luigi jovane 1,2 , kenneth l. verosub 1 , fabio florindo 2 and gary acton 1
DESCRIPTION
First Evidence for Milankovitch Forcing of Antarctic Climate in the Ross Sea Sector during the Quaternary. Luigi Jovane 1,2 , Kenneth L. Verosub 1 , Fabio Florindo 2 and Gary Acton 1 1 Geology Department, University of California, Davis, USA - PowerPoint PPT PresentationTRANSCRIPT
First Evidence for Milankovitch Forcing of Antarctic Climate in the Ross Sea Sector during the
Quaternary
Luigi Jovane1,2, Kenneth L. Verosub1,
Fabio Florindo2 and Gary Acton1 1Geology Department, University of California, Davis, USA2Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy
New Paleomagnetic Studies of Old Cores from the Ross Sea Sector
USNS Eltanin (1960s)USCGC Glacier (1970s)R/V Polar Duke (1980s)
Nathaniel B. Palmer (1990-present)Glomar Challenger (DSDP Leg 28)
First studied
by
Jim Kennett
&
Norm Watkins
Eltanin Cruise 27
Core 21
(1968)
Water Depth 3456 meters
Length 16 m
Eltanin 27-21
Ross Ice Shelf
Victoria Land
Sampling Site
Ross Sea
Cape Adare
682 samplesin plastic boxes
Ross Sea with other coring sites
Zijderveld Plots
Eltanin 27-21
Eltanin 27-21
Paleomagnetic record
682 samples
Correlation of
Elt-27-21 with
MPTS
Eltanin 27-21 ODP Site 1101
Tangent Cylinder Hypothesis
Environmental Magnetic Parameters
Environmental Magnetic Parameters
“40 kyr world”
“100 kyr world”
Mid-Pleistocene Transition
MIS Stages at Magnetic Boundaries
28
19
3135
637481
MIS Stage
This suggests, but does not prove, that the peaks in environmental magnetic record represent interglacial periods.
And is consistent with ARM/IRM data because higher values of ARM/IRM
are usually interpreted as finer magnetic grains.
Sediment versus Magnetic Grain Sizes
Output of Laser Granulometer
Environmental Magnetic Parameters
Normalized NRM Intensity
SINT-800 Global Paleointensity Stack
Because we have a • a magnetostratigraphic record• an orbital parameter record• a paleointensity record
Eltanin 27-21 could be the Rosetta Stone for
other studies of old cores from the Ross Sea sector.
Environmental magnetic data from 40-year old Eltanin core 27-17 clearly show that paleoclimatic processes were dominated by ~40 kyr cyclicity prior to the mid-Pleistocene transition and by ~100 kyr cyclicity afterward.
We don’t fully understand the nature of the signal but our working hypothesis is that peaks in the environmental magnetic record correspond to interglacials.
CONCLUSIONS
(For funding agencies.) If a 40-year old core can still produce exciting science so can a scientist after a 40-year career.
So don’t throw out your old cores or your old scientists.