luigi jovane 1,2 , kenneth l. verosub 1 , fabio florindo 2 and gary acton 1

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.