A complete high‐resolution Paleocene benthic stable isotope record for the central Pacific (ODP Site 1209)

Abstract

We have compiled the first stratigraphically continuous high‐resolution benthic foraminiferal stable isotope record for the Paleocene from a single site utilizing cores recovered at Pacific ODP Site 1209. The long‐term trend in the benthic isotope record suggests a close coupling of volcanic CO2 input and deep‐sea warming. Over the short‐term the record is characterized by slow excursions with a pronounced periodic beat related to the short (100 kyr) and long (405 kyr) eccentricity cycle. The phase relationship between the benthic isotope record and eccentricity is similar to patterns documented for the Oligocene and Miocene confirming the role of orbital forcing as the pace maker for paleoclimatic variability on Milankovitch time scales. In addition, the record documents an unusual transient warming of 2°C coeval with a 0.6‰ carbon isotope excursion and a decrease in carbonate content at 61.75 Ma. This event, which bears some resemblance to Eocene hyperthermals, marks the onset of a long‐term decline in δ13C. The timing indicates it might be related to the initiation of volcanism along Greenland margin.

Mass extinction of lizards and snakes at the Cretaceous–Paleogene boundary

“…However, diversity does not approach Cretaceous levels until the early Eocene, 10 My later, when diversity rapidly increases (Fig. 3B) with the onset of late Paleocene-early Eocene global warming (49). Thus, lizards recovered more slowly than mammals, which rebounded to Maastrichtian diversity levels within 1.5 My of the K-T extinction (44), and exceeded Cretaceous diversity within 5 My of the extinction (45) as they radiated to occupy niches left open by dinosaurs.…”

The 405 kyr and 2.4 Myr eccentricity components in Cenozoic carbon isotope records

“…C to the 405 kyr eccentricity cycle is ∼190 kyr, which is much higher than the 40 to 60 kyr during the Paleocene (Westerhold et al, 2011) and 20 to 30 kyr during the Oligocene (Pälike et al, 2006).…”

“…The question remains if this shifting of spectral power to lower frequencies also affects the much longer 2.4 Myr eccentricity cycle, for which indications have been found in geological records for the Eocene (Lourens et al, 2005), Paleocene (Westerhold et al, 2011), Oligocene (Pälike et al, 2006;Valero et al, 2014), and Miocene (Holbourn et al, 2007;Liebrand et al, 2016). The 2.4 Myr 20 cycle is present in the astronomical solution as both an amplitude modulator (AM) of the 124 and 95 kyr eccentricity cycles as well as a true eccentricity cycle and is caused by orbit-orbit resonance between Mars and Earth (g 4 − g 3 ) (Laskar et al, 2011).…”

“…Particularly distinctive is the imprint of the 405 kyr eccentricity term (Westerhold et al, 2011) on climate and the carbon cycle, under both ice-free (Paleocene-Eocene, Westerhold et al 2011;Lauretano et al 2015) and glaciated (Oligocene-Miocene, Pälike et al 2006;Holbourn et al 2015) climate regimes within the Cenozoic (Fig. 1).…”

“…Darker lines going through the records represent 20-point moving averages while darker lines at arbitrary heights represent the 405 kyr filtered records (at 2.47 ± 0.15 Myr −1 ). The Westerhold et al (2011) record was converted to the GTS2012 (Gradstein et al, 2012) time scale by converting magnetic chron ages and placing the PETM onset at 56.0 Ma.…”