Geomarine Research

St Johns, New Zealand

Geomarine Research

St Johns, New Zealand
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Bostock H.C.,NIWA - National Institute of Water and Atmospheric Research | Hayward B.W.,Geomarine Research | Neil H.L.,NIWA - National Institute of Water and Atmospheric Research | Currie K.I.,University of Otago | Dunbar G.B.,Victoria University of Wellington
Deep-Sea Research Part I: Oceanographic Research Papers | Year: 2011

We have compiled carbonate chemistry and sedimentary CaCO3% data for the deep-waters (>1500m water depth) of the southwest (SW) Pacific region. The complex topography in the SW Pacific influences the deep-water circulation and affects the carbonate ion concentration ([CO32-]), and the associated calcite saturation horizon (CSH, where ωcalcite=1). The Tasman Basin and the southeast (SE) New Zealand region have the deepest CSH at ~3100m, primarily influenced by middle and lower Circumpolar Deep Waters (m or lCPDW), while to the northeast of New Zealand the CSH is ~2800m, due to the corrosive influence of the old North Pacific deep waters (NPDW) on the upper CPDW (uCPDW). The carbonate compensation depth (CCD; defined by a sedimentary CaCO3 content of <20%), also varies between the basins in the SW Pacific. The CCD is ~4600m to the SE New Zealand, but only ~4000m to the NE New Zealand. The CaCO3 content of the sediment, however, can be influenced by a number of different factors other than dissolution; therefore, we suggest using the water chemistry to estimate the CCD. The depth difference between the CSH and CCD (δZCSH-CCD), however, varies considerably in this region and globally. The global δZCSH-CCD appears to expand with increase in age of the deep-water, resulting from a shoaling of the CSH. In contrast the depth of the chemical lysocline (ωcalcite=0.8) is less variable globally and is relatively similar, or close, to the CCD determined from the sedimentary CaCO3%. Geochemical definitions of the CCD, however, cannot be used to determine changes in the paleo-CCD. For the given range of factors that influence the sedimentary CaCO3%, an independent dissolution proxy, such as the foraminifera fragmentation % (>40%=foraminiferal lysocline) is required to define a depth where significant CaCO3 dissolution has occurred back through time. The current foraminiferal lysocline for the SW Pacific region ranges from 3100-3500m, which is predictably just slightly deeper than the CSH. This compilation of sediment and water chemistry data provides a CaCO3 dataset for the present SW Pacific for comparison with glacial/interglacial CaCO3 variations in deep-water sediment cores, and to monitor future changes in [CO32-] and dissolution of sedimentary CaCO3 resulting from increasing anthropogenic CO2. © 2010 Elsevier Ltd.

Grenfell H.R.,Geomarine Research | Hayward B.W.,Geomarine Research | Nomura R.,The University of Shimane | Sabaa A.T.,Geomarine Research
Marine and Freshwater Research | Year: 2012

The present study aimed to extract a sea-level history from northern New Zealand salt-marsh sediments using a foraminiferal proxy, and to extend beyond the longest nearby tide-gauge record. Transects through high-tidal salt marsh at Puhinui, Manukau Harbour, Auckland, New Zealand, indicate a zonation of dominant foraminifera in the following order (with increasing elevation): Ammonia spp.Elphidium excavatum, Ammotium fragile, Miliammina fusca, Haplophragmoides wilbertiTrochammina inflata, Trochamminita salsaMiliammina obliqua. The transect sample faunas are used as a training set to generate a transfer function for estimating past tidal elevations in two short cores nearby. Heavy metal, 210Pb and 137Cs isotope analyses provide age models that indicate 35cm of sediment accumulation since ∼1890 AD. The first proxy-based 20th century rates of sea-level rise from New Zealand's North Island at 0.28±0.05cmyear-1 and 0.330.07cmyear-1 are estimated. These are faster than the nearby Auckland tide gauge for the same interval (0.17±0.1cmyear-1), but comparable to a similar proxy record from southern New Zealand (0.28±0.05cmyear-1) and to satellite-based observations of global sea-level rise since 1993 (0.31±0.07cmyear-1). © CSIRO 2012.

Hayward B.W.,Geomarine Research
Journal of Foraminiferal Research | Year: 2014

Thirteen benthic foraminiferal species dominate modem " monospecific" faunas (dead faunas with >80% of one species in >63-pm samples) in New Zealand. These faunas occur in sheltered, often brackish, intertidal or shallow-subtidal environments, never deeper than 25 m. None occurs along exposed coasts or in the open ocean. Seven agglutinated species (Entzia macrescens, Haplophragmoides wilberti, H. manilaensis, Miliammina fusca, M. obliqua, Trochammina inflata, Trochamminita salsa) dominate " monospecific" faunas in salt marshes with varying salinity and elevational ranges. All but /. manilaensis have been recorded comprising 99-100% of at least one fauna. A further six species (Ammobaculites exiguus, Ammonia aoteana, Ammotium fragile, Elphidium excavatum clavatum, E. tvilliamsoni, E. gunteri) dominate "monospecific" faunas in unvegetated intertidal and shallow-subtidal (<3 m), sheltered estuary, inlet, or lagoon settings. "Monospecific" A mb. exiguus faunas are inferred to have been produced by dissolution of calcareous components. A further 17 species dominate modem near-monospecific faunas (50-80% of one species), 11 at depths <50 m and six in the open ocean at 504000-m depth. "Monospecific" and near-monospecific faunas are more common in higher latitudes, where overall species diversity is lower. Six species dominate "monospecific" early Miocene faunas in northern New Zealand: Elphidium crispum in a sheltered gravel beach; Nonionetla novozealandica in a deep-water (50100 m), possibly dysoxic harbour; and three larger, more robust species (Amphistegina aucklandica, Lepidocyclina orakiensis, Miogypsina intermedia) in current- or wave-concentrated beach or shallow-marine deposits. The only bathyal or abyssal "monospecific" fauna is dominated by Amphimorphinella butonensis occurring in a fossil hydrocarbon seep setting. Many of the modem " monospecific" faunas (especially those in salt marshes) are cosmopolitan whilst most of the fossil and some of the modem faunas are endemic to the New Zealand region. These high-dominance faunas are produced by taphonomic and ecological processes. Taphonomic causes include wave or current concentration by winnowing or transport in high energy shallow-marine environments and carbonate dissolution in low pH brackish salt marsh or deep-sea settings. Ecological drivers include highly specific adaptations that allow species to outcompete all others in stressful (intertidal) strongly variable (high-tidal brackish) or unusual (hydrocarbon seep) environments. Sometimes high test productivity of opportunistic species may result in near-monospecific faunas.

Haywardu B.W.,Geomarine Research | Triggs C.M.,University of Auckland
Journal of Foraminiferal Research | Year: 2016

A combination of five techniques was used to infer the paleobathymetry and paleoecology of 103 foraminiferal faunas (>63μm, census counts of 384 benthic species) from throughout the lower Miocene Waitemata Basin, Auckland, northern New Zealand. A canonical correspondence analysis ordination showed that environmental factors related to paleobathymetry were the main drivers of benthic foraminiferal composition and samples were sorted in approximate paleo-depth order using increasing planktic percentage and species diversity proxies. Cluster analysis recognised seven associations (A-G) and eight subassociations, which were interpreted in terms of paleo-bathymetry and paleoproductivity by qualitative comparison with modern faunas. Planktic-percentage-based regression (with benthic stress-indicator taxa removed) and a Modern Analogue Technique comparison (at generic level) of fossil benthic assemblages with a modern dataset (626 faunas from 0-5000 m) were both used to provide quantitative paleobathymetry estimates for each Miocene fauna. These paleo-depth estimates were refined using the upper-and lower-depth limits of some of the less common benthics present. No one technique appears to be better than others. All can provide anomalous paleo-bathymetric estimates that need to be explained. Paleo-depth estimates are most consistent and precise for inner-mid shelf faunas and become less precise and more frequently inconsistent with increasing depth. A number of faunas with inconsistent paleo-bathymetric estimates contain both shallow-and deep-water-restricted benthic tests. These are interpreted as resulting from the inclusion of reworked deep-water fossil tests into shallow faunas, or mixing of contemporaneous tests as sediment flowing from shelf depths down into the basin in turbidity currents and debris flows. The eight bathyal-abyssal associations and subassociations have overlapping depth ranges but only 3-4 of them were present in the basin at any one time. Their geographic distribution reflects a crude depth-related zonation, whereas their stratigraphie succession is inferred to have resulted from a period of increased carbon flux and decreased bottom oxygen sandwiched between periods of lower carbon flux and more oxic bottom conditions. The recognised associations are: A, Elphidium, intertidal-subtidal beach; B, Nonionella-Notorotalia, sheltered inner shelf; C, Amphistegina-Cibicides, exposed inner-outer shelf; D, Astrononion-Gyroidina, ≥mid-bathyal; E, Bolivina, mid-lower bathyal; F, Cibicides-Bolivina, bathyal; G, Oridorsalis-Neugeborina-Pullenia, ≥lower bathyal. The inferred paleoenvironment of the faunas is used to help resolve the paleogeographic history of the Waitemata Basin. Thin basal trasgressive sequences of lensing conglomerate, shelly sandstone and limestone containing shelf faunas (Assocs A-C) record initiation of basin subsidence over a wide area (300 × 100 km), ∼21 Ma. Continued subsidence (estimated from foraminiferal data at ∼1 mm/yr) was accompanied by sediment starvation with little or no sediment accumulating until the basin reached lower bathyal depths (F, G). This created sufficient slope for turbidity currents from the north to flow down submarine canyons and deposit three interfingering submarine fans of sandstone (800-1000 m thick). Displaced Cretaceous-Oligocene nappes and melange (Northland Allochthon) moved part way into the basin from the north and large sub-seafloor slides of mixed basinal sediment and allochthon sud off its advancing toe. These slides were triggered by uplift of the northern part of the basin, which created land fringed by a wide shelf (C). A large submarine stratovolcano built up on the west side of the basin and shed volcaniclastic sediment (C, D, F) down its eastern slopes with some debris flows transporting mixed shallow water faunas up to 30 km into the basin. The ∼4 million-year-life of this subduction-related basin came to an end with complete eversión before the end of the early Miocene.Grant: The field work, sample processing, and foraminiferal identifications which are the basis of this study were undertaken by the first author in the 1970s and 1980s, while on a post-doctoral fellowship at the Smithsonian Institution or while BWH was employed at the New Zealand Geological Survey (now GNS Science). BWH thanks Fred Brook for assistance in the field and the late Adrian Trask for assistance in the laboratory. The scanning electron microscope photographs are the work of Barry Burt, Sue Bishop, and Hugh Grenfell. BWH acknowledges the inspiration, gentle guidance, patience and encouragement of his post-doctoral and doctoral advisors Marty Buzas and the late PeterBallance, and his former boss at New Zealand Geological Survey the late Norcott Hornibrook. The manuscript has benefitted greatly from the constructive reviews and editorial comments of David Haig, Mike Isaac, Michael Kucera and Pam Hallock.

Callard S.L.,Victoria University of Wellington | Gehrels W.R.,University of Plymouth | Morrison B.V.,University of Tasmania | Grenfell H.R.,Geomarine Research
Marine Micropaleontology | Year: 2011

This paper aims to establish whether contemporary salt-marsh foraminifera from eastern Tasmania are suitably related to elevation and can therefore be used to reconstruct past sea levels. A proxy reconstruction of recent sea-level change in Tasmania is potentially useful because in New Zealand a prominent early 20th century acceleration of sea-level rise has been documented which requires regional confirmation. Forty-three surface samples were collected from two salt marshes in the Little Swanport Estuary. Common species are: Trochammina inflata, Jadammina macrescens, Miliammina fusca, Trochamminita irregularis and Trochamminita salsa. The latter two species have been previously grouped together as T. salsa, but are distinguished here because they occupy distinct vertical niches. We performed regression analyses on the agglutinated foraminifera and their surface elevations using the software package C2 and tested the accuracy of various regression models by comparing predicted heights of the two transects with surveyed heights. We found that the surveyed heights are closely matched by elevations predicted by Weighted-Average Partial-Least-Squares (WA-PLS) models. These models predict sea level to within ±0.10m. PLS models showed favourable statistical parameters but were unreliable when used for predictions. Applications of PLS regression models in sea-level reconstructions therefore require caution. We compare our results with other studies from around the world and conclude that microtidal coastlines provide the most advantageous conditions for precise sea-level reconstructions. © 2011 Elsevier B.V.

Hayward B.W.,Geomarine Research | Gregory M.R.,University of Auckland | Kennett J.P.,University of California at Santa Barbara
Geology | Year: 2011

Modern seafl oor hydrocarbon seeps are usually surrounded by an unusual macrobiota dominated by symbiont-bearing endemic bivalves and worms. Numerous species of foraminifera (shelled protists) also live around hydrocarbon seeps, but none have been found that are endemic to this environment. An extinct species of benthic foraminifera (Amphimorphinella butonensis) has been found in large numbers in a 15-m-diameter patch of siltstone surrounding a Miocene concretionary carbonate mound (inferred to be a fossil methane seep) in New Zealand. The tests exhibit highly negative δ 13C values, consistent with a methane-rich environment of recrystallization on or just below the seafl oor. This extremely rare species has been recorded only once before, from asphalt-impregnated Miocene muddy limestone in Indonesia, most likely also associated with hydrocarbon seepage. Is this the fi rst record of a foraminiferal species that was specifi cally adapted, and endemic, to hydrocarbon seep environments?. © 2011 Geological Society of America.

Johnson K.,Geomarine Research | Hayward B.W.,Geomarine Research | Holbourn A.,University of Kiel
Marine Micropaleontology | Year: 2011

Fifty-eight species of elongate, cylindrical benthic foraminifera (here referred to as the Extinction Group) belonging to genera that became extinct during the mid-Pleistocene Climate Transition (MPT), were documented (~. 50 kyr resolution) through the early middle Miocene (15-13 Ma) in two sites on opposite sides of the subtropical Pacific Ocean (ODP Sites 1146, South China Sea; ODP Site 1237, southeast Pacific). The study was undertaken to investigate the response of the Extinction Group (Ext. Gp) to the major cooling during the middle Miocene Climate Transition (MCT) to look for clues that might explain the causes of the extinction during the glacials of the mid-Pleistocene Climate Transition. Ext. Gp faunal differences between the two sites (attributed to regional and bathymetric differences in food supply to the seafloor) are greater than those that occurred through the 2 myr time span at either site. The middle Miocene Climate Transition was not an interval of enhanced species turnover or a decline in Ext. Gp abundance, in contrast to the major extinctions that occurred during the mid-Pleistocene Climate Transition. Distinct changes in the composition of the Ext. Gp faunas did occur through this time (more pronounced in Site 1237). At both sites the pre-middle Miocene Climate Transition faunas were transformed into their post-middle Miocene Climate Transition composition during the period of major cooling (14.0-13.7. Ma). During this transition interval the faunal composition swung back and forth between the two end member faunas. These faunal changes are attributed to changes in productivity (decrease in South China Sea, increase in southeast Pacific), brought about by major changes in global climate and continental aridity. © 2010 Elsevier B.V.

Hayward B.W.,Geomarine Research | Grenfell H.R.,Geomarine Research | Sabaa A.T.,Geomarine Research | Kay J.,Geomarine Research | And 2 more authors.
Quaternary Science Reviews | Year: 2010

This paper provides the first solid evidence in support of a century-old hypothesis that the mountainous Marlborough Sounds region in central New Zealand is subsiding. More recent hypotheses suggest that this may be a result of southward migration of a slab of subducted Pacific Plate causing flexural downwarping of the overlying crust in the vicinity of the transition between subduction and strike-slip on the Pacific-Australian plate boundary. The proxy evidence for gradual Holocene subsidence comes from micropaleontological study of seven intertidal sediment cores from the inner Marlborough Sounds (at Havelock, Mahau Sound and Shakespeare Bay). Quantitative estimates (using Modern Analogue Technique) of former tidal elevations based on fossil foraminiferal faunas provide evidence of tectonic (not compaction-related) subsidence in all cores. Estimates of subsidence rates for individual cores vary within the range 0.2-2.4 m ka-1. The wide variation within subsidence rate estimates are related to a combination of the accuracy limits of radiocarbon dates, elevation estimates, and particularly our poor knowledge of the New Zealand Holocene sea-level curve. The most consistent subsidence rate at all three sites for the mid-late Holocene (last 6-7 ka) is ∼0.7-0.8 m ka-1. This rate is consistent with the average subsidence rate in the adjacent 4-km thick Wanganui sedimentary basin for the last 5 myr. Subsidence is inferred to have migrated southwards from the Wanganui Basin to impinge on the inner Marlborough Sounds in just the last 100-200 ka. © 2009 Elsevier Ltd. All rights reserved.

Lindsay J.M.,University of Auckland | Leonard G.S.,Institute of Geological & Nuclear Sciences | Smid E.R.,University of Auckland | Hayward B.W.,Geomarine Research
New Zealand Journal of Geology and Geophysics | Year: 2011

Determining magnitude-frequency relationships, a critical first step in assessing volcanic hazard, has been hampered in the Auckland Volcanic Field (AVF) by the difficulty in dating past eruptions from the field's c. 50 centres. We assessed 186 age determinations from 27 centres for reliability and consistency. Results indicate that only three centres (Rangitoto 0.6 ka; Mt Wellington 10 ka; Three Kings 28.5 ka) are reliably and accurately dated. Eight are reasonably reliably dated within a small age range: Crater Hill, Kohuora, Mt Richmond, Puketutu, Taylors Hill and Wiri Mountain (all 32-34 ka); Ash Hill (32 ka); and Purchas Hill (11 ka). Tephrochronology of lake sediments and relative ages from stratigraphic relationships provide age constraints for a further 9 and 11 centres, respectively. Although recent Ar-Ar studies show promise, ages of AVF centres generally remain poorly understood; this has implications for any statistical treatment of the distribution of volcanism in the AVF. © 2011 The Royal Society of New Zealand.

Hayward B.W.,Geomarine Research | Grenfell H.R.,Geomarine Research | Sabaa A.T.,Geomarine Research
New Zealand Journal of Geology and Geophysics | Year: 2012

At Shag River estuary, North Otago, New Zealand, parts of an Archaic moa-hunter occupation site (AD 1340-1410) lie beneath 50 cm of saltmarsh sediment at a modern elevation of 0.3 m below mean high water. Fossil saltmarsh foraminiferal assemblages in the overlying cored sediment provide high-tidal palaeo-elevation estimates (Modern Analogue Technique) that indicate a gradual rise in relative sea level of 0.59 + 0.05 m since that time. This part of the moa-hunter site appears to have been located on an unvegetated high-tidal sand flat at the time of occupation. There is no evidence that supports previously hypothesised coseismic compaction of underlying sediment as a cause for the submergence during the time of occupation. Comparison with other saltmarsh foraminiferal records in southern New Zealand suggests that the moa-hunter occupation occurred during the interval of lowest sea level in the last millennium (early part of the Little Ice Age) and that approximately half the subsequent sea-level rise occurred after AD 1900. © 2012 The Royal Society of New Zealand.

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