Experiments on the Settling of Gastropod and Bivalve Shells: Biostratinomic Implications

McKittrick, M.A.

doi:10.1017/s2475262200004780

Cited by 3 publications

(2 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to evaluate the orientation of valves, it is important to keep in mind that valve orientation may be an ambiguous evidence of the action of a particular type of current (Mckittrich 1987).…”

Section: Taphofaciesmentioning

confidence: 99%

Shell bed stacking patterns in the Chachao Formation (early Valanginian) in Malargüe area, Mendoza province, Neuquen Basin-Argentina

Palma

Lanés

2001

Carbonates Evaporites

View full text Add to dashboard Cite

The Lower Cretaceous Chachao Formation in the Malargue anticline area consists of wackestone, packstone, and minor gramstone and mudstone rich in benthic fauna which were deposited in a shallow carbonate ramp. These shell beds are composed of a lowdiversity molluscan fauna mostly dominated by oysters, other benthic pelecypods (Eryphila sp., Ptychomya sp., Pecten sp., Pinna sp., Trigonia sp., Cucullaea sp.), serpulids (Sarcinella sp., Parsimoniasp.), and occasional ammonites (Olcosthepanus curacoensis).Most skeletal accumulations range from 15 to 70 em in thickness. Shell beds exhibit a sharp, flat and commonly undulating base. In some cases the tops were bioturbated pnncipally by Thalassinoides isp. Some shell beds show a densely packed biofabric (bioclastic-supported) but most of them have dispersed or loosely packed biofabric (mud-supported). Bioclasts include articulated or disarticulated shells, fragmented valves and shell debris. The analysis of shell concentrations of the Chachao Formation allow to recognize four taphofacies according to their taphonomic attributes.Different kind of processes, such as low-energy storm currents and waves, were interpreted, whose deposits are arranged into a coarseningand thickening-upward and then fining-and thinning upward trends. According to their biostratinomic features shell beds of Chachao Formationhave been interpreted as parautochthonous to autochthonous skeletal concentrations, mainly of sedimentologic origin.Towards the end ofthe Valanginian, the drowning ofthe carbonate ramp took place, related to a relative sea level rise and environmental stress. This drowning event was recorded by the alternating thin-to medium bedded dark gray carbonate and black shales (Agrio Formation) of LateValangiman-Late Hauterivian age.

show abstract

Section: Taphofaciesmentioning

confidence: 99%

Shell bed stacking patterns in the Chachao Formation (early Valanginian) in Malargüe area, Mendoza province, Neuquen Basin-Argentina

Palma

Lanés

2001

Carbonates Evaporites

View full text Add to dashboard Cite

show abstract

“…A number of detailed studies have evaluated the effect of shape, size, initial orientation, and grain size of the associated sediments on entrainment velocity of bivalve shells (Brenchley and Newall 1970;Trewin and Welsh 1972;Futterer 1982;Allen 1984;McKittrick 1987;Frey and Dö rjes 1988;Olivera and Wood 1997;; these experiments have shown that differences in these characteristics could alter the overall distribution of an assemblage by preferential removal of a particular group of shells (e.g., size class, shape class, taxa).…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Effects of Drill Holes on Postmortem Transportation of Bivalve Shells and Its Taphonomic Implications

Chattopadhyay

Rathie

Miller

et al. 2014

PALAIOS

View full text Add to dashboard Cite

Predatory drill holes in marine invertebrates are an important source of information on the nature of biotic interactions and are often used to explore the ecological and evolutionary roles of such interactions in deep time. Measures of drilling frequencies and drill-hole site stereotypy represent the raw data for inferring the intensity and selectivity of drilling predation. One potential source of bias explored in this study relates to the hydrodynamic properties of shells: presence of drill holes and/or drill-hole position may influence how shells behave when subjected to moving fluids. In a unidirectional flowtank study with the bivalve Donax scortum Linnaeus, 1758, we found that the threshold current velocity for the entrainment of undrilled convex-up shells is significantly lower than for centrally drilled shells, which could be explained by Bernoulli's principle. The position of the drill hole on a shell also affects its hydrodynamic properties because umbonally drilled shells require a lower entrainment velocity than centrally drilled shells. This difference could potentially result in assemblages of different stereotypic patterns. We also demonstrate the extent of alteration of an assemblage by this process using a simulation parameterized with experimental results. The latter show that a dramatic change in inferred drilling intensity, size selectivity, and stereotypic patterns from the original population can be produced by hydrodynamic sorting. Our study indicates that such sorting can yield a sample significantly different from the original one in terms of drill-hole characteristics. Hence, the effect of such bias should be assessed before inferring the nature of biotic interaction of fossil assemblages.

show abstract

Quantitative comparisons and models of time-averaging in bivalve and brachiopod shell accumulations

et al. 2010

View full text Add to dashboard Cite

The variation in time-averaging between different types of marine skeletal accumulations within a depositional system is not well understood. Here we provide quantitative data on the magnitude of time-averaging and the age structure of the sub-fossil record of two species with divergent physical and ecological characteristics, the brachiopodBouchardia roseaand the bivalveSemele casali.Material was collected from two sites on a mixed carbonate-siliciclastic shelf off the coast of Brazil where both species are dominant components of the local fauna.Individual shells (n= 178) were dated using amino acid racemization (aspartic acid) calibrated with 24 AMS radiocarbon dates. Shell ages range from modern to 8118 yearsb.p.for brachiopods, and modern to 4437 years for bivalves. Significant differences in the shape and central tendency of age-frequency distributions are apparent between each sample. Such differences in time-averaging magnitude confirm the assumption that taphonomic processes are subject to stochastic variation at all spatial and temporal scales. Despite these differences, each sample is temporally incomplete at centennial resolution and three of the four samples have similar right-skewed age-frequency distributions. Simulations of temporal completeness indicate that samples of both species from the shallow site are consistent with a more strongly right-skewed and less-complete age-frequency distribution than those from the deep site.We conclude that intrinsic characteristics of each species exert less control on the time-averaging signature of these samples than do extrinsic factors such as variation in rates of sedimentation and taphonomic destruction. This suggests that brachiopod-dominated and bivalve-dominated shell accumulations may be more similar in temporal resolution than previously thought, and that the temporal resolution of multi-taxic shell accumulations may depend more on site-to-site differences than on the intrinsic properties of the constituent organisms.

show abstract

Experiments on the Settling of Gastropod and Bivalve Shells: Biostratinomic Implications

Cited by 3 publications

References 13 publications

Shell bed stacking patterns in the Chachao Formation (early Valanginian) in Malargüe area, Mendoza province, Neuquen Basin-Argentina

Shell bed stacking patterns in the Chachao Formation (early Valanginian) in Malargüe area, Mendoza province, Neuquen Basin-Argentina

Hydrodynamic Effects of Drill Holes on Postmortem Transportation of Bivalve Shells and Its Taphonomic Implications

Quantitative comparisons and models of time-averaging in bivalve and brachiopod shell accumulations

Contact Info

Product

Resources

About