1872 H.M.S Challenger: first oceanographic expedition, collected bottom samples, showed distribution of planktonic organisms Late compared to land organisms (Linnaeus 1707-78) 1935 W. Schott (Gr.) published studies of short (1 m) cores, found 3 layers differing in foraminifera composition 1939 H.G. Stubbings - British Oceanographic Expedition Arabian Sea Core showed 4 layers of different foraminifera composition. Inferred 4 cold strata, 3 warm 1947-48 Albatross (Sw) used Kullenberg Piston Corer collected cores 10-15 m long. Demonstrated that the sedimentation rate is slow because there was less than 200 m of sediment on ocean floor 1950's beginning of collection of 100's of ocean cores stored at Columbia University, Lamont Geological Observatory (estate of T. Lamont) all NSF-sponsored oceanographic vessels take cores. 1955Cesare Emiliani.
University of Chicago, Classic Paper
(CALIBRATION of PROXY DATA)
Foraminifera in core V12-122 (Caribbean) were compared to foraminifera in 61 modern sediment samples and modern sea-surface temperature Tm=XFm : Tp=XFp "X" is the TRANSFER FUNCTION
Today maximum deposition ice-rafted sand off Greenland
18 K it was 1500 km SE
5. OXYGEN ISOTOPES
(1955) proposed a chronology for the history of Pleistocene fluctuations of the ratio of
18O/16O in the tests of foraminifera (more 18O during glacials).
Measured relative to arbitrary standard. Positive indicates grater than standard.
More positive (= less negative) values indicate colder, BUT positive delta 18O values
occur only in coldest periods.
(18O/16O) sample - (18O/16O) SMOW
δ 18O =
Two causes were initially proposed for 18O/16O fluctuations:
a. Biological fractionation in foram tests (Emiliani favored) 18O/16O ratio
in living forams increases 0.023 % C-1 (colder = more 18O)
b. 18O enrichment in oceans because 16O deposited in continental glaciers.
More ice = more 18O left in ocean (Shackleton, 1967)
Because of sedimentation rates, reworking, and differences among indicators
(δ 18O/16O, carbonates, fauna), the shapes of curves are used in correlations, not the amplitudes
Correlation with Milankovitch Curves: (Martinson et al., 1987)
changes in the earth's orbit that produce changes in the distribution
of energy over the earth's surface and may cause the glacial/interglacial cycle.
adjust frequency of sea-core climatic cycles to match frequencies of orbital
cycle 22,000 41,000 100,000 yr
OXYGEN ISOTOPE CHRONOLOGY
"MIS" Marine oxygen Isotope Stages
Nomenclature all follows Emiliani (1955)
TYPE CORE: V28-238, raised May 1971, in the equatorial Pacific, Depth 3120 m, 6.35 cm diameter, 16.2 m long (Kukla, 1977)
Odd numbered, low 18O = WARM, starting with Holocene (1)
5,7... previous interglacials + like modern
3 = mid-Wisconsin "interstadial"
Even numbered, high 18O = COLD, starting with Wisconsin (2)
major glaciations except no. 4
less uniform than interglacials - last 2-3 extreme
#14 very minor
minor fluctuations 4-6 per stage
e.g. 5 broken up into a,b,c,d,e (or decimals 5.1, 5.2 ...)
Abrupt Deglaciations: most consistent feature of pattern
delimited by abrupt decrease in δ 18O
Roman numerals, I = Wisconsin/Holocene, II, III, IV...
Termination IV (Stage 11/12) is middle-late Pleistocene Boundary (EPICA, 2004)
Interval between TERMINATIONS
capital letters, A-H during Brunhes normal magnetic chron A=Holocene, B=Wisconsin + Sangemon ,C...
WHAT IS THE Y-axis ?