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NARROW
GeoRef Subject
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all geography including DSDP/ODP Sites and Legs
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Africa
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East Africa
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Kenya
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Lake Magadi (1)
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Tanzania
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Oldoinyo Lengai (1)
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Olduvai Gorge (2)
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East African Lakes
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Lake Magadi (1)
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East Pacific Ocean Islands
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Hawaii (2)
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Europe
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Southern Europe
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Iberian Peninsula
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Spain
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Murcia Spain
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Caravaca Spain (1)
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Italy
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Veneto Italy (1)
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North America
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Rocky Mountains
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U. S. Rocky Mountains
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Absaroka Range (2)
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San Juan Mountains
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Creede Caldera (1)
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Oceania
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Polynesia
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Hawaii (2)
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Pacific Ocean
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North Pacific
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Northwest Pacific
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Hess Rise (1)
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West Pacific
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Northwest Pacific
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Hess Rise (1)
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Searles Lake (1)
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United States
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Alaska (1)
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Amargosa Desert (1)
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California
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Inyo County California (1)
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San Bernardino County California (1)
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Colorado
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Mineral County Colorado
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Creede Caldera (1)
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Creede mining district (1)
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Hawaii (2)
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Illinois
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Stephenson County Illinois (1)
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Illinois Basin (1)
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Midcontinent (1)
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Mississippi Valley
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Upper Mississippi Valley (1)
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Missouri (1)
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Nevada
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Nye County Nevada
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Yucca Mountain (1)
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Oregon (3)
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U. S. Rocky Mountains
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Absaroka Range (2)
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San Juan Mountains
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Creede Caldera (1)
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Wisconsin (1)
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Wyoming (4)
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commodities
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brines (1)
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metal ores (1)
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mineral deposits, genesis (2)
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zeolite deposits (1)
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elements, isotopes
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carbon
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C-13/C-12 (2)
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isotope ratios (1)
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isotopes
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stable isotopes
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C-13/C-12 (2)
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O-18/O-16 (3)
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metals
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alkali metals
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potassium (1)
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alkaline earth metals
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magnesium (1)
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oxygen
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O-18/O-16 (3)
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fossils
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Chordata
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Vertebrata
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Tetrapoda
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Mammalia
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Theria
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Eutheria
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Primates
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Hominidae (1)
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geochronology methods
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Ar/Ar (1)
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K/Ar (2)
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optical mineralogy (1)
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geologic age
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Cenozoic
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Quaternary (2)
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Tertiary
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John Day Formation (3)
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lower Tertiary (1)
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Neogene
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Pliocene (1)
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Paleogene
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Eocene
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Green River Formation (1)
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lower Eocene
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Willwood Formation (1)
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Wind River Formation (1)
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middle Eocene
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Aycross Formation (1)
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Oligocene (1)
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Paleocene (1)
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White River Group (1)
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Mesozoic
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Cretaceous
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Upper Cretaceous (1)
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Paleozoic
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Cambrian
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Upper Cambrian
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Mount Simon Sandstone (1)
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Carboniferous
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Mississippian (1)
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Devonian (1)
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lower Paleozoic (1)
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Ordovician
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Upper Ordovician
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Maquoketa Formation (1)
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Silurian (1)
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Precambrian
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upper Precambrian
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Proterozoic
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Neoproterozoic (1)
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igneous rocks
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igneous rocks
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carbonatites (1)
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plutonic rocks
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diabase (1)
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volcanic rocks
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glasses
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volcanic glass (1)
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nephelinite (1)
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pyroclastics
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tuff (3)
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volcanic ash (1)
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metamorphic rocks
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metamorphic rocks
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gneisses
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metasedimentary rocks (1)
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minerals
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carbonates
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trona (1)
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minerals (2)
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oxides
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magnetite (1)
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silicates
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framework silicates
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feldspar group
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alkali feldspar
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K-feldspar (3)
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orthoclase (1)
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sanidine (1)
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silica minerals
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quartz (1)
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zeolite group
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analcime (1)
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phillipsite (1)
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sheet silicates
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clay minerals
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kaolinite (1)
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illite (1)
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mica group
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glauconite (1)
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sulfides
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pyrite (1)
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Primary terms
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absolute age (4)
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Africa
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East Africa
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Kenya
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Lake Magadi (1)
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Tanzania
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Oldoinyo Lengai (1)
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Olduvai Gorge (2)
-
-
-
East African Lakes
-
Lake Magadi (1)
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-
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associations (1)
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brines (1)
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carbon
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C-13/C-12 (2)
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-
Cenozoic
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Quaternary (2)
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Tertiary
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John Day Formation (3)
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lower Tertiary (1)
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Neogene
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Pliocene (1)
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Paleogene
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Eocene
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Green River Formation (1)
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lower Eocene
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Willwood Formation (1)
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Wind River Formation (1)
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-
middle Eocene
-
Aycross Formation (1)
-
-
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Oligocene (1)
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Paleocene (1)
-
White River Group (1)
-
-
-
-
chemical analysis (1)
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Chordata
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Vertebrata
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Tetrapoda
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Mammalia
-
Theria
-
Eutheria
-
Primates
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Hominidae (1)
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-
-
-
-
-
-
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clay mineralogy (4)
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continental drift (1)
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crystal chemistry (1)
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Deep Sea Drilling Project
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IPOD
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Leg 62
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DSDP Site 465 (1)
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diagenesis (8)
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East Pacific Ocean Islands
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Hawaii (2)
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Europe
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Southern Europe
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Iberian Peninsula
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Spain
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Murcia Spain
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Caravaca Spain (1)
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Italy
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Veneto Italy (1)
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geochemistry (3)
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geology (1)
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hydrogeology (1)
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igneous rocks
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carbonatites (1)
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plutonic rocks
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diabase (1)
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volcanic rocks
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glasses
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volcanic glass (1)
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nephelinite (1)
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pyroclastics
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tuff (3)
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inclusions
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fluid inclusions (1)
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intrusions (1)
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isotopes
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stable isotopes
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C-13/C-12 (2)
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O-18/O-16 (3)
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magmas (1)
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Mesozoic
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Cretaceous
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Upper Cretaceous (1)
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metal ores (1)
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metals
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alkali metals
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potassium (1)
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alkaline earth metals
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magnesium (1)
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metamorphic rocks
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gneisses
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granite gneiss (1)
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metasedimentary rocks (1)
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metasomatism (2)
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mineral deposits, genesis (2)
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mineralogy (4)
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minerals (2)
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North America
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Rocky Mountains
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U. S. Rocky Mountains
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Absaroka Range (2)
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San Juan Mountains
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Creede Caldera (1)
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-
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Oceania
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Polynesia
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Hawaii (2)
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oceanography (1)
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oxygen
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O-18/O-16 (3)
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Pacific Ocean
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North Pacific
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Northwest Pacific
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Hess Rise (1)
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West Pacific
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Northwest Pacific
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Hess Rise (1)
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paleoclimatology (2)
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paleogeography (2)
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paleontology (1)
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Paleozoic
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Cambrian
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Upper Cambrian
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Mount Simon Sandstone (1)
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Carboniferous
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Mississippian (1)
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Devonian (1)
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lower Paleozoic (1)
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Ordovician
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Upper Ordovician
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Maquoketa Formation (1)
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Silurian (1)
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petrology (4)
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phase equilibria (1)
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plate tectonics (1)
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Precambrian
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upper Precambrian
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Proterozoic
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Neoproterozoic (1)
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sedimentary petrology (4)
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sedimentary rocks
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carbonate rocks (1)
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clastic rocks
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conglomerate (1)
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sandstone (1)
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sedimentation (2)
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sediments
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marine sediments (1)
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soils (1)
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springs (1)
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stratigraphy (4)
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tectonics (1)
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tectonophysics (1)
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United States
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Alaska (1)
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Amargosa Desert (1)
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California
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Inyo County California (1)
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San Bernardino County California (1)
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Colorado
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Mineral County Colorado
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Creede Caldera (1)
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Creede mining district (1)
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Hawaii (2)
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Illinois
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Stephenson County Illinois (1)
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Illinois Basin (1)
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Missouri (1)
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Nevada
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Yucca Mountain (1)
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Oregon (3)
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U. S. Rocky Mountains
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Absaroka Range (2)
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San Juan Mountains
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Creede Caldera (1)
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Wisconsin (1)
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Wyoming (4)
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volcanology (2)
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weathering (3)
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sedimentary rocks
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sedimentary rocks
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carbonate rocks (1)
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clastic rocks
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claystone (1)
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conglomerate (1)
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sandstone (1)
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volcaniclastics (2)
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sediments
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sediments
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clastic sediments
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clay (1)
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marine sediments (1)
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volcaniclastics (2)
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soils
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soils (1)
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Age and origin of authigenic K-feldspar in uppermost Precambrian rocks in the North American Midcontinent
Sedimentation Patterns in a Plio-Pleistocene Volcaniclastic Rift-Platform Basin, Olduvai Gorge, Tanzania
Abstract The Plio-Pleistocene sedimentary deposits of upper Bed I and lowermost Bed II in the Olduvai basin, Tanzania, are analyzed in terms of sedimentary processes, paleoenvironments, and paleoclimate. The sedimentary basin was a shallow, closed depression (∼ 50 km wide with strata ∼ 100 m thick) located adjacent to the East African Rift between Precambrian basement rocks to the west and the large Plio-Pleistocene Ngorongoro volcanic complex to the east. Olduvai lies on the west flank of the main rift valley, and this rift platform area was subjected to crustal extension resu I ting in normal block faulting and block tilting. Through time the axial part of the sedimentary basin episodically migrated eastward toward the main rift valley. Syndepositional volcanism included basalt flows, pyroclastic air falls, ground surges, and ignimbrites from eruptive centers of the Ngorongoro volcanic complex. Hay (1976) interpreted the paleolandscape to have had a central lake basin that was filled with detrital sediment, carbonate rocks, and tephra. Detrital sediment was provided both by rivers sourced in the Ngorongoro complex and by Precambrian rocks of the Serengeti to the north and west. Recent high-resolution stratigraphic studies of paleoenvironments in a time slice (1.85-1.75 Ma) found that the sedimentary facies vary temporally and spatially because of the interplay among five independent variables affecting the sedimentary record: (1) sediment flux (pyroclastic air fall, intermittent fluvial runoff and mudflows, and eolian), (2) sediment composition (Precambrian source rocks vs. volcanic source rocks), (3) hydrology and chemistry (lake water, surface water, and groundwater), (4) soil formation, and (5) tectonics associated with rift extension. Lake cycles, ephemeral fluvial systems, soil formation on the interfluves and lake margin, well as a large groundwater-fed wetland (> 3 km 2 ) are all part of the Olduvai rift-margin basin record and provide insights into the Plio-Pleistocene paleoclimate history of East Africa.