| dc.description.abstract | Large regions of the littoral lake bottom along structural platforms in Lake Tanganyika, Africa, are carpeted with shell beds of late Holocene age. The viviparous gastropod Neothauma tanganyicense (Neothauma) is the lead contributor to these accumulations but the snail itself is rarely found living on or adjacent to the shell accumulations (poor live-dead agreement), which makes it difficult to develop a model for the process(es) of shell accumulation and consequent community structuring of those organisms that occupy the shell beds.
In this study, time averaging and taphonomy of shell beds located in Kungwe Bay, Lake Tanganyika are examined to better understand paleoecology, paleoclimate, and the processes that lead to the formation of the shell beds. Radiocarbon dating indicates that Neothauma deposits in the region are time averaged over the last ~3300 years. Young shells are primarily located in shallow water, older shells are located in deep water, and temporal mixing varies based on the slope of river deltas. Taphonomic results indicate that water depth and siliciclastic deltaic input both influence the degree of Neothauma shell abrasion and encrustation. Shells coated with a black coating and reddish-orange oxidation patinas show signs of exposure, burial, and microbial activity. The shell beds accumulate as lake-level fluctuation impacts and reworks the river deltas where Neothauma live. The results from this study build a framework for climate, lake-level fluctuation, and deltaic depositional processes which play unique roles in the distribution and accumulation of shell beds in Lake Tanganyika, and can be used to interpret paleoenvironment in the geologic record. | en_US |
