Boltysh crater
Encyclopedia
The Boltysh Crater is an impact crater
in the Kirovohrad Oblast
province of Ukraine
. The crater is 24 kilometres (14.9 mi) in diameter
and its age of 65.17 ± 0.64 million years, based on argon
dating techniques, is within error of that of Chicxulub Crater
in Mexico, and the K–T boundary
. The Chicxulub impact is believed to have caused the mass extinction at the end of the Cretaceous
era, which included the extinction of the dinosaur
s. The Boltysh impact likely occurred several thousand years before Chicxulub, suggesting the extinction event may have been driven by multiple meteor strikes over an extended period of time about 65 million years ago.
, a tributary of the Dnieper River
. It is 24 kilometres (14.9 mi) in diameter, and is surrounded by an ejecta blanket of breccia
preserved over an area of 6500 square kilometres (2,509.7 sq mi). It is estimated that immediately after the impact, ejecta covered an area of 25000 square kilometres (9,652.6 sq mi) to a depth of 1 metres (3.3 ft) or greater, and was some 600 metres (1,968.5 ft) deep at the crater rim.
The crater contains a central uplift about 6 kilometres (3.7 mi) in diameter, rising about 550 metres (1,804.5 ft) above the base level of the crater. This uplift currently lies beneath about 500 metres (1,640.4 ft) of sediment deposited since the impact, and was discovered in the 1960s during oil shale
deposits exploration.
(98.9 to 93.5 million years ago) and Turonian
(93.5 to 89 million years ago) epochs. Bore samples of sediments overlying the crater contain fossils dating from the Paleocene
epoch, 65 to 54.8 million years ago. The age of the crater was thus constrained to between 54.8 and 98.9 million years.
Subsequent radiometric dating
reduced the uncertainty. The concentration of decay products in impact glasses from the crater were used to derive an age of 65.04 ± 1.10 million years. Analysis of argon
radioactive decay products yielded an age of 65.17 ± 0.64 million years. These ages are similar to that of Chicxulub Crater. An August 2010 study of ancient fern
spikes suggests the Boltysh impact likely occurred several thousand years before Chicxulub.
s, it does not necessarily follow that they formed at exactly the same time. At the estimated rate of impacts on the Earth, it would not be extremely unusual for a Boltysh-sized crater to be formed within half a million years of Chicxulub. The dating of these impact craters is not yet accurate enough to establish whether the impactors arrived thousands of years apart, perhaps as part of a generally elevated rate of impacts at that time, or were almost simultaneous, like the impacts of the fragments of Comet Shoemaker-Levy 9
on Jupiter
in 1994.
The discovery of the unconfirmed Silverpit crater
and the early report of its age as 65–60 million years initially gave greater weight to the hypothesis that the Earth was struck by multiple impactors at this time, however, the age estimate has now been broadened to 74–45 million years.
The controversial Shiva crater
is claimed to have formed around the same time, but its status as an impact crater is disputed.
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
in the Kirovohrad Oblast
Kirovohrad Oblast
Kirovohrad Oblast is an oblast of Ukraine. The administrative center of the oblast is the city of Kirovohrad.-Geography:The area of the province is , its population is 1.1 million....
province of Ukraine
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...
. The crater is 24 kilometres (14.9 mi) in diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
and its age of 65.17 ± 0.64 million years, based on argon
Argon-argon dating
Argon-argon dating is a radiometric dating method invented to supersede potassium-argon dating in accuracy. The older method required two samples for dating while the newer method requires only one...
dating techniques, is within error of that of Chicxulub Crater
Chicxulub Crater
The Chicxulub crater is an ancient impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named...
in Mexico, and the K–T boundary
K–T boundary
The K–T boundary is a geological signature, usually a thin band, dated to 65.5 ± 0.3 Ma ago. K is the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period...
. The Chicxulub impact is believed to have caused the mass extinction at the end of the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
era, which included the extinction of the dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s. The Boltysh impact likely occurred several thousand years before Chicxulub, suggesting the extinction event may have been driven by multiple meteor strikes over an extended period of time about 65 million years ago.
Overview
Boltysh Crater is located in central Ukraine, in the basin of the Tiasmyn RiverTiasmyn River
The Tiasmyn river is a right tributary of the Dnieper River in Ukraine. The Tiasmyn originates in the north central part of the Dnieper hills in the central Ukrainian province of Kirovohrad. From there it flows through the Cherkasy Oblast, where it finally flows into the Kremenchuk Reservoir. The...
, a tributary of the Dnieper River
Dnieper River
The Dnieper River is one of the major rivers of Europe that flows from Russia, through Belarus and Ukraine, to the Black Sea.The total length is and has a drainage basin of .The river is noted for its dams and hydroelectric stations...
. It is 24 kilometres (14.9 mi) in diameter, and is surrounded by an ejecta blanket of breccia
Breccia
Breccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix, that can be either similar to or different from the composition of the fragments....
preserved over an area of 6500 square kilometres (2,509.7 sq mi). It is estimated that immediately after the impact, ejecta covered an area of 25000 square kilometres (9,652.6 sq mi) to a depth of 1 metres (3.3 ft) or greater, and was some 600 metres (1,968.5 ft) deep at the crater rim.
The crater contains a central uplift about 6 kilometres (3.7 mi) in diameter, rising about 550 metres (1,804.5 ft) above the base level of the crater. This uplift currently lies beneath about 500 metres (1,640.4 ft) of sediment deposited since the impact, and was discovered in the 1960s during oil shale
Oil shale
Oil shale, an organic-rich fine-grained sedimentary rock, contains significant amounts of kerogen from which liquid hydrocarbons called shale oil can be produced...
deposits exploration.
Age
When first identified, the age of the crater could only be roughly constrained between the age of the impacted rocks (the target) and the age of overlying sediments. The target rocks date from the CenomanianCenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
(98.9 to 93.5 million years ago) and Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
(93.5 to 89 million years ago) epochs. Bore samples of sediments overlying the crater contain fossils dating from the Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
epoch, 65 to 54.8 million years ago. The age of the crater was thus constrained to between 54.8 and 98.9 million years.
Subsequent radiometric dating
Radiometric dating
Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
reduced the uncertainty. The concentration of decay products in impact glasses from the crater were used to derive an age of 65.04 ± 1.10 million years. Analysis of argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...
radioactive decay products yielded an age of 65.17 ± 0.64 million years. These ages are similar to that of Chicxulub Crater. An August 2010 study of ancient fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
spikes suggests the Boltysh impact likely occurred several thousand years before Chicxulub.
Likelihood of multiple impact
Although the ages derived for Chicxulub and Boltysh are the same to within their statistical errorErrors and residuals in statistics
In statistics and optimization, statistical errors and residuals are two closely related and easily confused measures of the deviation of a sample from its "theoretical value"...
s, it does not necessarily follow that they formed at exactly the same time. At the estimated rate of impacts on the Earth, it would not be extremely unusual for a Boltysh-sized crater to be formed within half a million years of Chicxulub. The dating of these impact craters is not yet accurate enough to establish whether the impactors arrived thousands of years apart, perhaps as part of a generally elevated rate of impacts at that time, or were almost simultaneous, like the impacts of the fragments of Comet Shoemaker-Levy 9
Comet Shoemaker-Levy 9
Comet Shoemaker–Levy 9 was a comet that broke apart and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of solar system objects. This generated a large amount of coverage in the popular media, and the comet was closely observed by...
on Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
in 1994.
The discovery of the unconfirmed Silverpit crater
Silverpit crater
Silverpit crater is a buried sub-sea structure under the North Sea off the coast of the United Kingdom. The crater-like form, named after the Silver Pit — a nearby sea-floor valley recognized by generations of fishermen — was discovered during the routine analysis of seismic data collected during...
and the early report of its age as 65–60 million years initially gave greater weight to the hypothesis that the Earth was struck by multiple impactors at this time, however, the age estimate has now been broadened to 74–45 million years.
The controversial Shiva crater
Shiva crater
The Shiva crater is a sea floor structure located beneath the Indian Ocean, west of Mumbai, India. It was named by the paleontologist Sankar Chatterjee after Shiva, the Hindu god of destruction and renewal....
is claimed to have formed around the same time, but its status as an impact crater is disputed.