Foraminiferal taphonomy - examples from Upper Cretaceous Forbes Formation
From the original living population of benthonic foraminifera on the sea floor to the final data presentation, the path of interpretation is fraught with pitfalls. Sediment input and bottom-water motion scatter, concentrate, or dilute tests. Bioturbation and ingestion by fauna destroy foraminifers, and chemical effects in the sediments remove others. Mechanical breakage, aided by chemical destruction, continues during burial and postdepositional diagenesis. Calcareous material is removed by ground water, and the further effects of late-stage diagenesis, including compaction and mineral overgrowth of specimens, complicate the picture. The Forbes Formation contains two unique foraminiferal assemblages. In the lower part, diverse species of calcareous and agglutinated foraminifera are present. In the upper and middle Forbes, the assemblage is largely agglutinated. Are these the intact, original fauna or are they preservational residues. The authors believe that the Forbes assemblages are of similar original composition, and the duality is the result of differential preservation related to bioturbation, net sediment-accumulation rates, and the position of the carbonate compensation depth. These effects are prediagenetic to syndiagenetic. Changes in the original environment can be deduced through taphonomy, and the original environmental conditions detected.
- Research Organization:
- Univ. of Southern California, Los Angeles
- OSTI ID:
- 6987344
- Report Number(s):
- CONF-8604187-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 70:4; Conference: American Association of Petroleum Geologist Pacific Section convention, Bakersfield, CA, USA, 16 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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