Uncorking the bottle; what triggered the Paleocene/Eocene thermal maximum methane release?

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doi: 10.1029/2000PA000615
Author(s): Katz, Miriam E.; Cramer, Benjamin S.; Mountain, Gregory S.; Katz, Samuel; Miller, Kenneth G.
Author Affiliation(s): Primary:
Rutgers University, Department of Geological Sciences, Piscataway, NJ, United States
Columbia University, United States
Rensselaer Polytechnic Institute, United States
Volume Title: Paleoceanography
Source: Paleoceanography, 16(6), p.549-562. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. Includes appendix. 85 refs.; illus., incl. sects., 1 table, sketch map
Summary: The Paleocene/Eocene thermal maximum (PETM) was a time of rapid global warming in both marine and continental realms that has been attributed to a massive methane (CH4) release from marine gas hydrate reservoirs. Previously proposed mechanisms for this methane release rely on a change in deepwater source region(s) to increase water temperatures rapidly enough to trigger the massive thermal dissociation of gas hydrate reservoirs beneath the seafloor. To establish constraints on thermal dissociation, we model heat flow through the sediment column and show the effect of the temperature change on the gas hydrate stability zone through time. In addition, we provide seismic evidence tied to borehole data for methane release along portions of the U.S. continental slope; the release sites are proximal to a buried Mesozoic reef front. Our model results, release site locations, published isotopic records, and ocean circulation models neither confirm nor refute thermal dissociation as the trigger for the PETM methane release. In the absence of definitive evidence to confirm thermal dissociation, we investigate an alternative hypothesis in which continental slope failure resulted in a catastrophic methane release. Seismic and isotopic evidence indicates that Antarctic source deepwater circulation and seafloor erosion caused slope retreat along the western margins of the North Atlantic in the late Paleocene. Continued erosion or seismic activity along the oversteepened continental margin may have allowed methane to escape from gas reservoirs trapped between the frozen hydrate-bearing sediments and the underlying buried Mesozoic reef front, precipitating the Paleocene/Eocene boundary methane release. An important implication of this scenario is that the methane release caused (rather than resulted from) the transient temperature increase of the PETM. Neither thermal dissociation nor mechanical disruption of sediments can be identified unequivocally as the triggering mechanism for methane release with existing data. Further documentation with high-resolution benthic foraminiferal isotopic records and with seismic profiles tied to borehole data is needed to clarify whether erosion, thermal dissociation, or a combination of these two was the triggering mechanism for the PETM methane release. Copyright 2001 by the American Geophysical Union.
Year of Publication: 2001
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Aliphatic hydrocarbons; Alkanes; Atlantic Ocean; Benthic taxa; Blake Nose; Blake Plateau; Cenozoic; Continental slope; DSDP Site 605; Deep Sea Drilling Project; Eocene; Faunal list; Foraminifera; Gas hydrates; Geophysical methods; Geophysical profiles; Geophysical surveys; Global change; Global warming; Heat flow; Hydrocarbons; IPOD; Invertebrata; Leg 171B; Leg 93; Marine environment; Marine sediments; Methane; Microfossils; Models; New Jersey; North Atlantic; North Carolina; ODP Site 1051; ODP Site 1052; Ocean Drilling Program; Organic compounds; Paleo-oceanography; Paleobathymetry; Paleocene; Paleocirculation; Paleoclimatology; Paleogene; Paleotemperature; Protista; Sediments; Seismic methods; Seismic profiles; Slope environment; Surveys; Tertiary; United States
Coordinates: N384431 N384432 W0723632 W0723634
N300311 N300311 W0762128 W0762128
N295705 N295705 W0763736 W0763736
Record ID: 2003041256
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