Goesta Wollin

Atlantic Deep-Sea Sediment Cores

Studies of lithology, particle-size distributions, and micropaleontology and chemical analyses of 221 Atlantic and Caribbean deep-sea cores lead to new conceptions of processes of sedimentation, rates of sediment accumulation, Pleistocene chronology, and pre-Pleistocene history of the Atlantic Basin. Anomalous layers of sand, silt, and lutite occur widely in the deep basins of the Atlantic. Evidence for deposition of these layers by turbidity currents is as follows: (1) the layers occur in submarine canyons, in deltalike features at the terminal ends of canyons, in basins and depressions, never on isolated rises; (2) they are interbedded with late Pleistocene sediments of abyssal facies; (3) they are well-sorted and commonly graded; and (4) they commonly contain organic remains of shallow-water origin. Late Pleistocene slumping of compacted Neogene sediments along the banks of the Hudson Submarine Canyon at depths exceeding 3000 m indicates deepening of the canyon by erosion by turbidity currents. Variations in the planktonic Foraminifera in 108 of the cores and extrapolation of rates of sediment accumulation determined by 37 radiocarbon dates in 10 cores show that the last period of climate comparable with the present ended about 60,000 years ago. A faunal change indicating climatic amelioration, probably corresponding to the beginning of postglacial time, occurred about 11,000 years ago. Cross-correlations by micropaleontological methods establish the continuity of the climatic record deduced from the planktonic Foraminifera. Study of variation in the Planktonic Foraminifera leads to a different Pleistocene chronology from that proposed by Emiliani (1955). Cross-correlations of faunal zones and radio-carbon dates show that rates of continuous sediment accumulation, as opposed to turbidity-current deposition, range from 0.5 cm to 274.4 cm in 1000 years, depending upon bottom configuration. Cross-correlations by means of changes in coiling direction of planktonic Foraminifera give relative rates of sediment accumulation beyond the range of the radiocarbon method of dating. Forty one of the cores contain pre-Pleistocene sediments. The oldest sediment is Upper Cretaceous. Foraminifera and discoasters indicate the ages. Absence of sediment older than Late Cretaceous and thickness, 800–1000 m, of sediment in the Atlantic Basin as determined by seismic methods suggest that a large-scale reorganization of the Atlantic Basin took place in the Mesozoic.

Magnetism of the earth and climatic changes

Abstract Variations in the earths magnetic intensity, fluctuations in atmospheric radiocarbon activity, and climatic changes of the earth surface and of the ocean during the last 7000 yr are correlated. Variations in magnetic intensity, fluctuations in magnetic inclination, and climatic changes in deep-sea sediment cores are correlated for the last 470,000 yr. We tentatively conclude that magnetism may modulate climate.

Pliocene-Pleistocene Boundary in Deep-Sea Sediments: Extinctions and evolutionary changes in microfossils clearly define the abrupt onset of the Pleistocene

For a hundred years students of the Pleistocene have looked for evidence of the climatic change which initiated the Pleistocene epoch. Glacial deposits on the continents have been of little help because of their discontinuity and because of the destructive effect of later glaciations. Hence, Pleistocene geologists have turned to the uplifted Pliocene-Pleistocene marine sediments of the Mediterranean region. In the absence of evidence of a single, clearly defined climatic change in this sedimentary section, they have agreed to define the beginning of the Pleistocene by the first appearance of Anomalina baltica, a species of benthic Foraminifera tolerant of cool water. This definition leaves much to be desired: It rests on a single benthic species whose areal distribution must have been partly determined by local conditions on the sea floor; it is useless outside of the Mediterranean region; and there is no convincing evidence that the first appearance of Anomalina baltica in the Mediterranean coincided with the onset of the first glaciation.

Correlation of six cores from the equatorial Atlantic and the Caribbean

Curves of late Pleistocene climatic variation based on vertical distribution of planktonic Foraminifera in six cores from the Equatorial Atlantic and Caribbean have been satisfactorily correlated. Variation in percentage of material coarser than 74 microns and variation in coiling direction of Globorotalia truncatulinoides have also been used in correlation. Such correlation is construed as evidence that the sediment sections in these cores have accumulated slowly, and without interruption by slumping or turbidity current deposition.

Micropaleontological and isotopic determinations of Pleistocene climates

Climatic curves derived from variations in planktonic foraminifera in three deep-sea cores are compared with isotopic temperature curves drawn by Emiliani on the basis of the same cores. There is close correlation in the upper part of the section, but increasing deviation downward. Micropaleontological and isotopic determinations of Pleistocene climates DAVID B. ERICSON AND GOESTA WOLLIN Lamont Geological Observatory Columbia University Palisades, New York

Climatic changes, magnetic intensity variations and fluctuations of the eccentricity of the earth's orbit during the past 2,000,000 years and a mechanism which may be responsible for the relationship

Abstract Our investigation of deep-sea climatic and magnetic records showing that high eccentricity of the earths orbit, low magnetic field intensity and warm climate occur together indicates the relative importance of eccentricity as perhaps the phenomenon which has most consistently modulated both climate and magnetism for at least the past 2,000,000 years. A speculative hypothesis regarding the mechanism which may be responsible for a relationship between the eccentricity of the earths orbit, geomagnetism, and climate is suggested.

Pleistocene Climates in the Atlantic and Pacific Oceans: A Comparison Based on Deep-Sea Sediments

Comparison of Pleistocene climatic records defined by variations in abundance of planktonic Foraminifera in three cores from the southeastern Pacific with similar records in cores from the Atlantic suggests that times of warm surface water in this region of the Pacific were at least partly synchronous with times of cool water in the Altantic. This conclusion opposes the Milankovitch theory of the causation of ice ages, but it harmonizes with a modified form of Simpsons hypothesis.

Synthesis of protein, nucleosides and other organic compounds from cyanamide and potassium nitrite under possible primitive earth conditions.

The mixing of cyanamide and KNO2 produced changes from white solids to yellow liquid and then to orange solid. The gases cyanogen and ammonia were formed. No external energy was used. The reactions were carried out with a small amount of O2. The presence of proteins in the reaction product formed 13 months after the mixing was indicated by the positive reactions of the cyanamide-KNO2 reaction product with ninhydrin, microbiuret, and Folin reagent; the ultraviolet absorption at about 280 nm; the yield of 24% of 15 amino acids; and molecular weight measurements of more than 160,000. The presence of nucleosides, nucleic acid bases, hydrocarbons, and organic esters in the reaction product formed 2 months after the mixing was indicated by ultraviolet absorption at about 260 nm, and the results of ligand-exchange chromatography, paper chromatography, infrared analysis, mass spectral analysis, and NMR spectroscopy. Possible cyanamide-mediated dehydration reactions and mechanisms are discussed.