Impact-induced replacement of plagioclase by K-feldspar in granitoids and amphibolites at the Kärdla Crater, Estonia

Puura, V.; Kärki, Aulis; Kirs, Juho; Kirsimäe, Kalle; Kleesment, A; Konsa, M.; Niin, M; Plado, Jüri; Suuroja, Kalle; Suuroja, Sten

doi:10.1007/bfb0027770

Cited by 10 publications

(10 citation statements)

References 8 publications

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“…The high lateral and vertical migration power of the vapor phase resulted in pervasive alteration of shock-destructured plagioclase in various settings within allochthonous and autochthonous breccias. However, the relative abundance of adularia in the Kärdla impactites (Puura et al 2000(Puura et al , 2004 suggests that the alteration was most intensive in the upper portion of the allochthonous breccias in and around the central peak.…”

Section: Temperature Evolution and Paragenetic Sequence Of Hydrothermmentioning

confidence: 99%

“…These include, for example, chloritization of amphibole in autochthonous and allochthonous breccias (Kirsimäe et al 2002), and replacement of plagioclase with orthoclase-type K-feldspar in impact affected granites and amphibolites (Puura et al 2000;2004). The latter is chemically expressed by Na and Ca depletion, and K-enrichment (Puura and Suuroja 1992).…”

Section: Impactitesmentioning

confidence: 99%

“…The latter consists of resurge conglomerates, conglomeratic turbidites, and sands which were eroded from uplifted walls before complete burial under the post-impact sediments (Puura and Suuroja 1992). The autochthonous breccias are composed of cataclastic crystalline basement rocks fractured and brecciated in various scales-from meter-size blocks and breccia dikes down to millimeter to submillimeter-size clasts in the breccia matrix, and micro-fracturing of mineral grains (Puura et al 2000). The allochthonous fragmental breccias consist of a polymict mixture of crystalline and sedimentary rock fragments.…”

Section: Impactitesmentioning

confidence: 99%

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Cooling of the Kärdla impact crater: I. The mineral paragenetic sequence observation

Versh

Kirsimäe

Jõeleht

et al. 2005

Meteorit & Planetary Scien

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Abstract-The impact-induced hydrothermal system in the well-preserved, 4 km-diameter Kärdla impact crater on Hiiumaa Island, western Estonia, was investigated by means of mineralogical, chemical, and stable C and O isotope studies. The mineralization paragenetic sequence, with gradually decreasing temperature, reveals at least three evolutionary stages in the development of the post-impact hydrothermal system: 1) an early vapor-dominated stage (>300 °C) with precipitation of submicroscopic adularia type K-feldspar; 2) the main stage (300 to 150/100 °C) with the development of a two-phase (vapor to liquid) zone leading to precipitation of chlorite/corrensite, (idiomorphic) euhedral K-feldspar, and quartz; and 3) a late liquid-dominated stage (<100 °C) with calcite I, dolomite, quartz, calcite II, chalcopyrite/pyrite, Fe-oxyhydrate, and calcite III precipitation.

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Section: Temperature Evolution and Paragenetic Sequence Of Hydrothermmentioning

confidence: 99%

Section: Impactitesmentioning

confidence: 99%

Section: Impactitesmentioning

confidence: 99%

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Cooling of the Kärdla impact crater: I. The mineral paragenetic sequence observation

Versh

Kirsimäe

Jõeleht

et al. 2005

Meteorit & Planetary Scien

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“…Primary plagioclase in biotite gneisses, granites, and amphibolites is in part replaced by submicroscopic orthoclase aggregates (Puura et al 2000a). Partially altered plagioclase can contain relict plagioclase with polysynthetic twinning as well as cryptocrystalline orthoclase replacing the plagioclase (e.g., Fig.…”

Section: Alteration Of Plagioclase and Hornblendementioning

confidence: 99%

“…Quartz with micro-scale fractures and voids is characteristic for a large volume of both allochthonous and autochthonous impact-affected rocks (Puura et al 2000a). PDFs in quartz were found predominantly in crystalline rock clasts of the granitoid-dominated polymict breccia from cores K1 and K18 and in slump breccia from K1.…”

Section: Deformation Of Quartzmentioning

confidence: 99%

Geology, petrography, shock petrography, and geochemistry of impactites and target rocks from the Kärdla crater, Estonia

Puura

Huber

Kirs

et al. 2004

Meteorit & Planetary Scien

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Abstract-The Kärdla crater is a 4 km-wide impact structure of Late Ordovician age located on Hiiumaa Island, Estonia. The 455 Ma-old buried crater was formed in shallow seawater in Precambrian crystalline target rocks that were covered with sedimentary rocks. Basement and breccia samples from 13 drill cores were studied mineralogically, petrographically, and geochemically. Geochemical analyses of major and trace elements were performed on 90 samples from allochthonous breccias, sub-crater and surrounding basement rocks. The breccia units do not include any melt rocks or suevites. The remarkably poorly mixed sedimentary and crystalline rocks were deposited separately within the allochthonous breccia suites of the crater. The most intensely shockmetamorphosed allochthonous granitoid crystalline-derived breccia layers contain planar deformation features (PDFs) in quartz, indicating shock pressures of 20-35 GPa. An apparent Kenrichment and Ca-Na-depletion of feldspar-and hornblende-bearing rocks in the allochthonous breccia units and sub-crater basement is interpreted to be the result of early stage alteration in an impact-induced hydrothermal system. The chemical composition of the breccias shows no definite sign of an extraterrestrial contamination. By modeling of the different breccia units with HMXmixing, the indigenous component was determined. From the abundances of the siderophile elements (Cr, Co, Ni, Ir, and Au) in the breccia samples, no unambiguous evidence for the incorporation of a meteoritic component above about 0.1 wt% chondrite-equivalent was found.

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Hydrothermal Processes Associated with Meteorite Impacts

Pirajno

2009

Hydrothermal Processes and Mineral Systems

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Impact-induced replacement of plagioclase by K-feldspar in granitoids and amphibolites at the Kärdla Crater, Estonia

Cited by 10 publications

References 8 publications

Cooling of the Kärdla impact crater: I. The mineral paragenetic sequence observation

Cooling of the Kärdla impact crater: I. The mineral paragenetic sequence observation

Geology, petrography, shock petrography, and geochemistry of impactites and target rocks from the Kärdla crater, Estonia

Hydrothermal Processes Associated with Meteorite Impacts

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