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Unformatted text preview: Lab 8 GY 402 Sedimentary Petrology (2012) Carbonate Thin-Sections 1: Tidal Flat and Evaporite Sedimentary Rocks Dolostones in thin section (field of view for each approximately 2 mm). The one on the right is supratidal. From Williams, H., Turner, F.J and Gilbert, C.M., 1954. Petrography. W.H. Freeman & Co., 406pp. Introduction: The rocks and thin sections that you will see today all come to you from ancient carbonate tidal flat environments. Some are from the Cambro-Ordovician Knox Group exposed near Centreville, Alabama. Others come from the Smackover Formation, a subsurface carbonate formation well known as a petroleum producer along the entire Gulf Coast. The rocks are dominated by finely crystalline dolomite and/or fine grained calcitic sediment. You may also encounter a few beasties in the rocks. I have also included a group of thin sections that contain algal materials. Some doubtless came from tidal flat environments, but some may be from slightly deeper environments. The dominant component that you will see in these rocks are oncoids. These are rolled up algal nodules that measure up to 2 cm across....
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- Fall '11