A Method for the Geometric Analysis of Rugose Coral Growth Ridges as Paleoenvironmental Indicators in the Middle Devonian Hungry Hollow Member of Widder Formation, Michigan Basin

Author

Andrew Thomson, The University of Western OntarioFollow

Degree

Master of Science

Program

Geology

Supervisor

Tstujia, Cameron J.,

2nd Supervisor

McCausland, Philip, J.A.,

Co-Supervisor

Abstract

Skeletons of Devonian rugose corals feature submillimetre-scale growth ridges on their outer surface (epitheca) that record the successive positions of the coral polyp during longitudinal corallite growth. Specimens of rugose corals Eridophyllum and Cystiphylloides from the Hungry Hollow Member of the Middle Devonian Widder Formation were sectioned longitudinally and imaged by SEM, and image processing techniques were applied to extract a line representing the epithecal surface. Local extrema found through peak detection allowed growth ridges to be represented as simplified triangles, so that geometric measurements (area, length) could be related to coral growth and analyzed in reference to possible paleoenvironmental cycles. This research has produced an objective method for the extraction of growth ridge data from a two-dimensional coral slice, although slice location was found to influence results. Results show potential sub-monthly bundles of ~15-17 ridges, not previously observed, which suggest a lunar/tidal influence on coral growth.

Recommended Citation

Thomson, Andrew, "A Method for the Geometric Analysis of Rugose Coral Growth Ridges as Paleoenvironmental Indicators in the Middle Devonian Hungry Hollow Member of Widder Formation, Michigan Basin" (2017). Electronic Thesis and Dissertation Repository. 5087.
https://ir.lib.uwo.ca/etd/5087