This week?s Friday Field Photo is from Torres del Paine National Park in southern Chile. In this view, the iconic peaks and towers of the Paine Massif are behind you. On the skyline in the distance is a mountain called Sierra del Toro and in the foreground a lake called Lago Sarmiento.
The darker-colored strata, which you can see dipping to the right, are mudstones and turbidite sandstones of the Upper Cretaceous (~85 million years old) Cerro Toro Formation. The structure in this area is characterized by mostly broad folds with local areas of more intense deformation (note how the dip of the strata changes as you track the beds into the distance).
The bright white rocks rimming the lake are 5,000-10,000 year old microbialites (calcium carbonate secreted by vast numbers of tiny organisms). The lake level has dropped over the past several thousand years exposing these older, now dead, microbialite structures. There are living structures in the water, going down about 10-20 meters deep if I remember correctly. I honestly don?t know a lot of details about this lake, but can try and dig up some stuff if anyone?s interested.
Happy Friday!
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Image: Turbidites and Microbialites / from my Flickr page
Source: http://www.wired.com/wiredscience/2011/05/friday-field-photo-143-turbidites-and-microbialites/
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