Sedimentation and Tectonics: Geologic History of the Appalachian Basin

Bosiljka Glumac
,
Smith College
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Summary

This culminating mini-project challenges students to utilize all the skills and knowledge acquired throughout the semester, thus effectively reviewing and summarizing many key concepts linking sedimentation and tectonics of the Appalachian basin.

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Context

Audience

An undergraduate required course in sedimentary geology that meets twice as week for 1 hr 20 minutes, and once a week for 2 hrs 50 minutes for a total of 13 weeks and has up to 20 students.

Skills and concepts that students must have mastered

Students know how to examine and interpret both siliciclastic and carbonate sedimentary rocks, and are familiar with various depositional environments and the concept of sea level change. Students also know (or can learn from this activity) about major mechanisms of basin formation and subsidence in different plate tectonic settings.

How the activity is situated in the course

This is a culminating mini-project, which also helps students decipher the relationship between sedimentation and tectonics for two large projects whose final reports are due near the end of the semester: 1) Ordovician sedimentation and collisional tectonics, eastern New York; and 2) geologic history of a Mesozoic rift basin, central Massachusetts.

Goals

Content/concepts goals for this activity

Petrology of sedimentary rocks (review), interpretation of depositional environments (review), sea level change, stratigraphy, basin subsidence, sedimentation and tectonics.

Higher order thinking skills goals for this activity

Observational and interpretational skills; synthesis of information from multiple sources; visual representation and interpretation of information.

Other skills goals for this activity

Compilation of data and performing sediment backstripping analysis; construction and interpretation of graphs (burial or subsidence curves); working in groups.

Description of the activity/assignment

To demonstrate potential links between sedimentation and tectonics students first examine a suite of samples from the southern Appalachians with the goal of interpreting depositional environments and reconstructing a history of relative sea level change. Next, the students compile stratigraphic information for 5 different regions throughout the Appalachian basin and construct burial curves using a sediment backstripping program. The observations and conclusions about sea level change and variable basin subsidence rates are then related to possible tectonic causes to reconstruct the geologic history of the Appalachians.

Determining whether students have met the goals

Students complete and turn in two worksheets (see the actual assignment) together with copies of all five subsidence curves they constructed and interpreted (labeled). The students also use the ideas from this activity in finalizing their two other major projects (on Ordovician of New York, and Mesozoic of Massachusetts).

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Teaching materials and tips

Other Materials

Supporting references/URLs


Basin subsidence:

Allen, P.A., and Allen, J.R., 1990, Basin Analysis: Principles and Applications: Blackwell, 451 p.: Figure 1.12. The three basic mechanisms for basin subsidence (p. 14); and Figure 6.11. Sequence of diagrammatic cross-sections of the Appalachian foreland basins (p. 156).

Einsele, G., 1992, Sedimentary basins: Evolution, Facies, and Sediment Budget: Springer-Verlag, 628 p.: Figure 12.30. Model showing transition from remnant oceanic basin to foreland basin (p. 486).

Sediment backstripping:

Wilkerson, M.S., and Hsui, A.T., 1989, Application of sediment backstripping corrections for basin analysis using microcomputers: Journal of Geological Education, v. 37, p. 337-340.

Larrieu, T.L., 1995, Basin analysis with a spreadsheet: Journal of Geoscience Education, v. 43, p. 107-113

OSXBackstrip by Nestor Cardozo (nfcd@mac.com) is freeware available from: http://www.apple.com/downloads/macosx/math_science/osxbackstrip.html

Tectonic history of the Appalachians:

Hatcher, R.D., Jr., 1989, Tectonic synthesis of the U.S. Appalachians, in Hatcher, R.D., Jr., Thomas, W.A., and Viele, G.W., eds., The Appalachian-Ouachita Orogen in the United States: The Geology of North America, v. F-2, p. 511-535. Focus on Figure 9.

Prothero, D.R., and Dott, R.H., 2004, Evolution of the Earth, 7th edition: McGraw Hill, 524 p.: Figure 11.36. Early Ordovician paleotectonic map showing inferred relationships of North America to Europe and Africa (p. 255); Figure 12.44. Paleotectonic map showing final closure of the proto-Atlantic (Iapetus) Ocean in middle Paleozoic time (p. 293); Figure 12.45. Hypothetical evolution of northern Appalachian-Caledonian orogenic system (p. 294); and Figure13.28. Hypothetical scenario for the evolution of the southern Appalachian orogenic belt (p. 320).

The Paleomap Project by Christopher R. Scotese (http://www.scotese.com/).

Depositional history of eastern Tennessee:

Walker, K.R., (ed) 1985, The geologic history of the Thorn Hill Paleozoic Section (Cambrian-Mississippian), eastern Tennessee, SE-GSA Filed Trip 6: University of Tennessee, Department of Geological Sciences, Studies in Geology 10, 128 p.

Appalachian stratigraphy:

COSUNA Charts: Correlation of Stratigraphic Units of North America (COSUNA) Project by the American Association of Petroleum Geologists, 1985: Southern Appalachian region, and Northern Appalachian Region.