Neodymium isotopic variations in seawater
- Creators
- Piepgras, Donald J.
-
Wasserburg, G. J.
Abstract
New data for the direct measurement of the isotopic composition of neodymium in Atlantic Ocean seawater are compared with previous measurements of Pacific Ocean seawater and ferromanganese sediments from major ocean basins. Data for Atlantic seawater are in excellent agreement with Nd isotopic measurements made on Atlantic ferromanganese sediments and are distinctly different from the observed compositions of Pacific samples. These results clearly demonstrate the existence of distinctive differences in the isotopic composition of Nd in the waters of the major ocean basins and are characteristic of the ocean basin sampled. The average ε_(Nd)(0) values for the major oceans as determined by data from seawater and ferromanganese sediments are as follows: Atlantic Ocean,ε_(Nd)(0) ≅ −12 ± 2; Indian Ocean,ε_(Nd)(0) ≅ −8 ± 2; Pacific Ocean,ε_(Nd)(0) ≅ −3 ± 2. These values are considerably less than ε_(Nd)(0) value sources with oceanic mantle affinities indicating that the REE in the oceans are dominated by continental sources. The difference in the absolute abundance of ^(143)Nd between the Pacific and Atlantic Oceans corresponds to ∼106 atoms ^(143)Nd per gram of seawater. The correspondence between the ^(143)Nd/^(144)Nd in seawater and in the associated sediments suggests the possible application of this approach to paleo-oceanography. Distinctive differences in ε_(Nd)(0) values are observed in the Atlantic Ocean between deep-ocean water associated with North Atlantic Deep Water and near-surface water. This suggests that North Atlantic Deep Water may be relatively well mixed with respect to Nd isotopic composition whereas near-surface water may be quite heterogeneous, reflecting different sources for surface waters relative to deep water. This suggests that it may be possible to distinguish the sources of water masses within an ocean basin on the basis of Nd isotopic composition. The Nd isotopic variations in seawater are used to relate the residence time of Nd and mixing rates between the oceans.
Additional Information
© 1980 Elsevier Scientific Publishing Company. Received March 3, 1980. Revised version received June 13, 1980. We would like to thank William Schmitz of the Woods Hole Oceanographic Institution and Jim Price of the University of Rhode Island as well as the crew of the R/V "Oceanus" for providing us with the necessary ship time needed to collect the Atlantic water samples. John Corliss and Roberta Conard of Oregon State University provided valuable assistance in teaching us how to carry out the bulk chemical preparations of the samples. T .L. Ku of the University of Southern California provided us with the manganese nodule (MN 139) analyzed in this study. This work has benefited greatly from lengthy discussions with K. Turekian, who reviewed this manuscript. We also wish to thank C. Wunsch, B. Schaule, and C. Patterson for invaluable comments. The results of this study were first presented in 1979 at the annual meeting of the Geological Society of America, San Diego, California [40]. This research was supported in part by grants from NSF PHY 76-83685 and NASA NGL 05-002-188.Additional details
- Eprint ID
- 42085
- DOI
- 10.1016/0012-821X(80)90124-7
- Resolver ID
- CaltechAUTHORS:20131028-084240231
- PHY 76-83685
- NSF
- NGL 05-002-188
- NASA
- Created
-
2013-10-28Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Other Numbering System Name
- Lunatic Asylum Lab
- Other Numbering System Identifier
- 338