Middle to late Miocene stepwise climate cooling: Evidence from a high-resolution deep water isotope curve spanning 8 million years.

Holbourn, Ann, Kuhnt, Wolfgang, Clemens, S., Prell, W. and Andersen, Nils (2013) Middle to late Miocene stepwise climate cooling: Evidence from a high-resolution deep water isotope curve spanning 8 million years. Paleoceanography, 28 (4). pp. 688-699. DOI 10.1002/2013pa002538.

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[1] We present high‐resolution (2–3 kyr) benthic foraminiferal stable isotopes in a continuous, well‐preserved sedimentary archive from the West Pacific Ocean (Ocean Drilling Program Site 1146), which track climate evolution in unprecedented resolution over the period 12.9 to 8.4 Ma. We developed an astronomically tuned chronology over this interval and integrated our new records with published isotope data from the same location to reconstruct long‐term climate and ocean circulation development between 16.4 and 8.4 Ma. This extended perspective reveals that the long eccentricity (400 kyr) cycle is prominently encoded in the δ13C signal over most of the record, reflecting long‐term fluctuations in the carbon cycle. The δ18O signal closely follows variations in short eccentricity (100 kyr) and obliquity (41 kyr). In particular, the obliquity cycle is prominent from ~14.6 to 14.1 Ma and from ~9.8 to 9.2 Ma, when high‐amplitude variability in obliquity is congruent with low‐amplitude variability in short eccentricity. The δ18O curve is additionally characterized by a series of incremental steps at ~14.6, 13.9, 13.1, 10.6, 9.9, and 9.0 Ma, which we attribute to progressive deep water cooling and/or glaciation episodes following the end of the Miocene climatic optimum. On the basis of δ18O amplitudes, we find that climate variability decreased substantially after ~13 Ma, except for a remarkable warming episode at ~10.8–10.7 Ma at peak insolation during eccentricity maxima (100 and 400 kyr). This transient warming, associated with a massive negative carbon isotope shift, is reminiscent of intense global warming events at eccentricity maxima during the Miocene climatic optimum.

Document Type: Article
Additional Information: Times Cited: 0 Holbourn, Ann Kuhnt, Wolfgang Clemens, Steven Prell, Warren Andersen, Nils
Keywords: benthic stable isotopes middle to late Miocene Pacific Ocean global climate cooling Miocene climatic optimum astronomical forcing
Research affiliation: Kiel University > Kiel Marine Science
OceanRep > The Future Ocean - Cluster of Excellence
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/2013pa002538
ISSN: 0883-8305
Projects: Future Ocean
Date Deposited: 08 Jul 2014 09:24
Last Modified: 22 Jul 2019 13:51
URI: http://oceanrep.geomar.de/id/eprint/25004

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