Carl
Brett
Sequence Stratigraphy, Depositional Environments and Paleoecology of Middle
Paleozoic (Middle Ordovician to Upper Devonian) Rocks in the Northern Appalachian
Basin
(with G. C. Baird; SUNY College at Fredonia).
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studies of paleoenvironments and basin analysis by Carl Brett and colleagues
involve high resolution event and sequence stratigraphy of Ordovician
to Devonian strata in the Appalachian. These studies utilize varied correlational
tools, including: condensed horizons, and paleontologic event beds (obrution
layers, epiboles), and fingerprinted K-bentonites. These approaches have
been used in developing bed level correlational frameworks throughout
the northern-central Appalachian Basin in Ontario, New York, Pennsylvania,
and Maryland. Brett and Baird are attempting to extend correlation into
the southern Appalachian and mid-continent region. The objectives of this
study include: a) development of a refined stratigraphic framework for
examining evolutionary ecology of middle Paleozoic marine communities,
b) establishment of detailed sequence stratigraphy and relative sea-level
curves for the Appalachian foreland basin, c) determination of patterns
of foreland basin evolution and syntectonic sedimentation, d) development
of models that relate patterns of temporal change in fossil assemblages
to sequence stratigraphy.
Results of this research on the Silurian System were presented at the
James Hall Symposium, held in August, 1996 at the University of Rochester,
and associated field trips. A parallel conference on the Devonian System,
including a field transect of Middle to Upper Devonian strata from Lake
Erie to the Catskill Front, was held July 20-21, 1997. For further imformation
contact Carl Brett (University of Rochester; cebh@dbl.cc.rochester.edu)
or William Kirchgasser (SUNY Potsdam; kirchgwt@potsdam.edu).
A recent initiative in this general area is the development of a detailed
sequence and cycle stratigraphy for the Upper Ordovician in the Cincinnati
Arch region (Algeo and Brett, 2001; Brett et al. 2002). Field work near
Cincinnati, with Thomas J. Algeo (UC) and graduate students Pat McLaughlin,
Susannah Taha McLaughlin, Brian Kirchner, and Russell Kohrs is focused
on refined stratigraphy and cycle interpretation, taphonomy, and paleoecology
of this interval (Algeo and Brett, 1999). Detailed field study in northern
Kentucky has corroborated a pattern of meter- to decameter scale cycles
previously identified by Steve Holland and his colleagues. In addition
we have found that stratal units at many scales, from individual cm-scale
beds to decameter scale submembers are traceable for about 100 km in the
study area. We are continuing this research with further correlation of
the Kope and underlying Point Pleasant and Lexington limestones into the
subsurface as well as to the south and southwest . We are also continuing
detailed comparative studies of proximal-distal changes along single beds
and bundles. The preliminary work suggests the feasibility of tying at
least the larger, decameter-scale cycles in with patterns previously recognized
for equivalent age strata in the Appalachian Basin. This work is providing
insights into the geometry and evolution of the enigmatic Sebree trough
in the Ohio-Kentucky subsurface and its relation to ongoing Taconic tectonism
to the northeast.Recent collaborative work with graduate student David
Ray and Warren Huff (University of Cincinnati) led to discovery of several
probable K-bentonites in the Silurian of western New York. These included
two unctuous smectitic clays from the Williamson Shale (latest Llandovery),
as well as K-bentonites in the Gasport Limestone (middle upper Wenlock),
and clay layers (possible bentonites) in the upper Irondequoit Limestone
and Rochester Shale. These findings are particularly intriguing in conjunction
with our discovery of additional new K-bentonites in the latest Llandovery
(Crab Orchard Shale, Osgood Shale) and middle-upper Wenlock (Bisher, Louisville
formations) in southern Ohio, Kentucky, and Indiana. We intend to pursue
this project with chemical fingerprinting of the bentonites and attempts
at correlations between the Appalachian foreland basin and the mid-continent
region.
We are also studying the detailed event and sequence stratigraphy of Silurian
units of the southeast flank of the Cincinnati Arch in southern Ohio and
northern Kentucky (Brett and Algeo, 1999). We have begun to trace out
two previously unrecognized disconformities, as well as major flooding
surfaces, in the Bisher Formation (Wenlock). These discontinuities appear
to be correlative with sequence bounding unconformities and flooding surfaces
already correlated in the Appalachian Basin. Moreover, reconnaissance
studies in southern Indiana suggest that these depositional sequences
can also be recognized on the west side of the Cincinnati Arch. It is
also intriguing that a newly recognized interval of strongly dolomitized
bioherms (previously considered to be collapse breccias) from the middle
upper Wenlock Lilly/upper Bisher formations may correlate with the widespread
Gasport “reef” tract in the Appalachian Basin. Together, these
studies indicate that a much more detailed, sequence based stratigraphy
for the Lower Silurian can be extended from the Appalchian Basin into
the North American Mid-continent, further supporting eustatic sea level
fluctuation as a cause for these sequences. A final interesting development
is the recognition of a 0.5 to 1 m interval of strongly deformed, silty
dolostones within the Bisher Formation of Ohio and Kentucky. This interval
appears to be coeval with the widespread deformed DeCew Dolostone of New
York and Ontario. If so, this could represent one of the most widespread
“seismite” horizons presently known.
.
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References
Brett, C. E. and Baird, G. C. 1994. Depositional sequences, cycles, and
foreland basin dynamics in the late Middle Devonian (Givetian) of the
Genesee Valley and western Finger Lakes region. New York State Geological
Association, 66th Annual Field Trip Guidebook, p. 505-590.
Brett, C. E. and Baird, G. C. 1997, Epiboles and larger bioevents, In
Brett, C. E. and Baird, G. C. eds. Paleontological Events: Stratigraphic,
Ecological, and Evolutionary Implications. Coumbia University Press.
Brett, C. E. and Calkin, P. E., 1996, Silurian stratigraphy and Quaternary
geology of the Niagara area. A Guidebook for Field trips in Niagara County,
New York for Northeast Section Meeting of the Geological Society of America,
State University of New York at Buffalo, Buffalo, New York; 93 p.
Brett, C. E. and Goodman, W. M., 1996, Upper Ordovician and Silurian sequence
stratigraphy and depositional environments in western New York: A Field
Guide for the James Hall Symposium, Second International Symposium on
the Silurian System; University of Rochester, Rochester, NY., 178 p.
Brett, C. E., and Baird, G. C. 1996, Middle Devonian sedimentary cycles
and sequences in the Northern Appalachian Basin. In Witzke, B. J., Ludvigson,
G. A., and Day, J., eds., Paleozoic Sequence Stratigraphy: Views from
the North American Craton. Geological Society of America Special Paper
306, p. 213-241.
Brett, C. E. and Goodman, W. M., 1996, Sequence stratigraphy of central
Pennsylvania and central New York State: A regional synthesis. In Broadhead,
T. W., ed., Sedimentary Environments of Silurian Taconia. University of
Tennessee Department of Geological Sciences Studies in Geology, V. 26,
p. 170-199.
Brett, C. E. and Goodman, W. M., 1996, Silurian stratigraphy of the type
Clinton area of central New York. In Broadhead, T. W., ed., Sedimentary
Environments of Silurian Taconia. University of Tennessee Department of
Geological Sciences Studies in Geology, v. 26, p. 200-230.
Brett, C. E., Goodman, W. M., and LoDuca, S. T., 1990, Sequences, cycles,
and basin dynamics in the Silurian of the Appalachian foreland basin.
Sedimentary. Geol. 69, 191-244.
Brett, C. E. and Ver Straeten, C.A. 1994. Stratigraphy and facies relationships
of the Eifelian Onondaga Limestone (Middle Devonian) in western and west-central
New York State. New York State Geological Association, 66th Annual Field
Trip Guidebook, p. 221-269.
Mayer, S. M., Baird, G. C., and Brett, C. E. 1994. Correlation of facies
divisions in the uppermost Ludlowville Formation (Givetian) across western
and central New York State. In Landing, E. Studies in Stratigraphy and
Honor of Donald W. Fisher. New York State Museum Bulletin 481, p. 229-264.
Baird, G.C., Brett, C.E., and Ver Straeten, C.A., 1999, The first great
Devonian flooding episodes in western New York: Reexamination of Union
Springs, Oatka Creek, and Skaneateles Formation successions (latest Eifelian-lower
Givetian) in the Buffalo- Seneca Lake region. New York State Geological
Association 71st Annual Meeting, Field Trip Guide book, Fredonia, NY,
p. A1-A44.
Brett, C.E., 1999, Wenlockian fossil communities in New York State and
adjacent areas. In Boucot, A.J. and Lawson, J.D., eds., Paleocommunities:
A Case Study from the Silurian and Lower Devonian. Cambridge University
Press. p. 592-637.
Brett, C.E., Goodman, W.M., LoDuca, S.T. and Tetreault, D.K., 1999, Silurian-Early
Devonian sequence stratigraphy, events, and paleoenvironments of western
New York and Ontario, Canada. New York State Geological Association 71st
Annual Meeting, Field Trip Guidebook, Fredonia, NY, p. B1-B58.
Brett, C.E. and Algeo, T.J., 2001, Sequence stratigraphy of Upper Ordovician
and Lower Silurian strata of the Cincinnati Arch region. In Algeo, T.J.
and Brett, C.E., eds., Sequence, Cycle and Event Stratigraphy of Upper
Ordovician & Silurian Strata of the Cincinnati Arch Region, Guidebook,
1999 Field Conference, Great Lakes Section SEPM-SSG (Society for Sedimentary
Geologists), p. 34-46.
Brett, C.E. and Algeo, T.J., 2001, Stratigraphy of the Upper Ordovician
Kope Formation in its type area, northern Kentucky, including revised
nomenclature. In Algeo, T.J. and Brett, C.E., eds., Sequence, Cycle and
Event Stratigraphy of Upper Ordovician & Silurian Strata of the Cincinnati
Arch Region, Guidebook, 1999 Field Conference, Great Lakes Section SEPM-SSG
(Society for Sedimentary Geologists), p. 47-64.
Brett, C.E. and Algeo, T.J., 2001, Event beds and small-scale cycles in
Edenian to lower Maysvillian strata (upper Ordovician) of northern Kentucky:
Identification, origin, and temporal constraints. In Algeo, T.J. and Brett,
C.E., eds., Sequence, Cycle and Event Stratigraphy of Upper Ordovician
& Silurian Strata of the Cincinnati Arch Region, Guidebook, 1999 Field
Conference, Great Lakes Section SEPM-SSG (Society for Sedimentary Geologists),
p.65-92.
Brett, C.E., Baarli, B.G., Chowns, T., Cotter, E., Driese, S., Goodman,
W., and Johnson, M.E., 1998. Early Silurian condensed intervals, ironstones,
and sequence stratigraphy in the Appalachian foreland basin. In Landing,
E., ed., New York State Museum Bulletin 491:, p. 89-143
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