Unveiling the nature of glassy impact spherules by analyzing pristine Chicxulub spherules from Gorgonilla Island
(2026) In Journal of South American Earth Sciences 169.- Abstract
The Chicxulub impact triggered a massive extinction event marked by the Cretaceous-Paleogene boundary (K-Pg ∼66Ma), ejecting vast amounts of dust, molten, and vaporized materials. While impact spherules are interpreted as products of impactor and target lithologies, their precise composition and distribution remain insufficiently constrained. Although previous studies restrict impactor contamination to the condensed spherules from the fireball layer and the K-Pg boundary clay, here we show asteroid contribution to the composition of large spherules from the base of the K-Pg bed. Despite those spherules displaying an apparent immiscible bimodal composition of yellow (Ca-rich) and black (Si-rich) glasses, novel nano-resolution analyses... (More)
The Chicxulub impact triggered a massive extinction event marked by the Cretaceous-Paleogene boundary (K-Pg ∼66Ma), ejecting vast amounts of dust, molten, and vaporized materials. While impact spherules are interpreted as products of impactor and target lithologies, their precise composition and distribution remain insufficiently constrained. Although previous studies restrict impactor contamination to the condensed spherules from the fireball layer and the K-Pg boundary clay, here we show asteroid contribution to the composition of large spherules from the base of the K-Pg bed. Despite those spherules displaying an apparent immiscible bimodal composition of yellow (Ca-rich) and black (Si-rich) glasses, novel nano-resolution analyses demonstrate enrichment of elements derived from the impactor. By analyzing pristine spherules from the normally-graded sequence of Gorgonilla Island K-Pg site, our results show the presence of metals and platinum group elements (PGEs) in glasses and vesicles within large molten spherules. Furthermore, needle-like and cubic-shaped nanostructures co-localizing Pt, Co, Ni, and Pb, and Cu, Os, and Zn, may represent the first evidence of quasicrystals (quasi-periodic solids, not found in terrestrial rocks, with symmetries forbidden for crystals) in Chicxulub-derived deposits. Those nanostructures challenge the definitions of microtektites and microkrystites, suggesting these classifications are misleading. We recommend abandoning such terminology, preserving the generic term "impact spherules," irrespective of composition, morphology, or size. Our findings contribute to refining the classification and interpretation of impact spherules, advancing our understanding of the processes underlying hypervelocity impacts. Moreover, these insights may hold relevance not only for terrestrial impacts but also for analogous extraterrestrial contexts.
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- author
- Bermúdez, Hermann D. ; Vajda, Vivi LU ; Sigfridsson Clauss, Kajsa G.V. LU ; Rundhaug, Courtney Jean ; Kenny, Gavin ; Bolívar, Liliana ; Bermúdez, Daniela and Cui, Ying
- organization
- publishing date
- 2026-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Chicxulub, Composition, Cretaceous-Paleogene boundary, Glassy impact spherules, Nanocrystals, Quasicrystals
- in
- Journal of South American Earth Sciences
- volume
- 169
- article number
- 105877
- publisher
- Elsevier
- external identifiers
-
- scopus:105024336202
- ISSN
- 0895-9811
- DOI
- 10.1016/j.jsames.2025.105877
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2025 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
- id
- fa19c672-9fef-436a-9e4a-5eb4d1acc8ea
- date added to LUP
- 2026-03-31 13:43:33
- date last changed
- 2026-03-31 13:44:28
@article{fa19c672-9fef-436a-9e4a-5eb4d1acc8ea,
abstract = {{<p>The Chicxulub impact triggered a massive extinction event marked by the Cretaceous-Paleogene boundary (K-Pg ∼66Ma), ejecting vast amounts of dust, molten, and vaporized materials. While impact spherules are interpreted as products of impactor and target lithologies, their precise composition and distribution remain insufficiently constrained. Although previous studies restrict impactor contamination to the condensed spherules from the fireball layer and the K-Pg boundary clay, here we show asteroid contribution to the composition of large spherules from the base of the K-Pg bed. Despite those spherules displaying an apparent immiscible bimodal composition of yellow (Ca-rich) and black (Si-rich) glasses, novel nano-resolution analyses demonstrate enrichment of elements derived from the impactor. By analyzing pristine spherules from the normally-graded sequence of Gorgonilla Island K-Pg site, our results show the presence of metals and platinum group elements (PGEs) in glasses and vesicles within large molten spherules. Furthermore, needle-like and cubic-shaped nanostructures co-localizing Pt, Co, Ni, and Pb, and Cu, Os, and Zn, may represent the first evidence of quasicrystals (quasi-periodic solids, not found in terrestrial rocks, with symmetries forbidden for crystals) in Chicxulub-derived deposits. Those nanostructures challenge the definitions of microtektites and microkrystites, suggesting these classifications are misleading. We recommend abandoning such terminology, preserving the generic term "impact spherules," irrespective of composition, morphology, or size. Our findings contribute to refining the classification and interpretation of impact spherules, advancing our understanding of the processes underlying hypervelocity impacts. Moreover, these insights may hold relevance not only for terrestrial impacts but also for analogous extraterrestrial contexts.</p>}},
author = {{Bermúdez, Hermann D. and Vajda, Vivi and Sigfridsson Clauss, Kajsa G.V. and Rundhaug, Courtney Jean and Kenny, Gavin and Bolívar, Liliana and Bermúdez, Daniela and Cui, Ying}},
issn = {{0895-9811}},
keywords = {{Chicxulub; Composition; Cretaceous-Paleogene boundary; Glassy impact spherules; Nanocrystals; Quasicrystals}},
language = {{eng}},
publisher = {{Elsevier}},
series = {{Journal of South American Earth Sciences}},
title = {{Unveiling the nature of glassy impact spherules by analyzing pristine Chicxulub spherules from Gorgonilla Island}},
url = {{http://dx.doi.org/10.1016/j.jsames.2025.105877}},
doi = {{10.1016/j.jsames.2025.105877}},
volume = {{169}},
year = {{2026}},
}