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Full-Text Articles in Physical Sciences and Mathematics
Stratigraphy, Sedimentology, And Deformational Significance Of Cambrian And Early Ordovician Strata Along The Southeast Wisconsin Arch, Allison Raeann Kusick
Stratigraphy, Sedimentology, And Deformational Significance Of Cambrian And Early Ordovician Strata Along The Southeast Wisconsin Arch, Allison Raeann Kusick
Theses and Dissertations
A detailed study of the stratigraphic units in and around the Wisconsin Arch of central and southeast Wisconsin are presented to refine the sedimentologic record and the geologic implications within the Cambrian and early Ordovician strata. The Cambrian and early Ordovician sediments in central and southeast Wisconsin unconformably overlie a topographic high composed of Precambrian basement rocks, called the Wisconsin Arch, and consist of various clastic deposits, dolostones, and several horizons of deformation. Bedrock cores, made available through the Wisconsin Geological and Natural History Survey (WGNHS), were analyzed, to understand sedimentation in the Cambrian and early Ordovician. My analyses focused …
Incorporation, Morphology, And Extinction Of Framework-Building Metazoans In Early Cambrian Reef Ecosystems From The Western Usa And Mongolia And Their Effects On Reef Diversity, David Russell Cordie
Incorporation, Morphology, And Extinction Of Framework-Building Metazoans In Early Cambrian Reef Ecosystems From The Western Usa And Mongolia And Their Effects On Reef Diversity, David Russell Cordie
Theses and Dissertations
The early Cambrian represents an important transition in the evolution of life, perhaps most vividly exemplified by reef ecosystems as they changed from microbial-supported to metazoan-supported framework reefs. Microbial reefs were initially composed of Renalcis- and Epiphyton-group calcifying microbes. Subsequent reefs began to incorporate archaeocyathan sponges within this framework. This represents a shift in the source of carbonate production, which can be quantified using thin section point counts. In archaeocyathan reefs from the western USA, carbonate contribution from metazoan framework builders increased from zero to 29.7%. Similar reefs from Mongolia increased from zero to 5.0%. Increases in Laurentian archaeocyath contributions …