 million years before present. A new chronology provides an age for the evolutionary first appearance datum of Globorotalia conomiozea at 6.1 +/- 0.1 million years, the beginning of a distinct latest Miocene cooling event associated with the Kapitean stage at 6.2 +/- 0.1 million years, and the beginning of a distinct shallowing of water depths at 6.1 +/- 0.1 million years. The Miocene-Pliocene boundary as recognized in New Zealand is now dated at 5.3 +/- 0.1 million years. Extension of carbon isotope stratigraphy to other shallow Late Miocene sequences should provide an important datum for international correlation of Late Miocene shallow and deep marine sequences.

The late Miocene to early Pliocene history of the Globorotalia miozea plexus from Blind River, New Zealand

Variation in the Globorotalia miozea plexus in Blind River section (Tongaporutuan, Kapitean, Opoitian Stages) is illustrated and described by reference to typical forms and by biometric study of the axial profile of the shell. Globorotalia puncticulata sphericomiozea is considered to arise from forms already present in the antecedent populations of G. miozea conoidea. Several intergrading morphotypes are recognized. The axial shape of chambers is more variable than in G. miozea conoidea but there is no evidence of multimodal distributions in an angular measure of the shape of the periphery of the last-formed chamber. The keel tends to weaken and is absent from some specimens. Globorotalia puncticulata sphericomiozea appears within the Kapitean Stage, possibly prior to the basal Pliocene, and is the earliest stage of a phyletic branch in the plexus. Populations in which the keel is absent are referred to G. puncticulata puncticulata. At this stage there is considerable inflation of the axial profile of chambers and the shell becomes globose. Globorotalia conomiozea is represented by very rare, crust-free, specimens that are difficult to separate from high-domed specimens of G. miozea conoidea. It is not useful as a datum for the base of the Kapitean Stage in this section and confusion as to its identity in other regions is noted. The sequence of populations from G. miozea conoidea to G. puncticulata puncticulata shows the gradual evolution of a globose shell form from a weakly truncatuline ancestor. The change in form may be a gradual adaptation to cooler water masses that developed in the middle latitudes of the Southern Hemisphere at the close of the Miocene. However, once initiated, the changes seem to have proceeded independently of concurrent climatic oscillations.

Variation inGloborotalia puncticulata sphericomiozeafrom New Zealand (Foraminiferida, Neogene)

Abstract The shape of shell profiles (spiral, axial) of Globorotalia puncticulata sphericomiozea from the type locality and from two early populations (also from Kapitean Stage, dose to Miocene-Pliocene boundary) is studied using Fourier amplitudes. Sample distributions for the major harmonics (2–4) and projections of 10 harmonics on to principal component axes are unimodal. There is a continuous spectrum of form (axial profile) from conical shells with keel at the angular periphery (G. conomiozea morphotype) to regularly curved shells that anticipate the shape of G. puncticulata puncticulata. Globorotalia puncticulata sphericomiozea seems to represent a stage in the transition from truncatuline form (G. conomiozea populations) to turborotaline form (G. puncticulata puncticulata and its descendant, G. inflata).

Molluscan evidence of warm sea temperatures in New Zealand during Kapitean (Late Miocene) and Waipipian (Middle Pliocene) time

Abstract Very cool sea temperatures have been suggested for the New Zealand Kapitean Stage from the evidence of planktonic Foraminiferida and for the Waipipian Stage on the basis of Foraminiferida, spores and pollen and oxygen isotopes, and the former has been used as evidence for a late Miocene glaciation. The Mollusca in rocks of these stages include several genera now living only to the north of New Zealand, and there is no molluscan evidence of lowered sea temperatures at these times. Planktonic foraminiferal faunas occurring with Kapitean molluscs vary markedly, and a 63% sinistral Globigerina pachyderma population from East Cape occurs with Amphistegina and Conus. Probably the ecology of planktonic foraminifers is not well enough known for them to be used as direct temperature indicators.

Late Miocene—Early Pliocene Paleomagnetic Stratigraphy, Paleoclimatology, and Biostratigraphy in New Zealand

The paleomagnetic stratigraphy, biostratigraphy, and paleoclimatology have been studied in two marine sections of late Miocene to early Pliocene age in New Zealand. A total of over 850 separately oriented cores were collected from 270 sites. The Blind River section (41°43′ S.) is now adjacent to the southernmost subtropical (temperate) water mass, but planktonic foraminifera indicate that the area was covered by subantarctic water during much of late Miocene and early Pliocene time. The Mangapoike River section (38°55′ S.) records temperature oscillations mainly within the subtropical water mass during late Miocene–early Pliocene age, with perhaps one subantarctic interval during latest Miocene time. The Miocene-Pliocene boundary in New Zealand has consistently been placed at the first evolutionary appearance of Globorotalia puncticulata at the boundary between the late Miocene Kapitean Stage and the early Pliocene Opoitian Stage. This boundary lies within sediments deposited during the Gilbert Reversed Epoch between the Nunivak Event (base at 4.14 m.y. B.P.) and the Gilbert C Event (top at 4.33 m.y. B.P.) in both sections. Thus, the Miocene-Pliocene boundary, as recognized in New Zealand, is dated as 4.3 ± 0.1 m.y., which appears to be slightly younger than the type (International) Miocene-Pliocene boundary in Italy (4.9 to 5.1 m.y.). Biostratigraphic ranges of planktonic foraminifera between New Zealand and the Mediterranean differ in detail, perhaps due to different paleo-oceanographic histories. A major cooling episode during the early Gilbert Reversed Epoch is recorded at Blind River and Mangapoike River. This cooling is more pronounced in the southern section examined, where it is represented by the occurrence of a central subantarctic planktonic foraminiferal assemblage. In the northern section, cooling was also pronounced, although of shorter duration, represented by a probably northern subantarctic assemblage. The Miocene-Pliocene boundary in Europe has still only been dated indirectly by means of non-Mediterranean sections. Interpretation of late Cenozoic paleomagnetic data from Mediterranean deep-sea cores collected from Glomar Challenger is rejected.

Izumonauta(Argonautidae, Cephalopoda Coleoidea) from the Kapitean Stage (uppermost Miocene) of New Zealand

Abstract The molluscan family Argonautidae is recorded for the first time from the Kapitean Stage of New Zealand. The single specimen is tentatively identified as a juvenile of Izumonauta lata Kobayashi, 1954, a name proposed for a unique shell from the Miocene of Japan.

A specimen of the nautiloid Aturia from the Kapitean Stage (uppermost Miocene) of New Zealand

Abstract The most recent occurrence of Aturia so far collected in New Zealand or elsewhere is a specimen from Bluecliff, Te Waewae Bay, Southland (Kapitean Stage). Its occurrence supports the uppermost Miocene age attributed to the Kapitean Stage.

Recognition and correlation of the Kapitean Stage (Upper Miocene, New Zealand)

Abstract The salient features of New Zealand Upper Miocene and Lower Pliocene microfaunas are outlined, and criteria for recognising the Kapitean Stage are summarised. Paleoecological evidence suggests that the Kapitean Age was a time when seas were relatively shallow, that the shallowing took place in the latest part of the Tongaporutuan Age, and that deepening took place in the earliest part of the Opoitian Age. The changes in sea level caused many changes in the fauna, and the Kapitean Stage is soundly based only on relatively few permanent changes of both macrofauna and microfauna. The Kapitean Stage is represented by shallow-water facies at many places, but it contains some moderately deep-water facies at other places. The two facies contain very few diagnostic fossils which are common to both, but usually can be correlated by a bioseries of planktonic Foraminifera—the Globorotalia crassaformis bioseries. In nearly all sections the Kapitean Stage is thin compared with the overlying Opoitian and the u...

New Zealand tertiary species of the deep-sea genusGaleoocorysKuroda and Habe (Gastropoda)

Abstract Cassidaria sulcata Hutton, briefly described in 1873 from the Pliocene of Kaniere, New Zealand, is redescribed from the holotype and topotypes and attributed to the genus Galeoocorys Kuroda and Habe. Related forms are recorded from the Kapitean Stage (uppermost Miocene) of the same Westland district, and one is described as G. allani n.sp. Living Galeoocorys inhabit archibenthal and abyssal seas, but the New Zealand fossil species apparently lived at considerably shallower depths.

Position of the Miocene-Pliocene boundary in New Zealand

Abstract Finlay and Marwick (1940) placed the Miocene-Pliocene boundary between the upper Miocene Urenuian Stage (later partly superseded by the Kapitean Stage) and the Lower Pliocene Opoitian Stage. This was done mainly on the evidence afforded by the record of Uvigerina pigmea d'Orbigny in the Italian type Plaisancian Stage and also in the Opoitian Stage.

The Kapitean stage (Upper Miocene) at Cape Foulwind, west coast

Abstract About 350 ft of Kapitean beds exposed in sea cliffs at Cape Foulwind are conformably overlain by Opoitian and conformably underlain by Tongaporutuan. Seven foraminiferal samples were collected from a uniform and continuous section of marine siltstone. A lithological column and a foraminiferal range chart are presented. Paleoecology and stratigraphic paleontology are discussed.