Sedimentation at MANOP Site H (eastern equatorial Pacific) over the past 400,000 years: Climatically induced redox variations and their effects on transition metal cycling
- 1 April 1988
- journal article
- Published by American Geophysical Union (AGU) in Paleoceanography and Paleoclimatology
- Vol. 3 (2) , 169-189
- https://doi.org/10.1029/pa003i002p00169
Abstract
Gravity cores recovered from Manganese Nodule Project site H (6°33′N, 92°49′W) show marked downcore variations in the abundance of calcium carbonate, organic carbon, opal, manganese, and other components deposited over the past 400,000 years. Variations in the downcore abundance of organic carbon, which ranges from 0.2 to 1.0%, can be used to hindcast redox conditions in the surface sediments over this time. The results indicate that the depth to the manganese redox boundary varied from about 5 to 25 cm below the seafloor during four major cycles. Downcore variations in solid phase Mn, Ni, and Cu can be produced by such changes in redox conditions. A model which predicts that solid phase Mn can be trapped and buried when the Mn redox boundary migrates rapidly upward is consistent with the observed organic carbon and Mn records and supports the reconstructed redox variations. The history of redox variations at site H can be explained by changes with time in surface water productivity. Major productivity variations at the site occur over 100‐kyr cycles, with relatively higher productivity occurring during glacial stages. Thus Quaternary climate changes influence surface water productivity, redox conditions in sediments, and the cycling of transition metals.Keywords
This publication has 66 references indexed in Scilit:
- The record of Late Pleistocene biogenic sedimentation in the eastern tropical Pacific OceanPaleoceanography and Paleoclimatology, 1988
- A 420,000‐year record of cyclicity in oceanic and atmospheric processes from the eastern equatorial PacificPaleoceanography and Paleoclimatology, 1986
- Flux comparisons between sediments and sediment traps in the eastern tropical Pacific: Implications for atmospheric C02 variations during the Pleistocene1Limnology and Oceanography, 1985
- Transport and release of transition elements during early diagenesis: Sequential leaching of sediments from MANOP Sites M and H. Part I. pH 5 acetic acid leachGeochimica et Cosmochimica Acta, 1984
- Glacial–Holocene transition in deep-sea sediments: manganese-spike in the east-eqautorial PacificNature, 1983
- Late Quaternary history of atmospheric and oceanic circulation in the eastern equatorial PacificMarine Micropaleontology, 1982
- Radiolarian assemblage distributions and paleoceanography of the eastern equatorial pacific ocean during the last 127 000 yearsPalaeogeography, Palaeoclimatology, Palaeoecology, 1981
- A detailed study of some uranium series nuclides at an abyssal hill area near the east Pacific Rise at 8°45′NEarth and Planetary Science Letters, 1980
- The reconstruction of sea surface temperatures in the Pacific Ocean of 18,000 B.P.Marine Micropaleontology, 1980
- Controls on the Preservation of Biogenic Opal in Sediments of the Eastern Tropical PacificScience, 1976