THE THREE TYPES OF ROCKS (Lets Rock N Roll)

This topic will bring you to understanding the three types of rocks that consist the Rock Cycle

1. Specific Learning Outcomes At the end of the lesson, I will be able to: I can identify and describe the three basic rock types; I can describe how and define what type of environment each of these rock types are formed; I can describe how rocks are transformed from one rock type to another through the rock cycle; I can identify and describe the different geologic processes that operate within the rock cycle.

2. 8 ELEMENTS comprising almost 99% of the minerals making up the Earth’s crust.

3. Approximately 85% of the Earth's crust is composed of oxygen and silicon. Together they form the silicon oxygen tetrahedron, which is the basic building block of silicate minerals. Silicates are also termed as (common) rock forming minerals. - ROCKS are an aggregate of minerals. A rock can be composed of a single mineral (e.g. Quartzite is a metamorphic rock composed predominantly of Quartz) or more commonly composed of an aggregate of two or more minerals. Can a name of a mineral be also used as a rock name?

4. Show a video of the different rock types. 3 Types of Rocks.mp4 How can we classify rocks? Would it be by color, hardness, texture, density or other physical properties? Is it by chemical composition?

5. 1. IGNEOUS ROCKS these are rocks that are derived from the cooling and solidification of magma or lava from solidified molten rock materials, usually hard and crystalline rate of cooling as one of the most important factors that control crystal size solidification can occur along the surface of the earth or beneath the surface of the earth

6. MAGMA VS LAVA Magma is a molten rock material beneath the surface of the earth. Lava is molten rock material extruded to the surface of the earth through a central vent (volcano) or as fissure eruption.

7. 1. Plutonic or Intrusive Rocks from solidified magma underneath the earth gradual lowering of temperature is indicated by the movement of magma from depth to surface causing slow cooling /crystallization Phaneritic textures Forms large interlocking crystals from cooling Examples: granite, diorite, gabbro 2 TYPES OF IGNEOUS ROCKS

8. 2. Volcanic or Extrusive Rocks from solidified lava at or near the surface of the earth fast rate of cooling/crystallization due to huge variance in the temperature between Earth’s surface and underneath common textures: aphanitic, porphyritic (define groundmass vs phenocrysts), vesicular Porphyritic texture : formed through two stages of crystallization where in magma partly cooled below the surface of the earth providing time for the large crystals to grow (phenocrysts) before it is extruded to the surface forming the fine-grained matrix (groundmass). Aphanitic texture : fine-grained texture; minerals not visible to the naked eye; relatively fast rates of cooling/ solidification prevent the formation of large crystals. Vesicular texture : voids created by rapid cooling which causes air bubbles to be trapped inside.

9. examples: rhyolite, andesite, basalt pyroclastic rocks : fragmental rocks usually associated with violent or explosive type of eruption. Examples tuff and pyroclastic flow deposits (ignimbrite)

10. Common intrusive rocks with their extrusive counterparts GRANITE RHYOLITE

11. DIORITE ANDESITE

12. GABBRO BASALT

13. Igneous rocks are also classified according to silica content and relative amounts of K, Na, Fe, Mg and Ca. They can be classified as felsic , intermediate , mafic and ultramafic , practically based on presence of light and dark colored minerals . The relatively dark minerals are olivine, pyroxene, hornblende and biotite. The relatively light colored minerals are plagioclases, K-feldspars, quartz and muscovite.

14. FELSIC : granitic: >65% silica, generally light-colored INTERMEDIATE : andesitic: 55-65% silica, generally medium colored (medium gray) MAFIC : basaltic: 45-55% silica, usually dark colored ULTRAMAFIC : <45% silica, generally very dark colored

15. 2. SEDIMENTARY ROCKS these are rocks that are formed at or near the surface of the Earth sedimentary processes include: weathering of rocks erosion deposition compaction Cementation Sediment are fragments of rock that have been broken down as a result of weathering

16. COMMON SEDIMENTARY FEATURES fossil assemblages remains and traces of plants and animals that are preserved in rocks Stratification stratification or layering (strata which is >1cm is called bedding and < 1cm is called lamination): layering is the result of a change in grain size and composition; each layer represents a distinct period of deposition

17. Photo of the Kapurpurawan Formation located at the coastal town of Burgos, Ilocos Norte, courtesy of riderako.com. Shows series of sedimentary strata

18. Two Types of Sedimentary Rocks

19. 1. Clastic sedimentary rocks Inorganic land derived sedimentary rocks Clastic sedimentary rocks form by weathering processes which break down rocks into pebble, sand, or clay particles by exposure to wind, ice, and water. Compacted and cemented sediments Clastic sedimentary rocks are named according to the grain size of the sediment particles

20. 2. Non-clastic sedimentary rocks Organic or crystalline Nonclastic sedimentary rocks form from chemical reactions, chiefly in the ocean. Nonclastic sedimentary rocks are named according to the mineral present. classified as evaporites (halite, gypsum and dolostone ), precipitates (limestone) and bioclastics (coal, coquina)

21. Evaporites: rocks formed from the evaporation of water leaving the dissolved minerals to crystallize Precipitates: rocks formed when minerals from a mineral supersaturated waters start to crystallize at the bottom of the solution Bioclastic: rock formed from compacted organic matter

22. Bioclastic: rock formed from compacted organic matter

23. Sedimentary rocks are the only type of rocks that may contain fossils, or evidence of past life.

24. METAMORPHIC ROCKS formed below the surface of the earth through the process of metamorphism with the recrystallization of minerals in rocks due to changes in pressure and temperature conditions contact and regional metamorphism

25. 1. CONTACT METAMORPHISM HEAT AND REACTIVE FLUIDS as main factors: occurs when a pre-existing rock gets in contact with magma which is the source of heat and magmatic fluids where metamorphic transformations occur around the contact / metamorphic aureole of the intruding magma and the rock layers. The aureole occurs on different scales depending on the sizes of the intruding magma and the amount of water in the intruded rocks and the reactive fluids coming from the magma. creates non-foliated metamorphic rocks example: hornfels

26. 2. REGIONAL METAMORPHISM PRESSURE as main factor: occurs in areas that have undergone considerable amount of mechanical deformation and chemical recrystallization occurs in a regional/large scale creates foliated metamorphic rocks examples: schist, gneiss non-foliated rocks like marble also form through regional metamorphism, where pressure is not intense, far from the main geologic event

27. Common Metamorphic Rocks.

28. THANK YOU FOR LISTENING!

29. Concept Mapping – Types of Rocks Each group will fill up the chart which correspond to the list of words provided to choose from . When done, the group leaders will present their work to class.

30. VIDEO SUMMARY Igneous Rocks.mp4 Sedimentary Rocks.mp4 Metamorphic Rocks.mp4

31. Evaluation (20 mins) 1 whole sheet of paper

32. How does a vesicular texture in a volcanic rock develop? How do clastic rocks differ from non-clastic rocks in terms of process of formation? Explain how the physical features of sediments change during transport. Differentiate between a foliated and non-foliated rock. What do butterflies and metamorphic rocks have in common? Heat is a major agent in metamorphism and igneous rock formation, but not in sedimentary rocks. Why? Does every rock go through the complete rock cycle, i.e. changing from igneous to sedimentary rock to metamorphic then back to igneous rocks? Explain.

33. Homework to be submitted on next meeting on a 1 whole sheet of paper. Each student will research on 3 rocks (one for each rock type). Include in the discussion the following: 1. common environment of formation 2. common textures 3. common use of the rock