Wednesday, March 6, 2013

Highlights—Grain Shape in Antarctica: the Cold, Hard Truth

The shapes of sedimentary particles can be useful for elucidating many aspects of their history, from origin to deposition to diagenesis.  Livsey et al. examine the utility of grain shape as a depositional proxy for glacially influenced sediment within the James Ross Basin and Joinville Plateau of the Antarctic Peninsula from the Eocene to the present.  The results from Fourier shape analyses of more than 6,000 quartz grains reveal changes through time, associated with climate shifts.  It shows that grain roughness increases with the onset of increased glaciation from the Late Oligocene to Middle Miocene, after an Early Pliocene warm period, and from the Pliocene to Pleistocene; in contrast, grain roughness decreases from the Middle Miocene through an Early Pliocene warm period. This study highlights the utility of Fourier grain-shape analysis for understanding the history of grains, and its potential application in polar studies.

Fourier grain-shape analysis of Antarctic marine core: the relative influence of provenance and glacial activity on grain shape by Daniel N. Livsey,  Alexander R. Simms, Warren G.  Clary, Julia S. Wellner, John B. Anderson, and John P. Chandler

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