Rock Forming Process, the Rock Cycle, and THE Rocks

1. Rock Forming Process, the Rock Cycle, and THE Rocks

2. Review of Minerals What are the four characteristics of a mineral? Naturally Occurring Crystalline Solid Specific Chemical Composition Inorganic

3. Review of Minerals What mineral is this? DOLOMITE

4. Review of Minerals What mineral is this? QUARTZ

5. Review of Minerals What mineral is this? GALENA

6. Review of Minerals What mineral is this? OLIVINE

7. Review of Minerals What mineral is this? ORTHOCLASE FELDSPAR

8. Review of Minerals What mineral is this? HEMATITE

9. Review of Minerals What mineral is this? FLOURITE

10. Review of Minerals What mineral is this? GYPSUM

11. Review of Minerals What mineral is this? PYROXENE - AUGITE

12. Review of Minerals What mineral is this? PYRITE

13. Review of Minerals What mineral is this? MAGNETITE

14. Review of Minerals What mineral is this? MUSCOVITE

15. Review of Minerals What mineral is this? CALCITE

16. Review of Minerals What mineral is this? HALITE

17. Review of Minerals What mineral is this? GARNET

18. Review of Minerals What mineral is this? AMPHIBOLE - HORNBLENDE

19. Review of Minerals What mineral is this? BIOTITE

20. Rock Forming Process, the Rock Cycle, and THE Rocks

21. Goals for this lab Learn the basics of rock identification Learn how to distinguish between 3 rock types Observe hand samples and infer how they might have been formed

22. What is a rock? *Solid aggregate of mineral grains, mineral crystals, or other rocks *Some exceptions **Obsidian is made of volcanic glass **Coal is made of plant fragments *The materials forming rocks come from the Earth’s mantle as magma, from space, from organisms, or from the breakdown of other rocks and minerals.

23. The Rock Cycle *Environmental changes and processes affect the rock forming materials and existing rocks *These changes and processes produce 3 distinct groups of rocks **IGNEOUS **SEDIMENTARY **METAMORPHIC

24. The Rock Cycle

25. Igneous Rocks…

26. What is an igneous rock? Crystalline or glassy rocks formed from the cooling and solidification of molten magma (below Earth’s surface)/lava (on Earth’s surface) Compose the majority of the earth Can use the texture and mineralogy of these rocks to determine where in the Earth they formed

27. Igneous Rock Textures • Where the rock forms in the Earth and how quickly it cools determines what kind of texture it will have

28. Cooling Rates and Igneous Textures The slower the crystals form, the larger they will be. Deep = Hot = Slow Cooling= Large Crystals = Phaneritic Shallow = Cooler = Fast Cooling = Small Crystals = Aphanitic Cooled slowly and then abruptly brought near surface and cooled quickly = both large and small crystals = Porphyritic Cooled extremely quickly = Glassy Cooled quickly and bubbles present = Vesicular Explosive welding of materials from volcanism = Pyroclastic/Fragmental

29. Igneous Rock Textures Glassy Vesicular Pyroclastic/Fragmental

31. What minerals are present also determine what kind of Igneous Rock forms.

32. Chemistry changes influence rock type

33. Minerals in Igneous Rocks Cont.

34. Chemistry changes influence rock type

35. Mineralogy cont. • Felsic rocks • dominated by K-feldspar, Na Plagioclase, quartz, and biotite • usually light in color • typical of continental crust (Granite and Rhyolite) • Intermediate rocks • dominated by plagiocase, amphibole, pyroxene, biotite, quartz • intermediate color • Andesite and diorite • Mafic rocks • Dominated by Ca-Plagioclase, pyroxene, olivine, amphibole • Usually dark in color • Typical of oceanic crusts (and the Moon, Mars, and Venus!) (Basalt, • Gabbro) • Ultramafic rocks • Dominated by olivine, minor amounts of pyroxene and Ca-plagioclase • Rarely seen on Earth’s surface • Major constituent of Earth’s Mantle • Peridotite

36. Sedimentary Rocks…

37. Type of rock and source material Rock-forming process Example IGNEOUS Melting of rocks Crystallization SEDIMENTARY Weathering and erosion of Exposed rocks Deposition, burial, and lithification

38. Sediments Grain Size Gravel >2mm Sand 1/16-2mm Silt 1/256-1/16mm Clay <1/256

39. Sediments cont. How are size and angularity affected by transport?

40. Sediments cont. Grain Sorting

41. Sedimentary Rocks Formed by surface processes Sediments are formed from weathering and erosion Weathering = chemical and physical processes that break up rocks into fragments of various sizes Erosion = set of processes that loosen soil and rock and move them

42. Sedimentary Rocks Loose sediments form sedimentary rocks through the process of lithification Lithification = converts sediment into solid rock by Compaction = grains are squeezed together by weight of overlying sediment into a mass denser than original Cementation = minerals precipitate around deposited particles and bind them together

43. The sedimentary stages of the rock cycle Weathering breaks down rocks. Erosion carries away particles. Transportation moves particles downhill. Glacier Delta Desert Deposition occurs when particles settle out or precipitate. Playa lake Burial occurs as layers of sediment accumulate. Sedimentary rocks Metamorphic rocks Plutons Diagenesis lithifies the sediment to make sedimentary rocks.

44. Sedimentary Rock Texture Step 1 in identifying a Sedimentary Rock 3 types Detrital/Siliclastic – rock made of fragments of other rocks Biochemical/Bioclastic – composed of organically derived material Chemical – sedimentary rocks precipitated out of solution

45. Step 2 in Identifying Sedimentary Rocks Detrital Rocks

46. Organic Matter Bioclastic Rocks Pressure Heat to 90° - 120° C Heat to 90° - 120° C Oil and gas Coal

47. Chemical rocks Evaporation  Precipitation

48. Breccia Chert Hematite Coal-Anthracite Conglomerate

49. Limestone Rocksalt Siltstone Sandstone Shale

50. Metamorphic Rocks…