1. Petrology All about rocks!

2. Essential Questions  What is the rock cycle?  What are the three types of rocks?

3. The Rock Cycle

5. Magma  Magma is molten rock material below the surface – –Lower density causes magma to move upward to the surface – –Magma at the surface is lava   There are 4 types of magma based upon the amount of silica present – –Felsic – –Intermediate – –Mafic – –Ultramafic   Silica controls the viscosity of the magma

6. Felsic Magma  SiO 2 >70%  Fe-Mg: ~ 2%  Temperature: < 900°C  Viscosity: High  Eruptive behavior: explosive or effusive  Distribution: hot spots in continental crust, continental rifts

7. Intermediate Magma  SiO 2 ~ 60%  Fe-Mg: ~ 3%  Temperature: ~1000°C  Viscosity: Intermediate  Eruptive behavior: explosive or effusive  Distribution: convergent plate boundaries, island arcs

8. Mafic Magma  2  SiO 2 < 50%   FeO and MgO typically < 10 wt%   Temperature: up to ~1300°C   Viscosity: Low   Eruptive behavior: gentle   Distribution: divergent plate boundaries, hot spots, convergent plate boundaries

9. Ultramafic Magma  SiO 2 < 45%  Fe-Mg >8% up to 32%MgO  Temperature: up to 1500°C  Viscosity: Very Low  Eruptive behavior: gentle or very explosive (kimberilites)  Distribution: divergent plate boundaries, hot spots, convergent plate boundaries

13. What are Sedimentary Rocks?  A kind of rock formed when a layer of sediment becomes solid.

14. Sedimentary Rocks Earth Revealed Series  Answer the questions provided while watching this video. http://www.learner.org/vod/vod_wind ow.html?pid=328 http://www.learner.org/vod/vod_wind ow.html?pid=328  30mins

15. Formation  Compaction –Is caused by the weight of the overlying rocks squeezing the sediments together  Cementation –Is a chemical process through which water carries and deposits dissolved minerals in the small spaces between the sediment particles.

16. Types of Sedimentary Rocks  Chemical sedimentary rocks –Such as rock limestone, halite, and gypsum –are formed from minerals left behind after water evaporates.  Clastic sedimentary rocks –Such as conglomerate, breccias, and sandstone –are formed when little pieces of broken-up rock pile up over time and are pressed and cemented together.  Organic sedimentary rocks –Such as coal and organic limestone, contain the remains of materials that were once alive. –Deposits of shells, dinosaur bones, and compressed plant remains become beds of coal.

17. Sedimentary Rock Characteristics  Often contains fossils  May react with acid  Often has layers, flat or curved  Has great color variety  Particle size may be the same or vary  Usually has pores between pieces  May have cross-bedding, mud cracks, worm burrows, raindrop impressions

24. What is a Metamorphic Rock?  A kind of rock formed when sedimentary rock or igneous rock undergoes a change due to pressure or heat in the earth.

25. Metamorphic Rocks Earth Revealed Series  Answer the questions provided while watching this video.  http://www.learner.org/vod/vod_win dow.html?pid=329 http://www.learner.org/vod/vod_win dow.html?pid=329 http://www.learner.org/vod/vod_win dow.html?pid=329  30 mins

26. Formation  Can occur beneath the surface of the earth, where the magma from the asthenosphere comes in contact with the bottom of he crust of the earth.  Metamorphism can occur to varying degrees depending upon the levels/amounts of heat, pressure, and chemically active fluids.

27. Types of Metamorphic Rock  Foliated metamorphic rocks –Form with layered bands. –Examples include slate, schist, and gneiss  Nonfoliated metamorphic rocks –Form without layered bands –Examples include marble and quartzite.

28. Metamorphic Rock Characteristics  Rarely has fossils  May react with acid  May have alternate bands of light and dark minerals  May be composed of only one mineral, ex. marble & quartzite  Usually made of mineral crystals of different sizes  Rarely has pores or openings  May have bent or curved foliation

32. What are Igneous Rocks?  Rock formed by the cooling of melted materials, such as magma inside the earth and lava about the ground.

33. Intrusive Igneous Rocks Earth Revealed Series  Answer the questions provided while watching this video. http://www.learner.org/vod/vod_wind ow.html?pid=325 http://www.learner.org/vod/vod_wind ow.html?pid=325 30 mins

34. Formation  formed through the cooling and solidification of magma or lava  may be formed below the surface as intrusive rocks or on the surface as extrusive rocks   formed as a result of activity at plate boundaries.   Igneous Rock Textures – –Refers to the size, shape, and arrangement of mineral grains – –Size relates to cooling rate, and indicates an intrusive or extrusive origin

35. Igneous Rock Characteristics  Classified by texture and composition  Normally contains no fossils  Rarely reacts with acid  Usually has no layering  Usually made of two or more minerals  May be light or dark colored  Usually made of mineral crystals of different sizes  Sometimes has openings or glass fibers  May be fine-grained or glassy (extrusive)

36. Igneous Rock types (based on texture)   Aphanitic: – –fine grained, rapid cooling   Phaneritic: – –coarse grained – –slow cooling   Porphyritic: – –phenocrysts and groundmass – –two stage cooling history   Glassy: –no crystal structure –Obsidian   Vesicular: –gas cavities –Scoria, Pumice   Pyroclastic: –fragments generated by explosive volcanism –Tuff, Breccia

38. Igneous rocks based on magma type   Rocks produced from felsic magma are: –composed of relatively high quantities of sodium, aluminum, and potassium and are composed of more than 65% silica –light in color because of the dominance of quartz, potassium and sodium feldspars, and plagioclase feldspar minerals –granite, granodiorite, dacite, and rhyolite   Rocks produced from intermediate magma are: –composed of silica amounts between 53 to 65% –composed predominantly of the minerals plagioclase feldspar, amphibole, and pyroxene –Andesite and diorite

39. Igneous rocks based on magma type continued…  Rocks produced from mafic magma are: –composed of relative low amounts of silica (< 45%) and are dominated by the minerals olivine, calcium-rich plagioclase feldspars, and pyroxene –Basalts and gabbros  Rocks produced from ultramafic magma are: – 18% MgO, high FeO, low potassium –composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron content) –Peridotite