A record of dust deposition in northern, mid-latitude Pangaea during peak icehouse conditions of the late Paleozoic ice age

• Published in: Journal of Sedimentary Research
• Main Authors: Oordt, Andrew J., Soreghan, Gerilyn S., Stemmerik, Lars, Hinnov, Linda A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Greenland; Wordiekammen; Spitsbergen
• Online Access: https://curis.ku.dk/portal/da/publications/a-record-of-dust-deposition-in-northern-midlatitude-pangaea-during-peak-icehouse-conditions-of-the-late-paleozoic-ice-age(d51bb7a4-2006-4362-b9d2-ecde5432aac0).html; https://doi.org/10.2110/jsr.2020.15

The Wordiekammen Formation, a carbonate ramp on Spitsbergen developed on the Northern Pangaean margin in Moscovian (Carboniferous) through Sakmarian (Permian) time at a paleolatitude of 30-358 N. The study site on the Nordfjorden High was isolated from any source of fluvio-deltaic input, such that detrital material that occurs in this system experienced eolian transport, thus forming a proxy for atmospheric dust loading. We analyzed two intervals, of Moscovian (10 m) and Asselian (27 m) age, at 20 cm resolution, and identified five mid-ramp subtidal facies organized in upwardly shallowing, high-frequency sequences 3-5 m thick. High-frequency sequence boundaries commonly exhibit signs of subaerial exposure (e.g., Microcodium) developed atop subtidal facies, recording glacioeustatic falls (glacial phases), although the Moscovian section has a severe karst overprint attributable to prolonged exposure on a paleohigh. Samples were processed to isolate the silicate-mineral fraction (SMF), which includes both detrital silicate material and authigenic silica mostly in the form of (fine-sand-size) doubly terminated quartz crystals. Detrital cores in these crystals, together with other evidence, indicate recrystallization from fine-grained (silt- and clay-size) dust. Analysis of the dust record demonstrates that the Asselian (peak icehouse) had a significantly higher atmospheric dust load than the Moscovian (moderate icehouse). In the Asselian interval, dust input varies commensurate with glacial-interglacial cyclicity. Highest dust contents correspond to transgressive facies immediately above sequence boundaries, indicating peak atmospheric dust loading at lowstand to incipient interglacial times. Provenance data from detrital-zircon and whole-rock geochemistry indicate two distinct source regions for the dust. Dust from the Moscovian and lower Asselian intervals reflects a continental island-arc signature consistent with sourcing from the basement of northeast Greenland. Dust from the upper Asselian interval is more ...