Ichnology and Sedimentology of Glaucony Greensands: Paleoenvironmental, Sequence Stratigraphic and Paleoclimatic Implications

University Of Utah, Salt Lake City UT

Investigators

Abstract

Title: Ichnology and Sedimentology of Glaucony Greensands: Paleoenvironmental, Sequence Stratigraphic and Paleoclimatic Implications Allan A. Ekdale University of Utah EAR-1052661 ABSTRACT This is a project to investigate trace fossil-bearing greensand deposits in different parts of the geologic column in order to interpret the significance of green marine sedimentary deposits ("glaucony") in terms of paleoecology, ichnology, sedimentology, and paleoenvironments, with the potential implications for sea level dynamics, paleoclimates, mineral authigenesis, sea floor geochemistry and sequence stratigraphy. The project will employ both field observations and laboratory analyses. The approach will be an unusual coupling of ichnology with sedimentary mineralogy by examining trace fossil associations and ichnofabrics (biogenic sedimentary fabrics) in relation to the dynamic sedimentologic and sea floor geochemical environment that promoted the formation of glaucony (glauconite and other green marine clay minerals). The principal scientific objectives of this research include the following: (a) to determine the precise mineralogy of the green marine grains in a spectrum of greensand occurrences of Cambrian through Tertiary age; (b) to identify the associated trace fossils and characteristic ichnofabrics and ichnofacies within beds and on bedding surfaces at each study site; (c) to detail the vertical changes in trace fossils, ichnofabrics and sediment types in the greensand facies within beds and within parasequences; (d) to integrate ichnologic and sedimentologic observations within the different facies of greensands from various parts of the geologic column; (e) to interpret the findings in the context of sequence stratigraphy and sea level dynamics, specifically in relation to passive-margin condensed sections; and (f) to clarify the paleoclimate regime(s) in which glaucony may have formed in the past. In order to investigate a broad spectrum of greensand occurrences and attempt to discern some common denominators about their mineralogy, sedimentology and ichnology, a variety of study sites in Utah, Wyoming, Texas, Alabama Wisconsin and eastern Spain will be investigated in this project. A graduate research assistant and undergraduate research assistant will assist the P.I. in both field work and lab work.