Back to Search
Start Over
Size-dependent isotopic composition of planktic foraminifers from Chukchi Sea vs. NW Atlantic sediments—implications for the Holocene paleoceanography of the western Arctic
- Source :
-
Quaternary Science Reviews . Feb2004, Vol. 23 Issue 3/4, p245. 16p. - Publication Year :
- 2004
-
Abstract
- In Arctic and sub Arctic seas, shell growth and/or secondary calcite overgrowth of Neogloboquadrina pachyderma (left coiled)—Npl—occur along the pycnocline, and their δ13C and δ18O-values are size and weight dependent. However, whereas the Npl 18O data from the NW Atlantic indicate near-equilibrium conditions with ambient waters and a positive relationship between shell weight and 18O-content, assemblages from box-cored sediments of the Chukchi Sea (western Arctic) are depleted by ∼2‰ with respect to equilibrium values with modern conditions, and depict a negative relationship between shell weight and its δ18O-value (−0.15±0.03‰/μg on VPDB scale). A similar feature is also depicted by the dextral form of N. pachyderma (Npd). We associate the reverse shell-size or weight vs. δ18O relationship to the reverse temperature gradient observed along the thermocline between the surface cold and dilute water layer, and the underlying near 3°C-warmer saline North Atlantic water mass. The analysis of two late to post-glacial sedimentary sequences from the Chukchi Sea indicates that such a water mass stratification with a reverse thermocline persisted throughout the Holocene, thus reflecting an early onset of the modern-like linkage between the Arctic Ocean and the North Atlantic. Moreover, lower δ18O-values in both Npl and Npd together with larger δ18O-gradients between the different shell sizes at ca 9–7 ka BP suggest ∼3°C higher temperatures in the upper North Atlantic water mass, in comparison with the present (approximately +1°C, at the study site), thus likely a higher inflow rate of this water mass during the early Holocene. [Copyright &y& Elsevier]
- Subjects :
- *PALEOCEANOGRAPHY
*FORAMINIFERA
*WATER masses
Subjects
Details
- Language :
- English
- ISSN :
- 02773791
- Volume :
- 23
- Issue :
- 3/4
- Database :
- Academic Search Index
- Journal :
- Quaternary Science Reviews
- Publication Type :
- Academic Journal
- Accession number :
- 12168760
- Full Text :
- https://doi.org/10.1016/j.quascirev.2003.08.006