2015, Wellington (MP143A)
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ABSTRACT VOLUME Conference Convenor Mike Hannah (Victoria University) Organising Committee Brent Alloway, Cliff Atkins, Katie Collins, Monika Hanson, Huw Horgan, Robert McKay, Kevin Norton, Martha Savage, Miranda Voke, Colin Wilson (Victoria University), James Crampton (Victoria University / GNS Science), Christian Timm (GNS Science) Administration Janet George (Absolutely Organised Ltd.) Field Trip Leaders Kevin Norton, Cliff Atkins, Dene Carroll, Tim Little, Dee Ninis, Ben Hines (Victoria University), Russ Van Dissen, Nicola Litchfield (GNS Science) Abstracts are organised in alphabetical order by family name of first author The bibliographic reference for abstracts is: Author, A.N. (2015). Title of Abstract. In: MacKay, R., Savage, M. and Wilson, C. (eds). Abstracts, Geosciences 2015, Wellington, Geoscience Society of New Zealand Miscellaneous Publication 143a. p. x. ISBN 978-1-877480-49-2 ISSN (print) 2230-4487 ISSN (online) 2230-4495 A NEW LOOK AT THE UPPER WAITAKI CANYON RECONSTRUCTING HOLOCENE CLIMATE AND OCEAN VARIABILITY OFF ADELIE COAST, C. Abbey1 & A.R. Gorman1 EAST ANTARCTIC MARGIN 1 University of Otago, Department of Geology, PO Box 56, Dunedin 9054 A. Albot1 & R. McKay1 [email protected] 1 Victoria University of Wellington, PO Box 600, Wellington There is considerable global interest in the use of [email protected] modern canyon settings in analogue studies that will help to understand ancient depositional This project aims to produce a detailed Holocene systems in deep-water environments. The Waitaki time series (12 ka BP to present) of ocean and Canyon, due to its status as the largest member of climate variability, at sub-centennial time scale, as the Otago Canyon System, its relative accessibility, preserved in an Antarctic margin marine sediment and the quantity and quality of pre-existing seismic core (U1357) collected by the International Ocean data in its vicinity provides a convenient real-world Discovery Program (IODP). Grain size analysis of the example where we may study one of these settings terrigenous component will permit changes in in detail. Recent seismic and bathymetric surveys sedimentary processes at this site to be conducted by the University of Otago and the investigated. Shifts in the physical sedimentary hydrocarbon industry have provided new insights processes in the region are driven by long-term into the sea-floor and near-surface features in the changes in sea ice extent, polynya activity, wind upper reaches of the canyon and surrounding shelf stress and diatom productivity. These drivers play a area. key role in identifying potential effects on the production of Antarctic Bottom Water (AABW)-a There is a large amount of data available that can first order control on global heat, gas, salt and be used to investigate the subsurface and seafloor nutrient transport via the Meridional Overturning in the vicinity of the Waitaki Canyon, ranging from Circulation (MOC) and an important mechanism for high-resolution multibeam and boomer seismic storing CO2 in the abyssal ocean. These systems will surveys (acquired by the University of Otago’s RV be examined through correlation of the grainsize Polaris II) to a commercial 3D seismic volume. These data with geochemical environmental and data provide an ideal opportunity for looking at the paleontological proxies from previous studies of the ancient form of the canyon and its modern seafloor IODP U1357 core, as well as with the Roosevelt expression. Features indicative of sedimentary Island Climate Evolution (RICE) ice core records. processes (e.g., submarine landslides) are visible in Little is known about Holocene natural variability in the bathymetric data, yet the extent of modern this region from marine records and how it may activity in the canyon is uncertain. relate to the pattern of recent warming in The combination of well-defined Pleistocene Antarctica, despite this being crucial for improved sequences on the shelf and the density of data prediction of the impact of future climate change. around the canyon are used to examine the Spectral analysis of the data will further aid in the temporal variation in activity levels within the assessment of different climatic and orbital forcing upper Waitaki Canyon. The integration of factors responsible for centennial to millennial bathymetric data and subsurface seismic data in climate variability in the Holocene. this research provides a novel approach to studying how canyons develop and evolve through time. By analysing the modern form of the seafloor our understanding of the processes that are currently involved in the development of the Waitaki Canyon will be enhanced, and this will assist in our interpretation of the extensive seismic datasets in the region. 1 FRICTIONAL CONTROLS ON HIGH-ANGLE REVERSE EARLY TERTIARY CONTOURITES ON THE FAULTING DURING COMPRESSIONAL BASIN MARBOROUGH PALEO-PLATFORM: INSIGHTS INVERSION FROM KAIKOURA WHARF S. Alder1, S.A.F. Smith1, T. Tesei2, 3 & C. Collettini2, 3 B. S. Andrew1, C.S. Nelson1 & C.J. Hollis2 1 Department of Geology, University of Otago, 9054 1 School of Science, University of Waikato, Private Dunedin, New Zealand Bag 3105, Hamilton 2 Dipartimento di Geologia, Universita’ La Sapienza, 2 GNS Science, P O Box 30-368, Lower Hutt Rome, Italy [email protected] 3 Istituto Nazionale di Geofisica e Vulcanologia (INGV), 00143 Rome, Italy During the greenhouse world of the late Cretaceous [email protected] to Eocene the Marlborough paleo-platform (MPP) sat at high latitudes (~55-60ºS) on the passive Large normal faults are often reactivated as high- eastern margin of Zealandia. During this period a angle reverse faults during compressional basin thick sequence of biopelagic sediments (~500 m inversion. Prevailing models to explain steep thick at Mead Stream) belonging in the Muzzle reverse slip call upon significant fluid overpressure. Group were deposited at bathyal depths Though such models are consistent with some throughout the region. seismological data and field observations from incipient (low-displacement) reverse faults, they There is evidence that the long-lived sedimentary remain largely untested in the case of basin-scale regime that otherwise dominated the MPP during faults. the Early Tertiary was punctuated by some significant short-lived climatic and oceanographic We present field and experimental data from the changes in the high-latitude Southwest Pacific >200 km long Moonlight Fault Zone in west Otago, conditions. These changes were accompanied by a an Oligocene basin-bounding normal fault that shift from pelagic sedimentation to periods of reactivated in the Miocene as a high-angle reverse unconformity formation, active erosion and fault (present dip angle 65°-75°). Excellent sediment transport across the MPP. exposures of the fault zone exhumed from c. 4-8 km depth are found in creek sections along the entire One of these periods is well represented strike length. Wall rocks are mainly quartz-albite- throughout southeastern Marlborough by the muscovite-chlorite schists with a strong foliation Teredo Limestone. This is a calcareous, bioturbated that is everywhere sub-parallel to the Moonlight greensand unit which overlies a regional Fault (i.e. dip angle 65°-75°). Although the overall unconformity surface. The Kaikoura Wharf section structure of the fault zone changes significantly is unique in that it contains two separate greensand along strike in response to wall rock composition, units of which, based on this study, only one is the <5 metre thick fault core everywhere contains correlated with the Teredo Limestone. interconnected layers of foliated cataclasite rich in Three sedimentary facies have been identified at authigenically-grown chlorite and muscovite/illite. Kaikoura Wharf, a siliceous micrite facies (F1), a Microstructural evidence suggests deformation in greensand facies (F2) and a micritic limestone facies the fault core by a combination of cataclasis, (F3). Both F1 and F3 are biopelagites and frictional slip along phyllosilicate seams and considered to represent ‘normal’ background dissolution-precipitation. sedimentation conditions. However, the presence Single-direct and double-direct friction experiments of perigenic/allogenic glauconite, siliciclastics and were performed with the BRAVA apparatus (INGV, phosphatised clasts in F2 is considered to be Rome) on saturated wafers (e.g. with intact associated with an energetic bathyal foliation) of foliated cataclasite at normal stresses transportation/sedimentation regime. up to 75 MPa. The foliated cataclasites have a Based on the presence of crossbedding and the friction coefficient of <0.25 and negligible frictional absence of Bouma structures at other locations in healing. In combination with dissolution- southeastern Marlborough, it is argued that both precipitation mechanisms, a friction coefficient of the F2 units at Kaikoura Wharf represent contourite <0.25 can account for slip on high-angle reverse deposits. These are associated with discrete Early faults if accompanied by only moderately high fluid Tertiary oceanographic events, possibly driven by pressures. Our results indicate that friction may be short cooling intervals due to ephemeral Antarctic equally as important as fluid pressure during ice sheet growth in the Early Tertiary greenhouse compressional basin inversion. world. 2 RECONSTRUCTING URBAN FOSSIL FUEL CO2 A NEW GENERATION OF DIGITAL MAPS EMISSIONS UTILISING THE RADIOCARBON SHOWING POTENTIAL PETROLEUM HABITATS IN COMPOSITION OF TREE