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Friday Field Photo #171: 75 Million Year-Old Plant Debris

August 17, 2012

Okay, back to posting some field photos after a >two-month long hiatus.

Today’s photo is from the Upper Cretaceous Tres Pasos Formation of the Magallanes foreland basin in Chilean Patagonia. The Tres Pasos is characterized by mudstone and sandstone that was deposited in relatively deep water (~700-1000 meters paleo water depth) through a variety of sediment gravity flow processes (e.g., turbidites, debris flow deposits, mass wasting deposits, etc.).

This deep-marine slope system was fed sediment by an evolving delta system, which, in addition to mud and sand, contained vast amounts of plant and other organic matter. Some of this material was transported by the same processes that moved the sediment, making its way down to the deeper water out in front of the delta. The photo above shows some of the larger chunks of woody material concentrated on the top of a turbidite bed.
Happy Friday!

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