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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ange of lower resolution or fragmentary records of<br />
climatic events, based on glacial landforms and<br />
deposits (central Southern Alps, South Island), river<br />
terraces and deposits, loess deposits (eastern North<br />
and South Islands), and aeolian quartz silt in nonquartzose,<br />
loess-like, andesitic tephric deposits of<br />
western North Island.<br />
The poster reflects work-in-progress and aims to<br />
assist comparison of the New Zealand<br />
paleoclimatic records with those from the wider<br />
Australasian region and elsewhere. The immediate<br />
goal is the establishment of an Australasian-<br />
INTIMATE climate event stratigraphy by the New<br />
Zealand and Australian paleoclimate communities,<br />
for presentation at the 2007 INQUA Cairns<br />
Symposium.<br />
POSTER<br />
LATE QUATERNARY DISPLACEMENTS ON<br />
THE WAITANGI FAULT, AVIEMORE DAM,<br />
SOUTH ISLAND, <strong>NEW</strong> ZEALAND<br />
D.J.A. Barrell 1 ,R.J.VanDissen 2 ,K.R.<br />
Berryman 2 & S.A.L. Read 2<br />
1 GNS Science, Private Bag 1930, Dunedin.<br />
2 GNS Science, P.O. Box 30-368, Lower Hutt.<br />
(d.barrell*gns.cri.nz)<br />
Aviemore Dam was constructed across the Waitaki<br />
River valley in the mid-1960s. The dam straddles<br />
the steeply WSW-dipping Waitangi Fault. At the<br />
time of construction, no evidence of late<br />
Quaternary movement was documented on the<br />
fault. However, in the mid-1990s, dam safety<br />
review investigations unearthed evidence of late<br />
Quaternary deformation, and this led to the detailed<br />
paleoseismological investigations that provided<br />
data for displacement characterisation of the fault<br />
and subsequent evaluations of dam safety under<br />
direct fault rupture loadings.<br />
The primary paleoseismology investigation method<br />
was the excavation of 10 trenches, the largest of<br />
which was up to 10 m deep and 180 m long, across<br />
faults and folds within 1 km of the dam,<br />
accompanied by geological mapping of surface<br />
exposures and landforms. Detailed logging of the<br />
trench walls (typically 1:20 scale) documented the<br />
geometry of Late Quaternary deposits and the<br />
locations, amount and sense of slip of the most<br />
recent fault displacements. Over 30 samples were<br />
dated to constrain the timing of past fault<br />
movements, using, where possible, at least two<br />
duplicate methods of luminescence, and<br />
complemented in a few instances by radiocarbon.<br />
The investigations documented two, and possibly<br />
three, surface rupture fault movements on the<br />
Waitangi Fault in the last c. 23,000 years, with the<br />
most recent movement between 13,100 and 14,100<br />
years ago. These ruptures were located on, or up to<br />
6 m west of, the bedrock fault that juxtaposes<br />
Mesozoic- and Tertiary-age rocks (respectively east<br />
and west of the fault). Relative upthrow has been to<br />
the west in the late Quaternary. This represents a<br />
reversal from a net westerly downthrow that<br />
accumulated during the late Tertiary as shown by<br />
the Mesozoic versus Tertiary rock relationships<br />
across the fault.<br />
The two most recent surface ruptures had singleevent,<br />
west-side-up, vertical separations of c. 0.5 m<br />
(penultimate) and c. 1.5 m (most recent).<br />
Slickenside-lineations, and other slip indicators,<br />
show an oblique right-lateral – reverse sense of late<br />
Quaternary rupture, with a horizontal (H)<br />
component greater than the vertical (V) component<br />
(ratios of displacement in the range of 1H:3V to<br />
1H:1V). In addition, a zone of “small-scale” late<br />
Quaternary faults and folds, with single-event<br />
vertical separations of up to 0.7 m, extends up to at<br />
least 150 m west of the Waitangi Fault.<br />
The fault displacement characteristics documented<br />
from the field investigations were subsequently<br />
used to derive earthquake performance assessments<br />
for the dam, and to evaluate dam safety under direct<br />
fault rupture loadings.<br />
ORAL<br />
THE DEVELOPMENT <strong>OF</strong> ANTARCTIC<br />
GLACIAL HISTORY OVER THE LAST<br />
FIFTY YEARS<br />
P. J. Barrett<br />
Antarctic Research Centre, Victoria University of<br />
Wellington, P O Box 600, Wellington.<br />
(peter.barrett*vuw.ac.nz)<br />
Fifty years ago it was thought that the Northern<br />
Hemisphere had experienced 4 glacial episodes<br />
over the last two million years, and no-one<br />
supposed the Southern Hemisphere would be much<br />
different. That view was changed radically in 1973<br />
with the first Antarctic offshore drilling by the<br />
Glomar Challenger in the Ross Sea. The cruise,<br />
which was led by Denny Hayes and Larry Frakes<br />
and included three New Zealanders, Derek Burns,<br />
Peter Webb and me, cored through glacial<br />
sediments that dated back 25 million years. The<br />
cruise that followed, Leg 29, led by Jim Kennett<br />
and Bob Houtz, cored a series of deep ocean sites to<br />
the north that covered the Cenozoic Era. This<br />
yielded the first oxygen isotope curve, from which<br />
they concluded there was Antarctic cooling and sea<br />
ice in the latest Eocene, and the formation of an ice<br />
sheet like today’s in the middle Miocene.<br />
The Leg 29 results could not, however, resolve the<br />
relative contributions of ice volume and<br />
temperature to the isotope signal, and gave no<br />
50 th <strong>Kaikoura</strong>05 -5- <strong>Kaikoura</strong> <strong>2005</strong>