Distribution of Chicxulub ejecta at the Cretaceous-Tertiary boundary

Abstract

The mineralogical, sedimentological, and geochemical information in a large database on the Cretaceous-Tertiary (K-T) boundary is used to document the distribution of impact debris derived from the Chicxulub crater. The database is coupled with a geographic information system (GIS) allowing the plotting of the information on a latest Cretaceous paleogeographic map. The database will be available in part on the internet in the near future, and contains data from 345 K-T boundary sites worldwide. However, relatively few sites are known in South America, Australia, Africa, and in the high latitudes. Major disturbances of sedimentation, such as massive debris flows, failure of platform margins, or significant erosion of Upper Cretaceous layers, occur throughout the Gulf of Mexico. Mass wasting of material also took place in the western and eastern parts of the Atlantic Ocean. Almost 100 K-T boundary sites analyzed for Ir recorded the positive anomaly; Ir is spread homogeneously throughout the world, but is diluted at proximal sites because of the high volume of sediment that was in suspension in the Gulf of Mexico after the impact. Shocked quartz is more common, and maybe larger in size west of the crater. The main advantage of the database is to provide a convenient method to manage the huge amount of data available in the literature, and to reveal patterns or characteristics of the data. The database can help refine the variables used in mathematical models and documents the origin, transport, and deposition of ejecta during a cratering event.

Rapid short-term cooling following the Chicxulub impact at the Cretaceous–Paleogene boundary

“…Some of these estimates do not include the time it takes for particles to sink from the sea surface to the seafloor, which significantly prolongs the settling time for the very fine fraction to which the impact-derived PGEs are believed to be associated (14,31). Moreover, the proposed extraordinary large storms during the initial impact winter phase might have temporarily resuspended material, both in the atmosphere and in the ocean, further delaying the deposition of PGE-bearing impact dust.…”

“…In the months to decades following the impact, the atmosphere probably stabilized, and dust began to rain down and accumulate in depositional settings. This included asteroid-derived trace elements, globally recognized as a peak in platinum group element (PGE; including iridium) concentrations in complete marine and terrestrial successions (14). Crucially, fossil evidence for this impact winter scenario is still missing because this period of reduced solar radiation may only have lasted several months to decades (8,10,15,16), generally too short to be captured in the ancient sedimentary record.…”

Triggering of the largest Deccan eruptions by the Chicxulub impact

“…In most cases, it would be very diffi cult to determine whether ordinary volcanoes were triggered right at Cretaceous-Paleogene time, since their eruption repeat intervals are typically fairly short. Also, the occurrence of well-studied Cretaceous-Paleogene boundary sections in nontectonic sedimentary sections is rare (Claeys et al, 2002), so it would be diffi cult to discern normal-size eruptions occurring at exactly Cretaceous-Paleogene time. Nevertheless, pursuing this question is clearly worthwhile, perhaps particularly in regard to the possibility of global eruptions along the mid-ocean-ridge system, which might generate some signal in ocean trace-element or isotope chemistry.…”

Paleoenvironmental changes across the Cretaceous/Tertiary boundary at Flaxbourne River and Woodside Creek, eastern Marlborough, New Zealand

“…While none of these explanations can be ruled out, the suggestion that a megatsunami may have removed the marl from shallower sections, such as Woodside Creek and the Clarence valley sections (Hollis et al 2003a), warrants further consideration. Probable proximal tsunami deposits have been identified in the Gulf of Mexico (Claeys et al 2002), and it is conceivable that the distal effects of a Pacific-crossing tsunami would be preserved in New Zealand.…”

“…Discovery of fullerenes in both Woodside and Flaxbourne boundary clays (Heymann et al 1994(Heymann et al , 1996 was further evidence for extensive wildfires. Given that Marlborough was nearly antipodal to the likely impact site in northern Yucatan, Mexico (Hildebrand et al 1991;Claeys et al 2002), these discoveries demonstrated the global nature of the asteroid's impact signature and primary effects. Despite lower Ir enrichment in the Flaxbourne River section compared to Woodside Creek-21 and 54-100 ng/g, respectively (Strong et al 1987; Gilmour & Anders 1989)- the Flaxbourne section is considered to be more complete (Strong 2000).…”