GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 36-6
Presentation Time: 9:00 AM-5:30 PM


SARDAR ABADI, Mehrdad, Geology and Geophysics, University of Oklahoma, 312 East Boyd St, #8, NORMAN, OK 73069, OWENS, Jeremy D., Department of Earth, Ocean & Atmospheric Science, Florida State University, 1017 Academic Way, Tallahassee, FL 32306, LIU, Xiaolei, School of Geology and Geophysics, University of Oklahoma, 100 East Boyd St, Norman, OK 73019, THEM II, Theodore R., College of Charleston, Charleston, SC 29424, CUI, Xingqian, Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 45 Carleton Street, Cambridge, MA 02139 and SOREGHAN, Gerilyn S., School of Geosciences, University of Oklahoma, 100 East Boyd St, Norman, OK 73019

The importance of dust as a source of iron (Fe) for marine primary production in modern oceans is well studied but remains poorly explored for deep time. Vast dust deposits are well recognized from the late Paleozoic, and provisionally implicated to drive biotic production through iron fertilization. Here, we document dust impacts on marine primary productivity in Moscovian (Middle Pennsylvanian, ~307 Ma) and Asselian (Lower Permian, ~295 Ma) carbonate strata from peri-Gondwanan terranes of Iran, at southern mid paleo-latitudes. Fossil community composition of both intervals shifted with FeHR/FeT in samples as shown by significant correlations between PCoA axis scores and FeHR/FeT. Autotrophic content of samples, detected by both point counting and lipid biomarker analysis, track concentrations of highly reactive Fe, consistent with the hypothesis that dust stimulated marine primary productivity, also promoting carbonate precipitation. Additionally, highly reactive Fe positively tracks the volume of the finest dust fraction. Consequently, dust likely stimulated both organic and inorganic carbon cycling, helping to maintain low pCO2 even as terrestrial repositories for organic carbon (peat/coal) diminished from the Carboniferous through Permian.