Mathematics – Logic
Scientific paper
Mar 1966
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1966esrv....1..105e&link_type=abstract
Earth Science Reviews, Volume 1, Issue 2-3, p. 105-132.
Mathematics
Logic
2
Scientific paper
SummaryThe more common types of deep-sea sediments are pelagic clays and calcareous or siliceous lutites rich in the remains of planktonic Protozoa and Protophyta. Accumulation of the various biogenous and mineral elements may take place by settling from the water column above; by transport along the bottom by submarine solifluction, slumping and turbidity currents; by transport and redeposition by gentle bottom currents; and by chemical and biochemical precipitation on the ocean floor. The regional oceanographic setting, rate of supply, bottom morphology, and post-depositional solution control the mode and rate of accumulation. Occasionally, these conditions combine to provide continuous and undisturbed sediment sections. Such sections are invaluable for the study of many geological, geochemical and biological parameters and their variations through time. Using 14C,231Pa/230Th, and 230Th/232Th dating methods, a time scale extending from the present to about 150,000 years ago has been established; and using the 18O/16O isotopic method of temperature analysis, the temperature variations during the past 400,000 years have been reconstructed. The surface temperature in the tropical seas appears to have oscillated between 21 22°C (glacial minima) and 26 27°C (interglacial maxima) with a periodicity of about 40,000 years. Rigorous application of classical methods of temperature analysis, based on the relative abundances of different species of pelagic Foraminifera and the ratio of warm to temperate or cold-water species, give results internally consistent and in general agreement with the isotopic method. No correlation between the accepted Plio-Pleistocene boundary, based on the classic Italian sections, and the deep-sea sediments has yet been made. It is most likely that none or few of the continuous and undisturbed deep-sea cores of Globigerina-ooze facies so far collected include sediments as old as those deposited at the Plio-Pleistocene boundary in Italy. It has been suggested by some that the Plio-Pleistocene boundary should be re-defined on the basis of events recognizable in deep-sea sediments, especially extinctions of pelagic organisms. Some of the extinctions observed happen to coincide with the last reversal of the earth's magnetic field, which has been dated at about 700,000 years ago by the 40K/40Ar method.
Emiliani Cesare
Milliman John D.
No associations
LandOfFree
Deep-sea sediments and their geological record does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Deep-sea sediments and their geological record, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Deep-sea sediments and their geological record will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1481794