The sedimentological signature of impact spherules and its relation to ejecta transport mechanisms during the Chicxulub asteroid impact (Cretaceous/Paleogene boundary)

Authors

Hermann D. Bermúdez, Montclair State UniversityFollow
Liliana Bolívar, Grupo de Investigación Paleoexplorer
José A. Arz, Universidad de Zaragoza
Ignacio Arenillas, Universidad de Zaragoza
Vicente Gilabert, Universidad de Zaragoza
Robert DePalma, The University of Manchester
George Phillips, Mississippi Museum Natural Science
Daniela Bermúdez, IE Universidad
Maurizia De Palma, Montclair State University
Clemencia Gómez, Universidad Nacional de Colombia
Ying Cui, Montclair State UniversityFollow

Document Type

Preprint

Publication Date

2-15-2025

Journal / Book Title

Journal of South American Earth Sciences

Abstract

The Chicxulub impact is the most likely cause of the Cretaceous/Paleogene boundary (KPB) mass extinction and the only impact event in Earth's history with a globally traceable ejecta bed. Although the impact spherules are thought to represent molten or vaporized material, precise genesis and transport mechanisms remain underconstrained. Here, we show that the morphology, size, internal structure, and distribution of the spherules within the KPB deposits are related to origin and transport processes. The study of thousands of spherules from KPB deposits in Colombia, the USA, and Spain has revealed the presence of three fractions related to three different distribution processes, each with a distinctive sedimentological signature. The coarser fraction (“aspergo deposit,” from the Latin aspergo, meaning splash) comprises rotational and agglutinated/irregular forms (size > 2 mm) containing abundant vesicles, unmelted inclusions, and schlieren, implying an origin from molten materials and transport following ballistic trajectories. The intermediate fraction (“pyrocloud deposit” from the Greek pyr, meaning fire) represents a mixture of molten and condensed droplets, including spheres, rotational, and agglutinated/irregular forms (size 0.3–2 mm), transported by the rapid expansion of a fast-moving, high-temperature turbulent cloud. The globally distributed finer fraction (“fireball layer”) is composed exclusively of spheres (size < 0.3 mm) condensed from a vapor plume after the Chicxulub impact. These observations provide valuable insights into ejecta distributions during massive asteroid impacts and enhance our understanding of the Chicxulub impact and its aftermath.

Comments

This accepted manuscript is being shared under a green open access license in accordance with publisher guidelines.

DOI

10.2139/ssrn.5022424

Journal ISSN / Book ISBN

85213845362 (Scopus)

MSU Digital Commons Citation

Bermúdez, Hermann D.; Bolívar, Liliana; Arz, José A.; Arenillas, Ignacio; Gilabert, Vicente; DePalma, Robert; Phillips, George; Bermúdez, Daniela; De Palma, Maurizia; Gómez, Clemencia; and Cui, Ying, "The sedimentological signature of impact spherules and its relation to ejecta transport mechanisms during the Chicxulub asteroid impact (Cretaceous/Paleogene boundary)" (2025). Department of Earth and Environmental Studies Faculty Scholarship and Creative Works. 734.
https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/734

Published Citation

Bermudez, H. D., Bolívar, L., Arz, J. A., Arenillas, I., Gilabert, V., DePalma, R., ... & Cui, Y. (2025). The sedimentological signature of impact spherules and its relation to ejecta transport mechanisms during the Chicxulub asteroid impact (Cretaceous/Paleogene boundary). Journal of South American Earth Sciences, 153, 105338.