Random Formation
| Random Formation | |
|---|---|
| Stratigraphic range: Early Cambrian | |
| Type | Formation |
| Underlies | Bonavista Fm |
| Overlies | Chapel Island Fm |
| Location | |
| Region | Newfoundland |
| Country | Canada |
The Random Formation is a near-shore rock unit dating to the early Cambrian period, incorporating quartzites, glauconitic and mud-cracked mudstones (now shales), and red channel sandstones.[1] It was deposited quickly and isn't super thick - 175m perhaps at a max.[2] The Blue Pinion Formation was originally recognized as a separate formation, but is now interpreted as an expression of the Random Fm.[3]
Age
The Stage 2 - Stage 3 bounrdary (Tommotian/Atdabanian) is thought to lie within the Random formation, or possibly in the overlying Bonavista Fm; the Smith Point Fm above that hosts the first trilobites.[4]
Palaeontology
The triolobite-like trace fossils Rusophycus & Cruziana occur in the Random Fm, alongside a range of other ichnofissils including Diplocraterion, Paleodictyon, Scolicia, and Squamodictyon.[4] Body fossils include the SSF Aldanella attleborensis assemblage.[5]
Refereces
- ^ Hiscott, Richard N. (1982). "Tidal deposits of the Lower Cambrian Random Formation, eastern Newfoundland: Facies and paleoenvironments". Canadian Journal of Earth Sciences. 19 (10): 2028. doi:10.1139/e82-180.
- ^ Crimes, Thomas Peter (1992). "The Record of Trace Fossils across the Proterozoic—Cambrian Boundary". Origin and Early Evolution of the Metazoa. Topics in Geobiology. Vol. 10. p. 177. doi:10.1007/978-1-4899-2427-8_6. ISBN 978-1-4899-2429-2.
- ^ Anderson, M. M. (1981). "The Random Formation of southeastern Newfoundland; a discussion aimed at establishing its age and relationship to bounding formations". American Journal of Science. 281 (6): 807. doi:10.2475/ajs.281.6.807.
- ^ a b Peter Crimes, T. (1987). "Trace fossils and correlation of late Precambrian and early Cambrian strata". Geological Magazine. 124 (2): 97–119. doi:10.1017/S0016756800015922.
- ^ Bengtson, Stefan; Fletcher, Terence P. (1983). "The oldest sequence of skeletal fossils in the Lower Cambrian of southeastern Newfoundland". Canadian Journal of Earth Sciences. 20 (4): 525. doi:10.1139/e83-050.