Work

Iron mineralogy and redox conditions during deposition of the mid-Proterozoic Appekunny Formation, Belt Supergroup, Glacier National Park

Year: 2016

Type: book-chapter

Abstract: The redox state of the mid-Proterozoic oceans, lakes, and atmospheres is still debated, but it is vital for understanding the emergence and rise of macroscopic organisms and eukaryotes.The Appekunny Formation, Belt Supergroup, Montana, contains some of these early macrofossils dated between 1.47 Ga and 1.40 Ga and provides a well-preserved record of paleoenvironmental conditions.We analyzed the iron chemistry and mineralogy in samples from Glacier National Park, Montana, by pairing bulk rock magnetic techniques with textural techniques, including light microscopy, scanning electron microscopy, and synchrotron-based X-ray absorption spectroscopy.Field observations of the Appekunny Formation combined with mineralogical information allowed revised correlations of stratigraphic members across the park.However, late diagenetic and/or metasomatic fluids affected primary iron phases, as evidenced by prevalent postdepositional phases including base-metal sulfides.On the west side of the park, pyrrhotite and chlorite rims formed during burial

Source: Geological Society of America Special Papers

DOI: 10.1130/2016.2522(09)

Authors: Sarah P. Slotznick, Don Winston, Samuel M. Webb, Joseph L. Kirschvink, Woodward W. Fischer

Institutions: Tokyo Institute of Technology, California Institute of Technology, Stanford Synchrotron Radiation Lightsource, University of Montana, Earth-Life Science Institute

Language: English

Topic: Paleontology and Stratigraphy of Fossils

Subfield: Paleontology

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: bronze