Recent developments in the analysis of the black mat layer and cosmic impact at 12.8 ka

Abstract

Recent analyses of sediment samples from “black mat” sites in outh merica and urope support previous interpretations of an impact event that reversed the Late Glacial demise of ice during the Bølling Allerød warming, resulting in a resurgence of ice termed the Younger Dryas (YD) cooling episode. The breakup or impact of a cosmic vehicle at the boundary coincides with the onset of a 1‐kyr long interval of glacial resurgence, one of the most studied events of the Late Pleistocene. New analytical databases reveal a corpus of data indicating that the cosmic impact was a real event, most possibly a cosmic airburst from Earth's encounter with the Taurid Complex comet or unknown asteroid, an event that led to cosmic fragments exploding interhemispherically over widely dispersed areas, including the northern ndes of enezuela and the Alps on the Italian/French frontier. While the databases in the two areas differ somewhat, the overall interpretation is that microtextural evidence in weathering rinds and in sands of associated paleosols and glaciofluvial deposits carry undeniable attributes of melted glassy carbon and e spherules, planar deformation features, shock‐melted and contorted quartz, occasional transition and platinum metals, and brecciated and impacted minerals of diverse lithologies. In concert with other black mat localities in the Western , the etherlands, coastal rance, yria, entral sia, eru, rgentina and exico, it appears that a widespread cosmic impact by an asteroid or comet is responsible for deposition of the black mat at the onset of the glacial event. Whether or not the impact caused a 1‐kyr interval of glacial climate depends upon whether or not the Earth had multiple centuries‐long episodic encounters with the Taurid Complex or asteroid remnants; impact‐related changes in microclimates sustained climatic forcing sufficient to maintain positive mass balances in the reformed ice; and/or inertia in the Atlantic thermohaline circulation system persisted for 1-kyr.

Key words:

• black mat impact
• Younger Dryas boundary
• SEM microtextures

Acknowledgements

This research was funded by the Garage Institute of Quaternary Surveys, Toronto. We are indebted to Gary Stowe and Jeremy Jernigan for assistance with the SEM/EDS analyses. We gratefully acknowledge support from the Petroleum Engineering Department, University of Oklahoma, Norman. We greatly appreciate critical reviews from the two anonymous reviewers.

Additional information

Notes on contributors

William C. Mahaney

William C. Mahaney, Quaternary Surveys, 26 Thornhill Ave., Thornhill, Ontario, Canada L4J 1J4 and Department of Geography, York University, North York, Ontario, Canada M3J 1P3

E‐mail: [email protected]

Leslie Keiser

Leslie Keiser, Department of Geological Sciences, University of Oklahoma, Norman, OK 73019‐1009, USA

E‐mail: [email protected]

David H. Krinsley

David H. Krinsley, Department of Geological Sciences, University of Oregon, Eugene, OR 97403‐1272, USA

E‐mail: [email protected]

Allen West

Allen West, GeoScience Consulting, Dewey, AZ 86327, USA

E‐mail: [email protected]

Randy Dirszowsky

Randy Dirszowsky, Department of Earth Science, Laurentian University, Sudbury, Ontario, Canada P3E 2C6

E‐mail: [email protected]

Chris C.r. Allen

Chris C.R. Allen, Department of Biological Sciences, Queen's University, Belfast, N. Ireland, UK.

E‐mail: [email protected]

Pedro Costa

Pedro Costa, Centro de Geologia, Faculdade de Ciências da Universidade de Lisboa, Edifício C6, Campo Grande, 1749‐016 Lisboa, Portugal, and Department of Geography, School of the Environment, University of Dundee, Nethergate, Dundee DD1 4HN, UK

E‐mail: [email protected]