The response of marine carbonate chemistry to rapid carbon injection during the Paleocene-Eocene Thermal Maximum

Online Access: Get full text
Author(s): Penman, Donald E.
Source: 160p. Institution: University of California at Santa Cruz, Santa Cruz, CA, United States
Note: In English. 300 refs. Doctoral dissertation
Summary: This dissertation reconstructs the response of marine carbonate chemistry to rapid carbon injection during the Paleocene-Eocene Thermal Maximum (PETM). Chapter 1 uses boron-based proxies to reconstruct ocean acidification during the PETM for the first time, concluding that surface seawater pH declined by ∼0.3 units at the onset of the event, and remained acidified for at least 70 thousand years before recovering in step with temperature and the carbon isotopic signature of the PETM. Chapter 2 describes a new sedimentary record of the PETM from the deep North Atlantic which provides the first evidence for a hypothesized "overshoot" of carbonate saturation in the aftermath of the PETM in response to long-term weathering feedbacks on climate. Stable isotope records from that section demonstrate that this overshoot occurred during the recovery of the PETM, ∼70 thousand years after its onset, which provides novel constraints on the evolution of the carbonate compensation depth over the event. Finally, Chapter 3 uses these new (and previous) records to constrain carbon cycle model simulations of the PETM. Consistent runs require both a large initial release as well as a protracted release over tens of thousands of years (possibly representing a slow positive feedback to warming) and the removal of isotopically light carbon to accelerate the PETM recovery, likely representing organic carbon burial. No consistent scenarios feature under-saturated conditions in the surface ocean during the PETM, consistent with the lack of calcifier extinctions during the event. Comparison of the most consistent PETM scenarios with forecasts of anthropogenic carbon emissions demonstrate that carbonate chemistry change during the PETM was less severe and far more gradual than what might be expected in coming centuries.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Acidification; Atlantic Ocean; B-11/B-10; Boron; C-13/C-12; Calcification; Carbon; Carbon cycle; Carbon sequestration; Carbonate compensation depth; Carbonates; Cenozoic; Depositional environment; Expedition 342; Foraminifera; Geochemical cycle; Geochemistry; IODP Site U1403; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Leg 198; Lithofacies; Marine environment; Microfossils; North Atlantic; North Pacific; Northwest Pacific; ODP Site 1209; Ocean Drilling Program; Pacific Ocean; Paleocene-Eocene Thermal Maximum; Paleoecology; Paleoenvironment; Paleogene; Protista; Reconstruction; Shatsky Rise; Silicates; Stable isotopes; Technology; Tertiary; Weathering; West Pacific
Coordinates: N395636 N395636 W0514811 W0514812
N323900 N324000 E1583100 E1583000
Record ID: 2016058554
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.