Metamorphic Rock Classification Metamorphic Rock Textures Textural Responses to Changes in Metamorphic Temperature-Pressure Foliated Textures Slaty Cleavage Sedimentary layers have just undergone folding Now the slaty cleavage has developed as the clay in the shale has transformed into the Be dd in g Slaty Cleavage ty a l S e g a v a e cl Slaty Cleavage Foliated Textures Slaty Cleavage http://www.env.duke.edu/eos/geo41/ims2.htm http://www.accd.edu/sac/EARTHSCI/1301.090/Lecture%2 Slaty Cleavage and its Practical Applications http://www.creativeroofsystems.com/services.htm http://www.restorationtrades.com/articles/roofsl Slaty Cleavage and its Practical Applications http://www.peartree12.freeserve.co.uk/topics/roofing.html http://www.bingleystone.com/stoneslate/ind Foliated Textures Schistosity and Mineral Banding develops into Which then Develops into Barrovian Gneiss Kyanite/ Sillimanite Granulite The Rock Cycle All rocks can be transformed Into other rocks But, all rocks originate and evolve from the parent rock The Earth as a Complex Evolutionary System volutionary Rock Cycle Evolutionary Rock Cycles Igneous Rocks Evolve Mafic Ocean Basalt/gabbro Alkali granite Early Fractional Melting Mafic Residue Intermediate Diorite, plagiogranite oc ea Alkaline Suite M af ic Later Fractional Melting n Mafic ocean Ultra-mafic Fractionation residue Parent Rock (Ultramafic/Mafic) Rising Decompressing Mafic/ultramafic Parent nd, Sedimentary Rocks Evolve nd, Metamorphic Rocks Evolve ~ 4.0 Ga ~ 4.0 Ga ~ 4.0 Ga Earth About Four Billion Years Ago Oceans are established and Volcanic Islands are springing up http://www.lpi.usra.edu/education/timeline/gallery/slide_18.ht ~ 4.0 Ga ~ 4.0 Ga ~ 4.0 Ga ~ 4.05 Ga Volcanic eruptions on the early Earth, showing the dark smoggy atmosphere and tremendous lightening displays that accompanied it The atmosphere would have been filled with thick, choking, poisonous gasses Land areas were small, while tides and ocean currents strong Evolutionary Rock Cycles o, the Entire Earth must have Evolve Hawaii Borneo New Guinea Fiji New Zealand http://ace.acadiau.ca/science/geol/rraeside/quizzes/worldmap3 Innumerable Volcanic Arcs and Collisions Among These Arcs Over Two Billion Years Build the Cores Of Modern Continents Small volcanoes andthrough microcontinents, moving All explained tectonic across the earth are bound to collide, and stick theory together to form even larger continents It was Our next subject this process that built the large continents we see today [...]... http://www2002.stoke.gov.uk/museums/pmag/Nof_website1/natural_history_static_exhibitions/identifying_rock_minerals _and Barrovian Metamorphism Amphibolite Schist http://www2.vscc.cc.tn.us/svinson/geo100/library /metamorphic/ large/amphibolite.jpg Measuring Metamorphic Intensity Zones and Facies Metamorphic rocks are important for a variety of reasons One is that many minerals are formed only during metamorphism, and many of these are extremely valuable Many gem minerals are metamorphic, such as rubies Other metamorphic. .. important in manufacturing Geologically, metamorphic rocks and minerals are valuable because they serve as barometers of temperature and pressure conditions of the times and places where they formed – always deep in the earth We are able to unravel the origin and history of not only We these but also canrocks see some of the Earth from the study of metamorphic rocks these changes in the phase diagrams... pure silica Limestone – pure CaCO3 Granular Textures Metamorphic Rock Classification and Formation Metamorphic Rock Classification and Formation The trouble with metamorphism is Any kind of rock, igneous, sedimentary, or metamorphic Can undergo any kind of metamorphism Producing every conceivable combination and permutation Metamorphic Rocks are Very Complex Barrovian Metamorphism Shale Slate... chemical formula transforms into three markedly different minerals with different http://www.lonelyplanet.com/mapshells/europe/scottish_highlands _and_ islands/scottish_highlands _and_ islands.htm http://www.clan-mackenzie.co.uk/graphics/highl Scottish Highlands http://www.scotland.de/photos/073l ... Mineral Banding Gneiss http://www.library.csi.cuny.edu/dept/as/me Foliated Textures – Mineral Banding Gneiss http://www.ut.ee/BGGM/miner/para_gn Foliated Textures – Mineral Banding Gneiss http://www.eas.slu.edu/Photos/3_2_Ga_gn Foliated Textures – Mineral Banding Gneiss http://www.gly.uga.edu/railsback/FieldImages/Bount Textural Responses to Changes in Metamorphic Temperature-Pressure Quartz sandstone... feldspar, mica, completely and many new intermixed Minerals large enough to be minerals easily identified Barrovian Metamorphism Problems with the term Schist - this term has several distinct and overlapping meanings, “Schist” making it the most confusing and complicated metamorphic term Frequently the term is combined with another giving the conjoined terms a distinct meaning and interpretation Schist:... and interpretation Schist: a type of layering or foliation typical of metamorphic rocks where minerals large enough to be seen by eye show definite orientations • Greenschist (chlorite dominated) • Blueschist (glaucophane dominated, plus many other minerals) • Amphibolite schist (Amphibole dominated) Then there is the issue of rocks and facies • Greenschist facies – low • Greenschist the rock grade •... A foliation is any planar fabric in a metamorphic rock In this case, the foliation is defined by aligned sheets of muscovite sandwiched between quartz grains http://www.geolab.unc.edu/Petunia/IgMetAtlas /meta-micro/quartzmicaschist.X.html Foliated Textures - Schistosity Schist http://www.accd.edu/sac/EARTHSCI/1301.090/Lecture%202.htm Foliated Textures – Mineral Banding Gneiss http://www.uwlax.edu/faculty/stoelting/Intro/Guides/Images2