Linking Sedimentary Textures to Neoproterozoic Climate Dynamics

• Other Authors: Reahl, Jocelyn (author), Monecke, Katrin (advisor), Bergmann, Kristin D. (advisor), Cantine, Marjorie D. (advisor), Geosciences (department)
• Format: Other/Unknown Material
• Language: unknown
• Published: 2019
• Subjects: Svalbard; Vanda; Lake Vanda; Antarc*; Antarctica
• Online Access: https://repository.wellesley.edu/islandora/object/ir%3A863/datastream/TN/view/Linking%20Sedimentary%20Textures%20to%20Neoproterozoic%20Climate%20Dynamics.jpg

The Br&#229vika Member in Northeastern Svalbard is a Cryogenian-aged (630 to 720 Ma), northward-thickening and coarsening-upward wedge of sandstones and dolomites that sits at the boundary between two vastly different climate states: the overlying Wilsonbreen Formation, representing the Marinoan Snowball Earth glaciation, and the underlying Elbobreen Formation, representing a nonglacial interval between the Sturtian and Marinoan glaciations. Large-scale sedimentological and isotopic studies of the Br&#229vika Member and the surrounding stratigraphy have resulted in three endmember hypotheses for the facies that the Br&#229vika represents: 1) a fluvial proglacial (sandur) facies related to the Wilsonbreen Formation (Halverson et al., 2004)&#59 2) a glacial or nonglacial aeolian facies (Halverson, 2011)&#59 and 3) a nonglacial fluvial facies related to the Elbobreen Formation (Hoffman et al., 2012). This study uses a combination of petrography, energy-dispersive spectroscopy (EDS), scanning electron microscope (SEM) microtextural analysis, and non-metric multi-dimensional scaling (NMDS) analysis to characterize and assess the facies represented in the mid-lower Br&#229vika Member in Buldrev&#229gen, Svalbard at a microtextural scale, and is the first study to do so. This study is also the first microtextural study to consider the viability of SelFrag electric pulse disaggregation (EPD) as a method to prepare consolidated samples for microtextural analysis. Two samples of the mid-lower Br&#229vika Member from Buldrev&#229gen and one modern periglacial aeolian sample from Lake Vanda, Antarctica were compared with 16 other samples from the literature using NMDS. The 16 literature samples represented five different facies: fluvial, glaciofluvial, nonglacial aeolian, periglacial aeolian, and till. The NMDS ordination showed that the two samples from the mid-lower Br&#229vika Member closely plotted with samples from periglacial aeolian facies. This evidence, taken in conjunction ...