Petrological relations in some Icelandic basaltic hyaloclastites

Mäkipää, H.

doi:10.17741/bgsf/50.1-2.008

Cited by 12 publications

(8 citation statements)

References 18 publications

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“…Although not diagnostic for ocean-floor basalts (cf. Downes, 1973;Mäkipää, 1978), such crystals do seem to be common in basalts of all ages which have erupted onto the ocean floor (Pearce & Donaldson, 1974). They have been described in modern ocean-floor basalts (see Muir et al, 1966;Bryan, 1972;Hermes & Schilling, 1976), as well as in Proterozoic metalavas (see Baragar, 1960;Pearce & Donaldson, 1976) and younger, often spilitic, pillow lavas associated with ophiolites (Liou, 1974;Seguir & Laurent, 1975) and other Alpine formations (see Vuagnat, 1959;Batley, 1956).…”

Section: Discussionmentioning

confidence: 99%

Komatiitic and tholeiitic metavolcanics of the Siivikkovaara area in the Archean Kuhmo greenstone belt, eastern Finland

Hanski¹

1980

Bull Geol Soc Finland

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HANSKI, EERO 1980: Komatiitic and tholeiitic metavolcanics of the Siivikkovaara area in the Archean Kuhmo greenstone belt, eastern Finland. Bull. Geol. Soc. Finland 52, Komatiitic metavolcanics are abundant and well-preserved in the Siivikkovaara area, which lies in the middle part of the Archean Kuhmo greenstone belt. Together with the underlying tholeiites, these form the Kellojärvi Group, which is divided into two formations, those of Pahakangas and Siivikkovaara. The Pahakangas Formation consists of pillowed and massive metalavas and intercalated banded iron formations. The metalavas are chemically typical Archean low-potassium tholeiites. The overlying Siivikkovaara Formation has three subunits, the Siivikko, Mäkinen and Raivio Members. The metavolcanics of the Siivikko Member, which are mainly peridotitic komatiites (MgO ^ 18 °/o), have many structures typical of extrusive rocks, including breccias, pillows, spinifex textures and polygonal jointing. The microspinifex-textured rocks richest in magnesium contain about 20 °/o MgO. The Mäkinen Member consists of basaltic and pyroxenitic komatiites (MgO < 18 °/o), which occur in the form of variolitic pillow lavas. The Raivio Member is composed of ultramafic to mafic metatuffs. The spinifex textures in the Siivikkovaara area were originally formed by clinopyroxene. Zones Ai, A-z, Bi and BL > can be distinguished in the spinifex-textured lava flows, and Ao has further subunits dominated by dendritic, platy or acicular hornblende pseudomorphs after clinopyroxene. The liquid composition of the spinifextextured flows is deduced to be in the range of pyroxenitic komatiite. These flows are differentiated mainly by olivine and minor pyroxene and chromite precipitation. Albite in the spinifex-textured rocks is formed through sodium metasomatism caused by sea-water. There are many indicators to support the notion of a deep-sea origin for the lavas of the Kellojärvi Group. Despite the relatively low MgO content of the komatiites in the Siivikkovaara Formation, two nickel-copper occurences have been found in the formation.

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Section: Discussionmentioning

confidence: 99%

Komatiitic and tholeiitic metavolcanics of the Siivikkovaara area in the Archean Kuhmo greenstone belt, eastern Finland

Hanski¹

1980

Bull Geol Soc Finland

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“…6. One of these has chromium spinel inclusions as described by Mäkipää (1978 a); all of them are slightly crystalline and the olivine crystals observed represent equilibrium (Mäkipää, 1978 b;Grönvold and Mäkipää, 1978).…”

Section: V T (°K)mentioning

confidence: 97%

“…The bulk composition of the glasses used as starting materials (before doping) are given in Table 1. Two of them are lavas from the 1975 and 1977 eruptions in northern Iceland (Grönvold and Mäkipää, 1978), four are older pleistocene tholeiites (Mäkipää, 1978 a) and two more MgO-rich lavas from northern Iceland. The composition varies from quartz normative to olivine normative tholeiites.…”

Section: Introductionmentioning

confidence: 99%

Partitioning of chromium, manganese, cobalt and nickel between olivine and basaltic liquid: an experimental study

Mäkipää¹

1980

Bull Geol Soc Finland

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“…KD = (FeO o1 ) (MgO 1 ) (FeO 1 ) (MgO o1 ) ma -macrophenocryst, mi -microphenocryst. Sample location is shown on the map and given in Appendix 1 (Mäkipää 1978 In Roeder and Emslie's (1970) experiments the K I( values are within 0.06 units (K D = 0.30, SD = 0.03) and the K,, values in the present study (Table 2) between 0.26 and 0.34 are assumed to represent equilibria.…”

Section: Equilibrium Distribution Coefficientmentioning

confidence: 98%

“…The purpose of this paper is to describe the mineral liquid relationships in some common natural Icelandic hyaloclastites. The rocks used here are described by Mäkipää (1978).…”

Section: Introductionmentioning

confidence: 99%

Mineral equilibria, geothermometers and geobarometers in some Icelandic hyaloclastites

Mäkipää¹

1978

Bull Geol Soc Finland

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Distribution coefficients between crystal and magma can be used to establish various properties of magmas. A number of natural hyaloclastites have been used to evaluate some of the established geothermometers and geobarometers. Comparison with experimental data on the same rocks shows that the olivine geothermometer gives the most reasonable results and in some cases plagioclase geothermometer can also be useful. However before mineral-liquid combinations can be used to evaluate magma properties equilibrium between the various phases must be established. This is not always simple and more experimental data is needed.

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Petrological relations in some Icelandic basaltic hyaloclastites

Cited by 12 publications

References 18 publications

Komatiitic and tholeiitic metavolcanics of the Siivikkovaara area in the Archean Kuhmo greenstone belt, eastern Finland

Komatiitic and tholeiitic metavolcanics of the Siivikkovaara area in the Archean Kuhmo greenstone belt, eastern Finland

Partitioning of chromium, manganese, cobalt and nickel between olivine and basaltic liquid: an experimental study

Mineral equilibria, geothermometers and geobarometers in some Icelandic hyaloclastites

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