Kärdla Impact (Hiiumaa Island, Estonia) — Ejecta Blanket and Environmental Disturbances

Suuroja, Sten; Suuroja, Kalle

doi:10.1007/3-540-25736-5_14

Cited by 4 publications

(6 citation statements)

References 35 publications

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“…Planar deformation features in quartz of the distal ejecta blanket were found as well (Fig. 5) (Suuroja and Suuroja 2006; Kleesment et al. 2006).…”

Section: Proven Impact Craters Of Estoniamentioning

confidence: 76%

“…1999), Kärdla was never reopened and its inner structure is perfectly preserved. Also, the ejecta blanket is well preserved (as assessed with 42 drill holes; Suuroja and Suuroja 2006), except at the crater rim where it was eroded prior to the formation of the sedimentary cover. The ejecta blanket lies in a succession of Upper Ordovician carbonate rocks as a 0.01–9.6 m thick bed of fragmented and disintegrated Cambrian and Lower Ordovician sand, silt, and clay, with minor admixture of fragments from all the other lithological units of the target.…”

Section: Proven Impact Craters Of Estoniamentioning

confidence: 99%

“…The Kärdla impact took place in an epicontinental sea of 20 (Puura and Suuroja 1992; Ormö and Lindström 2000) to 50 m (Suuroja et al. 2002b), or even 100 m (Suuroja and Suuroja 2006), depth, at approximately 455 Ma (dated biostratigraphically: the lowermost Diplograptus multidens graptolite zone, early Idavere age, lowermost Caradoc, Upper Ordovician; Grahn et al. 1996).…”

Section: Proven Impact Craters Of Estoniamentioning

confidence: 99%

“…1987). Thickness and grain size of the bed decrease with distance; the most distal occurrence was discovered in a drill core at 42 km from the crater center (Suuroja and Suuroja 2006).…”

Section: Proven Impact Craters Of Estoniamentioning

confidence: 99%

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Meteorite impact craters and possibly impact‐related structures in Estonia

Plado

2012

Meteorit & Planetary Scien

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Abstract-Three structures (Neugrund, Ka¨rdla, and Kaali) of proven impact origin make Estonia the most cratered country in the world by area. In addition, several candidate impact structures exist, waiting for future studies to determine their origin. This article is an overview of these proven and possible impact structures, including some breccia layers. It summarizes the information and descriptions of the morphology; geological characteristics; and mineralogical, chemical, and geophysical data available in the literature. The overview was prepared to make information in many earlier publications in local journals (many of which had been published in Estonian or Russian) accessible to the international community. This review summarizes the facts and observations in a historical fashion, summarizing the current state of knowledge with some additional comments, and providing the references.

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“…Planar deformation features in quartz of the distal ejecta blanket were found as well (Fig. 5) (Suuroja and Suuroja 2006; Kleesment et al. 2006).…”

Section: Proven Impact Craters Of Estoniamentioning

confidence: 76%

Section: Proven Impact Craters Of Estoniamentioning

confidence: 99%

Section: Proven Impact Craters Of Estoniamentioning

confidence: 99%

“…1987). Thickness and grain size of the bed decrease with distance; the most distal occurrence was discovered in a drill core at 42 km from the crater center (Suuroja and Suuroja 2006).…”

Section: Proven Impact Craters Of Estoniamentioning

confidence: 99%

See 2 more Smart Citations

Meteorite impact craters and possibly impact‐related structures in Estonia

Plado

2012

Meteorit & Planetary Scien

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“…From the distance of 20 km and up to as far as 40 km, the impactrelated siliciclastic layer cemented by carbonates is composed only of sandy to clayey material. The ejected matter contains PDF-quartz (Suuroja and Suuroja, 2006).…”

Section: The Ejecta Layersmentioning

confidence: 99%

A comparative analysis of two Early Palaeozoic marine impact structures in Estonia, Baltic Sea: Neugrund and Kärdla

Suuroja¹,

Suuroja²,

Flodén³

2013

Bull Geol Soc Finland

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Kärdla and Neugrund are two Early Palaeozoic offshore impact structures located some 50 km apart along the Estonian coast of the Baltic Sea. They share many similarities but differing features are also found. The Kärdla impact structure is located at the NE coast of Hiiumaa Island (58°58'N, 22°46'E). The inner crater has a 4 km rim-to-rim diameter and a c. 130 m high central uplift, surrounded by a ring fault, c. 12 km in diameter. The well-preserved buried inner crater is outlined in the landscape by a circular ridge of uplifted bedrock. The perimeter of the outer crater is outlined on the seafloor by a semicircular ridge of narrow shoals. The variable height of the rim wall (50-240 m above the crystalline basement level) and the asymmetric location of the inner crater is obviously a result of an oblique impact in a layered target and partial collapse of the rim wall. Shortly after the impact in a shallow epicontinental sea during Late Ordovician time (c. 455 My), calcareous biodetritic muds were deposited and the crater was buried. The Neugrund impact structure is located in the seabed at the entrance of the Gulf of Finland (59°20'N, 23°31'E). The inner crater has a 7 km rim-to-rim diameter and the outer limit of the structure passes through the Osmussaar Island to the southwest of the impact centre. The crater was buried in a shallow epicontinental sea with siliciclastic deposition shortly after the impact at Early Cambrian time, c. 535 My. It was partially re-exposed by erosion during Pliocene. The target had a three-layered composition: Precambrian metamorphic rocks covered by Ediacaran and Early Cambrian siliciclastic rocks (c. 150 m) and water (c. 100 m). The structure has been studied with seismoacoustic and sidescan sonar profiling, and by diving and sampling of submarine outcrops. Several hundred samples of impact breccias have been collected and investigated from erratic boulders distributed by glacial action in the west Estonian mainland, islands and sea floor.

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Distribution of ejecta from small impact craters

Шувалов

Dypvik

2013

Meteorit & Planetary Scien

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Abstract-The present study focuses both on the influence of impact scale on ejecta expansion and on specific features of ejecta deposits around relatively small craters (i.e., those a few kilometers in width). The numerical model is based on the SOVA multimaterial multidimensional hydrocode, considering subaerial vertical impacts only, applying a 2-D version of the code to projectiles of 100, 300, and 1000 m diameter. Ejecta can roughly be divided into two categories: "ballistic" ejecta and "convective" ejecta; the ballistic ejecta are the ejecta with which the air interacts only slightly, while the convective ejecta motion is entirely defined by the air flow. The degree of particle/air interaction can be defined by the time/length of particle travel before deceleration. Ejecta size-distributions for the impacts modeled can be described by the same power law, but the size of maximum fragment increases with scale. There is no qualitative difference between the 100 m diameter projectile case and the 300 m diameter projectile impact. In both cases, fine ejecta decelerate in the air at a small distance from launching point and then rise to the stratosphere by air flows induced by the impacts. In the 1000 m-scale impact, the mass of ejecta is so large that it moves the atmosphere itself to high altitudes. Thus, the atmosphere cannot decelerate even the fine ejecta and they consequently expand to the rarefied upper atmosphere. In the upper atmosphere, even fine ejecta move more or less ballistically and therefore may travel to high altitudes.

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Kärdla Impact (Hiiumaa Island, Estonia) — Ejecta Blanket and Environmental Disturbances

Cited by 4 publications

References 35 publications

Meteorite impact craters and possibly impact‐related structures in Estonia

Meteorite impact craters and possibly impact‐related structures in Estonia

A comparative analysis of two Early Palaeozoic marine impact structures in Estonia, Baltic Sea: Neugrund and Kärdla

Distribution of ejecta from small impact craters

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