GLGY 202 Lecture 11: Lecture 11
26 Apr 2016
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Document Summary
Form in equatorial, tropical zones rarely form in zones higher than with a latitude of 40 degrees. Sulfates (sulfur+oxygen) and halite most common evaporated mineral. Formed from organisms with shells, shallow waters because corals are distributed in shallow waters. After the death of tridacna, soft tissues are broken down, disintegrated into millions of smaller crystals. When packed in sediments look like cirlcles lined up side by side. Look for mud, grains and large sized organic fragments. If large sized organic fragments-known as a boundstone. If the rock has large grain fragments still mud supported over 10%-wakestone. Large grains dominate the rock mass- 20%- packstone. Very small amount of mud pores between grain stone small amounts of mud around 3-4%- grainstones. Evaporites-dominated by sulfates and halites-largest group from which we develop a genetic classification. Primary evaporites-form at the surface of the earth in a small basin for the first time easily recognizable fragile, low specific weight.
