Taphonomic reworking and stratal organization of tempestite deposition: Ordovician Kope Formation, northern Kentucky, USA

Citation
C. Drummond et H. Sheets, Taphonomic reworking and stratal organization of tempestite deposition: Ordovician Kope Formation, northern Kentucky, USA, J SED RES, 71(4), 2001, pp. 621-627
Citations number
15
Categorie Soggetti
Earth Sciences
Journal title
JOURNAL OF SEDIMENTARY RESEARCH
ISSN journal
15271404 → ACNP
Volume
71
Issue
4
Year of publication
2001
Part
B
Pages
621 - 627
Database
ISI
SICI code
1527-1404(200107)71:4<621:TRASOO>2.0.ZU;2-E
Abstract
Tempestite beds of the Ordovician Kope Formation of northern Kentucky provi de an interesting subject for numerical simulation and stratigraphic analys is, Taphonomic characteristics of these shell-rich beds suggest that they w ere formed by multiple reworking and amalgamation events. If so, then storm -driven redepositional processes could have led to temporal condensation wi thin the tempestite beds. Numerical simulation of tempestite formation indi cates that storm-bed abundance is maximized by frequent, weak storm events, whereas shell degradation is increased by frequent, strong storms. Convers ely, these stratigraphic and taphonomic parameters are insensitive to chang es in storm intensity when such events are relatively uncommon. Additionall y, the stratigraphic and taphonomic characteristics of tempestite formation are found to be largely insensitive to the abundance of shell material in the undisturbed shale, Lacunarity analysis of the vertical spacing of Kope Formation tempestite be ds (grainstones and packstones) demonstrates stratal clustering. Such clust ering was caused by either absolute or relative changes in storm intensity or frequency. Given the temporal scale of tempestite clustering within the Kope, changes in water depth across the shallow shelf-driven either by chan ges in sea level or sedimentation rate-is a likely mechanism by which such relative changes in storm processes occurred. Conversely, climatologic vari ability at the scale of tens to hundreds of thousands of years could drive absolute changes in storm intensity leading to stratigraphic clustering of tempestite beds.