Linking millennial scale variability to orbital frequencies using a high resolution foraminiferal climate record spanning the Pleistocene
| Author(s) | Scheinwald, Andre | |
| Date Accessioned | 2013-09-30T12:05:40Z | |
| Date Available | 2013-09-30T12:05:40Z | |
| Publication Date | 2013 | |
| Abstract | I hypothesize that millennial-scale variability in the subtropical northwest Atlantic Ocean is a result of advective communication from the Equator of a nonlinear response to orbital scale insolation forcing. To test the hypothesis, I have reconstructed sea surface hydrography in the northwestern subtropical Atlantic (31̊40.461’N, 75̊25.127’W) using a high resolution Globigerinoides ruber senso lato ?18O record. The data from this study has been spliced with data from other regional publications to fill a gap in the ?18O record from Marine Isotope Stages (MIS) 6 through 8 (129 Ka – 267 Ka) in order to reproduce a continuous, high resolution, ?18O record spanning the Pleistocene. The spliced record allows for examination of high frequency, sub-orbital climate fluctuations throughout the Pleistocene. Work performed prior to this study determined that there is a shift in dominant precessional periodicities between 0-338 Ka (23 kyr) and 338-900 Ka (23 and 19 kyr). In order to determine whether changes in precession induces changes at the millennial scale, statistical analysis was performed on the spliced record using spectral power of two time periods from 0-338 Ka and 338-875 Ka. Inthe 0-338 Ka spectral analysis results indicated the presence of a half precessional signal at 12.5 kyr, close to the expected value of 11.5 kyr based on a 23 kyr periodicity. A higher frequency at 5.2 kyr was interpreted here to represent the quarter precession cycle (expected value of 5.8 kyr). Results from 338-875 Ka demonstrates two precessional peaks at 23.3 and 19.4 kyr but are missing significant half precessional signals. Signals at 5.9 and 5.3 kyr are interpreted as the quarter precession cycle of the expected 23 kyr precessional signal with a resulting 5.8 kyr periodicity while the 4.9 and 4.4 kyr signals represent the quarter precession cycle of an expected 19 kyr signal with a resulting 4.8 kyr signal. However, multiple iterations of the age model determine that these results are not robust as the applied tuning method and age model used change the position and power of the peaks. Periodicities from ~1.5-4 kyr are resolvable at Site 1059 due to high sedimentation rates. This study shows that the timing of these peaks is age model independent and thus likely the results of processes occurring at higher frequencies such as heterodynes of centennial scale solar variations. Results demonstrate that changes in precessional timing and the resultant half and quarter precession signals may be related, but can only be resolved if the age model is precise. | en_US |
| Advisor | Billups, Katharina | |
| Degree | M.S. | |
| Department | University of Delaware, Department of Marine Studies | |
| URL | http://udspace.udel.edu/handle/19716/12628 | |
| Publisher | University of Delaware | en_US |
| dc.subject.lcsh | Paleoclimatology -- North Atlantic Ocean -- Pleistocene. | |
| Title | Linking millennial scale variability to orbital frequencies using a high resolution foraminiferal climate record spanning the Pleistocene | en_US |
| Type | Thesis | en_US |