New Zealand Journal of Geology & Geophysics abstracts
Miocene isotope zones, paleotemperatures, and carbon maxima events
at intermediate water-depth, Site 593, Southwest Pacific
Penelope J. Cooke1
Campbell S. Nelson1
Martin P. Crundwell1,2
1Department of Earth & Ocean Sciences
University of Waikato
Private Bag 3105
Hamilton 3240, New Zealand
c.nelson@waikato.ac.nz
2GNS Science
PO Box 30368
Lower Hutt 5040, New Zealand
Abstract Oxygen and carbon isotopic
stratigraphies are
presented from both benthic and planktic foraminifera for the late
early Miocene to earliest Pliocene interval (c. 19–5 Ma) of
intermediate water-depth DSDP Site 593 in the southern Tasman Sea. The
benthic values are interpreted as recording Miocene Southern Component
Intermediate Water, while the planktic species record the Miocene mode
and surface water signals. Comparisons are made between temperate Site
593 and the intermediate-depth polar Site 747 in the southern Indian
Ocean. Glacial Mi zones Mi1b–Mi6, representing extreme glacial events,
are evident in both the Site 593 intermediate and surface water
records. Miocene Southern Component Intermediate Water δ18O
values are generally lighter than the Holocene equivalent (Antarctic
Intermediate Water), indicating slightly warmer intermediate waters
and/or less global ice volume. The benthic-planktic gradient is
interpreted as indicating a less stratified Tasman Sea during the
Miocene. The benthic δ13C record contains most of the global
carbon maxima (CM) events, CM1–7 (CM1–6 = the Monterey Excursion). Like
global deep-water records, the Tasman Sea intermediate water δ13C
values indicate that most CM events correspond with Mi glacials,
including Mi4 at Site 593, not reported previously. Intermediate waters
play an important role in propagating climatic changes from the polar
regions to the tropics, and the Site 593 dataset provides a full water
column record of the structure of Miocene intermediate to surface
watermasses prior to the modern situation.
Keywords Tasman Sea; Miocene; DSDP Site
593; foraminifera;
carbon; oxygen; stable isotopes; Mi zones; Monterey Excursion; carbon
maxima events; watermasses
G06021; Online publication date 28 February 2008; Received 12 July
2006; accepted 23 October 2007
New Zealand Journal of Geology & Geophysics, 2008, Vol. 51:
1–22
0028–8306/08/5101–0001 © The Royal Society of New Zealand 2008
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