The Heartbeat of the Oligocene Climate System

Abstract

A 13-million-year continuous record of Oligocene climate from the equatorial Pacific reveals a pronounced “heartbeat” in the global carbon cycle and periodicity of glaciations. This heartbeat consists of 405,000-, 127,000-, and 96,000-year eccentricity cycles and 1.2-million-year obliquity cycles in periodically recurring glacial and carbon cycle events. That climate system response to intricate orbital variations suggests a fundamental interaction of the carbon cycle, solar forcing, and glacial events. Box modeling shows that the interaction of the carbon cycle and solar forcing modulates deep ocean acidity as well as the production and burial of global biomass. The pronounced 405,000-year eccentricity cycle is amplified by the long residence time of carbon in the oceans.

Late Oligocene obliquity-paced contourite sedimentation in the Wilkes Land margin of East Antarctica: implications for paleoceanographic and ice sheet configurations

“…Superimposed on the above long-term swings in the δ 18 O Oligocene record, fluctuations on timescales shorter than several 120 Myr were identified in the high-resolution record from ODP 1218 (Pälike et al, 2006). These fluctuations in periods of 405 kyr and 1.2 Myr are related to Earth's orbital variations in eccentricity and obliquity, respectively and have been referred as the short-term "heartbeat" of the Oligocene climate (Pälike et al, 2006). Oligocene records close to Antarctica are needed to better resolve Antarctic ice sheet and paleoceanographic configurations and variations at different timescales and 125 under scenarios of increasing atmospheric CO 2 values and δ 18 O records, which imply a climatic warming and/or ice volume loss.…”

“…Based on the study of the isotopic record in sediments from the Atlantic, the Indian and the equatorial Pacific, Pekar et al (2006) explained the conundrum of a glaciated Antarctica, and varying intrabasinal δ 18 O values with the coeval existence of two deep-water masses, one sourced from Antarctica and another, warmer bottom-water, sourced from lower latitudes. Superimposed on the above long-term swings in the δ 18 O Oligocene record, fluctuations on timescales shorter than several 120 Myr were identified in the high-resolution record from ODP 1218 (Pälike et al, 2006). These fluctuations in periods of 405 kyr and 1.2 Myr are related to Earth's orbital variations in eccentricity and obliquity, respectively and have been referred as the short-term "heartbeat" of the Oligocene climate (Pälike et al, 2006).…”

“…Nevertheless, there are marked differences between the late Oligocene low δ 18 O values recorded in 110 Pacific, Indian and Atlantic Ocean sites (e.g., Pälike et al, 2006;Cramer et al, 2009;Liebrand et al, 2011;Mudelsee et al, 2014;Hauptvogel et al, 2017), and the sustained high δ 18 O values recorded in Southern Ocean sites (Pekar et al, 2006;Mudelsee et al, 2014). High δ 18 O values in the Southern Ocean sediments are in agreement with the ice proximal record recovered by the Cape Roberts Project (CRP) in the Ross Sea, which show the existence of glaciers/ice sheets at sea level (Barrett et al, 2007; 115 Hauptvogel et al, 2017).…”

“…An interglacial mechanism has been proposed whereby the southward expansion of westerly winds and associated Ekman transport is compensated for by enhanced upwelling of warmer, CO 2 -rich CDW (Toggweiler et al, 2008), which also promotes atmospheric warming. In the equatorial Pacific, Pälike et al (2006) …”

The Cretaceous-Paleogene boundary and its 405-kyr eccentricity cycle phase: a new constraint on radiometric dating and astrochronology

“…In this case climatic variations influence the transfer of the detrital argillaceous fraction, coming from the platform top or the adjacent continental areas, and the carbonate sedimentation, which is constituted by benthic, pelagic, or winnowed platform top material. It was already shown that the lithological variations, induced by the variations of the Earth's orbit parameters in the MILANKOVITCH band (periods from 20 to 400 kyr; BERGER, 1978aBERGER, , 1978bLASKAR, 1988;BERGER & LOUTRE, 1991;LASKAR et al, 2004LASKAR et al, , 2011 were appropriate to establish a very precise time scale (e.g., HERBERT & D'HONDT, 1990;ten KATE & SPRENGER, 1993;HILGEN et al, 1993HILGEN et al, , 1999HOU-SE & GALE, 1995;HERBERT, 1999;SHACKLETON et al, 1999;CLEMENS, 1999;HINNOV, 2000HINNOV, , 2005PÄLIKE et al, 2001;GALEOTTI et al, 2003;HENNE-BERT & DUPUIS, 2003;DINARÈS-TURELL et al, 2003;LOURENS et al, 2005aLOURENS et al, , 2005bFIET et al, 2006;PÄLIKE et al, 2006;SPROVIERI et al, 2006;HINNOV & OGG, 2007;WESTERHOLD et al, 2007WESTERHOLD et al, , 2008HENNEBERT et al, 2009;HENNEBERT, 2012).…”