Geology Midterm Review

Introduction to Geology GEOL-101 Midterm 1 inspection Based on the textbook Understanding pedestal, 6th Edition, by Grotzinger and kettle of fish CH 1 earth schema Summary The human creative process, survey and lab observations, and experiments help geoscientists formulate testable hypotheses (models) for how the worldly concern works and its history. A surmise is a tentative explanation thinking attention on slick features and relationships of a working model. If a testable hypothesis is confirmed by a large body of data, it whitethorn be elevated to a theory. Theories argon abandoned when subsequent investigations show them to be false.Confidence grows in those theories that withstand ingeminate tests and successfully predict the results of new experiments. A set of hypothesis and theories may become the basis of a scientific model that represents an entire dodging too complicated to replicate in the laboratory. Often models be time-tested and revised in a series of c omputer simulations. Confidence in such a model grows as it successfully predicts the behavior of the system. The elevations of domain topography averages 12 kilometers supra sea level for land features and 45 kilometers below sea level for features of the deep ocean.The principle of uniformitarianism states that geologic processes have worked in the uniform focal point throughout time. demesnes interior is divided into concentric layers ( en resentmentation, chimneypiece, core) of sharply different chemical motif and density. The layered theme of the res publica is goaded by gravity. Only eighter of the 100 or so elements account for 99 percent of Earths mint. The lightest element (oxygen) is most rich in the surface crust and winding-clothes, while the densest (iron) makes up most of what is found deep in the core. Earths study interacting systems be the clime system, the nursing home tectonic system, and the geodynamic system.The climate system involves interacti ons among the atmosphere, hydrosphere, and biosphere. The dwelling house tectonic system involves interactions among the lithosphere, asthenosphere, and deep mantle. The geodynamic system involves interactions inside the central core that produce occasional reversals of Earths magnetised field. As the Earth cooled, an outer relatively rigid tucker, called the lithosphere, formed. Dynamic processes driven by heat transfer, density differences, and gravity broke the outer shell into shields that move around the Earth at rates of centimeters per year.Major components (atmosphere, hydrosphere, biosphere) of Earths surface systems be driven mostly by solar energy. Earths internal heat energizes the lithosphere, asthenosphere, deep mantle, and outer and inner core. wrong and Concepts Asthenosphere Convection Core Continental lithosphere Continental crust Earth systems Geology knowledgeable core Lithosphere Mantle Oceanic lithosphere Oceanic crust Plate tectonic system Principle of uniformitarianism Scientific method Topography CH 2 plate architectonics Summary For over the rifle century nearly geologists have argued for the concept of Continental drift based on he jigsaw-puzzle fit of the coasts on both sides of the Atlantic the geological similarities in stone ages and trends in geologic constructions on opposite sides of the Atlantic fossil show up suggesting that continents were joined at one time the distribution of glacial deposits as well as other paleoclimatic evidence In the last half(a) of the twentieth century the major elements of the plate tectonic theory were formulated. scratch in the 1940s (WWII), ocean floor mapping began to reveal major geologic features on the ocean floor.Then, the match between magnetic unusual person patterns on the seafloor with the paleomagnetic time outgo revealed that the ocean floor had a girlish geologic age and was systematically older away from the oceanic extend systems. The concepts for seafloor spread ing, subduction, and transform faulting evolved out of these and other observations. According to the theory of plate tectonics, the Earths lithosphere is broken into a dozen moving plates. The plates microscope slide over a partially molten, weak asthenosphere, and the continents, embedded in or so of the moving plates, atomic number 18 carried along.There are terzettosome major types of boundaries between lithospheric plates diverging boundaries, where plates move apart convergent boundaries, where plates move together and one plate often subducts beneath the other transform boundaries, where plates slide past distributively other Volcanoes, earthquakes, and crustal deformation are concentrated along the active plate boundaries. Mountains typically form along convergent- and transform-plate boundaries. Where divergent-plate boundaries are exposed on land, weaken basins and mafic volcanism are typical.Various methods have been used to estimate and measure the rate and tutel age of plate gestures. Today seafloor-spreading rates vary between a fewer to 24 cm per year. Seafloor isochrons provide the basis for reconstructing plate motions for intimately the last 200 one thousand million years. Distinct assemblages of shake offs characterize apiecetype of plate edge. Using symptomatic disputation-and-roll-and-roll assemblages embedded in continents and paleo-environmental data recorded by fossils and aqueous rocks, geologists have been able to reconstruct antediluvian patriarch plate tectonic events and plate configurations.Driven by Earths internal heat, convection of hot and cold social occasion inside the mantle, the force of gravity and the existence of an asthenosphere are important elements in each model for the driving mechanism of plate tectonics. Currently studies of the plate-driving forces focus on discovering the exact nature of the mantle convection. Questions being addressed take Where do the plate driving forces originate? At wha t depth does recycle authorise? What is the nature of rising Convection Currents? The assembly and subsequent break up of Pangaea represent a striking example of the effects of plate tectonics acting over geologic time.The story begins with the breakup of the ancient supercontinent of Rodinia 750 million years ago. Plate tectonic processes dispersed the fragments of Rodinia forming a system of ancient continents that existed from the late Proterozoic through much of the Paleozoic. Continued tectonic movement eventually resulted in a set of continental collisions and reformation of the ancient continents into Pangaea. Assembly was completed during the early Triasic, about 240 million years ago. Then, about 200 million years ago the rift that would evolve into the Atlantic Ridge began to open and the separation of Pangaea was underway.By the beginning of the Cenezoic, India was well on its way to Asia, and the Tethys sea that had separated Africa from Eurasia began to close into the modern inland sea that we know as the Mediterranean. Continued changes during the Cenozoic produced our modern world and its geography. footing and Concepts Continental drift Continent-continent convergent boundary Convergent boundary different boundary Island arc Isochron Lithospheric plates Magnetic anomaly Magnetic time scale Mid-ocean ridge Mountain range Ocean-ocean convergent boundary Ocean-continent convergent boundary Pangaea Plate tectonicsSeafloor spreading Spreading center Subduction Transform boundary Wegeners hypothesis CH 3 earth materials Summary Minerals are naturally occurring inorganic solids with a specific quartz glass structure and chemical man. Minerals form when atoms or ions chemically bond and come together in an orderly, three-dimensional geometric arraya crystal structure. chemical bonding may occur either as a result of simple electrostatic loss leader (ionic bond) or electron sharing (covalent bond). The strength of the chemical bonds and the crys talline structure determine many of the sensual properties, e. . , hardness, cleavage of minerals. Silicate minerals are the most abundant class of minerals in the Earths crust and mantle. Common silicate minerals are polymorphs of silicon ions arranged in either isolated tetrahedral (olivine), single shackles (pyroxene), double chains (amphibole), sheets (mica), or three-dimensional frameworks (feldspar). There are three important groups of silicates ferroatomic number 12 silicates, e. g. , olivine and pyroxene usual in the mantle feldspar and quartzcommon in the crust clay mineralcomm notwithstanding produced by chemical weatheringOther common mineral classes include carbonates, oxides, sulfates, sulfides, halides, and native metals. A rock is a naturally occurring solid aggregate of minerals. A few rocks consist of only one mineral and a few others consist of non-mineral matter. The properties of rocks and rock name are determined by mineral matter (the kinds and proportions of minerals that make up the rock) and texture (the size, shapes, and spatial arrangement of crystals or grains. There are three major rock types Igneous rocks solidify from molten liquid (magma) crystal size within pyrogenous rocks is largely determined by the cool rate of the magma body.Sedimentary rocks are made of alluviations formed from the weathering and erosion of any preexistent rock deposition, burial and lithification (compaction and cementation) transform loose sediments into sedimentary rocks. Metamorphic rocks are formed by an alteration in the solid state of any preexisting rock by high temperatures and draw. Terms and Concepts Anion Atomic mass Atomic number Carbonate Cation Cleavage Covalent bond vitreous silica Crystallization Electron sharing Electron transfer Isotope Magma Mineral Polymorph flow Rock CH 4 igneous rocks SummaryIgneous rocks can be divided into 2 broad textual classes coarsely crystalline rocks, which are intrusive (plutonic) and thereof cooled slowly finely crystalline rocks, which are extrusive (volcanic) and cooled rapidly. Within each of these broad textual classes, the rocks are subdivided according to their composition. General compositional classes of igneous rocks are felsic, intermediate, mafic and ultramafic, in decreasing silica and increasing iron and magnesium content. Figures 4. 1, 4. 2, 4. 3 and Table 4. 1 summarize common minerals and composition of igneous rocks.The trim down crust and upper mantle are typical places where physical conditions induce rock to melt. Temperature, push, rock composition, and the presenceof peeing all affect the liquescent temperature of the rock Increase temperature not all minerals melt at the same temperature refer to Figures 4. 6 and 4. 7, which explain how fractional crystallization results from Bowens chemical reaction series. The mineral composition of the rock affects the thawing temperature. Felsic rocks with high silica content melt at lower temperatures t han mafic rocks which contain less silica and more than iron/magnesium.Lower the confining pressure a drop-off in pressure can induce a hot rock to melt. A reduction in confining pressure on the hot upper mantle is thought to generate the basaltic magmas which intrude into the oceanic ridge system to form ocean crust refer to Figure 4. 15. Add water the presence of water in a rock can lower its melting temperatures up to a few hundred degrees. Water released from rocks subducting into the mantle along convergent plate boundaries is thought to be an important factor in magma generation at convergent plate boundaries.As subduction begins water detain in the rock is subjected to increasing temperature and pressure. Eventually the water is released into sedimentary layers above where it melts parts of the overlying plate refer to Figure 4. 16. Terms and Concepts Andesite Basalt plutonic rock Bomb Concordant intrusion Country rock Decompression melting Dike Discordant intrusion Diorit e Extrusive igneous rock Felsic rock Fractional crystallization Gabbro Granite Granodiorite Intermediate rock Intrusive igneous rock Lava Mafic rock Magma chamber Magmatic differentiation Partial melting Pegmatite Peridotite Pluton Rhyolite PorphyryPumice Pyroclast Rhyolite Sill Ultramafic rock Volcanic ash xenolith CH5 sedimentary rocks Summary Plate tectonic processes exploit an important role in producing depressions (basins) in which sediments accumulate. Sedimentary basins result from rifting, thermic sag, and flexure of the lithosphere. The sedimentary stages of the rock cycle involve the overlapping processes of weathering, erosion, transportation, deposition, burial, and diagenesis. Weathering and erosion produce the clastic particles and dissolved ions that compose sediment. Water, wind, and ice transport the sediment downhill to where it is deposited. sepulchre and diagenesis harden sediments into sedimentary rocks via pressure, heat, and chemical reactions. The two major types of sediments are clastic and chemical/biochemical. Clastic sediments are formed from rock particles and mineral fragments. Chemical and biochemical sediments originate from the ions dissolved in water. Chemical and biochemical reactions precipitate these dissolved ions from solution. Understanding the characteristics of sediments and modern sedimentary environments provides a basis for reconstructing past environmental conditions using the rock record.Sedimentary structures like bedding, ripple marks, and clay cracks, provide important clues about the sedimentary environment. Diagenesis transforms sediment into sedimentary rock. sepulture promotes this transformation by subjecting sediments to increasing heat and pressure. Cementation is especially important in the lithification of clastic sediments. The classification of clastic sediments and sedimentary rocks is based primarily on the size of the grains within the rock. The name of chemical and biochemical sediments and s edimentary rock is based primarily on their composition. Terms and Concepts Carbonate rockCarbonate sediment Cementation Chemical weathering Compaction Conglomerate Cross-bedding Crude oil Diagenesis Evaporite rock Flexural basin order Foraminifera Graded bedding Gravel Limestone Lithification Physical weathering Porosity Ripple saltiness Sandstone Sedimentary basin Sedimentary structure Shale Siliciclastic sediments Sorting Subsidence thermal subsidence basin CH 6 Metamorphic rocks Summary Metamorphism is the alteration in the solid state of preexisting rocks, including older metamorphic rocks. Increases in temperature and pressure and reactions with chemicalbearing fluids cause metamorphism.Metamorphism typically involves a rearrangement (recrystallization) of the chemical components within the parent rock. Rearrangement of components within minerals is facilitated by higher temperatures, which increase ion mobility within the solid state higher confining pressure compacts the r ock directed pressure associated with tectonic bodily process can cause the rock to shear (smear), which orients mineral grains and generates a leafing and chemical reactions with migrating fluids may remove or add materials and induce the gain of new minerals.The two major types of metamorphism are regional metamorphism, associated with orogenic processes that build mountains, data link metamorphism, caused by the heat from an intruding body of magma, and seafloor metamorphism, also known as metasomatism. Other less common kinds of metamorphism are burial metamorphism, associated with subsiding regions on continents, high-pressure metamorphism, occurring deep within subduction zones and upper mantle, and shock metamorphism due to meteor impact refer to Figure 6. 4.Metamorphic rocks fall into two major textural classes the foliaceous (displaying a preferred orientation of minerals, analogous to the grain within wood) and granoblastic (granular). The composition of the parent ro ck and the grade of metamorphism are the most important factors autocratic the mineralogy of the metamorphic rock. etamorphism usually causes little to no change in the plenty composition of the rock. The kinds of minerals and their orientation do change. Mineral assemblages within metamorphic rocks are used by geoscientists as a guide to the original composition of the parent rock and the conditions during metamorphism.Metamorphic rocks are characteristically formed in subduction zones, continental collisions, oceanic spreading centers, and deeply subsiding regions on the continents. Terms and Concepts Amphibolite Burial metamorphism Contact metamorphism Eclogite Foliation Gneiss Granoblastic rock marble Metasomatism Migmatite Phyllite Porphroblast Quartzite Regional metamorphism Schist Seafloor metamorphism Shock metamorphism destine Adapted for the GEOL101 course by Alfonso Benavides (2012)