CHICXULUB IMPACT AND MASS EXTINCTION

Deposition and age of Chicxulub impact spherules on Gorgonilla Island, Colombia

TitleDeposition and age of Chicxulub impact spherules on Gorgonilla Island, Colombia
Publication TypeJournal Article
Year of Publication2019
AuthorsMateo, P, Keller, G, Adatte, T, Bitchong, AM, Spangenberg, JE, Vennemann, T, Hollis, CJ
JournalGSA Bulletin
Volume132
Pagination215–232
Date Published06/2019
Abstract

The end-Cretaceous mass extinction (66 Ma) has long been associated with the Chicxulub impact on the Yucatan Peninsula. However, consensus on the age of this impact has remained controversial because of differing interpretations on the stratigraphic position of Chicxulub impact spherules relative to the mass extinction horizon. One side argues that the impact occurred precisely at the Cretaceous-Paleogene boundary, thus coinciding with the mass extinction; the other side argues that the impact predated the Cretaceous-Paleogene boundary, based on the discovery of primary impact spherules deposits in NE Mexico and Texas near the base of planktic foraminiferal zone CF1, dated at 170 k.y. before the Cretaceous-Paleogene boundary. A recent study of the most pristine Chicxulub impact spherules discovered on Gorgonilla Island, Colombia, suggested that they represent a primary impact deposit with an absolute age indistinguishable from the Cretaceous-Paleogene boundary. Here, we report on the Gorgonilla section with the main objective of evaluating the nature of deposition and age of the spherule-rich layer relative to the Cretaceous-Paleogene boundary.

The Gorgonilla section consists of light gray-yellow calcareous siliceous mudstones (pelagic deposits) alternating with dark olive-brown litharenites (turbidites). A 3-cm-thick dark olive-green spherule-rich layer overlies an erosional surface separating Maastrichtian and Danian sediments. This layer consists of a clast-supported, normally graded litharenite, with abundant Chicxulub impact glass spherules, lithics (mostly volcanic), and Maastrichtian as well as Danian microfossils, which transitions to a calcareous mudstone as particle size decreases. Mineralogical analysis shows that this layer is dominated by phyllosilicates, similar to the litharenites (turbidites) that characterize the section. Based on these results, the spherule-rich layer is interpreted as a reworked early Danian deposit associated with turbiditic currents. A major hiatus (>250 k.y.) spanning the Cretaceous-Paleogene boundary and the earliest Danian is recorded at the base of the spherule-rich layer, based on planktic foraminiferal and radiolarian biostratigraphy and carbon stable isotopes. Erosion across the Cretaceous-Paleogene boundary has been recorded worldwide and is generally attributed to rapid climate changes, enhanced bottom-water circulation during global cooling, sea-level fluctuations, and/or intensified tectonic activity. Chicxulub impact spherules are commonly reworked and redeposited into younger sediments overlying a Cretaceous-Paleogene boundary hiatus of variable extent in the Caribbean, Central America, and North Atlantic, while primary deposits are rare and only known from NE Mexico and Texas. Because of their reworked nature, Gorgonilla spherules provide no stratigraphic evidence from which the timing of the impact can be inferred.  PDF

URLhttps://doi.org/10.1130/b35287.1
DOI10.1130/b35287.1

Comments on "Post-impact event bed (tsunamite) at the Cretaceous-Palaeogene boundary deposited on a distal carbonate platform interior"

TitleComments on "Post-impact event bed (tsunamite) at the Cretaceous-Palaeogene boundary deposited on a distal carbonate platform interior"
Publication TypeJournal Article
Year of Publication2017
AuthorsFont, E, Keller, G, Sanders, D, Adatte, T
JournalTerra Nova
Volume29
Pagination329–331
Date Published08/2018
Abstract

Korbar, McDonald, Fućek, Fuček, and Posilović (2017) report a tsunamite, triggered by the Chicxulub impact on Yucatan, from the Likva Cove carbonate platform of the Island of Brač, Croatia, which is similar to that in an earlier report from the nearby Island of Hvar (Korbar et al., 2015). If true, such deposits in the Adriatic Sea would be truly anomalous given that no tsunamites are identified in well-preserved Cretaceous–Palaeogene (K–Pg) sections from the Basque-Cantabric Basin (Bidart, Zumaia, Hendaye and Sopelana sections), which are located more proximal and towards the hypothetical tsunami wave propagation front. We strongly question the authors’ criteria for identifying the presumed “tsunamite” as well as the K–Pg boundary (KPB) age attributed to these deposits based on planktic foraminifera.  PDF

URLhttps://doi.org/10.1111/ter.12282
DOI10.1111/ter.12282

Mass wasting and hiatuses during the Cretaceous-Tertiary transition in the North Atlantic: Relationship to the Chicxulub impact?

TitleMass wasting and hiatuses during the Cretaceous-Tertiary transition in the North Atlantic: Relationship to the Chicxulub impact?
Publication TypeJournal Article
Year of Publication2016
AuthorsMateo, P, Keller, G, Adatte, T, Spangenberg, JE
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume441
Pagination96–115
Date Published01/2018
Abstract

Deep-sea sections in the North Atlantic are claimed to contain the most complete sedimentary records and ultimate proof that the Chicxulub impact is Cretaceous-Tertiary boundary (KTB) in age and caused the mass extinction. A multi-disciplinary study of North Atlantic DSDP Sites 384, 386 and 398, based on high-resolution planktonic foraminiferal biostratigraphy, carbon and oxygen stable isotopes, clay and whole-rock mineralogy and granulometry reveals the age, stratigraphic completeness and nature of sedimentary disturbances. Results show a major hiatus across the KTB at Site 384 with Zones CF1, P0 and P1a missing, spanning at least ~ 540 ky, similar to other North Atlantic and Caribbean localities associated with tectonic activity and Gulf Stream erosion. At Sites 386 and 398, discrete intervals of disturbed sediments with mm-to-cm-thick spherule layers have previously been interpreted as the result of impact-generated earthquakes at the KTB destabilizing continental margins prior to settling of impact spherules. However, improved age control based on planktonic foraminifera indicates spherule deposition in the early Danian Zone P1a(2) (upper Parvularugoglobigerina eugubina Zone) more than 100 ky after the KTB. At Site 386, two intervals of white chalk contain very small (< 63 μm) early Danian Zone P1a(2) assemblages (65%) and common reworked Cretaceous (35%) species. In contrast, the in situ red-brown and green abyssal clays of this core are devoid of carbonate. In addition, high calcite, mica and kaolinite and upward-fining are observed in the chalks, indicating downslope transport from shallow waters and sediment winnowing via distal turbidites. At Site 398, convoluted red to tan sediments with early Danian and reworked Cretaceous species represent slumping of shallow water sediments as suggested by dominance of mica and low smectite compared to in situ deposition. We conclude that mass wasting was likely the result of earthquakes associated with increased tectonic activity in the Caribbean and the Iberian Peninsula during the early Danian well after the Chicxulub impact.  PDF

URLhttps://doi.org/10.1016/j.palaeo.2015.01.019
DOI10.1016/j.palaeo.2015.01.019

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

TitleThe Cretaceous-Palaeogene boundary at Gorgonilla Island, Colombia, South America
Publication TypeJournal Article
Year of Publication2016
AuthorsBermúdez, HD, García, J, Stinnesbeck, W, Keller, G, Rodríguez, JVicente, Hanel, M, Hopp, J, Schwarz, WH, Trieloff, M, Bolívar, L, Vega, FJ
JournalTerra Nova
Volume28
Pagination83–90
Date Published01/2016
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. PDF

URLhttp://onlinelibrary.wiley.com/doi/10.1111/ter.12196/abstract
DOI10.1111/ter.12196

Deccan volcanism, the Chicxulub impact, and the end-Cretaceous mass extinction: Coincidence? Cause and effect?

TitleDeccan volcanism, the Chicxulub impact, and the end-Cretaceous mass extinction: Coincidence? Cause and effect?
Publication TypeBook Chapter
Year of Publication2014
AuthorsKeller, G
Book TitleVolcanism, Impacts, and Mass Extinctions: Causes and Effects
Volume505
EditionGSA Special Papers
PaginationPp. 29-55
PublisherGeological Society of America
CityBoulder
Abstract

The recent discovery of the direct link between Deccan volcanism and the end-Cretaceous mass extinction also links volcanism to the late Maastrichtian rapid global warming, high environmental stress, and the delayed recovery in the early Danian. In comparison, three decades of research on the Chicxulub impact have failed to account for long-term climatic and environmental changes or prove a coincidence with the mass extinction. A review of Deccan volcanism and the best age estimate for the Chicxulub impact provides a new perspective on the causes for the end­Cretaceous mass extinction and supports an integrated Deccan-Chicxulub scenario. This scenario takes into consideration climate warming and cooling, sea-level changes, erosion, weathering, ocean acidification, high-stress environments with opportunistic species blooms, the mass extinction, and delayed postextinction recovery.The crisis began in C29r (upper CF2 to lower CF1) with rapid global warming of 4 °C in the oceans and 8 °C on land, commonly attributed to Deccan phase 2 eruptions. The Chicxulub impact occurred during this warm event (about 100–150 k.y. before the mass extinction) based on the stratigraphically oldest impact spherule layer in NE Mexico, Texas, and Yucatan crater core Yaxcopoil-1. It likely exacerbated climate warming and may have intensified Deccan eruptions. The reworked spherule layers at the base of the sandstone complex in NE Mexico and Texas were deposited in the upper half of CF1,  50–80 k.y. before the Cretaceous-Tertiary (K-T) boundary. This sandstone complex, commonly interpreted as impact tsunami deposits of K-T boundary age, was deposited during climate cooling, low sea level, and intensified currents, leading to erosion of nearshore areas (including Chicxulub impact spherules), transport, and redeposition via submarine channels into deeper waters. Renewed climate warming during the last  50 k.y. of the Maastrichtian correlates with at least four rapid, massive volcanic eruptions known as the longest lava flows on Earth that ended with the mass extinction, probably due to runaway effects. The kill mechanism was likely ocean acidification resulting in the carbonate crisis commonly considered to be the primary cause for four of the five Phanerozoic mass extinctions.  PDF

URLhttp://specialpapers.gsapubs.org/content/early/2014/06/10/2014.2505_03.1.abstract
DOI10.1130/2014.2505(03)

Chicxulub impact spherules in the North Atlantic and Caribbean: age constraints and Cretaceous–Tertiary boundary hiatus

TitleChicxulub impact spherules in the North Atlantic and Caribbean: age constraints and Cretaceous–Tertiary boundary hiatus
Publication TypeJournal Article
Year of Publication2013
AuthorsKeller, G, Khozyem, H, Adatte, T, Malarkodi, N, Spangenberg, J, Stinnesbeck, W
JournalGeological Magazine
Volume150
Issue05
Pagination885 - 907
Date Published01/2013
ISSN0016-7568
KeywordsChicxulub, impact spherules, KTB unconformity, North Atlantic
Abstract

The Chicxulub impact is commonly believed to have caused the Cretaceous-Tertiary boundary (KTB) mass extinction and a thin impact spherule layer in the North Atlantic and Caribbean is frequently cited as proof. We evaluated this claim in the seven best North Atlantic and Caribbean KTB sequences based on high-resolution biostratigraphy, quantitative faunal analyses and stable isotopes. Results reveal a major KTB unconformity spans most of Danian subzone P1a(1) and Maastrichtian zones CF1-CF2 (~400 kyr) in the NW Atlantic Bass River core, ODP Sites 1049A, 1049C and 1050C. In the Caribbean ODP Sites 999B and 1001B the unconformity spans from the early Danian zone P1a(1) through zones CF1-CF4  (~3 myr). Only in the Demerara Rise ODP Site 1259B is erosion relatively minor and restricted to the earliest Danian zone P0 and most of subzone P1a(1) (~150 kyr). In all sites examined Chicxulub impact spherules are apparently reworked into the early Danian subzone P1a(1) about 150-200 kyr after the mass extinction. A similar pattern of erosion and redeposition of impact spherules in Danian sediments has previously been documented from Cuba, Haiti, Belize, Guatemala, south and central Mexico. This pattern can be explained by intensified Gulf stream circulation at times of climate cooling and sea level changes. The age of the Chicxulub impact cannot be determined from these reworked impact spherule layers, but can be evaluated based on the stratigraphically oldest spherule layer in NE Mexico and Texas, which indicates this impact predates the KTB by about 130-150 kyr.  PDF

URLhttp://www.journals.cambridge.org/abstract_S0016756812001069
DOI10.1017/S0016756812001069
Short TitleGeol. Mag.

The Cretaceous-Tertiary boundary (KTB) transition in NE Brazil

TitleThe Cretaceous-Tertiary boundary (KTB) transition in NE Brazil
Publication TypeJournal Article
Year of Publication2013
AuthorsGertsch, B, Keller, G, Adatte, T, Berner, Z
JournalJournal of the Geological Society
Volume170
Issue2
Pagination249 - 262
Date Published01/2013
ISSN0016-7649
Abstract

The Cretaceous-Tertiary boundary (KTB) transition of the Poty Quarry near Recife, NE Brazil, is the most distant locality (7800 km from Yucatan) with reported Chicxulub impact-tsunami deposits, impact spherules and Ir anomaly. Investigations based on sedimentology, biostratigraphy, mineralogy, stable isotopes and elemental geochemistry failed to confirm these reports. The KTB is at an unconformity marked by erosion and bioturbation. Latest Maastrichtian planktic foraminiferal zones CF1 below the unconformity and early Danian zone P1a(1) above indicates a short hiatus with the KTB clay (zone P0), Ir anomaly and characteristic negative d13C excursion missing. Above the unconformity is an upward-fining micro-conglomerate with abundant reworked Cretaceous foraminifera, sub-angular phosphate clasts, calcitic and phosphatic spheroids along with an early Danian zone P1a(1) assemblage.

This deposit has previously been interpreted as impact-tsunami with impact spherules. However, the spheroids are common throughout the late Campanian-Maastrichtian and appear to be chamber infillings of the benthic foraminifer Dentalina alternata. The unconformity coincides with the latest Maastrichtian sea level fall, which is widely recognized globally. The upward fining micro-conglomerate is likely a gravity-flow deposit associated with the early Danian sea level rise. Two minor Ir anomalies (<0.7 ppb) in thin clay layers of zone Pla are unrelated to the Chicxulub impact. Although there is no evidence of the Chicxulub impact in the Poty Quarry, this section remains a very important distant example of the complex global environmental and sea level changes, including gravity flows, observed in KT sequences from North America through Mexico, Central America and the Caribbean and commonly misinterpreted as impact tsunami event.  PDF

URLhttp://jgs.geoscienceworld.org/cgi/doi/10.1144/jgs2012-029
DOI10.1144/jgs2012-029
Short TitleJournal of the Geological Society

Volcanism, impacts and mass extinctions (Long Version)

TitleVolcanism, impacts and mass extinctions (Long Version)
Publication TypeWeb Article
Year of Publication2012
AuthorsKeller, G, Armstrong, H, Courtillot, V, Harper, D, Joachimski, M, Kerr, A, MacLeod, N, Napier, W, Palfy, J, Wignall, P
Access Year2012
Access DateNovember
PublisherThe Geological Society
CityLondon
Type of MediumOnline version
Keywordsclimate change, Impacts, Mass extinctions, ocean anoxia, Phanerozoic, Volcanism
Abstract

The nature and causes of mass extinctions in the geological past have remained topics of intense scientific debate for the past three decades.  Central to this debate is the question of whether one or several large bolide impacts, the eruption of large igneous provinces (LIPS), or a combination of the two were the primary mechanism(s) driving the environmental and habitat changes that are universally regarded as the proximate causes for four of the five major extinction events.  Recent years have seen a revolution in our understanding of both the interplanetary environment and LIPS eruptions and their environmental effects such that the current impact-kill scenario no longer seems adequate for the KT (KPg) or any other mass extinction.  Massive sequential volcanic eruptions and the breakup of giant comets leading to rapid climate change, ocean anoxia and ozone destruction emerge as the leading causes in major mass extinctions.  PDF

URLhttp://www.geolsoc.org.uk/Geoscientist/Archive/November-2012/Volcanism-impacts-and-mass-extinctions-2
Alternate TitleVolcanism, impacts and mass extinctions (long version)

Biostratigraphy, Age of Chicxulub Impact, and Depositional Environment of the Brazos River KTB Sequences

TitleBiostratigraphy, Age of Chicxulub Impact, and Depositional Environment of the Brazos River KTB Sequences
Publication TypeBook Chapter
Year of Publication2011
AuthorsKeller, G, Abramovich, T, Adatte, T, Berner, Z
Book TitleThe End-Cretaceous Mass Extinction and the Chicxulub Impact in Texas
VolumeNo. 100
EditionSEPM, Special Publication
Pagination81-122
PublisherSEPM (Society for Sedimentary Geology)
CityTulsa
ISBN978-1-56576-308-1
KeywordsBiostratigraphy, Brazos, Chicxulub impact, Cretaceous-Tertiary, d13C shift, Evolution, Ir anomaly, mass extinction, Sandstone complex, Sea level, Texas
Abstract

Integrated biostratigraphy, sedimentology and stable isotopes of 11 outcrops and wells along the Brazos River of Falls County, Texas, U.S.A., reveal the stratigraphic separation and sequential depositional history of the Chicxulub impact, followed by the sandstone complex and associated sea-level fall, which in turn was followed by the Cretaceous-Tertiary boundary (KTB). The KTB was identified up to 1 m above the sandstone complex based on three global standard criteria: the mass extinction in planktic foraminifera, the evolution of first Danian species and the negative d13C shift. No Ir anomaly is associated with the KTB or the Chicxulub impact-ejecta layers. Late Maastrichtian sediment deposition occurred in a middle-shelf environment that shallowed to inner-shelf depth at the time of deposition of the sandstone complex. At this time, Brazos sections show distinct shallowing from inner neritic in the north to subtidal and lagoonal at Cottonmouth Creek, with further shallowing to intertidal swamp or marsh conditions in the Darting Minnow Creek area to the south. The sandstone complex is the most prominent feature of the Brazos sections. At the base of this unit are reworked Chicxulub impact spherules and lithified clasts with impact spherules and mud cracks that bear witness to erosion of an older primary spherule deposit. This primary Chicxulub impact-ejecta layer was discovered between 45 and 60 cm below the sandstone complex in a (3 cm thick) impact-glass layer that is diagenetically altered to yellow clay. The sandstone complex, the reworked impact spherules, the spherule-rich clasts, and the yellow clay layer all clearly predate the KTB. PDF

Nature of the KTB Controversy

TitleNature of the KTB Controversy
Publication TypeBook Chapter
Year of Publication2011
AuthorsKeller, G, Adatte, T
Book TitleThe End-Cretaceous Mass Extinction and the Chicxulub Impact in Texas
VolumeNo. 100
EditionSEPM, Special Publication
ISBN978-1-56576-308-1
Abstract

One of the liveliest debates among scientists concerns potential causes of catastrophic extinction events, but none have garnered the imagination of scientists and public alike as the Cretaceous–Tertiary boundary (KTB) mass extinction including the demise of the dinosaurs 65 million years ago. Over three decades ago the discovery of anomalous concentrations of iridium in a thin clay layer between Cretaceous limestones and Tertiary claystones led Alvarez and collaborators to propose that a large meteorite crashed into Earth and caused the KTB mass extinction (Alvarez et al., 1980). Because iridium is rare on Earth’s surface, relatively common deep in Earth’s interior where it can surface via volcanic eruptions, but most abundant in some meteorites, this hypothesis rapidly gained support. With the discovery of the 175 km diameter Chicxulub impact crater on Yucata´n in 1991 (Hildebrand et al., 1991), followed by discoveries of impact glass spherule ejecta throughout the Caribbean, Central America, and North America in stratigraphic proximity of the KTB mass extinction (Izett et al., l99l; Swisher et al., l992; Smit et al., 1992) there seemed little doubt that the smoking gun had been found in the Chicxulub impact crater and that the impact-kill hypothesis was all but proven. For many scientists, the impact-kill hypothesis became a Eureka moment—a beautiful theory that could be expanded with many corollaries to account for virtually all observations. It was reconfirmed by 41 scientists in a recent Science article (Schulte et al., 2010) and expressed well by Birger Schmitz (2011) in his review of Ted Nield’s new book Incoming—Or why we should stop worrying and learn to love the meteorite. Nield (2011) writes a riveting account on meteorites that begins with fascinating historical facts, heresy, and beliefs through the ages before leading into the scientific geological account of the meteorite theory and an objective treatment of the controversy based on evidence inconsistent with this theory. There is nothing worse than destroying a beautiful theory with facts. Schmitz takes issue with Nield’s suggestion that doubters like Gerta Keller and her small team may have a point—the impact harmed nature, but the mass extinction had more varied causes. Schmitz considers this a compromise that belongs in politics, not in science. He goes on to state that he started his career in the 1980s as a non-believer of the impact theory, but has now seen the KTB clay layer in over 50 localities ‘‘where the iridium enriched layer always occurs exactly at the level at which the microscopic foraminifera typical of Cretaceous oceans disappear almost completely . . . The precise coincidence of these two events is so compelling that it is difficult to understand how anyone can doubt the direct relationship between them’’ (Schmitz, 2011).  PDF

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