A RECORD OF MID-LATITUDE ATMOSPHERIC DUST LOADING FROM A PENNSYLVANIAN-PERMIAN CARBONATE RAMP ON CENTRAL SPITSBERGEN

Permo-Pennsylvanian dust and loess deposits from western equatorial Pangea provide a record of atmospheric dust flux from low latitudes. These studies show increased atmospheric dust loading during glacial intervals of the Late Paleozoic Ice Age (LPIA) at low latitudes. Here, we focus on a mid-latitude dust record from the Wordiekammen Formation, a carbonate ramp on Spitsbergen. The ramp developed on the Northern Pangean margin in Moscovian (Pennsylvanian) through Sakmarian (Permian) time at a paleolatitude of 30-35°N. The study site on the Nordfjorden High formed isolated from any source of fluvio-deltaic input, such that detrital material records atmospheric (eolian) dust input. We analyzed two intervals, of Moscovian (10 m) and Asselian (27 m) age, at 20 cm resolution. We identified five facies organized in upwardly shallowing cycles 3-12 m thick. Microcodium occurs at cycle tops, recording subaerial exposure. We processed samples to remove carbonates, organics, pyrite and oxidized iron, leaving the silicate mineral fraction (SMF). This fraction includes both detrital silicates, and authigenic chert. Unambiguously detrital grains are <120 µm. Material exceeding this size is entirely authigenic, albeit with silica potentially sourced atmospherically. Preliminary processing results show significant variation in the volume of the SMF throughout the study intervals. XRF data will enable assessment of variations in elements (e.g. K, Al, Ti, Zr) typically associated with eolian dust, to help test whether variations in SMF correlate with dust proxies, and bears any relation to (glacioeustatic) cyclicity. Dust records from this mid-latitude location will help determine whether or not this time period records a globally dusty atmosphere, and whether the Asselian – a time of peak icehouse conditions—was dustier than the Moscovian.