Cryogenian-Ediacaran boundary (basal Nuccaleena Formation, Neoproterozoic; Enorama Creek section, Flinders Ranges, South Australia) 11 : 無料・フリー素材/写真
Cryogenian-Ediacaran boundary (basal Nuccaleena Formation, Neoproterozoic; Enorama Creek section, Flinders Ranges, South Australia) 11 / 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 | This is a "GSSP", a global stratotype section and point. Stratigraphers have been establishing these for important boundaries on the geologic time scale for many years now. This particular GSSP is in the Flinders Ranges of South Australia - it defines the boundary between the last two systems of the Precambrian, the Cryogenian (below) and the Ediacaran (above).The reddish rocks in the lower part of the photo are sandstones in the basal Nuccaleena Formation, which overlie dark reddish glacial tillites of the Elatina Formation (just out of frame here). The tillites were deposited during the Marinoan Glaciation, which was one of two or three Snowball Earth glaciations in the Neoproterozoic - all or almost all of Earth was covered in ice. Each Snowball Earth glaciation was followed by a super-greenhouse climate, which resulted in the deposition of "cap carbonates" (= buff-colored dolostones in the top part of the photo).The Cryogenian-Ediacaran boundary is a bit above the reddish-to-buff color change in the section.Stratigraphy: Ediacaran-Cryogenian boundary in the basal Nuccaleena Formation, middle-upper Neoproterozoic boundaryLocality: outcrop along Enorama Creek, Brachina Gorge Geologic Trail, Flinders Ranges National Park, South Australia (31° 19.892’ South latitude, 138° 38.001’ East longitude)--------------------------------See info. at:en.wikipedia.org/wiki/Cap_carbonateanden.wikipedia.org/wiki/Marinoan_glaciationanden.wikipedia.org/wiki/Snowball_Earth |
| 撮影日 | 2006-08-19 21:57:36 |
| 撮影者 | James St. John |
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