| Autor: |
K E, Karlstrom, S A, Bowring, C M, Dehler, A H, Knoll, S M, Porter, D J, Des Marais, A B, Weil, Z D, Sharp, J W, Geissman, M B, Elrick, J M, Timmons, L J, Crossey |
| Rok vydání: |
2001 |
| Předmět: |
|
| Zdroj: |
Geology. 28(7) |
| ISSN: |
0091-7613 |
| Popis: |
The Chuar Group (approximately 1600 m thick) preserves a record of extensional tectonism, ocean-chemistry fluctuations, and biological diversification during the late Neoproterozoic Era. An ash layer from the top of the section has a U-Pb zircon age of 742 +/- 6 Ma. The Chuar Group was deposited at low latitudes during extension on the north-trending Butte fault system and is inferred to record rifting during the breakup of Rodinia. Shallow-marine deposition is documented by tide- and wave-generated sedimentary structures, facies associations, and fossils. C isotopes in organic carbon show large stratigraphic variations, apparently recording incipient stages of the marked C isotopic fluctuations that characterize later Neoproterozoic time. Upper Chuar rocks preserve a rich biota that includes not only cyanobacteria and algae, but also heterotrophic protists that document increased food web complexity in Neoproterozoic ecosystems. The Chuar Group thus provides a well-dated, high-resolution record of early events in the sequence of linked tectonic, biogeochemical, environmental, and biological changes that collectively ushered in the Phanerozoic Eon. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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