Carl
Brett
Comparative Taphonomy and Paleoecology of Paleozoic and Mesozoic Mud Rock
Facies
(NATO funded collaborative research with Peter A. Allison, Imperial College,
London, England; and W. David Liddell, Utah State University).
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The aims of this research are a) to develop broader models of mudrock
taphofacies and biofacies; and b) to relate patterns of taphonomic and
biotic change to sequence and event stratigraphy. Brett and Allison are
testing the generality of hypotheses originally generated for middle Paleozoic
marine strata of the Appalachian Basin (e.g. Brett, 1995), in other geologic
times and places. To this end, Allison and Brett have undertaken a series
of comparative taphofacies-sequence stratigraphic studies in two major
areas in which general stratigraphic settings are similar to those previously
studied in the mid Paleozoic: a) Middle Cambrian of western North America;
b) Jurassic of England.
Research on the taphofacies of early Paleozoic mudrock facies has included:
a) study on the taphonomy of the famed Middle Cambrian Burgess Shale (Allison
and Brett, 1995), and b) a collaborative field project, involving Brett,
David Liddell (Utah State University) and Gordon Baird (SUNY College at
Fredonia), on the sequence stratigraphy, and tapho- and biofacies of the
Middle Cambrian of Utah. Brett and colleagues have delineated a series
of small, intermediate, and large scale cycles within the Wheeler and
Marjum Formations that can be correlated in south-central Utah. Large
scale cycles and fourth order sequences display distinct boundaries and
flooding surfaces with condensed fossil rich beds that are analogs to
condensed shell beds previously identified and mapped in the Paleozoic
of the Appalachian Basin. Within this framework, we are documenting patterns
of biofacies and taphofacies and attempting to test and refine some predictive
models for . In the fall of 1997, Liddell and Brett intend to run a GSA
post-meeting field conference to examine aspects of the Middle Cambrian
sequence stratigraphy, paleoecology, and taphonomy.
Brett, Allison, and graduate student Heather Moffat have also begun a
comparative study of Ordovician-Devonian dark gray shale facies with those
of the Lower Jurassic shales in the Dorset, Somerset, and Yorkshire coastal
sections of Great Britain. Preliminary field work demonstrates the feasibility
of recognizing analogous patterns of sequence stratigraphy and distribution
of taphofacies in the Paleozoic and Jurassic. Furthermore, we have recognized
that the dark shale facies constitute parts of larger sequences in both
systems. Brett and colleagues intend a more thorough comparison of the
taphonomy, paleoecology, and geochemistry of the Devonian and Jurassic
shales and their relationship to large scale and small scale, probable
Milankovitch-related cyclicity.
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References
Allison, P. A. and Brett, C. E. 1995. In situ benthos and paleo-oxygenation
in the Middle Cambrian Burgess Shale, British Columbia, Canada. Geology
23: 1079-1082.
Allison, P. A., Wignall, P., and Brett, C. E. 1995. Palaeo-oxygenation:
effects and recognition. In Bosence, D. W. and Allison, P. A., eds., Marine
Palaeoenvironmental Analysis from Fossils. Geological Society Special
Publication 83: 97-112.
Allison. P. A., Brett, C. E., Liddell, W. D. and Wright, E. 1995. Repetitive
tapho-, bio-, and lithofacies within the Middle Cambrian Swasey-Wheeler
Shale transition of Utah. Geological Society of America, Abstracts with
Programs 27 (6): A 374.
Brett. C. E. 1995. Sequence stratigraphy, biostratigraphy, and taphonomy
in shallow marine environments. Palaios 10: 597-516.
Brett, C. E. and Baird, G. C. 1993. Taphonomic approaches to temporal
resolution in stratigraphy: Examples from Paleozoic marine mudrocks. In
Kidwell, S. M. and Behrensmeyer, A. K., eds., Taphonomic Approaches to
Time Resolution in Fossil Assemblages. Short Courses in Paleontology;
Paleontological Society Special Publications 6: 250-274.
Brett, C. E. and Allison, P. A. (in press). Paleontological approaches
to the environmental interpretation of marine mudrocks. In J. Schieber
, ed., Mudrocks and their Paleoenvironmental Interpretation
Liddell, W. D., Wright, E. J., Brett, C. E., Allison, P. A. and Baird,
G. C. 1995. A sequence stratigraphic model for Middle Cambrian trilobite
assemblages from the eastern Great Basin. Geological Society of America,
Abstracts with Programs 27 (6): A 374. 1995
Brett, C.E., Whiteley, T.E., Allison, P.A., and Yochelson, E.L. 1999
The Walcott-Rust quarry: A Middle Ordovician trilobite Konservat-Lagerstätten.
Journal of Paleontology v. 73, p. 288-305.
Parsons-Hubbard, K.M., Callender, W.R., Powell, E.N., Brett, C.E.,
Walker, S.E., Raymond, A.L., and Staff, G.M. 1999, Rates of burial and
disturbance of experimentally-deployed molluscs: Implications for
preservation potential, Palaios, v.14, p.
Walker, S.E., Parsons-Hubbard, K., Powell, E.N., and Brett, C.E., 1998.
Bioerosion or bioaccumulation? Shelf-slope trends for epi-and endobionts
on experimentally deployed gastropod shells, Historical Biology, 13, p.
61-72.
Parsons-Hubbard, K.M., Powell, E.N., Staff, G.M., Callender, W.R., Brett,
C.E., and Walker, S.E., (2002). The effect of burial on shell
preservation and epibiont cover in Gulf of Mexico and Bahamas shelf and
slope environments: A two-year experimental study. Organism-Sediment Interactions,
J.Y. Aller, S.A. Woodin, and R.C. Aller, editors; Univ. of South Carolina
Press, Belle W. Baruch Marine Laboratory Library on Marine Research, Volume
21.
Walker, S.E., Parsons-Hubbard, K.M., Powell, E., and Brett, C. E., (in
revision), Predation on experimentally deployed molluscan shells from
shelf to slope depths in a tropical carbonate environment, Palaios.
Callender, W.R., Staff, G.M., Parsons-Hubbard, K.M., Powell, E.N., Rowe,
G.T., Walker, S.E., Brett, C.E., Raymond, A., Carlson, D., White, S.,
Heiss, E., (in review), Taphonomic trends along a forereef slope: Lee
Stocking Island, Bahamas. I. Location and water depth. Palaios.
Staff, G.M., Callender, W.R., Powell, E.N., Parsons-Hubbard, K.M., Brett,
C.E., Walker, S.E., Carlson, D., White, S., Raymond, A., Heiss, E.,
Taphonomic trends along a forereef slope: Lee Stocking Island, Bahamas.
II. Time, Palaios.
Powell, E.N., Parsons-Hubbard, K.M., Callender, W.R., Staff, G.M., Rowe,
G.T., Brett, C.E., Walker, S.E., Raymond, A., Carlson, D., White, S.,
Heise, E., Taphonomy on the continental shelf and slope: Two-year trends
- Gulf of Mexico and Bahamas, Palaios.
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