The Clemente Formation is a geologic formation composed of 210 m (690 ft) of Ediacaran siltstone, sandstone, quartzite, conglomerate, and minor dolomite. It is exposed in the exposed in the area of Cerro Rajon south of Caborca, northern Sonora, Mexico. It contains an oolitic dolomite marker bed correlated with the Johnnie Oolite in Death Valley, California, and preserves an isotopic record of the Shuram excursion.[1][3]
| Clemente Formation | |
|---|---|
| Stratigraphic range: Ediacaran [1] | |
| Type | Geological formation |
| Unit of | Caborca miogeoclinal succession |
| Underlies | Pitiquito Quartzite |
| Overlies | Caborca Formation |
| Thickness | 210 m (690 ft) |
| Lithology | |
| Primary | siltstone, sandstone, quartzite, and conglomerate[2] |
| Other | oolitic and aphanitic dolomite |
| Location | |
| Coordinates | 30°18′24″N 111°56′24″W / 30.30667°N 111.94000°W |
| Region | Cerro Rajon region, northern Sonora, Mexico |
| Country | Mexico |
| Type section | |
| Named for | Cerro Clemente[2] |
| Named by | Stewart and others (1984)[2] |
The Clemente Formation is named for Cerro Clemente, Sonora, which lies about 11 km (6.8 mi) south-southwest of the location of its composite type section. Cerro Rajon lies about 2.3 km (1.4 mi) south-southeast of the type section.[2][4]
Fossils
editMark McMenamin has reported from the Clemente Formation a Neoproterozoic Ediacaran biome as well as trace fossils and new taxa of enigmatic fossils.[5][6] Ben Waggoner has questioned whether these are fossils. He also noted that they predate the majority of Ediacaran biota by at least 50 million years.[3][7]
See also
edit
References
edit- ^ a b Loyd, S.J., Marenco, P.J., Hagadorn, J.W., Lyons, T.W., Kaufman, A.J., Sour-Tovar, F., and Corsetti, F.A., 2013. Local δ34S variability in 580Ma carbonates of northwestern Mexico and the Neoproterozoic marine sulfate reservoir. Precambrian Research, 224, p. 551- 569.
- ^ a b c d Stewart, J.H., McMenamin, M.A.S., and Morales-Ramirez, J.M., 1984. Upper Proterozoic and Cambrian rocks in the Caborca region, Sonora, Mexico—Physical stratigraphy, biostratigraphy, paleocurrent studies, and regional relations. U.S. Geological Survey Professional Paper, 1309, 36 pp. Reston, Virginia, U.S. Geological Survey.
- ^ a b Stewart, J.H., Amaya-Martínez, R., and Palmer, A.R., 2002. Neoproterozoic and Cambrian strata of Sonora, Mexico: Rodinian supercontinent to Laurentian Cordilleran margin, in Barth, A., ed., p. 5–48. Contributions to Crustal Evolution of the Southwestern United States. Special Paper, 36. Boulder, Colorado, Geological Society of America. 326 pp. ISBN 978-0-813-72365-5
- ^ El Prieto quadrangle, H12A77, l:50,000-scale map.
- ^ McMenamin, M.A., 1996. Ediacaran biota from Sonora, Mexico. Proceedings of the National Academy of Sciences, 93(10), pp.4990-4993.
- ^ McMenamin, M.A., 2018. Deep Time Analysis: A Coherent View of the History of Life. 288 pp. Berlin, Germany, Springer International Publishing. ISBN 978-3-319-74256-4, bibcode=2018dtac.book.....M
- ^ Waggoner, B., 1999. Biogeographic analyses of the Ediacara biota: a conflict with paleotectonic reconstructions. Paleobiology, 25(4) pp. 440-458.
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