Volcanic origin for Younger Dryas geochemical anomalies ca. 12,900 cal B.P

N Sun; A D Brandon; S L Forman; M R Waters; K S Befus

doi:10.1126/sciadv.aax8587

Volcanic origin for Younger Dryas geochemical anomalies ca. 12,900 cal B.P

Sci Adv. 2020 Jul 31;6(31):eaax8587. doi: 10.1126/sciadv.aax8587. eCollection 2020 Jul.

Authors

N Sun¹, A D Brandon¹, S L Forman², M R Waters³, K S Befus²

Affiliations

¹ Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77004, USA.
² Department of Geosciences, Baylor University, Waco, TX 76798, USA.
³ Center for the Study of the First Americans, Department of Anthropology, Texas A&M University, College Station, TX 77843, USA.

Abstract

The Younger Dryas (YD) abrupt cooling event ca. 12.9 ± 0.1 ka is associated with substantial meltwater input into the North Atlantic Ocean, reversing deglacial warming. One controversial and prevailing hypothesis is that a bolide impact or airburst is responsible for these environmental changes. Here, highly siderophile element (HSE; Os, Ir, Ru, Pt, Pd, and Re) abundances and ¹⁸⁷Os/¹⁸⁸Os ratios were obtained in a well-dated sediment section at Hall's Cave, TX, USA to test this hypothesis. In Hall's Cave, layers below, above, and in the YD have ¹⁸⁷Os/¹⁸⁸Os ratios consistent with incorporation of extraterrestrial or mantle-derived material. The HSE abundances indicate that these layers contain volcanic gas aerosols and not extraterrestrial materials. The most likely explanation is that episodic, distant volcanic emissions were deposited in Hall's Cave sediments. Coupled ¹⁸⁷Os/¹⁸⁸Os ratios and HSE concentration data at close stratigraphic intervals are required to effectively differentiate between bolide and volcanic origins.

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