cee 437 lecture 2 minerals - university of washingtoncee 437 lecture 2 history of geology geologic...
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CEE 437 Lecture 2History of Geology
Geologic Time Plate Tectonics
Thomas Doe
Geology — Brief History
Origins in late 18th and early 19th CenturiesCatastrophism and Uniformitarianism
Age of EarthUniformity of Processes
Plate Tectonics Revolution (1950’s to 1980’s)Neo-Catastrophism
Siccar Point Unconformity
Rock Cycle
Metamorphic Rocks
Sedimentary Rocks
Igneous Rocks
Sediments
Lithification
Magma
Weathering, Erosion
Burial, metamorphism, recrystallization
Melting
Crystallization at depth or extrusion at surface
Burial, metamorphism, recrystallization
Relative Time
Principle of SuperpositionFossil EvidenceCross Cutting RelationshipsUnconformitiesAlterationFracture Termination
Geologic Time Scale — Eras
Precambrian — Minimal fossil recordEra, Period, EpochBased on major changes — extinctions, mountain building events
Paleozoic (Old Life) —Brachiopods, Trilobites, Fish
Periods based on English GeologyCambrian for Latin WalesOrdovician and Silurian for ancient Welsh TribesDevonian for DevonCarboniferous for Coal Measures (also Mississippian and Pennsylvanian in US)Permian for Perm Basin in Ukraine
Mesozoic (Middle Life) —Ammonites, Dinosaurs
Triassic based on distinctive three-layer stratigraphy in southern GermanyJurassic based on Jura Mountains in France and SwitzerlandCretaceous (Latin for Chalk) based on chalk unit that forms Dover’s cliffs
Cenozoic (Recent Life) —Mammals, Modern marine fauna
(foraminifera)
Periods are Tertiary (before Ice Ages) and Quaternary (ice ages)Primary and secondary have been long replacesRocks of western Washington are primarily Tertiary and Quaternary in age
Age of the Earth
Kelvin and a basis in heat flow (set at 20 million years)Problem of fitting all of evolution in this timeRutherford and the introduction radioactive decayAdded a head source, pushed ages back to 4.5 billion years
Absolute Time
Basis on radiometric dating Common dating tools
14C, K-Ar, Rb-Sr,Uranium decay series
Development of Plate Tectonics
Evidence from ocean floor magnetism and agesEvidence from seismicityEvidence from cross-continent correlations of rocks
Global Seismicity
Benioff Zone
Seafloor Spreading — Sediment Ages
Sea-floor Spreading
Mantle convection driven
Evolution of Spreading Sea Floor — Atlantic Analog
Convergent Margins
Ocean to ContinentContinent to Continent
Convergent Margin - Continental
Subduction Zone – Island Arc
Evolution of Continents — North American Craton
North American Accretion