50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...
50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...
50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...
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This paper explores what we know of New<br />
Zealand’s fossil freshwater fishes, and seeks to<br />
place them in the context of the extant fauna (based<br />
largely on material collected in the last few years<br />
by a student from the Geology Department,<br />
University of Auckland; Liz Kennedy of GNS,<br />
Lower Hutt; and Daphne Lee and Jon Lindqvist,<br />
Geology Department, Otago University.)<br />
In the more distant past WRB Oliver mentioned<br />
eleotrids from the Pliocene (now known to be mid-<br />
Pleistocene) of the Ormond Valley, inland from<br />
Gisborne, and also some galaxiids from near<br />
Dunedin; Gerald Stokell added galaxiids from near<br />
Middlemarch, and I reported on all of these and<br />
provided a summary some 30 years ago.<br />
Things have moved rapidly in the past year or so,<br />
and we can now report on:<br />
1. A couple of scales from an undetermined lower<br />
perciform family from an Early Miocene<br />
deposit near Bannockburn;<br />
2. The first fossil record of grayling<br />
(Prototroctes) from the mid-Pleistocene of the<br />
Ormond Valley, as well as:<br />
3. Additional eleotrids of the genus<br />
Gobiomorphus from the Ormond Valley;<br />
4. An additional eleotrid from Early Miocene<br />
deposits near St Bathans; and<br />
5. A series of Early Miocene galaxiid fossils from<br />
diatomite deposits near Middlemarch.<br />
There are also numerous fish otoliths in Geology<br />
Department, University of Otago collections that<br />
have not yet been looked at seriously, and which<br />
have potential to provide new revelations.<br />
I will seek to clarify the significance of these fossils<br />
in the evolutionary history of the fauna.<br />
ORAL<br />
A PRELIMINARY SEDIMENTATION<br />
MODEL FOR BENEATH THE MCMURDO<br />
ICE SHELF<br />
R. McKay 1 ,P. Barrett 1 , G. Dunbar 1 ,T.Naish 1 ,<br />
M. Harper 2 &L.Carter 1<br />
1 Antarctic Research Centre, Victoria University of<br />
Wellington, PO Box 500 Wellington<br />
2 School of Earth Sciences, Victoria University of<br />
Wellington, PO Box 500, Wellington<br />
(robert.mckay*vuw.ac.nz)<br />
Ross Island has been depressing the crust under its<br />
own weight for at least the last million years, and at<br />
the same time has been acting as the western<br />
pinning point for the Ross Ice Shelf. As a result, a<br />
thick sedimentary sequence has accumulated in a<br />
sea floor depression now 900 m deep beneath the<br />
McMurdo-Ross Ice Shelf on the south side of Ross<br />
Island in Windless Bight. These sediments record<br />
the history of ocean currents and the ice shelf itself<br />
to be investigated as part of the ANDRILL project<br />
(http://www.andrill.org/).<br />
Here we present results of two 60-cm-long gravity<br />
cores taken from the sea floor beneath the ice shelf<br />
in January 2003, and which record recent<br />
sedimentation there. Core 1 was taken 5km east of<br />
the ice shelf front, and contains a record of the past<br />
~20,000 years. The basal unit is a diamict that<br />
contains clasts, some subrounded and striated, and<br />
derived from Transantarctic Mountains. This is<br />
interpreted as representing basal debris from an<br />
expanded Ross Ice Shelf/Sheet at the LGM. This<br />
passes upwards into a well-sorted sand layer, which<br />
represents locally derived sediment either deposited<br />
through a retreating ice shelf or beneath the ice<br />
shelf as a result of slope instability. Overlying the<br />
sand is a series of fine muds and muddy sands,<br />
which are indicative of sub-ice shelf conditions,<br />
with only minor fluctuations of the ice shelf front.<br />
The biogenic content also suggests that the Ross Ice<br />
Shelf front has not retreated significantly from its<br />
present position during the Holocene and that<br />
seasonally open water has been present in<br />
McMurdo Sound for much of this period.<br />
Core 2, taken 12 km east of the ice shelf front,<br />
contains a record of the past ~10,000 years. It<br />
consists mainly of locally derived sandy mud, and<br />
contains a higher biogenic component of diatoms<br />
and sponge spicules, typically more than 20%. The<br />
uniform nature of this core suggests that current<br />
flow has varied little from the present regime (5-20<br />
cm/sec; Robinson, <strong>2005</strong>), and also supports the<br />
view that the ice shelf front has varied little during<br />
the Holocene.<br />
Additional cores are planned for <strong>2005</strong>/06 field<br />
season and will be used to develop a high resolution<br />
sedimentation model in preparation for deep<br />
drilling planned by ANDRILL for the 2006/07<br />
season.<br />
ORAL<br />
LATE QUATERNARY<br />
PALEOEARTHQUAKES ON THE<br />
NORTHERN NORTH ISLAND FAULT<br />
SYSTEM, <strong>NEW</strong> ZEALAND<br />
V. Mouslopoulou 1,2 ,A.Nicol 2 , T. Little 1 ,<br />
D. Beetham 2 , K. Berryman 2 ,R. Langridge 2 ,<br />
P. Villamor 2 &S.Beanland 1,2†<br />
1 Victoria University of Wellington, School of<br />
Earth Sciences, PO Box 600, Wellington.<br />
2 Institute of Geological and Nuclear Sciences, PO<br />
Box 30 368, Lower Hutt.<br />
(V.Mouslopoulou*gns.cri.nz)<br />
† Deceased<br />
50 th <strong>Kaikoura</strong>05 -55- <strong>Kaikoura</strong> <strong>2005</strong>