Komatiite pebble- & BIF pebble-bearing polymict conglomerate (Timiskaming Conglomerate, Neoarchean, <2.674 Ga; Kirkland Lake, Ontario, Canada) : 無料・フリー素材/写真
Komatiite pebble- & BIF pebble-bearing polymict conglomerate (Timiskaming Conglomerate, Neoarchean, <2.674 Ga; Kirkland Lake, Ontario, Canada) / 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 | Polymict conglomerate (6.0 cm across) having pebbles of komatiite and banded iron formation from the Timiskaming Conglomerate (Neoarchean, <2.674 billion years) at Kirkland Lake, Ontario, Canada.Komatiite pebble = dark green clast with criss-crossing blackish needle structures (spinifex texture) at upper right.BIF pebble = dark red clast at left.------------This is the most amazing conglomerate I’ve ever seen. This is the Timiskaming Conglomerate of Ontario, Canada. It’s a polymict conglomerate, which means it consists of pebbles of many different lithologies (rock types). Apart from the striking colors and shapes, this polymict conglomerate is especially spectacular for the presence of pebbles of rare rock types. The sample shown here includes pebbles of the rare ultramafic extrusive igneous rock komatiite. The komatiite pebbles are easily recognizable based on their spinifex texture (long, needle-shaped crystals). There’s also a small clast of banded iron formation. The Timiskaming Conglomerate is a fluvial to alluvial fan deposit. Its clasts are a wonderful variety of Archean rock types, including intrusive igneous rocks (diorites, anorthosites), extrusive igneous rocks (basalts, komatiites, dacites, rhyolites), sedimentary rocks (graywackes, siltstones, cherts), and other clasts such as vein quartz and even pyrite pebbles (Gray & Hutchinson, 2001). The komatiite pebble is consistent with eastern Ontario’s Pyke Hill Komatiite (2.710 to 2.718 billion years). Unit & Age: Timiskaming Conglomerate, upper Neoarchean, <2.674 billion years. Locality: Kirkland Lake, northeastern Timiskaming District, eastern Ontario, southeastern Canada.-----------Reference Cited: Gray, M.D. & R.W. Hutchinson. 2001. New evidence for multiple periods of gold emplacement in the Porcupine Mining District, Timmins area, Ontario, Canada. Economic Geology 96: 453-475. |
| 撮影日 | 2014-08-25 21:56:40 |
| 撮影者 | James St. John |
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