111lab-3 - GY 111 Lecture Note Series Lab 3: Introduction...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
1 GY 111 Lecture Note Series Lab 3: Introduction to Sedimentary Rocks Lecture Goals: A) Sedimentary Rock Classification B) Grain Size C) Siliciclastic Rocks D) Biochemical Rocks E) Other sedimentary rocks References: GY 111; Earth Materials Lab Manual; Chapter 3. A) Sedimentary Rock Classification Sedimentary rocks are not classified in the same systematic way that the igneous rocks are classified. Instead, we look primarily at the composition of the sediment particles or grains. Secondary classification is done on the basis of grain size . If grains are dominated by silicate minerals like quartz, feldspar, muscovite, clays etc, we classify the sediment as siliciclastic and the rocks formed from these grains siliciclastic sedimentary rocks. If the grains are composed of calcium carbonate (calcite and aragonite) that was mostly derived from living organisms (e.g., shells, skeletons, tests), we classify the sediment as biochemical ( or bioclastic) and called the rocks formed from this sediment biochemical sedimentary rock . For our purposes, most biochemical rocks are limestones . Chemical sedimentary rocks are derived from mineral precipitation from water. Sea water evaporation leads to the evaporite minerals ( halite, sylvite, dolomite, gypsum and anhydrite ). Evaporation of saline lakes leads to banded gypsum . Water percolating underground may result in precipitation of calcite in caves. The stalactites and stalagmites that commonly fill caves are composed of this “calcite”, of course to keep your life difficult, we don’t call it calcite. Cave precipitates composed of CaCO3 are called travertine and they are pretty easy to identify because of their banding and “anatomically correct” shape (you’ll see what I mean when you see our sample in the lab!). Organic sedimentary rocks were produced from plant material. Four of the five specimens that you will need to identify are considered coals (peat, lignite, bituminous coal, anthracite) . The other organic sedimentary rock in our collection is amber (fossilized tree sap). None of these materials is particularly difficult to distinguish, but if you are wise, you will look at all 4 coals together. Telling them apart is a critical means of identification.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/04/2012 for the course GLY 111 taught by Professor Haywick during the Fall '11 term at S. Alabama.

Page1 / 4

111lab-3 - GY 111 Lecture Note Series Lab 3: Introduction...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online