A reference time scale for Site U1385 (Shackleton Site) on the SW Iberian Margin

Hodell, D. and Lourens, L. and Crowhurst, S. and Konijnendijk, T. and Tjallingii, R. and Jiménez-Espejod, F. and Skinner, L. and Tzedakis, P. C. and Abrantes, Fatima and Acton, Gary D. and Alvarez Zarikian, Carlos A. and Bahr, André and Balestra, Barbara and Barranco, Estefanìa Llave and Carrara, Gabriela and Ducassou, Emmanuelle and Flood, Roger D. and Flores, José-Abel and Furota, Satoshi and Grimalt, Joan and Grunert, Patrick and Hernández-Molina, Javier and Kim, Jin Kyoung and Krissek, Lawrence A. and Kuroda, Junichiro and Li, Baohua and Lofi, Johanna and Margari, Vasiliki and Martrat, Belen and Miller, Madeline D. and Nanayama, Futoshi and Nishida, Naohisa and Richter, Carl and Rodrigues, Teresa and Rodríguez-Tovar, Francisco J. and Roque, Ana Cristina Freixo and Sanchez Goñi, Maria F. and Sierro Sánchez, Francisco J. and Singh, Arun D. and Sloss, Craig R. and Stow, Dorrik A. V. and Takashimizu, Yasuhiro and Tzanova, Alexandrina and Voelker, Antje and Xuan, Chuang and Williams, Trevor (2015) A reference time scale for Site U1385 (Shackleton Site) on the SW Iberian Margin. Global and Planetary Change, 133. pp. 49-64. ISSN 0921-8181 DOI https://doi.org/10.1016/j.gloplacha.2015.07.002

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Variations in sediment color contain very strong precession signals at Site U1385, and the amplitude modulation of these cycles provides a powerful tool for developing an orbitally-tuned age model. We tuned the U1385 record by correlating peaks in L* to the local summer insolation maxima at 37°N. The benthic δ18O record of Site U1385, when placed on the tuned age model, generally agrees with other time scales within their respective chronologic uncertainties. The age model is transferred to down-core data to produce a continuous time series of log(Ca/Ti) that reflect relative changes of biogenic carbonate and detrital sediment. Biogenic carbonate increases during interglacial and interstadial climate states and decreases during glacial and stadial periods. Much of the variance in the log(Ca/Ti) is explained by a linear combination of orbital frequencies (precession, tilt and eccentricity), whereas the residual signal reflects suborbital climate variability. The strong correlation between suborbital log(Ca/Ti) variability and Greenland temperature over the last glacial cycle at Site U1385 suggests that this signal can be used as a proxy for millennial-scale climate variability over the past 1.5 Ma. Millennial climate variability, as expressed by log(Ca/Ti) at Site U1385, was a persistent feature of glacial climates over the past 1.5 Ma, including glacial periods of the early Pleistocene (‘41-kyr world’) when boundary conditions differed significantly from those of the late Pleistocene (‘100-kyr world’). Suborbital variability was suppressed during interglacial stages and enhanced during glacial periods, especially when benthic δ18O surpassed ~ 3.3–3.5‰. Each glacial inception was marked by appearance of strong millennial variability and each deglaciation was preceded by a terminal stadial event. Suborbital variability may be a symptomatic feature of glacial climate or, alternatively, may play a more active role in the inception and/or termination of glacial cycles.

Item Type: Article
Uncontrolled Keywords: 2015AREP;IA70;
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
07 - Gold Open Access
Journal or Publication Title: Global and Planetary Change
Volume: 133
Page Range: pp. 49-64
Identification Number: https://doi.org/10.1016/j.gloplacha.2015.07.002
Depositing User: Sarah Humbert
Date Deposited: 28 Apr 2016 12:09
Last Modified: 01 May 2016 01:35
URI: http://eprints.esc.cam.ac.uk/id/eprint/3643

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