PETROLOGY
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Petrology is the study of rocks and their origins, compositions, textures, and structures. There are three main types of rocks: igneous rocks formed from cooled magma, sedimentary rocks formed from compressed sediments, and metamorphic rocks formed from existing rocks subjected to heat and pressure. Rocks are constantly changing between these types through geological processes in the rock cycle, powered by Earth's interior heat and the energy from the sun. Igneous rocks can become sedimentary rocks through weathering and erosion then become metamorphic rocks through burial and increased heat and pressure, and metamorphic rocks can melt to form new magma and igneous rocks.
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PETROLOGY
- 1. PETROLOGYPETROLOGY Dr. P. Sarathbabu M.Sc. B.Ed. Ph.D. Department of Geology Acharya Nagarjuna University
- 2. Introduction: Petrology deals with the study of rocks Petro = rock , ( litho=rock ) Logos = study Petrology comprises the Origin, Association Occurrence Mineral composition Texture Structure Physical properties etc.. of rocks
- 3. Rock: Aggregated solids of minerals is called rock. (Or) A rock may be defined as “an unit of the earth’s crust All rocks are made of two or more minerals, but minerals are not made of rocks.
- 4. Geological Classification of Rocks • There are three main types of rocks: 1.1. IgneousIgneous - formed when molten rock cools. 2.2. MetamorphicMetamorphic – rocks changed by the effect of heat and pressure. 3.3. SedimentarySedimentary – formed by the consolidation of sediments in the layered or bedded rocks deposited in the ocean bottom or huge lakes, etc.
- 5. What type of rock is formed when magma cools and hardens? Characteristics A tough, frozen melt with little texture or layering; mostly black, white and/or gray minerals; may look like granite or like lava
- 6. What type of rock is formed when change occurs from heat and pressure in the Earth? Characteristics Hardened sediment with layers (strata) of sandy or clayey stone; mostly brown to gray; may have fossils and water or wind marks
- 7. What type of rock is formed when weathering and erosion cause sediments to press together in layers? Characteristics Tough rock with layers (foliation) of light and dark minerals, often curved; various colors; often glittery from mica
- 9. Rock Cycle • The three different types of rocks--- igneous, sedimentary and metamorphic---are constantly being changed from one type to another type through various geological processes.
- 10. Early stage of Earth = Molten stage
- 22. MAGMA Volcanic IGNEOUS Plutonic SEDIMENT SEDIMENTARY METAMORPHIC Uplift Burial Increased P&T Melting Crystallization Weathering Erosion Transport Deposition Can you see any shortcuts?
- 24. • The rock cycle demonstrates the relationships among the three major rock groups • It is powered by the interior heat of the Earth • As well as earth’s momentum and… • The energy from the sun • It involves processes on the Earth’s surface as well as the Earth’s interior • It connects the “hydrologic cycle” with the “tectonic cycle”. In Conclusion…
- 29. Granite
- 30. Marble
- 31. Sandstone
- 32. Civil Engineering importance of Petrology • Petrology provides a proper concept and logical basis for interpreting physical properties of rocks. • The study of texture, structure, mineral composition, chemical composition etc., gives all necessary details regarding the strength,durabiliy,colour,appeareance, workability, etc., These inherent characters of rocks are of chief concern for a civil engineer to judiciously assess the suitability occurring at project site for required purpose