Published on September 20, 2007
Slide1: ESCI 101: Lecture Rocks February 16, 2007 Copy of this lecture will be found at: http://www.owlnet.rice.edu/~esci101 With Some Graphics from Press et al., Understanding Earth, 4th Ed. (Copyright © 2004 by W. H. Freeman andamp; Company) From http://geology.about.com/library/ bl/images/blbif.htm Banded Iron Formation Rocks: Rocks A rock is a naturally occurring, solid aggregate of minerals. Fig 4.1 Three Classes of Rocks: Three Classes of Rocks Igneous (made by 'fire') - Solidified from molten rock (i.e., magma). Sedimentary - Deposited and buried at Earth’s surface. Metamorphic ('changed form') - Transformed from preexisting rocks under high pressure and temperature. Distinguishing Characteristics: Distinguishing Characteristics Mineralogy - Constituent minerals and their relative proportions. Texture - Sizes, shapes, and arrangements of minerals within the rock, e.g., Course-grained Fine-grained Foliated (planar fabric) All are clues to a rock’s origin and history. Three Classes of Rocks: Three Classes of Rocks Fig 4.2 Igneous Rocks: Igneous Rocks Minerals crystallize from melt, derived from deep within Earth’s crust or mantle High temperatures, up to 700° C or more!! Crystal size depends on cooling rate. Intrusive rocks cool slowly within deep magma chambers: Course, interlocking crystals Extrusive rocks cool rapidly at (or near) the surface of the earth: Fine-grained, often 'glassy' Igneous Rocks: Igneous Rocks Common in volcanic areas andamp; plate boundaries Fig 4.3 Slide8: Igneous Silicates predominate High melting temperatures Abundance of silicon Sedimentary Rocks: Sedimentary Rocks Loose particles (sand, silt, marine shells) accumulate on shorelines, basins, rivers, etc., Clastic Sediments Minerals precipitate from dissolved chemicals in water Chemical andamp; Biochemical Sediments All are the products of Weathering - that breaks up and decays rocks, and Erosion - that transports from source to point of deposition Slide10: Weathering andamp; Erosion Transport Deposition Basement Rocks Chemical: Limestone Fig 4.4 Common along passive margins (and other basins) Clastic: Sandstone Slide11: Sedimentary Silicates (esp. Clays) Carbonates Sulfates andamp; Halides (Precipitates) Metamorphic Rocks: Metamorphic Rocks High temperatures and pressures at depth cause changes in mineralogy, texture, and composition Changes take place in Solid State by recrystallization and chemical reactions Temperatures greater than 250°, less than 700° Regional Metamorphism - High pressures and temperatures derive from regional collision, deformation and mountain building. Contact Metamorphism - Locally high temperatures, adjacent to intrusions. Metamorphic Rocks: Metamorphic Rocks Fig 4.6 Common at collisional plate boundaries Metamorphic Rocks: Metamorphic Rocks Fig 4.6 Foliations - Planar fabric defined by Alignment of platy minerals (micas andamp; clays) Alternating bands of mineral types Indicative of high pressures and deformation during formation Pressure-Temperature-time paths Not Foliated Distinct low- pressure minerals Slide15: Metamorphic Silicates predominate Due to silicate source rocks Distinctive mineral types indicative of solid state reactions Characteristic Metamorphic Minerals: Characteristic Metamorphic Minerals For more images: http://skywalker.cochise.edu/wellerr/mineral/ kyanite andalusite sillimanite staurolite garnet Rock Types: Rock Types Fig 4.6 Sedimentary rocks are most abundant near Earth’s surface - poor preservation Igneous and Metamorphic rocks make up most of the crustal volume - limited exposure! Outcrops Sediments make up only 5% by volume Sediments make up 75% surface area Outcrop Exposures: Outcrop Exposures Fig 4.7 Measure orientation andamp; thickness Record regional patterns on geologic maps Infer what lies below Slide19: Fig 4.8 Slide20: Fig 4.8 Slide21: Fig 4.8 Slide22: Fig 4.8 Slide23: Fig 4.8 Slide24: Fig 4.8 ?? ?? ?? ?? ?? Rock Types: Rock Types Fig 4.6 How can we sample what lies below the surface? Ocean Drilling Continental Drilling Outcrops Sediments make up only 5% by volume Sediments make up 75% surface area By drilling: e.g., Oceans - all over, passive margins rifting andamp; spreading convergent hot spots Continents San Andreas Fault Chelungpu Fault Hawaii The Rock Cycle: The Rock Cycle Melting andamp; Intrusion Solidification of melt Mountain Building Uplift andamp; Exposure Weathering Erosion andamp; Transport Deposition andamp; Burial Metamorphism Melting andamp; Intrusion Fig 4.9 (a) The Rock Cycle: (a) The Rock Cycle Fig 4.9 Convergent Plate Boundary Subducting slab Mantle melting Bouyant rise of melt (b) The Rock Cycle: (b) The Rock Cycle Fig 4.9 Convergent Plate Boundary Solidification of melt Mountain building (c) The Rock Cycle: (c) The Rock Cycle Fig 4.9 Precipitation andamp; Weathering Moisture laden air Precipitation and run-off Freezing andamp; thawing (d) The Rock Cycle: (d) The Rock Cycle Fig 4.9 Sediment Transport to Oceans Deposition Burial andamp; lithification Chemical precipitation (e) The Rock Cycle: (e) The Rock Cycle Fig 4.9 Deformation andamp; Metamorphism Continental collision (i.e., orogeny) Burial andamp; deformation Increased pressure andamp; temperature (a) The Rock Cycle: (a) The Rock Cycle Fig 4.9 Convergent Plate Boundary Subducting slab Mantle melting Bouyant rise of melt Plate Tectonics & Climate: Plate Tectonics andamp; Climate Plate tectonics drives uplift andamp; subsidence Climatic processes weather andamp; transport sediment Interactions control the rock cycle Fig 4.9
Vocabulary words for ESCI 101. Includes studying games and tools such as flashcards.
Rating and reviews for Professor Jason Price from Millersville University Millersville, PA United States.
Rating and reviews for Professor Richard Mayer from Western Washington University Bellingham, WA United States.
CO (GE Comput/Info Literacy) CR (98/2000 GE Critical Thinking) CU (Int. Issues Cultures & Civiliz) EX (Int. Issues Expl. in Nat. Sci.) FI (GE Fine ...