Extraterrestrial Impact Event Research Articles

The Geology of Silali Basin (Kenya) as an Extra-Terrestrial Impact Crater (ETIC)

Certain rocks, rock minerals and rock formations have come to be associated with ETICs (Extra-terrestrial Impact Craters). An extra-terrestrial impact crater is a crater that is formed by an extra-terrestrial impact event whereby a heavenly body (a meteor, comet, or asteroid) hits the earth’s surface and creates a crater; before it cools on the earth’s surface as a meteorite or completely gets squashed by the thermodynamics of space transit. The crater created can be dry or filled with water and may be a simple crater or a complex one, also denoted as a basin. The objective of this paper is to describe the geology of the Silali basin as an Extra-Terrestrial Impact Crater (ETIC), highlight the importance of some of its ETIC rocks and explain the formation of the Silali basin resulting from extra-terrestrial impact. Data was collected through field observation, remote sensing, analysis of past geographical and geological studies, interviewing and laboratory analysis. Information has been presented in the form of analyzed satellite images, pictures, tables, and maps. Notably, this is the first study on extra-terrestrial impact cratering (ETIC) in Kenya. Consequently, the Silali basin, as an ETIC, and its environs, is a virgin field for further scientific research.

The Geology of Silali Basin (Kenya) as an Extra-Terrestrial Impact Crater (ETIC)

Certain rocks, rock minerals and rock formations have come to be associated with ETICs (Extra-terrestrial Impact Craters). An extra-terrestrial impact crater is a crater that is formed by an extra-terrestrial impact event whereby a heavenly body (a meteor, comet, or asteroid) hits the earth’s surface and creates a crater; before it cools on the earth’s surface as a meteorite or completely gets squashed by the thermodynamics of space transit. The crater created can be dry or filled with water and may be a simple crater or a complex one, also denoted as a basin. The objective of this paper is to describe the geology of the Silali basin as an Extra-Terrestrial Impact Crater (ETIC), highlight the importance of some of its ETIC rocks and explain the formation of the Silali basin resulting from extra-terrestrial impact. Data was collected through field observation, remote sensing, analysis of past geographical and geological studies, interviewing and laboratory analysis. Information has been presented in the form of analyzed satellite images, pictures, tables, and maps. Notably, this is the first study on extra-terrestrial impact cratering (ETIC) in Kenya. Consequently, the Silali basin, as an ETIC, and its environs, is a virgin field for further scientific research.

Altered impact glass from the Devonian Norwood Member of the Antrim Shale, southeast Michigan

The presence of microtektites, indicative of a single short-lived event, may be a useful tool for constraining the timing of barren and monotonous beds thereby enabling more accurate long-distance correlation. While the Paleozoic Laurentian epeiric seas have been studied for more than a century, their geologically complex histories, large areal expanse, and seeming monotony of contained barren stratigraphic units precludes simple extrabasinal correlation. Recent investigations of the Upper Devonian succession in western New York have yielded evidence of extraterrestrial impact events in the form of microtektites. Geothermal well spoils from the coeval Antrim Shale (Norwood Member) of the Michigan Basinwere collected and completely digested. Sediments retrieved from these spoils (shale, clay, and limestone) contain four genera of benthic foraminifera, algal cysts, and other microfossils confirming a Devonian age. The sediments also contain microspherules inferred to be microtektites similar to those recovered from western New York and are potentially evidence of a large impact event. The microspherules may be a useful inter-basin marker event within the Late Devonian beds in North America that has gone previously unreported.

Evidence of wildfires and elevated atmospheric oxygen at the Frasnian–Famennian boundary in New York (USA): Implications for the Late Devonian mass extinction

Abstract The Devonian Period experienced significant fluctuations of atmospheric oxygen (O2) levels (∼25–13%), for which the extent and timing are debated. Also characteristic of the Devonian Period, at the Frasnian–Famennian (F–F) boundary, is one of the “big five” mass extinction events of the Phanerozoic. Fossilized charcoal (inertinite) provides a record of wildfire events, which in turn can provide insight into the evolution of terrestrial ecosystems and the atmospheric composition. Here, we report organic petrology, programmed pyrolysis analysis, major and trace element analyses, and initial osmium isotope (Osi) stratigraphy from five sections of Upper Devonian (F–F interval) from western New York, USA. These data are discussed to infer evidence of a wildfire event at the F–F boundary. Based on the evidence for a wildfire at the F–F boundary we also provide an estimate of atmospheric O2 levels of ∼23–25% at this interval, which is in agreement with the models that predict elevated pO2 levels during the Late Devonian. This, coupled with our Os isotope records, support the currently published Osi data that lacks any evidence for an extra-terrestrial impact or volcanic event at the F–F interval, and therefore to act as a trigger for the F–F mass extinction. The elevated O2 level at the F–F interval inferred from this study supports the hypothesis that pCO2 drawdown and associated climate cooling may have acted as a driving mechanism of the F–F mass extinction.

Impact ejecta at the Paleocene-Eocene boundary.

Extraterrestrial impacts have left a substantial imprint on the climate and evolutionary history of Earth. A rapid carbon cycle perturbation and global warming event about 56 million years ago at the Paleocene-Eocene (P-E) boundary (the Paleocene-Eocene Thermal Maximum) was accompanied by rapid expansions of mammals and terrestrial plants and extinctions of deep-sea benthic organisms. Here, we report the discovery of silicate glass spherules in a discrete stratigraphic layer from three marine P-E boundary sections on the Atlantic margin. Distinct characteristics identify the spherules as microtektites and microkrystites, indicating that an extraterrestrial impact occurred during the carbon isotope excursion at the P-E boundary.

An impactful event

Global Climate Change Glassy silica spherules have been found in marine sediments from three sites across a wide area off the Atlantic coast of the United States, near the stratigraphic level of the Paleocene-Eocene boundary. The characteristics of these specimens are consistent with those of microtektites associated with extraterrestrial impact events. This discovery by Schaller et al. is evidence of an impact event at the time of the Paleocene-Eocene Thermal Maximum, a period during which global temperatures increased rapidly and the carbon cycle was substantially perturbed. Science , this issue p. [225][1] [1]: /lookup/doi/10.1126/science.aaf5466

Osmium isotope evidence for a large Late Triassic impact event

Anomalously high platinum group element concentrations have previously been reported for Upper Triassic deep-sea sediments, which are interpreted to be derived from an extraterrestrial impact event. Here we report the osmium (Os) isotope fingerprint of an extraterrestrial impact from Upper Triassic chert successions in Japan. Os isotope data exhibit a marked negative excursion from an initial Os isotope ratio (187Os/188Osi) of ∼0.477 to unradiogenic values of ∼0.126 in a platinum group element-enriched claystone layer, indicating the input of meteorite-derived Os into the sediments. The timing of the Os isotope excursion coincides with both elevated Os concentrations and low Re/Os ratios. The magnitude of this negative Os isotope excursion is comparable to those found at Cretaceous–Paleogene boundary sites. These geochemical lines of evidence demonstrate that a large impactor (3.3–7.8 km in diameter) produced a global decrease in seawater 187Os/188Os ratios in the Late Triassic.

Geological structure of Charity Shoal crater, Lake Ontario, revealed by multibeam bathymetry

Acoustic images of Charity Shoal in Lake Ontario, derived from a 1 × 1 m grid model of bathymetry assembled by the Canadian Hydrographic Service in 2010–2011, confirm the existence of a crater, as revealed by its surface morphology. With these higher quality data, it is possible to describe the crater in much greater detail, and arrive at a better interpretation of the geology than was possible using the earlier bathymetry of Lake Ontario. This new bathymetry of Charity Shoal reveals a continuous rim encircling an ovoid-shaped crater floor 1,200–1,500 m in diameter, with the crater floor being largely devoid of relief. Extending 3–4 km southwest of the crater is a ridge capped by a linear zone of unstratified debris that resembles a medial moraine. NE–SW erosional valleys cut across the crater rim in its southwestern sector. Apparently, glacial erosion has stripped the soil zone off stratified bedrock beneath the crater rim, exposing an intricate pattern of micro-ridges and grooves that bear the record of differential resistance to erosion of successive beds within the sequence of rock strata. Mapping of the shallow structure of the bedrock reveals a continuous ring anticline coinciding with the crater rim, with rock strata dipping gently in both directions away from the rim axis. In combination with existing evidence on the regional stratigraphy, these observations and interpretations are consistent with the Charity Shoal crater having formed in a shallow marine environment by an extraterrestrial impact event in the Middle Ordovician, followed by post-impact sedimentation, and much later, erosion during Pleistocene glaciations. Apparently, post-impact sediments infilled the crater and eventually covered the crater rim, leaving only a diminished structural expression of a crater having no more than 20 m of surface relief. Further details of crater history and origin, and a test of the hypothesis of impact, will likely come from acoustic reflection profiling and direct sampling.

Inconsistent impact hypotheses for the Younger Dryas

Israde-Alcantara et al. (1) presented evidence from Lake Cuitzeo sediments and argued that it supports the Younger Dryas (YD) impact hypothesis of Firestone et al. (2) for a major extraterrestrial impact event “involving multiple airburst(s) and/or ground impact(s) at 12.9 ka.” Firestone et al. (2) did not specify the details of the impact but proposed that it had “continent-wide effects” and was “most likely a comet.” The YD hypothesis “requires an energy of 107 …

Accumulation of impact markers in desert wetlands and implications for the Younger Dryas impact hypothesis

The Younger Dryas impact hypothesis contends that an extraterrestrial object exploded over North America at 12.9ka, initiating the Younger Dryas cold event, the extinction of many North American megafauna, and the demise of the Clovis archeological culture. Although the exact nature and location of the proposed impact or explosion remain unclear, alleged evidence for the fallout comes from multiple sites across North America and a site in Belgium. At 6 of the 10 original sites (excluding the Carolina Bays), elevated concentrations of various "impact markers" were found in association with black mats that date to the onset of the Younger Dryas. Black mats are common features in paleowetland deposits and typically represent shallow marsh environments. In this study, we investigated black mats ranging in age from approximately 6 to more than 40ka in the southwestern United States and the Atacama Desert of northern Chile. At 10 of 13 sites, we found elevated concentrations of iridium in bulk and magnetic sediments, magnetic spherules, and/or titanomagnetite grains within or at the base of black mats, regardless of their age or location, suggesting that elevated concentrations of these markers arise from processes common to wetland systems, and not a catastrophic extraterrestrial impact event.

Absence of geochemical evidence for an impact event at the Bølling-Allerød/Younger Dryas transition.

High concentrations of iridium have been reported in terrestrial sediments dated at 12.9 ka and are interpreted to support an extraterrestrial impact event as the cause of the observed extinction in the Rancholabrean fauna, changes in the Paleoindian cultures, and the onset of the Younger Dryas cooling [Firestone RB, et al. (2007) Proc Natl Acad Sci USA 104:16016-16021]. Here, we report platinum group element (PGE: Os, Ir, Ru, Rh, Pt, Pd), gold (Au) concentrations, and (187)Os/(188)Os ratios in time-equivalent terrestrial, lacustrine, and marine sections to seek robust evidence of an extraterrestrial contribution. First, our results do not reproduce the previously reported elevated Ir concentrations. Second, (187)Os/(188)Os isotopic ratios in the sediment layers investigated are similar to average crustal values, indicating the absence of a significant meteoritic Os contribution to these sediments. Third, no PGE anomalies distinct from crustal signatures are present in the marine record in either the Gulf of California (DSDP 480, Guaymas Basin) or the Cariaco Basin (ODP 1002C). Our data show no evidence of an extraterrestrial (ET)-PGE enrichment anomaly in any of the investigated depositional settings investigated across North America and in one section in Belgium. The lack of a clear ET-PGE signature in this sample suite is inconsistent with the impact of a large chondritic projectile at the Bølling-Allerød/Younger Dryas transition.

Evidence from the northwestern Venezuelan Andes for extraterrestrial impact: The black mat enigma

A carbon-rich black layer encrusted on a sandy pebbly bed of outwash in the northern Venezuelan Andes, previously considered the result of an alpine grass fire, is now recognized as a ‘black mat’ candidate correlative with Clovis Age sites in North America, falling within the range of ‘black mat’ dated sites (~ 12.9 ka cal BP). As such, the bed at site MUM7B, which dates to < 11.8 ka 14C years BP (raw dates) and appears to be contemporaneous with the Younger Dryas (YD) cooling event, marks a possibly much more extensive occurrence than previously identified. No fossils (megafauna) or tool assemblages were observed at this newly identified candidate site (3800 a.m.s.l.), as in the case of the North American sites. Here, evidence is presented for an extraterrestrial impact event at ~ 12.9 ka. The impact-related Andean bed, located ~ 20 cm above 13.7–13.3 ka cal BP alluvial and glaciolacustrine deposits, falls within the sediment characteristics and age range of ‘black mat’ dated sites (~ 12.9 ka cal BP) in North America. Site sediment characteristics include: carbon, glassy spherules, magnetic microspherules, carbon mat ‘welded’ onto coarse granular material, occasional presence of platinum group metals (Rh and Ru), planar deformation features (pdfs) in fine silt-size fragmental grains of quartz, as well as orthoclase, and monazite (with an abundance of Rare Earth Elements—REEs). If the candidate site is ‘black mat’, correlative with the ‘black mat’ sites of North America, such an extensive occurrence may support the hypothesized airburst/impact over the Laurentide Glacier, which led to a reversal of Allerød warming and the onset of YD cooling and readvance of glaciers. While this finding does not confirm such, it merits further investigation, which includes the reconnaissance for additional sites in South America. Furthermore, if confirmed, such an extensive occurrence may corroborate an impact origin.

Synsedimentary brecciation in the Eifelian (Middle Devonian) Baltic Basin: sudden catastrophe or diagenetic collapse?

AbstractThe Eifelian sedimentary record in the epeiric Baltic Basin contains an extensive brecciated interval known as the Narva Breccia. During recent decades, the origin of this breccia has been attributed to (1) palaeoseismicity, (2) extraterrestrial impact event or (3) diagenetic collapse. Our studies show the presence of two different breccia types that form 11 stratigraphic horizons and contain several laterally and stratigraphically unrelated breccias. The occurrence of Type‐1 and Type‐2 breccias, together with carbonate sabkha and carbonate inter‐ to supratidal tidal flat deposits on the basin margins, indicates synsedimentary brecciation formed in a sabkha environment. Type‐2 breccia could also originate from wave‐cycling loading.

Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling

A carbon-rich black layer, dating to approximately 12.9 ka, has been previously identified at approximately 50 Clovis-age sites across North America and appears contemporaneous with the abrupt onset of Younger Dryas (YD) cooling. The in situ bones of extinct Pleistocene megafauna, along with Clovis tool assemblages, occur below this black layer but not within or above it. Causes for the extinctions, YD cooling, and termination of Clovis culture have long been controversial. In this paper, we provide evidence for an extraterrestrial (ET) impact event at approximately equal 12.9 ka, which we hypothesize caused abrupt environmental changes that contributed to YD cooling, major ecological reorganization, broad-scale extinctions, and rapid human behavioral shifts at the end of the Clovis Period. Clovis-age sites in North American are overlain by a thin, discrete layer with varying peak abundances of (i) magnetic grains with iridium, (ii) magnetic microspherules, (iii) charcoal, (iv) soot, (v) carbon spherules, (vi) glass-like carbon containing nanodiamonds, and (vii) fullerenes with ET helium, all of which are evidence for an ET impact and associated biomass burning at approximately 12.9 ka. This layer also extends throughout at least 15 Carolina Bays, which are unique, elliptical depressions, oriented to the northwest across the Atlantic Coastal Plain. We propose that one or more large, low-density ET objects exploded over northern North America, partially destabilizing the Laurentide Ice Sheet and triggering YD cooling. The shock wave, thermal pulse, and event-related environmental effects (e.g., extensive biomass burning and food limitations) contributed to end-Pleistocene megafaunal extinctions and adaptive shifts among PaleoAmericans in North America.

Asteroid/comet impact clusters, flood basalts and mass extinctions: Significance of isotopic age overlaps

Morgan et al. [J. Phipps Morgan, T.J. Reston, C.R. Ranero. Earth Planet. Sci. Lett. 217 (2004) 263–284.], referring to an overlap between the isotopic ages of volcanic events and four epoch/stage extinction boundaries, suggest a dominant role of Continental Flood Basalts (CFB) and of explosive CO 2-rich volcanic pipes (“Verneshots”) as mass extinction triggers. Here I point out that Morgan et al. overlook 3 overlaps between the ages of extraterrestrial impacts, volcanic and mass extinction events, and 3 overlaps between the ages of extraterrestrial impact and volcanic events. These overlaps suggest that both extraterrestrial impacts and volcanism served as extinction triggers separately or in combination. A protracted impact cluster overlaps extinctions at the end-Devonian (∼374–359 Ma) and impact-extinction age overlaps occur in the end-Jurassic (∼145–142 Ma), Aptian (∼125–112 Ma); Cenomanian–Turonian (∼95–94 Ma); K–T boundary (∼65.5 Ma) and mid-Miocene (∼16 Ma) ( Table 1). Morgan et al. appear to question the uniqueness of shock metamorphic and geochemical criteria used to identify asteroid/comet impacts. However, shock pressures at 8–35 GPa, indicated by intra-crystalline planar deformation features (PDF), exceed lithospheric and volcanic explosion pressures by an order of magnitude and are not known to be associated with explosive volcanic diatremes, kimberlites or lamproites. These authors make reference to apparent iridium anomalies of volcanic origin. However, platinum group element (PGE) abundance levels, volatile/refractory PGE ratios, and Cr and Os isotopes of meteoritic materials are clearly distinct from those of terrestrial volcanics. Given a Phanerozoic time-integrated oceanic/continent crustal ratio > 2.5 and the difficulty in identifying oceanic impacts, I suggest the effects of large impacts on thin thermally active oceanic crust–capable of triggering regional to global mafic volcanic events and ensuing environmental effects–provide an essential clue for understanding the relationships between impacts and volcanic events which, separately or in combination, result in deleterious environmental effects, in some instances leading to mass extinctions.

Review of the mineralogy of the Cretaceous-Tertiary boundary clay: evidence supporting a major extraterrestrial catastrophic event

AbstractThe proposed impact event at the end of the Cretaceous resulted in mass extinctions and subsequently significant variations in the geochemical and mineralogical composition of the sediments marking the K/T boundary. The impact-generated material derived from target rocks produced the ejecta layer deposits around Chicxulub crater, which were subsequently diagenetically altered to mainly smectite in marine sections and to kaolinite in continental sections. The fireball layer represents the cosmic dust dispersed and deposited globally and contains smectite derived from the alteration of microkrystites and the finest fraction. The lowermost Danian clay layer, recognized in marine sections, resulted from the sudden decrease in ocean productivity and represents a reduced sedimentation deposit. Its clay mineral associations depend on local environmental conditions and diagenetic processes. Overall, the diagenetic alteration of the boundary materials resulted in a significant modification of original signatures. The composition of the clay mineral phases can, however, still be evidence of the nature of the precursor materials providing evidence for an extraterrestrial impact event.

An atmospheric pCO2 reconstruction across the Cretaceous-Tertiary boundary from leaf megafossils.

The end-Cretaceous mass extinctions, 65 million years ago, profoundly influenced the course of biotic evolution. These extinctions coincided with a major extraterrestrial impact event and massive volcanism in India. Determining the relative importance of each event as a driver of environmental and biotic change across the Cretaceous-Tertiary boundary (KTB) crucially depends on constraining the mass of CO(2) injected into the atmospheric carbon reservoir. Using the inverse relationship between atmospheric CO(2) and the stomatal index of land plant leaves, we reconstruct Late Cretaceous-Early Tertiary atmospheric CO(2) concentration (pCO(2)) levels with special emphasis on providing a pCO(2) estimate directly above the KTB. Our record shows stable Late Cretaceous/Early Tertiary background pCO(2) levels of 350-500 ppm by volume, but with a marked increase to at least 2,300 ppm by volume within 10,000 years of the KTB. Numerical simulations with a global biogeochemical carbon cycle model indicate that CO(2) outgassing during the eruption of the Deccan Trap basalts fails to fully account for the inferred pCO(2) increase. Instead, we calculate that the postboundary pCO(2) rise is most consistent with the instantaneous transfer of approximately 4,600 Gt C from the lithic to the atmospheric reservoir by a large extraterrestrial bolide impact. A resultant climatic forcing of +12 W.m(-2) would have been sufficient to warm the Earth's surface by approximately 7.5 degrees C, in the absence of counter forcing by sulfate aerosols. This finding reinforces previous evidence for major climatic warming after the KTB impact and implies that severe and abrupt global warming during the earliest Paleocene was an important factor in biotic extinction at the KTB.

Discovery and significance of microspherules at Lower-Middle Devonian boundary of Guangxi, South China

Microspherules are found in different facies at the Lower-Middle Devonian boundary, Guangxi, South China. There are more than 20 grains per kilogram rock sample. Composition and form of the microspherules are very similar to those of the microtektites from modern deposits of South Pacific Ocean and F-F boundary (Devonian). This may indicate that the microspherules from Guangxi are most likely the products of an extraterrestrial impact event that occurred at the end of Early Devonian Epoch. The event may be responsible for the biomass reduction and extinction of benthic organisms at the end of Early Devonian. The impact products (ejecta) can be used as a potential tool for stratigraphic correlation.

Global cooling accelerated by early late Eocene impacts?

At Ocean Drilling Program Site 689 (Maud Rise, Southern Ocean), δ18O records of fine-fraction bulk carbonate and benthic foraminifers indicate that accelerated climate cooling took place following at least two closely spaced early late Eocene extraterrestrial impact events. A simultaneous surface-water productivity increase, as interpreted from δ13C data, is explained by enhanced water-column mixing due to increased latitudinal temperature gradients. These isotope data appear to be in concert with organic-walled dinoflagellate-cyst records across the same microkrystite-bearing impact-ejecta layer in the mid-latitude Massignano section (central Italy). In particular, the strong abundance increase of Thalassiphora pelagica is interpreted to indicate cooling or increased productivity at Massignano. Because impact-induced cooling processes are active on time scales of a few years at most, the estimated 100 k.y. duration of the cooling event appears to be too long to be explained by impact scenarios alone. This implies that a feedback mechanism, such as a global albedo increase due to extended snow and ice cover, may have sustained impact-induced cooling for a longer time after the impacts.

Stable Isotope Event Markers Near the Permo-Triassic Boundary in the Karavanke Mountains (Slovenia)

Permo-Triassic (P/Tr) boundary events, which took place approximately 250 Ma ago, led to the most extensive mass extinction in the history of life. A number of possible explanations for this profound break in the evolution of life have been proposed, such as volcanic activity, sea-level fluctuation, changes in sea-water chemistry, an extra-terrestrial impact event and various related factors (YOICHI, 1994). The most recently proposed cause of the mass extinction at the end of the Permian is a combination of these more or less co-occurring events operating in three phases (ERVIN, 1996). The first began with the marine regression during the Late Permian and resulted in the destruction of many marine basins, reduction in the habitat area of many organisms and increased climatic instability. The second phase involved the eruption of the Siberian Traps and further environmental degradation. The final phase may have started immediately prior to the boundary when the Late Permian regression ended and the earliest Triassic transgression begun. The global events outlined above coincide with isotope and elemental anomalies recorded in several P/ Tr boundary sections all