50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...

the LGM grass peak. This period of fine sediment
deposition is also present in the Skiffington Swamp
results but is less distinct. Galway Tarn samples
were found to have a very high phytolith content,
which may have contributed to the less distinct
grain size results. The mineralogy of the
Skiffington Swamp core was examined by optical
microscope using point counting methods. A peak
in micaceous mineral content (as a percentage of
total mineral grains) was found corresponding with
the end of the LGM. A rapid reduction in mica
content was found to correlate well with the rise in
organic content as shown by the loss on ignition
results. This is interpreted to represent a reduction
in mica supply as outwash areas were re-vegetated
after glacier retreat.
Vandergoes, M. J.; Fitzsimons, S. J. 2003: The Last
Glacial-Interglacial transition (LGIT) in South
Westland, New Zealand: paleoecological insight into
mid-latitude Southern Hemisphere climate change
Quaternary Science Reviews 22: 1461-1476.
POSTER
MUDDY WATERS ~ OFFSHORE RECORDS
OF ONSHORE RESPONSES TO ABRUPT
CLIMATE EVENTS
Penelope J. Cooke 1 , Chris H. Hendy 2 ,
Campbell S. Nelson 1 & Helen L. Neil 3
1 Dept. of Earth Sciences, University of Waikato,
Private Bag 3105, Hamilton
2 Dept. of Chemistry, University of Waikato
3 NIWA, Private Bag 14901, Wellington
(p.cooke*waikato.ac.nz)
Most palaeoclimate proxies recorded from marine
sediments, are in fact of a marine origin, e.g., � 18 O,
� 13 C and alkenones, and therefore record the
oceanic systems’ responses to the changing climate.
However, the terrigenous sediment which has
accumulated in large quantities in the offshore area
around New Zealand, started life onshore. Erosion
of the South Island of New Zealand contributes
almost 0.7% of the total riverine sediment loading
to the oceans per year and is inferred to have been
much greater during glacials, particularly during
transitions between climate states. Hence the
timing of events, which generate the sediment are
likely to be offset from the records of the same
events in marine proxies.
The arrival of terrigenous sediment into the marine
system is likely to be delayed by its transit from the
site of origin to the marine system. Sediment
supplied to the Bounty Trough off eastern South
Island is first trapped by the large natural lakes
which retain about 15% of the sediment yield to the
east of the Alps. Configuration of the Canterbury
Shelf during glacials is such that the delivery of this
sediment by-passes the shelf and is directly
deposited into the troughs and canyons east of
South Island. In core MD97-2120, arrival of
characteristic silt-sized grains is offset by over 50
cm at both Termination II (MOIS 6/5) and
Termination I (MOIS 2/1), this equates to
approximately 10,000 years based on the existing
� 18 O records, i.e., the sediment did not arrive in the
Bounty Trough until interglacial warming was at its
maximum.
The modern west coast system is slightly different
as it lacks the trapping capacity of the lakes and the
proximity of the Southern Alps is much closer.
Approximately 10 times more sediment is injected
into the west coast system than into the Bounty
Trough.
New core sites (TAN0409-173 and -174) off the
Hokitika and Haast Canyons in the Tasman Sea, are
being investigated to determine how much greater
the sediment loading is and what the delivery rate is
compared with the east coast sediment system. We
suggest this high sediment loading would be
exacerbated during glacial times and during the
climate transitions.
The west coast cores will enable us to assess how
abrupt climate changes will be expressed in the
sediment record, given the delivery rate should be
faster and lacking the ‘holding’ capacity of the
lakes. Knowing this will contribute to climate
change modelling and our understanding of the
climate system.
POSTER
HOW GOOD IS THE FOSSIL RECORD?
NEW ZEALAND MIGHT HAVE THE
ANSWER
R. A. Cooper 1 ,P.A.Maxwell 2 ,J.S.Crampton 1 ,
A. G. Beu 1 ,C.M.Jones 1 ,B.A.Marshall 3
1 GNS Science, PO Box 30368, Lower Hutt, New
Zealand
2 Bathgates Road, R.D. 10, Waimate, South
Canterbury, New Zealand
3 Museum of New Zealand Te Papa Tongarewa, PO
Box 467, Wellington, NZ
(r.cooper*gns.cri.nz)
Estimates of past biodiversity, speciation rates and
extinction rates based on the fossil record, have
built-in assumptions about completeness of the
fossil record. Biodiversity change and evolutionary
rate metrics have become increasingly sophisticated
in recent years, but there has been no corresponding
improvement in estimates of completeness. This is
because completeness of fossil populations is
extremely difficult to measure. It is widely
recognised that a major contributor to
incompleteness is size bias – the preferential loss of
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