Large-Amplitude Variations in Carbon Cycling and Terrestrial Weathering during the Latest Paleocene and Earliest Eocene: The Record at Mead Stream, New Zealand

Abstract

A B S T R A C TThe late Paleocene to early Eocene was marked by major changes in Earth surface temperature and carbon cycling. This included at least two, and probably more, geologically brief (!200-k.yr.) intervals of extreme warming, the Paleocene-Eocene thermal maximum (PETM) and the Eocene thermal maximum-2 (ETM-2). The long-term rise in warmth and short-term "hyperthermal" events have been linked to massive injections of 13 C-depleted carbon into the ocean-atmosphere system and intense global climate change. However, the causes, environmental impact, and relationships remain uncertain because detailed and coupled proxy records do not extend across the entire interval of interest; we are still recognizing the exact character of the hyperthermals and developing models to explain their occurrence. Here we present lithologic and carbon isotope records for a 200-m-thick sequence of latest Paleoceneearliest Eocene upper slope limestone exposed along Mead Stream, New Zealand. New carbon isotope and lithologic analyses combined with previous work on this expanded section shows that the PETM and ETM-2, the suspected H-2, I-1, I-2, and K/X hyperthermals, and several other horizons are marked by pronounced negative carbon isotope excursions and clay-rich horizons. Generally, the late Paleocene-early Eocene lithologic and d 13 C records at Mead Stream are similar to records recovered from deep-sea sites, with an important exception: lows in d 13 C and carbonate content consistently span intervals of relatively high sedimentation (terrigenous dilution) rather than intervals of relatively low sedimentation (carbonate dissolution). These findings indicate that, over ∼6 m.yr., there was a series of short-term climate perturbations, each characterized by massive input of carbon and greater continental weathering. The suspected link involves global warming, elevated greenhouse-gas concentrations, and enhanced seasonal precipitation.

Frequency, magnitude and character of hyperthermal events at the onset of the Early Eocene Climatic Optimum

“…During the PETM global temper-V. Lauretano et al: Frequency, magnitude and character of hyperthermal events ature rose by 5-8 • C, and massive amounts of carbon were released as evidenced by a significant negative carbon isotope excursion (CIE) of > 3 ‰ in the ocean/atmosphere carbon pools, and widespread dissolution of seafloor carbonate (Kennett and Stott, 1991;Dickens et al, 1995;Thomas and Shackleton, 1996;Zachos et al, 2005Zachos et al, , 2008Sluijs et al, 2007;McInerney and Wing, 2011). A series of similar events are recorded in carbonate records from marine and continental deposits from the early Paleogene, as expressed by negative excursions in δ 13 C and δ 18 O often accompanied by dissolution horizons (e.g., Cramer et al, 2003;Lourens et al, 2005;Agnini et al, 2009;Galeotti et al, 2010;Stap et al, 2010;Zachos et al, 2010;Abels et al, 2012Abels et al, , 2015Slotnick et al, 2012;Kirtland Turner et al, 2014;Littler et al, 2014). Orbitally tuned records for this geological interval provide evidence that the early Eocene hyperthermal events were paced by variations in the Earth's orbit, specifically in the long-and short-eccentricity cycles.…”

“…html, modified). Also shown the locations of ODP Sites 690 and 1051 and DSDP Sites 550 and 577 (Cramer et al, 2003) and Mead Stream (Slotnick et al, 2012).…”

Astronomical calibration of the Ypresian timescale: implications for seafloor spreading rates and the chaotic behavior of the solar system?

“…The Ypresian stage, from 56.0 to 47.8 Ma, represents the first ∼ 8 million years of the Eocene epoch (Vandenberghe et al, 2012), an interval characterized by the warmest deep-sea temperatures of the Cenozoic era , multiple transient global warming events (Cramer et al, 2003;Lourens et al, 2005;Agnini et al, 2009;Galeotti et al, 2010;Leon-Rodriguez and Dickens 2010;Stap et al, 2010;Zachos et al, 2010;Sexton et al, 2011;Slotnick et al, 2012;Littler et al, 2014;Kirtland Turner et al, 2014;Lauretano et al, 2015Lauretano et al, , 2016, and major faunal turnovers (Thomas and Shackleton, 1996;Gingerich, 2003;Clyde et al, 2007). Climatic records from the Ypresian greenhouse are of special interest because they potentially capture the behavior of Earth's climate system under pCO 2 concentrations likely to be reached in the near future Meinshausen et al, 2011).…”

Stable isotope and calcareous nannofossil assemblage record of the late Paleocene and early Eocene (Cicogna section)

“…1) and bulk carbonate in numerous marine sediment sequences (Shackleton, 1986;Corfield, 1994;Cramer et al, 2003;Zachos et al, 2008Zachos et al, , 2010Westerhold et al, 2011;Slotnick et al, 2012). An overall increase in δ 13 C occurred through most of the Paleocene, which climaxed in a Cenozoic high at ca.…”