Thermal Radiation and Fires After Impacts of Cosmic Objects

Abstract

After impacts of cosmic bodies their kinetic energy transforms into heat. Materials of an impactor, target, and air are heated to high temperatures; therefore, it seems natural that impacts of cosmic objects are followed by fires. The traces of large fires were first searched for in the layers of sedimentary rocks that approach the periods of biotic mass extinctions in age. There is a widely known hypothesis of Alvarez et al. (1980) about mass extinctions at the Cretaceous-Tertiary (K/T) boundary after the impact of the cosmic object that created the Chicxulub crater. This impact hypothesis is confirmed by high concentrations of iridium and the presence of crater ejecta particles in the global clay layer of an appropriate age (65 million years). Significant amounts of reduced carbon, soot, and charcoal have been discovered in this layer as well; carbon and soot have been found at the K/T boundary over the whole Earth (Wolbach et al. 2003). This clearly points to global fires of that period, which probably caused global atmospheric darkening. Soot could have remained in the atmosphere for months after the impact (

Dating a small impact crater: An age of Kaali crater (Estonia) based on charcoal emplaced within proximal ejecta

“…The most probable scenario (mechanism 2) is that (1) the projectile entered the atmosphere and started to heat up (Artemieva and Shuvalov ); (2) shortly before hitting the ground, the radiative heat of the bolide ignited the trees (Svetsov ); (3) the air‐blast crashed and heated trees in vicinity of impact site; (4) the excavation process mixed heated wood and “colder” rocks into ejecta; (5) ignited wood continued to change into charcoal for a relatively short time within the ejecta blanket. This scenario would explain the intermixing of charred organic material of the similar 14 C age from Picea branches within ejecta, with most of the charcoal present within the till‐rich ejecta, and few larger fragments within dolomite‐rich ejecta.…”

“…B) TPQ (1530-1450 BC) for the Kaali impact based on the combined results of 11 samples (mean value: 3237 AE 10 14 C yr BP, v 2 test passed), excluding the samples Kaali 4.4a,4.4a*,4.4b,and 4.4b*. Calibration is based on IntCal13 atmospheric curve (Reimer et al 2013), plot is from OxCal v4.2.4 (Ramsey and Lee 2013). bolide ignited the trees (Svetsov 2008); (3) the air-blast crashed and heated trees in vicinity of impact site; (4) the excavation process mixed heated wood and "colder" rocks into ejecta; (5) ignited wood continued to change into charcoal for a relatively short time within the ejecta blanket. This scenario would explain the intermixing of charred organic material of the similar 14 C age from Picea branches within ejecta, with most of the charcoal present within the till-rich ejecta, and few larger fragments within dolomite-rich ejecta.…”

Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago. 2. Lake, Marine, and Terrestrial Sediments

“…One of those, the Tunguska airburst in 1908 over Siberia, created impact-related magnetic spherules, meltglass, nanodiamonds, and iridium, as discussed in Florenskiy (1965), Kirova and Zaslavskaya (1966), Firestone et al (2007), Bunch et al (2012), and Kinzie et al (2014). This airburst produced a high-pressure blast wave energetic enough to topple 80 million trees across ∼2000 km 2 (Florenskiy 1965;Svetsov 2008).…”

“…The thermal pulse scorched trees near the epicenter, before transient high temperatures rapidly subsided from 110,0007C at the center of the fireball. Numerous sampling sites at Tunguska indicate that temperatures and the severity of biomass burning decreased outward with distance from ground zero, initially igniting ∼200 km 2 and subsequently spreading to consume ∼500 km 2 of forest (Svetsov 2008). Because the impact-ignited fires were of low intensity, the burn layer contained charcoal amounts similar to those associated with normal, nonimpact ground fires (Svetsov 2008).…”

Trace element distribution and implications in sediments across the allerød–younger dryas boundary in the netherlands and belgium

“…() showed that although wildfires can ignite as a response to meteoritic impact(s), they would unlikely be ignited globally and mostly in the downrange direction. Recent studies by Svetsov (), Daniau (), Daniau et al . (), and Marlon et al .…”