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Cometary airbursts and atmospheric chemistry; Tunguska and a candidate Younger Dryas event

Adrian L. Melott, Brian C. Thomas, Gisela Dreschhoff and Carey K. Johnson
Cometary airbursts and atmospheric chemistry; Tunguska and a candidate Younger Dryas event
Geology (Boulder) (April 2010) 38 (4): 355-358

Abstract

We find agreement between models of atmospheric chemistry changes from ionization for the A.D. 1908 Tunguska (Siberia region, Russia) airburst event and nitrate enhancement in Greenland Ice Sheet Project 2 (GISP2H and GISP2) ice cores, plus an unexplained ammonium spike. We then consider a candidate cometary impact at the Younger Dryas onset (YD). The large estimated NO (sub x) production and O (sub 3) depletion are beyond accurate extrapolation, but the ice core peak is much lower, possibly because of insufficient sampling resolution. Ammonium and nitrate spikes in both Greenland Ice Core Project (GRIP) and GISP2 ice cores have been attributed to biomass burning at the onset of the YD. A similar result is well resolved in Tunguska ice core data, but that forest fire was far too small to account for this. Direct input of ammonia from a comet into the atmosphere is adequate for YD ice core data, but not for the Tunguska data. An analog of the Haber process with hydrogen contributed by cometary or surface water, atmospheric nitrogen, high pressures, and possibly catalytic iron from a comet could in principle produce ammonia, accounting for the peaks in both data sets.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 38
Serial Issue: 4
Title: Cometary airbursts and atmospheric chemistry; Tunguska and a candidate Younger Dryas event
Affiliation: University of Kansas, Department of Physics and Astronomy, Lawrence, KS, United States
Pages: 355-358
Published: 201004
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 35
Accession Number: 2010-039405
Categories: Quaternary geologyGeneral geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
N60°00'00" - N84°00'00", W70°00'00" - W20°00'00"
N37°00'00" - N83°00'00", W170°00'00" - E28°00'00"
N50°00'00" - N80°00'00", W170°00'00" - E60°00'00"
Secondary Affiliation: Washburn University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201022
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