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NARROW
GeoRef Subject
-
all geography including DSDP/ODP Sites and Legs
-
Africa
-
North Africa
-
Egypt (3)
-
Libya (1)
-
-
West Africa
-
Ivory Coast (3)
-
-
-
Antarctica
-
James Ross Island (1)
-
Transantarctic Mountains (1)
-
Victoria Land (1)
-
-
Arctic region
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Greenland
-
Northern Greenland (1)
-
-
-
Asia
-
Central Asia
-
Kazakhstan
-
Aktyubinsk Kazakhstan
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Zhamanshin Crater (1)
-
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Far East
-
China
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Tengger Desert (1)
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Indochina (1)
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Indonesia (1)
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Laos (1)
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Thailand (1)
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Vietnam
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Dalat Vietnam (1)
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Himalayas (1)
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Indian Peninsula
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Nepal (1)
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Southeast Asia (1)
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Atlantic Ocean
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East Atlantic (1)
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North Atlantic
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Caribbean Sea
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Venezuelan Basin (1)
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Gulf of Mexico
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Campeche Scarp (1)
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Northwest Atlantic (4)
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Australasia
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Australia
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Great Artesian Basin (1)
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Queensland Australia
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Century Deposit (1)
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Mount Isa Inlier (2)
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South Australia (1)
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Western Australia
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Hamersley Basin (1)
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Yilgarn Craton (2)
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Canada
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Nunavut (1)
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Queen Elizabeth Islands (1)
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Chesapeake Bay impact structure (2)
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Chicxulub Crater (1)
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Commonwealth of Independent States
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Kazakhstan
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Aktyubinsk Kazakhstan
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Zhamanshin Crater (1)
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Europe
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Central Europe
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Germany
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Bavaria Germany
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Ries Crater (2)
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Southern Europe
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Italy
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Marches Italy
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Ancona Italy
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Massignano Italy (1)
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Western Europe
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Scandinavia
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Sweden
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Dalarna Sweden
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Siljan (1)
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United Kingdom
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Great Britain
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England
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Lincolnshire England (1)
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Scotland (1)
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Indian Ocean
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Mexico
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Pacific Ocean
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North Pacific
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South China Sea (1)
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South Pacific
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Southwest Pacific (1)
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West Pacific
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South America
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Argentina (1)
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Colombia (2)
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Maryland (1)
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Michigan
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Michigan Lower Peninsula
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New Jersey (1)
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Otero County New Mexico (1)
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Virginia (1)
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Western Desert (1)
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commodities
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glass materials (6)
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metal ores
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bismuth ores (1)
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lead ores (2)
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lead-zinc deposits (1)
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silver ores (1)
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zinc ores (1)
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mineral deposits, genesis (1)
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mineral exploration (3)
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elements, isotopes
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carbon
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C-13 (1)
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C-13/C-12 (1)
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isotope ratios (6)
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isotopes
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radioactive isotopes
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Be-10 (4)
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Os-187/Os-186 (1)
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stable isotopes
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C-13 (1)
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C-13/C-12 (1)
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Cr-53/Cr-52 (1)
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He-3 (1)
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Nd-144/Nd-143 (1)
-
O-18 (1)
-
O-18/O-16 (1)
-
Os-187/Os-186 (1)
-
Os-188/Os-187 (1)
-
Sr-87/Sr-86 (2)
-
W-182 (1)
-
-
-
metals
-
alkaline earth metals
-
beryllium
-
Be-10 (4)
-
-
strontium
-
Sr-87/Sr-86 (2)
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-
-
chromium
-
Cr-53/Cr-52 (1)
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-
iron
-
ferric iron (2)
-
ferrous iron (2)
-
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nickel (1)
-
platinum group
-
iridium (1)
-
osmium
-
Os-187/Os-186 (1)
-
Os-188/Os-187 (1)
-
-
-
rare earths
-
neodymium
-
Nd-144/Nd-143 (1)
-
-
-
tungsten
-
W-182 (1)
-
-
-
noble gases
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helium
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He-3 (1)
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-
-
oxygen
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O-18 (1)
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O-18/O-16 (1)
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-
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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
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Homo
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Homo erectus (1)
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-
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-
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fossil man (1)
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Invertebrata
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Arthropoda
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Mandibulata
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Crustacea
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Ostracoda (1)
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Trilobitomorpha
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Brachiopoda (1)
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Hyolithes (1)
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Protista
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microfossils (4)
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acritarchs (1)
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Dinoflagellata (3)
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miospores (1)
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Plantae
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algae
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nannofossils (2)
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Spermatophyta
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Gymnospermae
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Glossopteridales
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Glossopteris
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Glossopteris flora (1)
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thallophytes (1)
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geochronology methods
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Ar/Ar (3)
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fission-track dating (3)
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K/Ar (3)
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optical mineralogy (1)
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thermoluminescence (1)
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U/Pb (1)
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geologic age
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Cenozoic
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Quaternary
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Holocene (1)
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middle Pleistocene (3)
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upper Quaternary (1)
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Tertiary
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Neogene
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Miocene (1)
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Paleogene
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Eocene
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upper Eocene (4)
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Oligocene
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lower Oligocene (1)
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Paleocene
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lower Paleocene
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Danian (1)
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K-T boundary (4)
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Mesozoic
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Cretaceous
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Upper Cretaceous
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Campanian (1)
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K-T boundary (4)
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Maestrichtian (2)
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Senonian (2)
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Jurassic (1)
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Triassic
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Upper Triassic (1)
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Paleozoic
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Cambrian (2)
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Devonian
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Upper Devonian (2)
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Ordovician
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Upper Ordovician (1)
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Phanerozoic (2)
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Precambrian
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Archean
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Neoarchean (2)
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Transvaal Supergroup (1)
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upper Precambrian
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Proterozoic
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Isan Orogeny (1)
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Paleoproterozoic (1)
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-
-
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igneous rocks
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igneous rocks
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plutonic rocks
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granites
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pyroclastics (1)
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metamorphic rocks
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metasedimentary rocks (1)
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minerals
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carbonates (1)
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native elements
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phosphates
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framework silicates
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cristobalite (1)
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quartz (1)
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orthosilicates
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nesosilicates
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zircon group
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zircon (3)
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sheet silicates
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chlorite group
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clinochlore (1)
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mica group
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phlogopite (1)
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sulfides
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pyrite (1)
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pyrrhotite (1)
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tungstates
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scheelite (1)
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Primary terms
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absolute age (6)
-
Africa
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North Africa
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Egypt (3)
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Libya (1)
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West Africa
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Ivory Coast (3)
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-
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Antarctica
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James Ross Island (1)
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Transantarctic Mountains (1)
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Victoria Land (1)
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-
Arctic region
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Greenland
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Northern Greenland (1)
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-
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Asia
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Central Asia
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Kazakhstan
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Aktyubinsk Kazakhstan
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Zhamanshin Crater (1)
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-
-
-
Far East
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China
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Tengger Desert (1)
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Indochina (1)
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Indonesia (1)
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Laos (1)
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Thailand (1)
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Vietnam
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Dalat Vietnam (1)
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Himalayas (1)
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Indian Peninsula
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Nepal (1)
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Southeast Asia (1)
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asteroids (1)
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Atlantic Ocean
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East Atlantic (1)
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North Atlantic
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Caribbean Sea
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Venezuelan Basin (1)
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Gulf of Mexico
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Campeche Scarp (1)
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Northwest Atlantic (4)
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-
-
atmosphere (1)
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Australasia
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Australia
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Great Artesian Basin (1)
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Queensland Australia
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Century Deposit (1)
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Mount Isa Inlier (2)
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South Australia (1)
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Western Australia
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Hamersley Basin (1)
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Yilgarn Craton (2)
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biogeography (1)
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biography (1)
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Canada
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Nunavut (1)
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Queen Elizabeth Islands (1)
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carbon
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C-13 (1)
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C-13/C-12 (1)
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Cenozoic
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Quaternary
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Holocene (1)
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Pleistocene
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middle Pleistocene (3)
-
-
upper Quaternary (1)
-
-
Tertiary
-
Neogene
-
Miocene (1)
-
-
Paleogene
-
Eocene
-
upper Eocene (4)
-
-
Oligocene
-
lower Oligocene (1)
-
-
Paleocene
-
lower Paleocene
-
Danian (1)
-
K-T boundary (4)
-
-
-
-
-
-
Chordata
-
Vertebrata
-
Tetrapoda
-
Mammalia
-
Theria
-
Eutheria
-
Primates
-
Hominidae
-
Homo
-
Homo erectus (1)
-
-
-
-
-
-
-
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-
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climate change (1)
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continental drift (1)
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continental slope (1)
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data processing (1)
-
Deep Sea Drilling Project
-
IPOD
-
Leg 95
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DSDP Site 612 (3)
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Leg 10
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DSDP Site 94 (1)
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Leg 15
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DSDP Site 149 (1)
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Earth (2)
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ecology (1)
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Europe
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Germany
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Southern Europe
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Italy
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Western Europe
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Scandinavia
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Sweden
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Siljan (1)
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United Kingdom
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geology (1)
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geomorphology (3)
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geophysical methods (1)
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glacial geology (1)
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heat flow (1)
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igneous rocks
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plutonic rocks
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granites
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leucogranite (1)
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volcanic rocks
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basalts (1)
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glasses
-
volcanic glass (2)
-
-
pyroclastics (1)
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rhyolites (1)
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trachyandesites (1)
-
-
-
inclusions (2)
-
Indian Ocean
-
East Indian Ocean (1)
-
-
Invertebrata
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Arthropoda
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Mandibulata
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Crustacea
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Ostracoda (1)
-
-
-
Trilobitomorpha
-
Trilobita (1)
-
-
-
Brachiopoda (1)
-
Mollusca
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Hyolithes (1)
-
-
Protista
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Foraminifera (2)
-
Radiolaria (2)
-
-
-
isotopes
-
radioactive isotopes
-
Be-10 (4)
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Os-187/Os-186 (1)
-
-
stable isotopes
-
C-13 (1)
-
C-13/C-12 (1)
-
Cr-53/Cr-52 (1)
-
He-3 (1)
-
Nd-144/Nd-143 (1)
-
O-18 (1)
-
O-18/O-16 (1)
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Os-187/Os-186 (1)
-
Os-188/Os-187 (1)
-
Sr-87/Sr-86 (2)
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W-182 (1)
-
-
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lava (2)
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magmas (2)
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Mesozoic
-
Cretaceous
-
Upper Cretaceous
-
Campanian (1)
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K-T boundary (4)
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Maestrichtian (2)
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Senonian (2)
-
-
-
Jurassic (1)
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Triassic
-
Upper Triassic (1)
-
-
-
metal ores
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bismuth ores (1)
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gold ores (1)
-
lead ores (2)
-
lead-zinc deposits (1)
-
silver ores (1)
-
zinc ores (1)
-
-
metals
-
alkaline earth metals
-
beryllium
-
Be-10 (4)
-
-
strontium
-
Sr-87/Sr-86 (2)
-
-
-
chromium
-
Cr-53/Cr-52 (1)
-
-
iron
-
ferric iron (2)
-
ferrous iron (2)
-
-
nickel (1)
-
platinum group
-
iridium (1)
-
osmium
-
Os-187/Os-186 (1)
-
Os-188/Os-187 (1)
-
-
-
rare earths
-
neodymium
-
Nd-144/Nd-143 (1)
-
-
-
tungsten
-
W-182 (1)
-
-
-
metamorphic rocks
-
impactites
-
impact breccia
-
suevite (1)
-
-
-
metasedimentary rocks (1)
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mylonites
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pseudotachylite (1)
-
-
-
metamorphism (14)
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metasomatism (1)
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meteorites
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stony meteorites
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achondrites
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angrite (1)
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eucrite (1)
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chondrites
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ordinary chondrites
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L chondrites (2)
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Mexico
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Yucatan Mexico (1)
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mineral deposits, genesis (1)
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mineral exploration (3)
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Moon (1)
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noble gases
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helium
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He-3 (1)
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North America (2)
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Ocean Drilling Program
-
Leg 150
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ODP Site 903 (3)
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ODP Site 904 (3)
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Leg 174A
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ODP Site 1073 (1)
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oxygen
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O-18 (1)
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O-18/O-16 (1)
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Pacific Ocean
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Equatorial Pacific (1)
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North Pacific
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Northwest Pacific
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South China Sea (1)
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South Pacific
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Southwest Pacific (1)
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West Pacific
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Northwest Pacific
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South China Sea (1)
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Southwest Pacific (1)
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paleoclimatology (2)
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paleoecology (2)
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paleogeography (2)
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Paleozoic
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Cambrian (2)
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Devonian
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Upper Devonian (2)
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Ordovician
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Upper Ordovician (1)
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-
-
palynomorphs
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acritarchs (1)
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Dinoflagellata (3)
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miospores (1)
-
-
petrology (2)
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Phanerozoic (2)
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Plantae
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algae
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nannofossils (2)
-
-
Spermatophyta
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Gymnospermae
-
Glossopteridales
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Glossopteris
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Glossopteris flora (1)
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-
-
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-
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plate tectonics (1)
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Precambrian
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Archean
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Neoarchean (2)
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-
Transvaal Supergroup (1)
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upper Precambrian
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Proterozoic
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Isan Orogeny (1)
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Paleoproterozoic (1)
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sea-level changes (1)
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sedimentary rocks
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carbonate rocks (1)
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clastic rocks
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sandstone (1)
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shale (1)
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siltstone (1)
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coal (1)
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sedimentary structures
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planar bedding structures
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sedimentation (2)
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sediments
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marine sediments (6)
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South America
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spectroscopy (1)
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tektites (24)
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United States
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Maryland (1)
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Michigan
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Michigan Lower Peninsula
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Saginaw County Michigan (1)
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New Jersey (1)
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New Mexico
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Virginia (1)
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weathering (3)
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X-ray analysis (1)
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rock formations
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Lopez de Bertodano Formation (1)
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Australasian strewn field
Map showing Australasian strewn field (after Glass and Wu, 1993 ). Long-da...
North American microtektites are more oxidized than tektites
Microtektites from Victoria Land Transantarctic Mountains
Tektite origin by hypervelocity asteroidal or cometary impact: Target rocks, source craters, and mechanisms
Tektites are natural glasses that occur on earth in four distinct strewn fields (North American, Central European, Ivory Coast, and Australasian). Geochemical arguments have shown that tektites have been derived by hypervelocity impact melting from terrestrial upper crustal rocks, most likely sediments. The contents of Be-10 in tektites are evidence for a derivation of tektites from surface rocks, thus precluding an origin from greater depth in the crater. For two of the four tektite strewn fields (Ivory Coast, Central European), a possible connection to impact craters (Bosumtwi, and Ries, respectively) has been suggested on the basis of chemical, isotopic, and age data. No clear crater identifications have been made for the North American or Australasian strewn fields, although there are good candidates for both. Even though the geochemistry of tektites is in unequivocal favor of an origin by impact melting of terrestrial rocks, the unambiguous demonstration of the presence of an extraterrestrial contribution to the chemistry of tektites remains a problem. However, recent osmium isotope studies have shown that there is a clear meteoritic signature in at least some tektites. The exact mechanism of tektite formation is still not obv3ious, although some facts become increasingly clear. Tektite production requires specific impact conditions—otherwise there would be many more tektite strewn fields connected to the 150 or so known impact craters. Tektites are produced by nonequilibrium shock melting of surficial rocks, and the superheated melt may be subjected to a plasma phase during which they are subjected to partial reduction. They are then lofted through the atmosphere (probably in the wake of the expanding vapor cloud), quenched, and distributed over a geographically extended area—the strewn field. Some tektites solidify in a near-vacuum and re-enter the atmosphere. During the re-entry they melt again and form ablation-shaped tektites. Larger tektites, from a lower part of the target stratigraphy, are only distributed closer to the source crater. Many of them are more inhomogeneous melts and show a layered structure; they are called Muong Nong–type tektites. The study of tektites and the identification of possible new strewn fields provide important contributions toward the understanding of impact cratering.
Coesite and shocked quartz discovered in the, Australasian and North American, microtektite layers
Abstract This account covers the history of tektites, from prehistoric times, through the descriptions by the Chinese in medieval times, their discovery and description in the Austro-Hungarian Empire in the 18th century, Charles Darwin’s encounter with a flanged button australite at what is now Albany, Western Australia, in the early 19th century, and the descriptions by Lacroix and others of further discoveries in Indo-China, the Ivory Coast and the USA, in the first half of the 20th century. F.E. Suess and R.H. Walcott first suggested a meteoritic provenance about 1900, and L.J. Spencer suggested ejection from terrestrial impact sites. Up to the 1950s, sophisticated research techniques were not available and speculation ruled, with many highly imaginitive and fanciful hypotheses emerging. As the Apollo landing approached, many new sophisticated research methods were developed and research proliferated. Evidence for terrestrial origin accumulated at this time, although lunar origin remained popular, and it was confirmed by rejection of lunar provenance following the Apollo and Luna recovery missions. The favoured mode of origin became ejection from a minority of large-scale impact sites on the Earth, and the relationship between the Ries impact structure and moldavites, and between Bosumtwi Crater and Ivory Coast tektites, was firmly established. Then in the 1990s the Chesapeake Bay structure was discovered, the source of the North American tektites? Wind-tunnel experiments by D.R. Chapman showed that flanged-button australites were produced by albation on descending through the atmosphere. Prolific researches, led by B.P. Glass, on deep-sea cores revealed the existence of microtektites, thus extending three of the strewn fields to large areas covered by sea. Kindred occurrences at Zhamanshin and Popigai in the USSR, in a Pliocene structure beneath the south Pacific Ocean, at the Cretacetus-Tertiary (K/T) boundary in Haiti and Mexico, and within late Devonian sediments in Belgium and China are briefly described, as well as natural glasses in Libya and Tasmania, of obscure origin. There remain a number of unsolved questions — among them the source of the huge Australasian Strewn Field, the enigma of the manner of dispersal of large, irregular Muong Nong-type tektites, the relationship of microtektites to the larger tektites found on land, and the relationship of all tektites to the geology of the likely target area of the source impact and processes of jetting from impact sites.
Australasian tektite and microtektite strewn field (dashed line; Glass and...
Australasian microtektites and the stratigraphic age of the australites
Abstract Tektites are natural glasses found scattered across wide areas of the surface of Earth. In a Science paper entitled ‘Tektites are Terrestrial’, written at a time when many argued tektites were from the moon, Henry Faul (1966 , p. 1) said, ‘To anyone who has worked with them, tektites are probably the most frustrating stones ever found on Earth’. At the time these sentiments reflected the difficulties in defining a genetic model; some 40 years later we are much closer to understanding the formation of tektites, having ruled out ideas of an extraterrestrial origin ( Taylor 1973 ). It is clear that tektites are derived from melting of terrestrial rocks and sediments during hypervelocity impact cratering (e.g. Koeberl 1994 ). Tektites are found in four clearly defined strewn fields; in three of these fields tektites are strewn around known craters that are contemporaneous and, in target rocks with a geochemical and isotopic composition, compatible with the parent materials from which the tektite glass formed during impact melting. These three tektite-strewn fields are: (1) North American, from Chesapeake Bay Impact Structure, USA (35 Ma) ( Koeberl et al . 1996 ); (2) West African, from Bosumtwi Crater, Ghana (1.07 Ma) ( Koeberl et al . 1997 ); and (3) Central European, from Ries Crater, Germany (14.7 Ma) ( Engelhardt et al . 1987 ). The fourth is the c . 800 ka Australasian ( Kunz et al . 1995 ) strewn field from a currently undiscovered crater. Non-tektite impact glasses with genetic similarities to
A: The Australasian tektite-microtektite (MTK) strewn-field (modified after...
Australasian tektite strewn field. After Cavosie et al. (2018) .
Shocked quartz and other mineral inclusions in Australasian microtektites
New clues from Earth’s most elusive impact crater: Evidence of reidite in Australasian tektites from Thailand
ABSTRACT Australasian tektites represent the largest group of tektites on Earth, and their strewn field covers up to one sixth of Earth’s surface. After several decades of fruitless quest for a parent crater for Australasian tektites, mostly in the main part of the strewn field in Indochina, the crater remains undiscovered. We elaborate upon a recently suggested original hypothesis for the impact in the Alashan Desert in Northwest China. Evidence from geochemical and isotopic compositions of potential source materials, gravity data, and geographic, paleoenvironmental, and ballistic considerations support a possible impact site in the Badain Jaran part of the Alashan Desert. In further support of an impact location in China, glassy microspherules recovered from Chinese loess may be the right age to relate to the Australasian tektite event, perhaps as part of the impacting body. The most serious shortcomings of the commonly accepted Indochina impact location include signs of little chemical weathering of source materials of Australasian tektites, unlike highly weathered sedimentary targets in Indochina, and questionable assumptions about transport of distal ejecta.
Clues on the Australasian impact crater site inferred from detailed mineralogical study of a monazite inclusion in a Muong Nong tektite
ABSTRACT This thesis embraces and expands upon a century of research into disparate geological enigmas, offering a unifying catastrophic explanation for events occurring during the enigmatic mid-Pleistocene transition. Billions of tons of “Australasian tektites” were dispatched as distal ejecta from a target mass of continental sediments during a cosmic impact occurring ca. 788 ka. The accepted signatures of a hypervelocity impact encompass an excavated astrobleme and attendant proximal, medial, and distal ejecta distributions. Enigmatically, the distal tektites remain the only accepted evidence of this impact’s reality. A protracted 50 yr search fixated on impact sites in Southeast Asia—the location of the tektites—has failed to identify the requisite additional impact signatures. We postulate the missing astrobleme and proximal/medial ejecta signatures are instead located antipodal to Southeast Asia. A review of the gradualistic theories for the genesis and age of the “Carolina bay” landforms of North America finds those models incapable of addressing all the facts we observe. Research into 57,000 of those oriented basins informs our speculation that they represent cavitation-derived ovoid basins within energetically delivered geophysical mass surge flows emanating from a cosmic impact. Those flows are seen as repaving regions of North America under blankets of hydrated impact regolith. Our precisely measured Carolina bay orientations indicate an impact site within the Laurentide ice sheet. There, we invoke a grazing regime impact into hydrated early Mesozoic to late Paleozoic continental sediments, similar in composition to the expected Australasian tektites’ parent target. We observe that continental ice shielded the target at ca. 788 ka, a scenario understood to produce anomalous astroblemes. The ensuing excavation allowed the Saginaw glacial lobe’s distinctive and unique passage through the Marshall Sandstone cuesta, which encircles and elsewhere protects the central region of the intracratonic Michigan Basin. Subsequent erosion by multiple ice-age transgressions has obfuscated impact evidence, forming Michigan’s “Thumb” as an enduring event signature. Comprehensive suborbital modeling supports the distribution of distal ejecta to the Australasian tektite strewn field from Michigan’s Lower Peninsula. The mid-Pleistocene transition impact hypothesis unifies the Carolina bays with those tektites as products of an impact into the Saginaw Bay area of Lake Huron, USA. The hypothesis will be falsified if cosmogenic nuclide burial dating of Carolina bay subjacent stratigraphic contacts disallows a coeval regolith emplacement ca. 788 ka across North America. We offer observations, interdisciplinary insights, and informed speculations fitting for an embryonic concept involving a planetary-scale extraterrestrial impact.
Montanari, A. & Koeberl, C. 2000. Impact Stratigraphy. The Italian Record. : Lecture Notes in Earth Sciences Series no. 93. xiii+364 pp. Berlin, Heidelberg, New York, London, Paris, Tokyo, Hong Kong: Springer-Verlag. Price DM 198.00, Ös 1446.00, SFr 171.00, £68.50, US $110.00 (paperback). ISBN 3 540 66368 1.
We studied the oxidation state of Fe in silicate glasses produced during the first atomic bomb blast at the Trinity test site (New Mexico) by X-ray absorption–near edge spectroscopy (XANES). The sample consists of green glass resulting from melting of the quartz-bearing sand present at the test site; some relict unmelted sand is still fused to the bottom of the sample. Comparison of the pre-edge peak data with model compounds of known Fe oxidation state and coordination number shows that in the Trinity glass sample, Fe is in the divalent state and, on average, in a mixture of 4- and 5-fold coordination. XANES spectra collected at various heights of the sample, from the bottom of the sample up to the exposed surface, show no variation of the pre-edge peak and, thus, of the Fe oxidation state with the distance from the sand-glass interface. However, XANES analysis of a portion of the sand at the bottom of the sample shows Fe to be a mixture of Fe 2+ and Fe 3+ , with a Fe 3+ /(Fe 2+ + Fe 3+ ) ratio close to 0.5. This demonstrates that during the nuclear explosion, the ground rock was instantaneously reduced, transforming all the iron from mostly trivalent state to almost exclusively divalent. Pre-edge peak features (intensity and energy) are consistent with those of tektites from the Ivory Coast studied here and with literature data of tektites from all the other known strewn fields (Australasian, Central European, and North American). The reduction of Fe to divalent state during Trinity glass formation, the homogeneity of the Fe oxidation state within the glass, and the Fe structural role suggest that this glass represents a good analog of tektite glass.