Crystallization history of some postmetamorphic diabases in Åland, Häme and Satakunta, Finland. A theoretical and experimental study

Mäkipää, H.

doi:10.17741/bgsf/51.1-2.010

Cited by 2 publications

(2 citation statements)

References 7 publications

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“…The curves of Murase and McBirney (1973) and Wright and Peck (1978) indicate an intrusion temperature of 1150°-1160 °C. These values are in good agreement with the intrusion temperature 1140°-1170 °C determined by Mäkipää (1979) using phase-equilibria. From approximation of the curve given by Peck et al (1966), the cooling rate corresponding to a glass content of 90 % is as high as about 1200 °/h.…”

Section: Generalsupporting

confidence: 86%

“…The only indications nowadays of the glassy origin of many Precambrian rocks are the outlines of perlitic cracks and the presence of spherulites (Marshall 1961). In the olivine diabase dyke set of Häme, Finland, described by Laitakari (1969) and Mäkipää (1979), undevitrified Precambrian glass was found. It appears in diabase apophyses some ten metres long and about ten centimetres wide.…”

Section: Introductionmentioning

confidence: 99%

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Glass and amygdules in Precambrian diabases from Orivesi, southern Finland

Lindqvist¹,

Laitakari²

1980

Bull Geol Soc Finland

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Glassy apophyses of a Precambrian diabase dyke appear at Orivesi, southern Finland. In chemical composition the glass is a subalkaline tholeiite. The glass content of the apophyses is 90 °/o, the only crystals found being two generations of plagioclase and some sporadic olivine. The intrusion temperature is 1150°-1160°C and the mineral assemblage indicates low pressure. Although the water content of the glass is high, only weak signs of devitrification are present. The preservation of the glass proves that no temperature rise has taken place in the area during the last 1600 Ma. Diabase in another dyke of the same set shows amygdaloidal structure. The amygdules that appear at the upper contact are spheroidal and consist of calcite and euhedral quartz. Since the formation of amygdules is a phenomenon of shallow depths, the present erosion level is close to the 1600-Ma-old Precambrian one.

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Section: Generalsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Glass and amygdules in Precambrian diabases from Orivesi, southern Finland

Lindqvist¹,

Laitakari²

1980

Bull Geol Soc Finland

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Assumptions about the presence of natural glasses on Mars

Bouska

Bell

1993

J. Geophys. Res.

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Natural glasses occur not only on Earth but also in lunar rocks and in some meteorites. On geological grounds, natural glasses could be expected on the surface of Mars and their presence would have important implications for the weathering and alteration of the near‐surface layer. Ultramafic and mafic magmatism rich in iron and some volatiles appears to have been important on Mars as has been impact cratering, volcanism, and possibly hydrothermal alteration. Available data indicate that we can presume the past or present existence of volcanic basaltic glasses, impact glasses formed by thermal fusion of meteorite‐impact targets, and diaplectic (mainly maskelynite) glasses. Conditions appear unsuitable for the formation of tektites on the Martian surface, and the production of measurable amounts of fulgurite or combustion glass seems improbable. Prospects for the remote and in situ identification of Martian glasses and their subsequent weathering products are discussed and include orbital reflectance and thermal emission spectroscopic measurements and Mössbauer spectroscopy from a surface lander.

show abstract

Crystallization history of some postmetamorphic diabases in Åland, Häme and Satakunta, Finland. A theoretical and experimental study

Cited by 2 publications

References 7 publications

Glass and amygdules in Precambrian diabases from Orivesi, southern Finland

Glass and amygdules in Precambrian diabases from Orivesi, southern Finland

Assumptions about the presence of natural glasses on Mars

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