Geology 2312: Petrology Name 1LAB 13: INTERPRETATION OF METAMORPHIC TERRANES Developed by John Goodge Folded amphibolite to granulite facies gneisses Purpose: In this lab you will study a suite of metamorphic rocks of different composition and grade in order to determine protoliths types and address the conditions of metamorphism. For this suite of samples you will be asked to interpret the protolith (precursor) rock composition and the P-T conditions of metamorphism in each sample. Your primary data sets will be the minerals and textures you identify in each sample. Think of the minerals as small chemical packets – considering their modal abundances, use the chemical compositions of the minerals to help you determine protoliths. You may also find textural evidence of protolith type, at least whether igneous or sedimentary. Once you have studied the sample suite, you will plot your samples on a P-T, or facies, grid and interpret a setting of metamorphism. SWA 1-1 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): Notes: The mineral that looks like muscovite is talc. Be sure to note its optical properties below and consider what its composition tells you about the protolith.Geology 2312: Petrology Name 2SWA 43-1 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): Notes: Note the narrow cross-cutting veins of a nearly colorless mineral. The small porphyroblasts of opaque mineral are pyrite. M14151 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): 3081 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): Notes: This rock contains one of the Al-silicate polymorphs.Geology 2312: Petrology Name 3M14173 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): Notes: There are two notable minerals to find in this rock – anthophyllite (orthoamphibole) and cordierite. Describe their optical properties and sketch their textures below. NM 11-2 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): Notes: The major opaque mineral in this rock is magnetite. Also look for grunerite (clinoamphibole). What does it’s presence tell you about rock composition? Is it consistent with the other minerals?Geology 2312: Petrology Name 4SY 60 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): Notes: This rock has a mineral you have not studied before in thin section, but we have discussed its importance. Determine which mineral it is (thinking about mineral associations will help!) and list its optical properties below. PR 1-2 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): Notes: If you’re stumped, go back to 3081.Geology 2312: Petrology Name 5AU 6-3 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): Notes: There are three important metamorphic minerals in this rock. One of them, typically fine-grained and blocky, will be easier to identify if you think of your igneous minerals! NM 1-1 Mineralogy: Textures: Name: Metamorphic facies: Protolith (provide justification): Notes: This rock contains thin layers – consider what these represent. They are best observed under low power.Geology 2312: Petrology Name 6On the P-T diagram below, place each sample number in its appropriate metamorphic facies. Sketch with a line the general trend of the different P-T conditions that connect these samples. This is referred to as a metamorphic facies series, or association of conditions for individual rocks that reflect the geothermal conditions in the environment during metamorphism. Describe what type of metamorphic setting is represented by these samples (e.g., regional, contact, burial, etc.), providing justification for your answer. Discuss in general terms what types of textural and mineralogical changes you can reconstruct with changing metamorphic conditions; to address this, consider all of the samples representative of a particular