MICROBIAL EVIDENCE IN THE NEOPROTEROZOIC KELLEY CANYON FORMATION, ANTELOPE ISLAND STATE PARK, UTAH

The lower member of Kelley Canyon Formation is a Neoproterozoic dolomite overlying the glacial Mineral Fork tillite on Antelope Island State Park in Northwestern Utah. Previous studies have described this member as recrystallized dolostone with laminations, domal structures, ripples, tube structures, and local deformation. This member is interpreted to be a cap carbonate which is defined as thin pink to buff carbonates that overlie glacial deposits. Similar cap carbonates display microbial features, such as the nearby Perry Canyon Formation in Utah, Pocatello Formation in Idaho and the Noonday Dolomite in California, as well as globally in the Ghaub Formation in Namibia and the Stelfox Formation in Canada. Previous studies interpreted the wavy laminations in the Kelley Canyon Formation to be from deformation and not from microbial activity. The purpose of this study is to analyze the laminations, domal structures and tube structures in the Kelley Canyon Formation to determine if they are microbial in origin.This study collected 20 samples from the Kelley Canyon Formation on Antelope Island and observed wavy laminations, layered mineral-filled vugs, domal and tube structures. Irregular tube structures are 1cm in diameter, ~2.5cm apart, and line up in parallel vertical patterns. Domal structures range from 7.6 to 15.2cm wide and display domed laminations with surrounding horizontal bedding. 17 samples show laminations of mineral-filled layered vugs that are interpreted to be filamentous cell remains. These field observations are interpreted to be microbial structures. If these features are microbial, this is addition evidence that the lower member of the Kelley Canyon Formation is shallow-water above fair-weather wave base as previously interpreted.