The Cretaceous–Palaeogene boundary at Gorgonilla Island, Colombia, South America

Abstract

The discovery of a new Cretaceous/Palaeogene (K/Pg) bathyal marine sequence on Gorgonilla Island, SW Colombia, extends the presence of Chicxulub impact spherule deposits to the Pacific region of northern South America and to the Eastern Pacific Ocean. The Gorgonilla spherule layer is approximately 20 mm thick and consists of extraordinarily well-preserved glass spherules up to 1.1 mm in diameter. About 70-90% of the spherules are vitrified, and their chemical composition is consistent with Haiti (Beloc) impact glass spherules. Normal size-grading, delicate spherule textures, welded melt components and an absence of bioturbation or traction transport suggest that the Gorgonilla spherule layer represents an almost undisturbed settling deposit.Additional Supporting Information may be found in the online version of this article:Appendix S1. Spherule geochemistry.Appendix S2. Stratigraphy of Gorgonilla section.Appendix S3. Spherule geochemistry tables.90

Multi-proxy record of the Chicxulub impact at the Cretaceous-Paleogene boundary from Gorgonilla Island, Colombia

“…As with the Haitian tektites, the Ca/K values (derived from 37 Ar/ 39 Ar data) of Gorgonilla samples display a large range both between and within individual tektites. This is consistent with the observations of Bermúdez et al (2016) from Gorgonilla, and of several electron probe microanalysis (EPMA) studies (Izett et al, 1991;Sigurdsson et al, 1991) of Haitian tektites, showing that individual tektites commonly contain mixtures of compositionally distinct glasses. Comparing plateau ages with integrated plateau values of Ca/K shows no correlation, verifying that the spherules of diverse composition were cogenetic, and that the Cainterference corrections (for reactor-produced 36 Ar and 39 Ar) are accurate.…”

“…1) overlies mafic and ultramafic basement rocks that form part of the Caribbean plateau, generated by the present Galapagos hotspot in the mid Cretaceous (Kennan and Pindell, 2009). It was located at 2000-3000 km southwest of the Chicxulub crater and represents a bathyal depth deposit (Bermúdez et al, 2016). Exposed near the southern tip of Gorgonilla Island, the section comprises ~40 m of interbedded tuffaceous sandstones and marls, with an ~20-mm-thick bed of normal-size-graded spherules occurring in mid-section ( Fig.…”

“…Although intense work has sought to identify Chicxulub impact ejecta on the South American continent (e.g., Gertsch et al, 2013, and references therein), the first tektite deposit connected to this impact was described by Bermúdez et al (2016), who concluded that the spherule-bearing layer at Gorgonilla Island, Colombia, could have been deposited at any time within 200 ka of the KPB, which would permissibly support the persistent contention that the Chicxulub impact preceded the KPB by >100 ka (Stinnesbeck et al, 2001;Keller et al, 2007, and references therein). Here we present new micropaleontological data (planktic foraminifera and palynomorphs) and geochronological data ( 40 Ar/ 39 Ar) showing that the Gorgonilla spherule bed was synchronous with the KPB to within ~10 ka or less.…”

Discovery of Cosmic Spherules from the Mesoproterozoic Strata and its Significance—in Case of the Ming Tombs Area, Beijing

“…Lowe et al reported the largest impact glass spherule beds of the Archean Barberton Greenstone Belt in South Africa (Lowe et al, 2003(Lowe et al, , 2014Hofmann et al, 2006). The reports show important evidence of the occurrence of glass spherules, which may be impact-related in the K-Pg boundary deposits of Denerara Rise, Western Atlantic (Schulte et al, 2009) and Gorgonilla Island, Colombia, South America (Bermúdez et al, 2015). Spheres of transparent brown glass on the surface of the Chelyabinsk meteorite were observed (Galimov et al, 2013).…”

Global bioevents and the Cretaceous/Paleogene boundary in Texas and Alabama: Stratigraphy, correlation and ocean acidification

“…Rise) within about one hour of the impact (Alvarez et al, 1995;MacLeod et al, 2007). In almost all shallower-water successions where spherules are recorded (e.g., New Jersey (Olsson et al, 1997), Colombia (Bermúdez et al, 2016) Rise records an in-situ, graded bed that may have taken approximately one month to accumulate (allowing for the time to settle through the water column). Belcher (2009) indicates that the heat provided by the spherules to the surface was <325°C, lasting only for a very short period of time.…”