Date of Award:
5-1981
Document Type:
Thesis
Degree Name:
Master of Science (MS)
Department:
Geosciences
Department name when degree awarded
Geology
Committee Chair(s)
Richard R. Alexander
Committee
Richard R. Alexander
Committee
Peter T. Kolesar
Committee
Robert Q. Oaks
Committee
Clyde T. Hardy
Abstract
Morphology of corals of the Late Ordovician through mid-Silurian Fish Haven and Laketown Formations were analyzed to document adaptations to inferred enviromental conditions, i.e., (bathymetry, illumination, sedimentation, currents, and energy), under which their enclosing sediment was deposited. Specimens and data were collected from six sites. Insoluble-residue tests were performed on the corals' matrices.
Individual corallites of radial-lensoidal corals radiate in all directions. Vertical growth, however, was restricted in turbulent conditions. Umbrellic, radial-lensoidal corals feature downward facing corallites, considered to be an adaptation to a well illuminated environment.
On tabular lensoidal corals, constituent corallites faces exclusively upward, an orientation needed under relatively poor illumination. Orientation of these coralla at oblique angles to bedding planes and to other coralla signify soft-sediment slumping or edge-first sinking into a semi-fluid substrate.
Hemispherical coralla prevailed under moderately high energy condition and negligible sedimentation. Conic coralla, formed during prodigious sediment accumulation, are extreme modifications of hemispherical coralla. The lower the rate of sediment accumulation, the less acute the angle of the apex (budding center of the 11cone").
Circumrotary corals, or those that are distinguished by corallites radiating in virtually all directions, are considered to have dwelled in heavy surf, by analogy to certain modern corals.
Composite corals, those that exhibit more than one morphotype or a repetition of the same morphotype, reflect a change in growth during the life of the colony.
Internal features of individual corallites were examined and measured. Most of the corals in this study feature corallites suggestive of low-sediment rejection capability. Corallite packing arrangements, as well as indicating cleansing ability, are interpreted as adaptations to different levels of hydraulic stress.
Checksum
f3b929be40b4778db3d6b9f1cb6b5784
Recommended Citation
Rich, Thomas B., "Growth-Form Analysis and Paleoecology of the Corals of the Late Ordovician Through Mid-Silurian Fish Haven and Laketown Formations, Bear River Range, North-Central Utah" (1981). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 5783.
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