Cosmic Airburst on Developing Allerød Substrates (Soils) in the Western Alps, Mt. Viso Area

• Autorzy: Mahaney W. C. , West A. , Milan A. , Krinsley D. H. , Somelar P. , Schwartz S. , Milner M. W. , Allen C. C. R.

Identyfikatory

DOI

10.2478/squa-2018-0001

• Języki publikacji: EN

Abstrakty

EN

Although much has been written about a cosmic impact event in the Western Alps of the Mt. Viso area, the event closely tied with the Younger Dryas Boundary (YDB) of 12.8 ka and onset of the Younger Dryas (YD), the affected land surface is considered to contain a similar black mat suite of sediment found on three continents. While work elsewhere has focused on recovered sediment from lake and ice cores, buried lacustrine/alluvial records, and surface glacial and paraglacial records, no one has traced a mountain morphosequence of deposits with the objective of investigating initial weathering/soil morphogenesis that occurred in ice recessional deposits up to the YDB when the surface was subjected to intense heat, presumably, as hypothesized by Mahaney et al. (2016a) from a cosmic airburst. With the land surface rapidly free of ice following glacial retreat during the Bølling-Allerød interstadial, weathering processes ~13.5 to 12.8 ka led to weathering and soil morphogenesis in a slow progression as the land surface became free of ice. To determine the exposed land character in the mid- to late-Allerød, it is possible to utilize an inverted stratigraphic soil morphogenesis working backward in time, from known post-Little Ice Age (LIA) (i.e. time-zero) through LIA (~0.45 to ~0.10 ka), to at least the middle Neoglacial (~2 ka), to answer several questions. What were the likely soil profile states in existence at the end of the Allerød just prior to the cosmic impact/airburst (YDB)? Assuming these immature weathered regolith sections of the Late Allerød approximated the <1 ka old profiles seen today, and assuming the land surface was subjected to a hypothesized instant temperature burst from ambient to ~2200oC at ~12.8 ka, what would be the expected effect on the resident sediment? To test the mid-LG (YDB) to YD relationship we analyzed the paleosols in both suites of deposits – mid-LG to – to test that the airburst grains are restricted to Late Allerød paleosols and using relative-age-determination criteria, that the overlapping YD to mid-LG moraines are closely related in time. These are some of the questions about the black mat that we seek to answer with reference to sites in the upper Guil and Po rivers of the Mt. Viso area.

Słowa kluczowe

EN

Black Mat impact airburst; reconstructed soil at time of YDB; mid-LG-YD paleosol; sedimentary products of cosmic impact; glacial recession

• Wydawca: Institute of Geological Science Polish Academy of Science
• Czasopismo: Studia Quaternaria
• Rocznik: 2018
• Tom: Vol. 35, Nr 1
• Strony: 3--23
• Opis fizyczny: Bibliogr. 74 poz., tab., rys.

Twórcy

autor

Mahaney W. C.

• Quaternary Surveys, 26 Thornhill Ave., Thornhill, Ontario, Canada, L4J1J4
• Department of Geography, York University, 4700 Keele St., North York, Ontario, Canada, M3J1P3

autor

West A.

• Geo-Science Consulting, 830 S. Dewey Rd., Dewey, Arizona, U.S., 86327

autor

Milan A.

• Department of Geography, York University, 4700 Keele St., North York, Ontario, Canada, M3J1P3,

autor

Krinsley D. H.

• Department of Geological Sciences, University of Oregon, Eugene, Oregon, U.S. 97403-1272

autor

Somelar P.

• Department of Geology, Tartu University, Tartu, Estonia

autor

Schwartz S.

• Université Grenoble Alpes, ISTerre-UMR 5275, F-38041 Grenoble, France

autor

Milner M. W.

• MWM Consulting, 182 Gough Ave, Toronto, Ontario, Canada, M4K 3P1

autor

Allen C. C. R.

• Queens University Belfast, School of Biological Sciences, Belfast BT7 1NN, UK

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