Sandorite lamprophyre with xenoliths (Sandor Dike, Neoarchean, 2.703 Ga; Route 17 roadcut northeast of Wasp Lake & north of Wawa, Ontario, Canada) 6 : 無料・フリー素材/写真
Sandorite lamprophyre with xenoliths (Sandor Dike, Neoarchean, 2.703 Ga; Route 17 roadcut northeast of Wasp Lake & north of Wawa, Ontario, Canada) 6 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Lamprophyre with xenoliths in the Precambrian of Ontario, Canada.This is part of an igneous dike composed of a rare igneous rock called lamprophyre. Such rocks are ultrapotassic, mafic to ultramafic, intrusive igneous rocks. This one is a diamondiferous spessartite lamprophyre called sandorite, with 47% silica and 5% black amphibole macrocrysts, up to 3 millimeters in size. The sandorite here has xenoliths ("xeno" = foreign; "lith" = rock), which are pieces of rock that have fallen from the walls or roof of a cooling magma chamber. At this site, they include mantle and crustal xenoliths. The banded structure at center and right is a gneiss xenolith.Spessartite lamprophyres are defined in the literature as lamprophyres having phenocrysts of hornblende amphibole or clinopyroxene in a groundmass of sodic plagioclase feldspar, with accessary olivine, biotite mica, apatite, and opaque oxide minerals.Sandorite dikes here represent the hypabyssal facies of a sandorite volcanic complex. The surrounding host rocks are 2.7 billion year old gabbros and volcanic tuffs of the Catfish Assemblage.Geologic unit and age: Sandor Dike, Neoarchean, 2.703 Ga (a zircon from a gneissic xenolith has been dated to 2.684 Ga)Locality: roadcut on the eastern side of Route 17, northeast of Wasp Lake & east of McCormick Lake, north of the town of Wawa, Ontario, southeastern Canada (48° 12’ 42.13" North latitude, 84° 50' 52.24" West longitude)--------------------------------See info. at:en.wikipedia.org/wiki/Lamprophyreanden.wikipedia.org/wiki/Xenolith |
| 撮影日 | 2012-07-13 07:38:28 |
| 撮影者 | James St. John |
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