Projectile Identification in Terrestrial Impact Structures and Ejecta Material

Goderis, Steven; Paquay, François S.; Claeys, Philippe

doi:10.1002/9781118447307.ch15

Cited by 30 publications

(35 citation statements)

References 121 publications

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“…The mineralogical and geochemical characterization of the peak-ring rocks will provide key information on target rock composition (Koeberl et al, 2012). We will also search for an extraterrestrial signature using platinum group element (PGE) analyses and Os and Cr isotopes (Gelinas et al, 2004;Tagle and Hecht, 2006;Trinquier et al, 2006;Goderis et al, 2012;Sato et al, 2013 to determine whether a measurable fraction of the projectile remains at the impact site or whether most projectile material ends up within the global K-Pg layer (Artemieva and Morgan, 2009). High-resolution 40 Ar/ 39 Ar analyses and electron microscopy on shocked and melted impactites, as well as U/Pb dating of zircon and other geo-and thermochronometers, will be used to study their pressure-temperature-time and deformational history and for highprecision dating of the Chicxulub impact.…”

Section: Eocene and Paleocene Hyperthermals And The Petm Transitionmentioning

confidence: 99%

Volume 364: Chicxulub: Drilling the K-Pg Impact Crater

Morgan¹,

Gulick²,

Mellett³

et al. 2017

Proceedings of the International Ocean Discovery Program

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The Chicxulub impact crater, on the Yucatán Peninsula of Méx-ico, is unique. It is the only known terrestrial impact structure that has been directly linked to a mass extinction event and the only terrestrial impact with a global ejecta layer. Of the three largest impact structures on Earth, Chicxulub is the best preserved. Chicxulub is also the only known terrestrial impact structure with an intact, unequivocal topographic peak ring. Chicxulub's role in the Cretaceous/Paleogene (K-Pg) mass extinction and its exceptional state of preservation make it an important natural laboratory for the study of both large impact crater formation on Earth and other planets and the effects of large impacts on the Earth's environment and ecology. Our understanding of the impact process is far from complete, and despite more than 30 years of intense debate, we are still striving to answer the question as to why this impact was so catastrophic.During International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) Expedition 364, Paleogene sedimentary rocks and lithologies that make up the Chicxulub peak ring were cored to investigate (1) the nature and formational mechanism of peak rings, (2) how rocks are weakened during large impacts, (3) the nature and extent of post-impact hydrothermal circulation, (4) the deep biosphere and habitability of the peak ring, and (5) the recovery of life in a sterile zone. Other key targets included sampling the transition through a rare midlatitude Paleogene sedimentary succession that might include Eocene and Paleocene hyperthermals and/or the Paleocene/Eocene Thermal Maximum (PETM); the composition and character of suevite, impact melt rock, and basement rocks in the peak ring; the sedimentology and stratigraphy of the Paleocene-Eocene Chicxulub impact basin infill; the geo-and thermochronology of the rocks forming the peak ring; and any observations from the core that may help constrain the volume of dust and climatically active gases released into the stratosphere by this impact. Petrophysical properties measurements on the core and wireline logs acquired during Expedition 364 will be used to calibrate geophysical models, including seismic reflection and potential field data, and the integration of all the data will calibrate models for impact crater formation and environmental effects. The drilling directly contributes to IODP Science Plan goals:Climate and Ocean Change: How does Earth's climate system respond to elevated levels of atmospheric CO 2 ? How resilient is the ocean to chemical perturbations? The Chicxulub impact represents an external forcing event that caused a 75% species level mass extinction. The impact basin may also record key hyperthermals within the Paleogene.Biosphere Frontiers: What are the origin, composition, and global significance of subseafloor communities? What are the limits of life in the subseafloor? How sensitive are ecosystems and biodiversity to environmental change? Impact craters can create habitats fo...

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Section: Eocene and Paleocene Hyperthermals And The Petm Transitionmentioning

confidence: 99%

Volume 364: Chicxulub: Drilling the K-Pg Impact Crater

Morgan¹,

Gulick²,

Mellett³

et al. 2017

Proceedings of the International Ocean Discovery Program

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“…This is commented on by Daly and Schultz (2013). Indeed, a recent review of terrestrial impact structures shows that, in around 50 of the 180 or so known impact craters on Earth, geochemical means can be used to find traces of projectile material via modified elemental abundances or isotope ratios (Goderis et al, 2013). Indeed, in 13 cases, projectile fragments (usually metallic) have been recovered at terrestrial impact sites (Table 15.1, Goderis et al, 2013).…”

Section: Introductionmentioning

confidence: 97%

“…Similarly, being metallic implies a greater strength than for a rocky body, again increasing the chance of survival (although nonmetallic materials can also survive). Projectile fragments have however, also been recovered from larger craters with ages of order 100 million years (e.g., Chixulub crater, 64.98 ± 0.05 million years old and Morokweng crater, 145.0 ± 0.8 million years old, see Goderis et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Given that there is clearly evidence of survival of metallic impactor material at terrestrial impact sites (e.g., see Goderis et al, 2013), plus various examples of projectile material on other Solar System bodies, and that there is indeed the specific example of a man-made impact of a predominantly copper projectile on a comet (Tempel-1), we have conducted a study of the survival of copper projectiles in high speed impacts on porous ice. This study uses copper projectiles of 1-2 mm diameter, fired at porous ice targets (porosity % 0.53) with impact speeds in the range 1.00-7.05 km s À1 .…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, a recent review of terrestrial impact structures shows that, in around 50 of the 180 or so known impact craters on Earth, geochemical means can be used to find traces of projectile material via modified elemental abundances or isotope ratios (Goderis et al, 2013). Indeed, in 13 cases, projectile fragments (usually metallic) have been recovered at terrestrial impact sites (Table 15.1, Goderis et al, 2013). Most of the craters which have yielded fragments are small (most of the craters being less than 1 km in diameter) and young (most are less than 1 million years old), although as noted below, this is not always the case.…”

Section: Introductionmentioning

confidence: 99%

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Survivability of copper projectiles during hypervelocity impacts in porous ice: A laboratory investigation of the survivability of projectiles impacting comets or other bodies

McDermott

Price

Cole

et al. 2016

Icarus

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a b s t r a c tDuring hypervelocity impact (>a few km s À1 ) the resulting cratering and/or disruption of the target body often outweighs interest on the outcome of the projectile material, with the majority of projectiles assumed to be vaporised. However, on Earth, fragments, often metallic, have been recovered from impact sites, meaning that metallic projectile fragments may survive a hypervelocity impact and still exist within the wall, floor and/or ejecta of the impact crater post-impact. The discovery of the remnant impactor composition within the craters of asteroids, planets and comets could provide further information regarding the impact history of a body. Accordingly, we study in the laboratory the survivability of 1 and 2 mm diameter copper projectiles fired onto ice at speeds between 1.00 and 7.05 km s À1 . The projectile was recovered intact at speeds up to 1.50 km s À1 , with no ductile deformation, but some surface pitting was observed. At 2.39 km s À1 , the projectile showed increasing ductile deformation and broke into two parts. Above velocities of 2.60 km s À1 increasing numbers of projectile fragments were identified post impact, with the mean size of the fragments decreasing with increasing impact velocity. The decrease in size also corresponds with an increase in the number of projectile fragments recovered, as with increasing shock pressure the projectile material is more intensely disrupted, producing smaller and more numerous fragments. The damage to the projectile is divided into four classes with increasing speed and shock pressure: (1) minimal damage, (2) ductile deformation, start of break up, (3) increasing fragmentation, and (4) complete fragmentation. The implications of such behaviour is considered for specific examples of impacts of metallic impactors onto Solar System bodies, including LCROSS impacting the Moon, iron meteorites onto Mars and NASA's ''Deep Impact" mission where a spacecraft impacted a comet.

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V‐type near‐Earth asteroids: Dynamics, close encounters and impacts with terrestrial planets

2017

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Asteroids colliding with planets vary in composition and taxonomical type. Among Near-Earth Asteroids (NEAs) are the V-types, basaltic asteroids that are classified via spectroscopic observations. In this work, we study the probability of Vtype NEAs colliding with Earth, Mars and Venus, as well as the Moon. We perform a correlational analysis of possible craters produced by V-type NEAs. To achieve this, we performed numerical simulations and statistical analysis of close encounters and impacts between V-type NEAs and the terrestrial planets over the next 10 Myr. We find that V-type NEAs can indeed have impacts with all the planets, the Earth in particular, at an average rate of once per ∼ 12 Myr. There are four candidate craters on Earth that were likely caused by V-type NEAs.

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Projectile Identification in Terrestrial Impact Structures and Ejecta Material

Cited by 30 publications

References 121 publications

Volume 364: Chicxulub: Drilling the K-Pg Impact Crater

Volume 364: Chicxulub: Drilling the K-Pg Impact Crater

Survivability of copper projectiles during hypervelocity impacts in porous ice: A laboratory investigation of the survivability of projectiles impacting comets or other bodies

V‐type near‐Earth asteroids: Dynamics, close encounters and impacts with terrestrial planets

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