Thursday, November 8, 2012

Highlights – Not All Mud Is Transported Equally...

Understanding the genesis of muddy successions, although widespread and stratigraphically and economically important, has lagged behind that of its coarser counterparts.  In this paper, Plint et al. address the question of how was mud transported for more than 200 km across a shallow, low-gradient ramp in the Upper Cretaceous foreland basin of Alberta, Canada?  Microscopic examination shows that organic-rich mudstone (up to 11% TOC; a major source-rock) was transported mainly in the form of low density silt-size aggregates of clay mineral grains.  Aggregates are relatively well consolidated and are interpreted to have been reworked from shallowly-buried (cm-dm) sediment and transported as bedload by storms-driven combined and geostrophic flows on this extremely low-gradient ramp.  These results illustrate a means by which clay mineral-rich sediment, far removed from their source, can accumulate in relatively shallow water and preserve organic matter.


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