Settings of Meteorite Impact Structures in the Svecofennian Crustal Domain

Puura, V.; Plado, Jüri

doi:10.1007/3-540-27548-7_8

Cited by 12 publications

(17 citation statements)

References 59 publications

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“…Among the 11 impact structures confirmed to date in Finland (Pesonen et al 2005), Paasselkä, with a diameter of ∼10 km (Pesonen et al 1999;Earth Impact Database 2007), is the third largest. The whole structure has been deeply eroded since its formation, especially by Pleistocene glaciation (see Puura and Plado 2005). A negative gravimetric anomaly associated with Lake Paasselkä was first noted and discussed by Elo (1979) and Elo et al (1984).…”

Section: Introduction Previous Work and Geological Settingmentioning

confidence: 99%

Impact melt rocks from the Paasselkä impact structure (SE Finland): Petrography and geochemistry

Schmieder

Moilanen²,

Buchner

2008

Meteorit & Planetary Scien

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Abstract-Recently, samples of allochthonous melt rocks from the ∼10 km and ≤1.9 Ga Paasselkä impact structure, SE Finland, were obtained. In this study, we present a first detailed petrographic and geochemical description of clast-rich Paasselkä impact melt rocks. Shock metamorphic features comprise shocked feldspar grains, intensely shocked and toasted quartz, marginally molten and recrystallized clasts thought to have been diaplectic quartz glass, largely fresh and recrystallized feldspar glasses, decomposed biotite flakes, recrystallized fluidal silica glass (originally probably lechatelierite) in partially molten sandstone clasts, all set into a glassy to cryptocrystalline melt matrix. The degree of shock metamorphism of clasts suggests initial whole-rock melting at peak shock pressures of ≥35 GPa and post-shock temperatures of up to ∼1500 °C. Glass components vary in geochemical composition corresponding to the mixed character of the crystalline target rock (i.e., representing different monomineralic and mixed-mineral melts). Feldspar glasses and the fresh glassy to cryptocrystalline melt matrix indicate that the Paasselkä melt rocks are not intensely altered. The geochemical composition of the Paasselkä impact melt rocks is roughly consistent with the compositions of melt rocks from a number of impact structures located within the crystalline basement of the Baltic Shield.

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Section: Introduction Previous Work and Geological Settingmentioning

confidence: 99%

Impact melt rocks from the Paasselkä impact structure (SE Finland): Petrography and geochemistry

Schmieder

Moilanen²,

Buchner

2008

Meteorit & Planetary Scien

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“…Cam brian dikes pre served in the base ment fis sures (Martinsson, 1956), Pa leo zoic out li ers in tec tonic grabens/depres sions or im pact crat ers (Puura et al, 1996;Puura and Plado, 2005), as well as al tered Lower Cam brian clay min er als and acritarchs (Hagenfeldt, 1997;Kirsimäe et al, 1999) re veal that the Bal tic Shield re gion in the East Eu ro pean Craton in terior was once cov ered by a much thicker Vendian to De vo nian rocks that ex tended fur ther north. In ac cor dance with the regional tec tonic de vel op ment and struc tural set ting, a great amount of Early Pa leo zoic rocks have been re moved from the Bal tic Shield area.…”

Section: Introductionmentioning

confidence: 99%

Paleozoic rocks structure versus Cenozoic cuesta relief along the Baltic Shield–East European Platform transect

Tuuling

2017

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1 Uni ver sity of Tartu, In sti tute of Ecol ogy and Earth Sci ences, Ravila 14A, 50411 Tartu, Es to nia Tuuling, I., 2017. Pa leo zoic rocks struc ture ver sus Ce no zoic cuesta re lief along the Bal tic Shield-East Eu ro pean Plat form transect. Geo log i cal Quar terly, 61 (2): 396-412, doi: 10.7306/gq.1342Based on struc tural maps, the bed rock struc ture on the south ern slope of the Bal tic Shield is ana lysed. Gently south erly dipping (0.1-0.2°) Paleozoic lay ers from Es to nia to the Swed ish east coast form the Bal tic Homocline (BH). Nu mer ous monoclinal folds, forced by base ment fault ing, in duce slight vari a tions in bed rock at ti tude across the BH. Stud ies on faults ex posed in South ern Fin land sug gest that many monoclinal folds in duc ing base ment faults within the BH are of Pre cam brian or i gin and have been ac tive in pulses. The pres ent mono clines were shaped by the Cal edo nian Orog eny. Submeridional tectonic hinge-lines in duce mi nor re gional-scale changes in the struc tural set ting and con trol trends/styles of the forced folds. From the west, the BH bounds with the Bal tic-Bothnian mo bile zone that has been in ter mit tently ac tive since Mesoproterozoic times. The evolv ing Bal tic Syneclise in the Si lu rian re ar ranged the struc tural set ting typ i cal for the Or do vician Bal tic Ba sin. The Ce no zoic up lift of Scan di na via cre ated a SE-to-E-dip ping bed rock se quence around the Gotland-Öland area. As the lat ter area had a dif fer ent at ti tude than the BH, two Ce no zoic cuesta-sets started to evolve around the north ern Bal tic Proper. They both had an out let to the N-S-flow ing Eridanos River around the Gotska Sandön area, cre at ing thus two in de pend ent sec tions of the Bal tic Klint.

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“…Shatter cones up to 20-30 cm long occur in metasiltstones (Masaitis et al 1976(Masaitis et al , 1999. These metasiltstones probably belong to the Late Precambrian cover, which was overlain by the crystalline basement at the time of impact (see also Puura et al 2005).…”

Section: Geographical and Geological Settingmentioning

confidence: 99%

“…The possible post-Caledonian burial of the area would be too young to cause this 500 Myr remagnetization; Moreover, this cover and its extent are highly controversial (e.g., Hendriks et al 2005 and references therein). The origin of a possible remagnetizations could be also chemical as according to Puura et al (2005) the Jänisjärvi impact structure was buried under the sea 500 Myr ago. However, the fact that we again see the socalled impact component (C) as an overprint in some but not all target rocks does not support the idea of remagnetization.…”

Section: Paleomagnetic Poles and Age Determinationsmentioning

confidence: 99%

“…Due to the impact event, the schists around the lake are fractured. Puura et al (2005) claim that Jänisjärvi was formed in a composite target consisting of crystalline basement covered by Precambrian sediments during the Neoproterozoic. From the Early Paleozoic until the Mesozoic, marine sediments have been depositing over the Jänisjärvi structure.…”

Section: Geographical and Geological Settingmentioning

confidence: 99%

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Paleomagnetism and petrophysics of the Jänisjärvi impact structure, Russian Karelia

Salminen

Donadini

Pesonen

et al. 2006

Meteoritics &Amp; Planetary Science

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Abstract-Paleomagnetic, rock magnetic, and petrophysical results are presented for impactites and target rocks from the Lake Jänisjärvi impact structure, Russian Karelia. The impactites (tagamites, suevites, and lithic breccias) are characterized by increased porosity and magnetization, which is in agreement with observations performed at other impact structures. Thermomagnetic, hysteresis, and scanning electron microscope (SEM) analysis document the presence of primary multidomain titanomagnetite with additional secondary titanomaghemite and ilmenohematite. The characteristic impact-related remanent magnetization (ChRM) direction (D = 101.5°, I = 73.1°, α 95 = 6.2°) yields a pole (Lat. = 45.0°N, Long. = 76.9°E, dp = 9.9°, dm = 11.0°). Additionally, the same component is observed as an overprint on some rocks located in the vicinity of the structure, which provides proofs of its primary origin. An attempt was made to determine the ancient geomagnetic field intensity. Seven reliable results were obtained, yielding an ancient intensity of 68.7 ± 7.6 μT (corresponding to VDM of 10.3 ± 1

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Settings of Meteorite Impact Structures in the Svecofennian Crustal Domain

Cited by 12 publications

References 59 publications

Impact melt rocks from the Paasselkä impact structure (SE Finland): Petrography and geochemistry

Impact melt rocks from the Paasselkä impact structure (SE Finland): Petrography and geochemistry

Paleozoic rocks structure versus Cenozoic cuesta relief along the Baltic Shield–East European Platform transect

Paleomagnetism and petrophysics of the Jänisjärvi impact structure, Russian Karelia

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