LectureCh.16. Cenozoic Earth - Ch. 16 Cenozoic Geologic...

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Unformatted text preview: Ch. 16 Cenozoic Geologic History: The Paleogene and Neogene Topics: Breakup of Pangaea continues Orogenies Margin of Pacific Ocean E-W through Europe and Asia (Alps, Himalayas) Laramide orogeny cont. Present-day Appalachians form The Cenozoic Era Paleogene Period (66-23 m.y.) Paleocene Epoch Eocene Epoch Oligocene Epoch Neogene Period (23 m.y. to present) Miocene Epoch Pliocene Epoch Pleistocene Epoch Holocene Epoch 1.5 % of all geologic time Cenozoic Plate Tectonics Mid-Atlantic Ridge, East Pacific Rise (Americas separate from Europe and Africa) Indian Plate moves N (collision with Asia: Himalayas) African Plate moves N (closure of Tethys Sea) Eocene Epoch Miocene Epoch Cenozoic Plate Tectonics cont. Neogene rifting: E-Africa, Red Sea, and Gulf of Aden Triple junction; East African Rift System Cenozoic Orogenic Belts Orogeny = episode of mountain building, deformation over elongate area Volcanism, plutons, regional metamorphism Two main areas Alpine-Himalayan orogenic belt Circum-Pacific orogenic belt Orogenic activity, Cenozoic Era Alpine-Himalayan Orogenic Belt E'ward from Spain into SE Asia Closure of Tethys Sea (N movement of African and Indian plates) The Alps Alpine Orogeny Began during Mesozoic, Eocene to Late Miocene important N movement of African and Arabian plates against Eurasia Also: collision of several smaller plates with Europe Mountains: Pyrenees, Apennines, Alps, Atlas Overturned folds (nappes) Very complicated geology! Alps, Switzerland Alps, Switzerland Alps, S-Germany The Mediterranean Sea "Leftover" Tethys Sea Isolated during Late Miocene: evaporites (2 km) The Himalayas Collision India-Asia India separated from Gondwana during Early Cretaceous Subduction of oceanic plate: volcanic chain and large granitic plutons (now Tibet) Continent-continent collision (about 40-50 m.y. ago): Himalayas Origin of the Himalay Origin of the Himalaya The Circum-Pacific Orogenic Belt Several orogens along W margins of S-and NAmerica E margin of Asia Islands N of Australia and New Zealand W and N Pacific: subduction of oceanic lithosphere --> deformation, volcanism; e.g. Japan E Pacific: Cocos and Nasca plates move W, subduction zones in Central and S-America --> deformation, volcanism, seismic activity; e.g. Andes Sea of Japan, Back-arc sp The Andes Mountains Prior 200 mio years ago Andes, Chile North America The North American Cordillera Alaska to central Mexico Pacific to Rocky Mountains (1200 km) Geologic evolution Neoproterozoic/Paleozoic: sedimentation Devonian: Antler orogeny Late Jurassic-Eocene: Cordilleran orogeny (Nevadan, Sevier, Laramide) After Eocene: block-faulting, volcanism, vertical uplift and erosion Change from subduction zone to transform fault, W margin of Cordilleran (second half of Cenozoic) --> earthquakes The Laramide Orogeny Late Cretaceous to Eocene Different from Nevadan and Sevier orogenies Further inland (middle and southern Rockies) +/- no volcanism or plutons Vertical, fault-bounded uplifts (not folding and thrusting) Change in subduction angle of Farallon plate underneath N-American plate Mantle plume Large overthrust faults, e.g. Lewis overthrust Laramide Orogeny Lewis Overthrust, Montana Fault line (light color) Chief Mountain Teton Range, Wyoming Teton Range Cordilleran Igneous Activity Mesozoic: large batholiths Cenozoic: Small plutons, e.g. UT, NE, AZ, NM Lava flows, calderas, e.g. Yellowstone area, Columbia River basalts Volcanism, e.g. San Francisco Peaks, AZ Cenozoic Volcanics Western - US Columbia River basalts, Washington Snake River plain, Idaho Old Faithful geyser, Yellowstone NP, Wyoming Volcanic rocks, CO Cenozoic Volcanism C Cenozoic Volcanism A San Francisco Mountains, AZ Cascade Range Large composite volcanoes, e.g. Mt. St. Helens Lava dome (Lassen Peak) Subduction Juan de Fuca plate beneath N America Oligocene-today Cascade Range Volcan Mt St. Helens, Cascade Range Basin and Range Province Basin and Range Province N-S oriented mountain ranges and basins Bounded by steep normal faults Before faulting: deformation during Nevadan, Sevier, and Laramide orogenies Paleogene: erosion Miocene: lava flows, faulting --> basins and ranges W: Sierra Nevada Sierra Nevada Pliocene/Pleistocene: Uplift and tilting to W Now 3000m above basins to E Basin and Range climate changed from subtropical to arid Basin and Range Province Basin and Range Provin Snake Range, Nevada Sierra Nevada The Colorado Plateau Colorado Plateau CO, UT, AZ, NM Permian and Triassic: red beds Cretaceous: marine deposits Paleogene: Laramide orogeny Broad anticlines, arches, basins, normal faults Little deformation Neogene: uplift Today: 1200m above sea level Canyons carved by rivers The Colorado Plateau Valley of the Gods, Utah Colorado NM, Colorado Rio Grande Rift Rio Grande Rift N-S from CO to Mexico (ca. 1000 km) Rift bounded by normal faults Seismic activity, volcanoes, calderas Rifting since ca. 30 mio years ago (today <2mm/y Displacement up to 8000 m The Rio Grande Rift Bandelier Tuff Pacific Coast Pacific Coast Before Eocene: convergent plate boundary (Farallon plate - N-American plate) Pacific-Farallon ridge Today: Juan de Fuca and Cocos plate San Andreas transform fault Volcanism, seismic activity Collision N-America with Pacific-Farallon Ridge San Andreas Fault Continental Interior Continental Interior Interior Lowlands Great Plains and Central Lowlands Great Plains Cretaceous: Zuni Sea Early Paeogene: ocean only in N Dakota, rest mainly fluvial deposits Sediments: transition marine-terrestrial, e.g. Paleocene Cannonball Formation Local sediment source: Black Hills, deposited into e.g. Badlands NP area Little igneous activity, e.g. Devil's Tower (Eocene) Fossils: mammals etc. -->change from semitropical forest to grasslands Pleistocene: glacial deposits Central Lowlands Cenozoic: time of erosion Sediments deposited on Gulf Coastal Plain Scott's Bluff NM, Nebraska Theodore Roosevelt NP, Sout Badlands NP, South Dakota Shiprock, New Mexico Devil's Tower, Wyoming Appalachian Mountains Appalachian Mountains Neoproterozoic: Grenville orogeny Paleozoic: Taconic and Acadian orogenies, Hercynian-Alleghenian orogeny (closure Iapetus Ocean) Late Triassic: block-faulting (breakup Pangaea) End Mesozoic: erosion, plains Cenozoic: uplift and erosion NE-SW trending ridges and valleys Landsat Image of Apalachian Evolution Topography Appalachian Mountains Southern and Eastern Continental Margins Southern and Eastern Continental Margins Atlantic Coastal Plain, Gulf Coastal Plain Area of deposition, sediments from Appalachians, Interior Lowlands Seaward dipping strata, deposited by streams Gulf Coastal Plain Cretaceous: Zuni Sea Early Cenozoic: Tejas Sea Sediments from: Cordillera, Appalachians, Interior Lowlands Transition terrestrial, transitional, marine sediments 8 transgressive-regressive cycles of Tejas Sea Intertonguing of facies Source and reservoir rocks for hydrocarbons The Gulf Coastal Plain Atlantic Continental Margin Atlantic Coastal Plain Passive continental margin Sedimentation began during Jurassic Period Sediments from Appalachians Seaward thickening wedges (up to 14 km) Continental margin E N-Am Sedimentary rocks, Atlantic Co Calvert Cliffs, Maryland (Miocene marine deposits) Paleogene and Neogene Mineral Resources Green River Formation Oil shale (80 billion barrels), evaporites (trona) Phosphorus (Florida) Diatomite (CA, OR, WA) Coal (Northern Great Plains) Gold (CA) Hydrocarbons (Gulf Coastal Plain, S-CA) Phosphorus-rich rocks, Florida Field Question 1, p. 346 Field Question 1, p. 346 Miocene sandstones (red: stream channel, ligh Paleocene, Montana Eocene, Utah Miocene, CA ...
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This note was uploaded on 03/27/2012 for the course GEOL 2413 taught by Professor Moody during the Spring '10 term at Texas A&M University, Corpus Christi.

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LectureCh.16. Cenozoic Earth - Ch. 16 Cenozoic Geologic...

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