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Pliocene and Pleistocene Diatom Datum levels from the Equatorial Pacific
Published online by Cambridge University Press: 20 January 2017
Abstract
Eight diatom and two silicoflagellate datum levels from the Pliocene and Pleistocene of the equatorial Pacific are ranked and related to the paleomagnetic reversal record, calcium carbonate fluctuations, and the oxygen isotope record. The datum levels and their position with respect to the paleomagnetic reversal record are as follows: (1) last occurrence of Thalassiosira convexa midway between the top of the Gauss and the base of the Olduvai; (2) transition from Rhizosolenia praebergonii to Rhizosolenia praebergonii var. A just below the base of the Olduvai; (3) first appearance of Pseudoeunotia doliolus in the lower part of the Olduvai; (4) last occurrence of Rhizosolenia praebergonii just above the Olduvai; (5) first appearance of Asteromphalus hiltonianus midway between the top of the Olduvai and the base of the Jaramillo; (6) first appearance of Mesocena elliptica just below the base of the Jaramillo; (7) last occurrence of Mesocena elliptica midway between the top of the Olduvai and the base of the Brunhes; (8) upward increase in abundance of Thalassiosira oestrupii just below the base of the Olduvai; (9) last occurrence of Nitzschia reinholdii just above the base of the Olduvai; (10) peak occurrence of Roperia tesselata var. ovata just above Datum Level 9. By second-order correlation it is possible to relate these datum levels to the oxygen isotope record. Such a correlation suggests that some datum levels may be climate related.
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- University of Washington
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