Igneous Rock.pptx
- 1. Rocks
- 2. Rocks • A rock is an aggregate to one or more minerals which may or may not contain glass, organic matter, and mineraloids. • Any solid mass of mineral or mineral-like matter occurring naturally as part of our planet.
- 3. • Studying rocks would be an essential part to understanding the one of the earth’s systems, the geosphere. • And because these rocks are components that revolve around the system, understanding the processes that transform them from one form to another will help us understand more about the planet as a whole.
- 5. Igneous rock is formed by the crystallization of molten magma.
- 6. Sedimentary rock is formed from the weathered of preexisting rocks that been transported, compacted, and cemented. Sedimentary cliff strata, Zion Canyon, Utah
- 7. Metamorphic rock is formed by the alteration of pre- existing rock deep within Earth (but still in the solid state) by heat, pressure, and/or chemically active fluids.
- 8. The Rock Cycle Shows the interrelationships among the three rock types (igneous, sedimentary, and metamorphic)
- 9. • Magma is molten material that forms deep beneath the Earth’s surface. • Lava is magma that reaches the surface.
- 10. • Weathering is a process in which rocks are broken down by water, air, and living things • Sediment is weathered pieces of Earth elements.
- 11. Energy That Drives the Rock Cycle Processes driven by heat from the Earth’s interior are responsible for forming both igneous rock and metamorphic rock. Weathering and the movement of weathered materials are external processes powered by energy from the sun. External processes produce sedimentary rocks.
- 12. Igneous Rocks: Rocks formed by fire • Magma is defined as molten rock with associated solid materials and gaseous phases. • Lava is simply a term to describe magma that has breached the surface.
- 13. The Source of Heat The best way to generate magma is to heat a portion of the solid earth. 1. Remnant heat from the formation of the earth is no longer that high and readily available 2. Heat from radioactive decay of certain elements • The earth is actually cooling from the sun (that’s why we have solid crust) • Going in ( and we still have molten materials inside along with the trapped heat) • We get a glimpse of such energy when we witness volcanic eruptions which spews out molten material we call lava (in areas we call hotspots)
- 14. Other Ways to Melt Rocks • Decompression is the removal or decrease of a certain pressure applied on a body. • Given a rock that is undergoing pressure at certain temperature, a decrease in pressure will allow a change in phase once the ambient temperature is enough to do so at the new prevalent pressure. • Read the example on page 31.
- 15. Mid-oceanic Ridges • The regions of the earth where new oceanic material is extruded on the surface. • This extrusion of oceanic material causes the expansion of oceanic crust which in effect, extends the oceanic basin. • Oceanic basins are regions on the surface of the earth located below sea level.
- 16. 3 Major Regions of the Ocean Floor 1. Mid-oceanic Region • Extensive stretch of volcanic centers forming new oceanic crust.
- 17. 3 Major Regions of the Ocean Floor 2. Deep Ocean Margins • Between continental margins and oceanic ridges, deep ocean margins are found. • Ocean margins are defined by relatively flat topography called abyssal plains.
- 18. 3 Major Regions of the Ocean Floor 3. Continental Margins Adjacent to continental land mases, continental margins do not simply start where shore lines the boundary. Instead, continental margins grade into continental shelf, slope, and rise. a) Continental shelf is the gently sloping platform from the shore extending seaward b) Continental slopes line the boundary between continents and deep ocean basins. c) Continental rise marks areas where trenches are absent marking the end of continental regime.
- 20. Magma, Minerals, and Igneous Rocks • The fundamental material required to produce igneous rock rocks would be magma. • Minerals are the primary components of all rocks on earth. • Majority of the minerals we see in rocks can actually be grouped together to form what we call Common Rock-forming Minerals. • The minerals that you will observe in your igneous rocks will then be a reflection of the composition of the magma it came from.
- 21. Igneous Rock Crystallization or cooling The process that transforms magma into solid igneous rock.
- 22. • Rocks that formed on the surface are called volcanic rocks (from lava) while rocks that cooled beneath the surface are called plutonic rocks. • The distinction between volcanic and plutonic rocks is evident in textures.
- 23. Classification of Igneous Rocks • Phaneritic texture • Aphanitic texture Texture • Ultramafic • Mafic • Intermediate • Felsic Mineral composition
- 24. Texture
- 25. Mineral Composition Olivine, Pyroxene Olivine, Pyroxene, Amphibole Pyroxene, Amphibole, Biotite Quartz, K-Feldspar, Muscovite Minerals
- 26. Ultramafic: Peridotites and Komatiites • Igneous rocks composed of mainly olivine and pyroxene are called peridotites (phaneritic) or komatiites (aphanitic). • Characterizes by the abundance of ferromagnesian minerals and are usually dark green to black in color.
- 27. Mafic: Gabbro & Basalt • Majority of igneous rocks produced by mid-oceanic ridges are within the compositional group of gabbro and basalts. • Lower iron and magnesium content compared with ultramafic
- 28. Intermediate: Diorite and Andesite • Minerals in transition from mafic to felsic • Its no longer ultramafic nor mafic but not yet achieving felsic compositions
- 29. Felsic: Granite and rhyolite • Interaction between magma and the surrounding rocks
- 30. The Study of Igneous Rocks • The study of Igneous rocks is an imperative window that permits understanding of the processes occurring deep within the earth • Igneous rocks pioneer the other two rocks types • Ultimately, any rock will trace back its lineage to an igneous one.