Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

PALAIOS

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by BRADSHAW, C. Articles by SCOFFIN, T. P. Search for Related Content GeoRef GeoRef Citation

Differential Preservation of Gravel-sized Bioclasts in Alpheid- versus Callianassid-Bioturbated Muddy Reefal Sediments

¹ Port Erin Marine Laboratory, University of Liverpool, Isle of Man IM9 6JA, UK
² Department of Geology and Geophysics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, UK

ABSTRACT

Infaunal bivalve shells were extracted from sediment cores taken in shallow seas off Phuket, South Thailand, and were scored for four types of taphonomic degradation to assess the effect that different types of bioturbation have on the preservation of such bioclasts. This gravel-sized fraction of off-reef biogenic (bivalve) sediments showed variation in the extent of degradation, depending on whether it was found in an area bioturbated by callianassid or alpheid shrimps. Cores taken in the alpheid area have a higher proportion of grains with poorly defined shape and ornamentation, a loss of surface luster and high levels of microbioerosion. In contrast, those from the callianassid area have a higher proportion of shiny, sharply defined fragments and a lower level of microbioerosion than those from the alpheid area. It is concluded that the different nature of bioturbation in the two areas accounts for the difference in preservation. In working the sediment, callianassids bury the gravel fraction, while alpheids repeatedly bring it to the sediment surface, thus exposing it to higher levels of physical and microbiological erosion. The shrimps' activities result in a difference in preservation potential of fine and coarse sediments, and this taphonomic bias will affect taphofacies interpretation. Rapid burial of gravel by callianassids also has implications for time-averaging, as a shell fragment's condition is more indicative of its residence time at the surface-water interface than its age.

This article has been cited by other articles:

				A. Tomasovych and M. Zuschin Variation in brachiopod preservation along a carbonate shelf-basin transect (Red Sea and Gulf of Aden): Environmental sensitivity of taphofacies Palaios, October 1, 2009; 24(10): 697 - 716. [Abstract] [Full Text] [PDF]

				S. J. Beavington-Penney, V. P. Wright, and A. Racey The Middle Eocene Seeb Formation of Oman: An Investigation of Acyclicity, Stratigraphic Completeness, and Accumulation Rates in Shallow Marine Carbonate Settings Journal of Sedimentary Research, October 1, 2006; 76(10): 1137 - 1161. [Abstract] [Full Text] [PDF]

				Analysis of the Effects of Abrasion on the Test of Palaeonummulites venosus: Implications for the Origin of Nummulithoclastic Sediments Palaios, April 1, 2004; 19(2): 143 - 155.