Global cooling accelerated by early late Eocene impacts?

Online Access: Get full text
doi: 10.1130/0091-7613(2000)28<687:GCABEL>2.0.CO;2
Author(s): Vonhof, Hubert B.; Smit, Jan; Brinkhuis, Henk; Montanari, Alessandro; Nederbragt, Alexandra J.
Author Affiliation(s): Primary:
Free University, Faculty of Earth Sciences, Amsterdam, Netherlands
Utrecht University, Netherlands
Osservatorio Geologico di Coldigioco, Italy
University College London, United Kingdom
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 28(8), p.687-690. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. With GSA Data Repository Item 200077. 33 refs.; illus.
Summary: At Ocean Drilling Program Site 689 (Maud Rise, Southern Ocean), δ18O records of fine-fraction bulk carbonate and benthic foraminifers indicate that accelerated climate cooling took place following at least two closely spaced early late Eocene extraterrestrial impact events. A simultaneous surface-water productivity increase, as interpreted from δ13C data, is explained by enhanced water-column mixing due to increased latitudinal temperature gradients. These isotope data appear to be in concert with organic-walled dinoflagellate-cyst records across the same microkrystite-bearing impact-ejecta layer in the mid-latitude Massignano section (central Italy). In particular, the strong abundance increase of Thalassiphora pelagica is interpreted to indicate cooling or increased productivity at Massignano. Because impact-induced cooling processes are active on time scales of a few years at most, the estimated 100 k.y. duration of the cooling event appears to be too long to be explained by impact scenarios alone. This implies that a feedback mechanism, such as a global albedo increase due to extended snow and ice cover, may have sustained impact-induced cooling for a longer time after the impacts.
Year of Publication: 2000
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Antarctic Ocean; Benthic taxa; Cenozoic; Clastic sediments; Climate effects; Cooling; Correlation; Dinoflagellata; Eocene; Europe; Foraminifera; Global change; Impacts; Invertebrata; Isotope ratios; Isotopes; Italy; Leg 113; Marches Italy; Marine environment; Marine sediments; Massignano Italy; Maud Rise; Microfossils; Nannofossils; O-18/O-16; ODP Site 689; Ocean Drilling Program; Ooze; Oxygen; Paleoclimatology; Paleoecology; Paleogene; Palynomorphs; Plantae; Productivity; Protista; Rates; Sediments; Southern Europe; Southern Ocean; Stable isotopes; Tertiary; Thalassiphora pelagica; Upper Eocene; Weddell Sea
Coordinates: N433213 N433213 E0133536 E0133536
S643101 S643100 E0030600 E0030559
Record ID: 2000056043
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States