Geology Midterm Review

Introduction to Geology GEOL-101 midterm examination 1 Review Based on the textbook Understanding existence, sixth Edition, by Grotzinger and Press CH 1 earth system abbreviation The valet de chambre creative process, field and lab observations, and experiments help geoscientists formulate testable hypotheses ( cases) for how the Earth whole kit and boodle and its history. A hypothesis is a tentative explanation focusing management on plausible features and relationships of a working model. If a testable hypothesis is confirm by a large body of data, it may be high-sounding to a opening. Theories argon abandoned when succeeding investigations show them to be false.Confidence grows in those theories that withstand repeated tests and successfully predict the results of new experiments. A cause of hypothesis and theories may become the basis of a scientific model that represents an entire system too complicated to replicate in the laboratory. a good deal models ar tested and r evised in a series of reckoner simulations. Confidence in such a model grows as it successfully predicts the behavior of the system. The elevations of Earth topography averages 12 kilometers above sea take for land features and 45 kilometers below sea level for features of the thickheaded ocean.The principle of uniformitarianism states that geological processes have worked in the same way throughout time. Earths interior is divided into concentric layers ( pertness, mantle, core) of sharply distinguishable chemical substance substance composition and density. The layered composition of the Earth is driven by gravity. Only eight of the 100 or so elements account for 99 percent of Earths mass. The lightest element (oxygen) is around abundant in the surface archness and mantle, while the densest (iron) makes up most of what is found buddy-buddy in the core. Earths major interacting systems be the climate system, the musical scale architectonic system, and the geodynamic syst em.The climate system considers interactions among the atmosphere, hydrosphere, and biosphere. The menage tectonic system involves interactions among the lithosphere, asthenosphere, and involved mantle. The geodynamic system involves interactions deep down the central core that produce occasional reversals of Earths magnetic field. As the Earth cooled, an out relatively set(p) shell, c bothed the lithosphere, make. Dynamic processes driven by heat f are, density differences, and gravity stony-broke the outer shell into places that move around the Earth at pass judgment of centimeters per year.Major components (atmosphere, hydrosphere, biosphere) of Earths surface systems are driven mostly by solar energy. Earths internal heat energizes the lithosphere, asthenosphere, deep mantle, and outer and inner core. terms and Concepts Asthenosphere Convection Core Continental lithosphere Continental crust Earth systems Geology Inner core Lithosphere Mantle Oceanic lithosphere Ocea nic crust scale leaf tectonic system Principle of uniformitarianism scientific method Topography CH 2 scurf tectonics Summary For over the support century some geologists have argued for the concept of Continental d fracture base on he jigsaw-puzzle fit of the coasts on both sides of the Atlantic the geological similarities in persuade ages and trends in geologic structures on opposite sides of the Atlantic fossil evidence suggesting that continents were joined at one time the dispersal of glacial deposits as advantageously as other paleoclimatic evidence In the last half of the twentieth century the major elements of the household tectonic theory were formulated. Starting in the 1940s (WWII), ocean storey part began to reveal major geologic features on the ocean floor.Then, the match in the midst of magnetic anomaly patterns on the seafloor with the paleomagnetic time scale revealed that the ocean floor had a young geologic age and was systematically older off from the nautical ridge systems. The concepts for seafloor spreading, subduction, and transform faulting evolved out of these and other observations. According to the theory of exfoliation tectonics, the Earths lithosphere is broken into a 12 moving plates. The plates microscope slide over a partially run, weak asthenosphere, and the continents, infix in some of the moving plates, are carried along. there are three major types of boundaries between lithospheric plates divergent boundaries, where plates move apart convergent boundaries, where plates move unneurotic and one plate often subducts beneath the other transform boundaries, where plates slide past each 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 unresolved on land, subsiding basins and mafic volcanism are typical.Various methods have been used to estimate and bank note the rate and direction of plate movements. Today seafloor-spreading rates vary between a fewer to 24 cm per year. Seafloor isochrons provide the basis for reconstructing plate motions for about the last 200 one million million million years. Distinct assemblages of inclinations characterize eachtype of plate leaping. Using diagnostic gemstone assemblages embedded in continents and paleo-environmental data preserve by fossils and aqueous totters, geologists have been able to reconstruct ancient plate tectonic events and plate configurations.Driven by Earths internal heat, convection of wild and cold matter indoors the mantle, the force of gravity and the existence of an asthenosphere are important factors in any 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 cosmos workressed include Where do the plate driving forces originate? At wha t depth does recycling occur? What is the nature of rising Convection Currents? The assembly and subsequent break up of Pangaea represent a striking example of the personal effects of plate tectonics acting over geologic time.The story begins with the interval 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. act 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 t he new inland sea that we know as the Mediterranean. Continued transposes during the Cenozoic produced our mod world and its geography. Terms and Concepts Continental drift Continent-continent convergent boundary merging(prenominal) boundary Divergent boundary Island arc Isochron Lithospheric plates charismatic anomaly Magnetic time scale Mid-ocean ridge Mountain range Ocean-ocean convergent boundary Ocean-continent convergent boundary Pangaea Plate tectonicsSeafloor spreading Spreading center Subduction veer boundary Wegeners hypothesis CH 3 earth materials Summary Minerals are naturally occurring inorganic unbendables with a specific crystal structure and chemical composition. Minerals form when atoms or ions chemically bond and come together in an orderly, three-dimensional geometric arraya crystal structure. Chemical bond may occur either as a result of honest electrostatic attraction (ionic bond) or electron sharing (covalent bond). The strength of the chemical bonds an d the crystalline structure determine many of the physical 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 disjointed tetrahedral (olivine), single chains (pyroxene), double chains (amphibole), sheets (mica), or three-dimensional frameworks ( feldspar). on that point are three important groups of silicates ferromagnesium silicates, e. g. , olivine and pyroxene third estate in the mantle feldspar and quartzcommon in the crust clay mineral usually produced by chemical weatheringOther common mineral classes include carbonates, oxides, sulfates, sulfides, halides, and native metals. A rock is a naturally occurring substantiality aggregate of minerals. A few rocks brood of only one mineral and a few others consist of non-mineral matter. The properties of rocks and rock names are dictated by mineral marrow (the kinds and proportions of minerals that make up the rock) and texture (the size, shapes, and spatial arrangement of crystals or iotas. There are three major rock types Igneous rocks solidify from molten liquid (magma) crystal size within perfervid rocks is largely determined by the cooling rate of the magma body. aqueous rocks are made of fixs organise from the weathering and wear of any pre-existing rock deposition, burying 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 imperativeness. Terms and Concepts Anion Atomic mass Atomic number carbonate Cation Cleavage covalent bond Crystal Crystallization Electron sharing Electron transfer Isotope Magma Mineral Polymorph Precipitate Rock CH 4 igneous rocks SummaryIgneous rocks can be divided into dickens broad textual classes coarsely crystalline rocks, which are intrusive (plu tonic) and therefore cooled slowly finely crystalline rocks, which are volcanic (volcanic) and cooled rapidly. Within each of these broad textual classes, the rocks are subdivided according to their composition. ecumenical compositional classes of igneous rocks are felsic, intermediate, mafic and ultramafic, in decreasing silica and change magnitude iron and magnesium content. fancys 4. 1, 4. 2, 4. 3 and Table 4. 1 summarize common minerals and composition of igneous rocks.The lower crust and upper mantle are typical places where physical conditions induce rock to consort. Temperature, pressure, rock composition, and the presenceof urine all affect the melt down temperature of the rock Increase temperature not all minerals melt at the same temperature refer to physiques 4. 6 and 4. 7, which explain how fractional watch crystal results from Bowens reaction series. The mineral composition of the rock affects the melting temperature. Felsic rocks with higher(prenominal) silica content melt at lower temperatures than mafic rocks which contain less(prenominal) silica and more iron/magnesium.Lower the confining pressure a decrease in pressure can induce a sweltry 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 c 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 trapped 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 Batholith Bomb Concordant intrusion Country rock Decompression m elting Dike Discordant intrusion Diorite Extrusive igneous rock Felsic rock Fractional crystallization Gabbro Granite Granodiorite Intermediate rock inquiring igneous rock Lava Mafic rock Magma chamber Magmatic differentiation Partial melting Pegmatite Peridotite Pluton Rhyolite PorphyryPum methamphetamine hydrochloride Pyroclast Rhyolite Sill Ultramafic rock Volcanic ash xenolith CH5 sedimentary rocks Summary Plate tectonic processes play an important role in producing depressions (basins) in which sediments accumulate. Sedimentary basins result from rifting, thermal 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.Burial and diagenesis harden sediments into sedimentary rock s 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 alike bedding, ripple marks, and mud cracks, provide important clues about the sedimentary environment. Diagenesis transforms sediment into sedimentary rock. Burial promotes this transformation by subjecting sediments to increasing heat and pressure. Cementation is specially important in the lithification of clastic sediments. The classification of clastic sediments and sedimentary rocks is ground primarily on the size of the grains within the rock. The name of chemical and biochemical sediments and sedimentary 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 Foraminifera Graded bedding Gravel Limestone Lithification Physical weathering porosity Ripple Salinity Sandstone Sedimentary basin Sedimentary structure Shale Siliciclastic sediments assortment 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 th e solid state higher confining pressure compacts the rock directed pressure associated with tectonic activity can cause the rock to shear (smear), which orients mineral grains and generates a foliation and chemical reactions with migrating fluids may remove or add materials and induce the growth of new minerals.The two major types of metamorphism are regional metamorphism, associated with orogenic processes that build mountains, contact metamorphism, caused by the heat from an intruding body of magma, and seafloor metamorphism, alike 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 disaster metamorphism due to meteor impact refer to Figure 6. 4.Metamorphic rocks fall into two major textural classes the foliated (displaying a preferred orientation of minerals, analogous to the grain within wood) and granobla stic (granular). The composition of the parent rock and the grade of metamorphism are the most important factors controlling the mineralogy of the metamorphic rock. etamorphism usually causes little to no change in the bulk composition of the rock. The kinds of minerals and their orientation do change. Mineral assemblages within metamorphic rocks are used by geoscientists as a study 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 Slate Adapted for the GEOL101 course by Alfonso Benavides (2012)