High latitude hydrological changes during the Eocene Thermal Maximum 2

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doi: 10.1016/j.epsl.2014.07.029
Author(s): Krishnan, Srinath; Pagani, Mark; Huber, Matthew; Sluijs, Appy
Author Affiliation(s): Primary:
Yale University, Department of Geology and Geophysics, New Haven, CT, United States
Other:
University of New Hampshire, United States
Utrecht University, Netherlands
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, Vol.404, p.167-177. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 117 refs.; illus.
Summary: The Eocene hyperthermals, including the Paleocene-Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM2), represent extreme global warming events ∼56 and 54 million years ago associated with rapid increases in atmospheric greenhouse gas concentrations. An initial study on PETM characteristics in the Arctic region argued for intensification of the hydrological cycle and a substantial increase in poleward moisture transport during global warming based on compound-specific carbon and hydrogen isotopic (2H/1H) records from sedimentary leaf-wax lipids. In this study, we apply this isotopic and hydrological approach on sediments deposited during ETM2 from the Lomonosov Ridge (Integrated Ocean Drilling Program Expedition 302). Our results show similar 2H/1H changes during ETM2 as during the PETM, with a period of 2H-enrichment (∼20 ppm) relative to "pre-event" values just prior to the negative carbon isotope shift (CIE) that is often taken as the onset of the hyperthermal, and more negative lipid δ 2H values (∼-15ppm) during peak warming. Notably, lipid 2H-enrichment at the base of the event is coeval with colder TEXH85 temperatures. If 2H/1H values of leaf waxes primarily reflect the hydrogen isotopic composition of precipitation, the observed local relationship between temperature and 2H/1H values for the body of ETM2 is precisely the opposite of what would be predicted using a simple Rayleigh isotope distillation model, assuming a meridional vapor trajectory and a reduction in equator-pole temperature gradients. Overall, a negative correlation exists between the average chain length of n-alkanes and 2H/1H suggesting that local changes in ecology could have impacted the hydrogen isotopic compositions of leaf waxes. The negative correlation falls across three separate intervals - the base of the event, the initial CIE, and during the H2 hyperthermal (of which the assignment is not fully certain). Three possible mechanisms potentially explain 2H-enriched signals at the base of the event, including (1) intense local drying and cooling leading to evaporative 2H-enrichment; (2) changes in frequency/intensity of storm events and its impact on high latitude amount effects; and (3) changes in low-latitude temperatures. Evidence for hydrological shifts at the base of both hyperthermals suggests that hydrological change or the factors promoting hydrological change played a role in triggering the release of greenhouse gases. Generation of similar high-resolution isotopic- and temperature records at other latitudes is crucial for understanding the causal links between temperature and hydrological changes and may help constrain the source and mechanism of carbon release that triggered the early Eocene hyperthermals. Abstract Copyright (2014) Elsevier, B.V.
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Aliphatic hydrocarbons; Alkanes; Arctic Coring EXpedition; Arctic Ocean; Biomarkers; C-13/C-12; Carbon; Cenozoic; D/H; Eocene; Eocene Thermal Maximum 2; Evaporation; Evapotranspiration; Expedition 302; Global change; Global warming; Greenhouse gases; Hydrocarbons; Hydrogen; Hydrologic cycle; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; Latitude; Leaves; Lomonosov Ridge; Mass spectra; N-alkanes; Organic compounds; Paleogene; Paleohydrology; Spectra; Stable isotopes; Storms; Tertiary; Waxes
Coordinates: N875100 N875600 E1393300 E1361000
Record ID: 2014094278
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands