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GeoRef Subject
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all geography including DSDP/ODP Sites and Legs
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Africa
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North Africa
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Tunisia
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El Kef Tunisia (1)
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Asia
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Indian Peninsula
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India
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Andhra Pradesh India (1)
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Cauvery Basin (4)
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Chhattisgarh India (2)
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Gujarat India
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Kutch India
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Bhuj India (1)
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Saurashtra (1)
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Kerala India (1)
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Madhya Pradesh India
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Chhindwara India (1)
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Jabalpur India (2)
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Shahdol India (1)
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Maharashtra India
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Nagpur India (1)
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Northeastern India
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Assam India (1)
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Meghalaya India (1)
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Pondicherry India (1)
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Rajasthan India
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Jaisalmer India (1)
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Sohagpur coal field (1)
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Tamil Nadu India
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Vridhachalam India (1)
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-
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Atlantic Ocean
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Equatorial Atlantic (1)
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North Atlantic
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Blake Plateau
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Blake Nose (1)
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Northwest Atlantic
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Demerara Rise (1)
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South Atlantic
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Walvis Ridge (1)
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West Atlantic (1)
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Europe
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Western Europe
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United Kingdom
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Great Britain
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England (1)
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Indian Ocean
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Bay of Bengal (2)
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Krishna-Godavari Basin (2)
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Southern Ocean
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Weddell Sea
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Maud Rise (1)
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United States
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Colorado
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Pueblo County Colorado
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Pueblo Colorado (1)
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commodities
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petroleum (1)
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elements, isotopes
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carbon
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C-13/C-12 (3)
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C-14 (1)
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isotope ratios (6)
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isotopes
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radioactive isotopes
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C-14 (1)
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stable isotopes
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C-13/C-12 (3)
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O-18/O-16 (2)
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Os-188/Os-187 (1)
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Sr-87/Sr-86 (2)
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metals
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alkaline earth metals
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strontium
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Sr-87/Sr-86 (2)
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platinum group
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osmium
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Os-188/Os-187 (1)
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oxygen
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O-18/O-16 (2)
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fossils
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burrows (1)
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Chordata
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Vertebrata
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Tetrapoda
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Reptilia
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Diapsida
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Archosauria
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dinosaurs (2)
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cyanobacteria (2)
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eukaryotes (1)
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ichnofossils
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Planolites (1)
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Skolithos (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 (3)
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Protista
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Foraminifera
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Miliolina
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Miliolacea
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Alveolinellidae
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Alveolina (1)
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Rotaliina
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Rotaliacea
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Elphidium (1)
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Nummulitidae
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Nummulites (1)
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-
-
-
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Radiolaria (1)
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-
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microfossils (21)
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palynomorphs
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acritarchs (1)
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Dinoflagellata (1)
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miospores
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pollen (2)
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Plantae
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algae
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Chlorophyta (1)
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nannofossils (3)
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Phaeophyta (1)
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Rhodophyta (1)
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geologic age
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Cenozoic
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Quaternary
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Holocene
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middle Holocene (1)
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upper Holocene (1)
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Tertiary
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Paleogene
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Barail Group (1)
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Eocene
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lower Eocene
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Ypresian (1)
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middle Eocene (1)
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Oligocene (1)
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Paleocene
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lower Paleocene
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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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Cenomanian
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upper Cenomanian (1)
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K-T boundary (4)
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Lameta Formation (1)
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Maestrichtian
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upper Maestrichtian (1)
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Turonian
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lower Turonian (1)
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Jurassic
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Middle Jurassic
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Callovian (1)
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Upper Jurassic
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Oxfordian
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lower Oxfordian (1)
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Paleozoic
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Permian
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Upper Permian (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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volcanic rocks
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basalts
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flood basalts (1)
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minerals
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silicates
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sheet silicates
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clay minerals (1)
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Primary terms
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Africa
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North Africa
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Tunisia
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El Kef Tunisia (1)
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Asia
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Indian Peninsula
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India
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Andhra Pradesh India (1)
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Cauvery Basin (4)
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Chhattisgarh India (2)
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Gujarat India
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Kutch India
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Bhuj India (1)
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Saurashtra (1)
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Kerala India (1)
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Madhya Pradesh India
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Chhindwara India (1)
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Jabalpur India (2)
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Shahdol India (1)
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Maharashtra India
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Nagpur India (1)
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Northeastern India
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Assam India (1)
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Meghalaya India (1)
-
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Pondicherry India (1)
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Rajasthan India
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Jaisalmer India (1)
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Sohagpur coal field (1)
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Tamil Nadu India
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Vridhachalam India (1)
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-
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Atlantic Ocean
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Equatorial Atlantic (1)
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North Atlantic
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Blake Plateau
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Blake Nose (1)
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Northwest Atlantic
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Demerara Rise (1)
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-
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South Atlantic
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Walvis Ridge (1)
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West Atlantic (1)
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biogeography (1)
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carbon
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C-13/C-12 (3)
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C-14 (1)
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Cenozoic
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Quaternary
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Holocene
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middle Holocene (1)
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upper Holocene (1)
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-
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Tertiary
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Paleogene
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Barail Group (1)
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Eocene
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lower Eocene
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Ypresian (1)
-
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middle Eocene (1)
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Oligocene (1)
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Paleocene
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lower Paleocene
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K-T boundary (4)
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-
-
-
-
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Chordata
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Vertebrata
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Tetrapoda
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Reptilia
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Diapsida
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Archosauria
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dinosaurs (2)
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-
-
-
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continental shelf (1)
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Deep Sea Drilling Project
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IPOD
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Leg 74
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DSDP Site 525 (1)
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Europe
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Western Europe
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United Kingdom
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Great Britain
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England (1)
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-
-
-
-
ichnofossils
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Planolites (1)
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Skolithos (1)
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igneous rocks
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volcanic rocks
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basalts
-
flood basalts (1)
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-
-
-
Indian Ocean
-
Bay of Bengal (2)
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Invertebrata
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Arthropoda
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Mandibulata
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Crustacea
-
Ostracoda (3)
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-
-
-
Protista
-
Foraminifera
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Miliolina
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Miliolacea
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Alveolinellidae
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Alveolina (1)
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-
-
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Rotaliina
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Rotaliacea
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Elphidium (1)
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Nummulitidae
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Nummulites (1)
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-
-
-
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Radiolaria (1)
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-
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isotopes
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radioactive isotopes
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C-14 (1)
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stable isotopes
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C-13/C-12 (3)
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O-18/O-16 (2)
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Os-188/Os-187 (1)
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Sr-87/Sr-86 (2)
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-
-
Mesozoic
-
Cretaceous
-
Upper Cretaceous
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Cenomanian
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upper Cenomanian (1)
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-
K-T boundary (4)
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Lameta Formation (1)
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Maestrichtian
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upper Maestrichtian (1)
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Turonian
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lower Turonian (1)
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-
-
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Jurassic
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Middle Jurassic
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Callovian (1)
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Upper Jurassic
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Oxfordian
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lower Oxfordian (1)
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-
-
-
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metals
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alkaline earth metals
-
strontium
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Sr-87/Sr-86 (2)
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-
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platinum group
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osmium
-
Os-188/Os-187 (1)
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Ocean Drilling Program
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Leg 113
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ODP Site 690 (1)
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Leg 171B
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ODP Site 1050 (1)
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Leg 207
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ODP Site 1258 (1)
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oxygen
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O-18/O-16 (2)
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paleoclimatology (2)
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paleoecology (5)
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paleontology (1)
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Paleozoic
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Permian
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Upper Permian (1)
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-
-
palynomorphs
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acritarchs (1)
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Dinoflagellata (1)
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miospores
-
pollen (2)
-
-
-
petroleum (1)
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Plantae
-
algae
-
Chlorophyta (1)
-
nannofossils (3)
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Phaeophyta (1)
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Rhodophyta (1)
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-
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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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-
-
-
sea-level changes (4)
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sedimentary rocks
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clastic rocks
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sandstone (1)
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-
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sediments
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marine sediments (2)
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Southern Ocean
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Weddell Sea
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Maud Rise (1)
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-
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United States
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Colorado
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Pueblo County Colorado
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Pueblo Colorado (1)
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-
-
-
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rock formations
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Deccan Traps (4)
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Intertrappean Beds (1)
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sedimentary rocks
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sedimentary rocks
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clastic rocks
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sandstone (1)
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-
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sedimentary structures
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burrows (1)
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sediments
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sediments
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marine sediments (2)
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GeoRef Categories
Era and Period
Epoch and Age
Book Series
Date
Availability
Maastrichtian to Eocene Subsurface Stratigraphy of the Cauvery Basin and Correlation with Madagascar Available to Purchase
Sedimentary Core Analysis: Implications on the Evolution of Pulicat Lake, East Coast of India Available to Purchase
Multiproxy Evidence of Main Deccan Traps Pulse near the Cretaceous-Tertiary Boundary Available to Purchase
Abstract: Recent studies indicate that the bulk (80%) of Deccan trap eruptions occurred over a relatively short time interval in magnetic polarity C29r, whereas multiproxy studies from central and southeastern India place the Cretaceous-Tertiary (KT) mass extinction near the end of this main phase of Deccan volcanism suggesting a cause-and-effect relationship. Beyond India multiproxy studies also place the main Deccan phase in the uppermost Maastrichtian C29r below the KTB (planktic foraminiferal zones CF2-CF1), as indicated by a rapid shift in 187 Os/ 188 Os ratios in deep-sea sections from the Atlantic, Pacific and Indian Oceans, coincident with rapid climate warming, coeval increase in weathering, a significant decrease in bulk carbonate indicative of acidification due to volcanic SO 2 , and major biotic stress conditions expressed in species dwarfing and decreased abundance in calcareous microfossils (planktic foraminifera and nannofossils). These observations indicate that Deccan volcanism played a key role in increasing atmospheric CO 2 and SO 2 levels that resulted in global warming and acidified oceans, respectively, increasing biotic stress that predisposed faunas to eventual extinction at the KTB.
Paleoclimate and Paleoenvironment of the Naredi Formation (Early Eocene), Kutch, Gujarat, India Available to Purchase
Abstract : The Naredi Formation of Kutch, Gujarat, India, is early Eocene in age and marks the first marine transgression above the last Deccan traps. Sediment deposition occurred in a shallow inner shelf environment that varied from a brackish lagoon to brackish, normal inner shelf and to marginal marine environments. The section can be divided into 2 main transgressive cycles interrupted by a regression phase that is marked by a well-defined sequence boundary marked by a root-bearing paleosoil. Three intervals yielded common to abundant benthic foraminiferal assemblages. Planktic foraminifera are few to rare and restricted to the top of the section, except for Chiloguembelina trinitatensis. An early Eocene age can be attributed to the Naredi section based primarily on larger benthic foraminifera (SBZ8 to SBZ11, equivalent to planktic foraminiferal biozones E4 to E6), rare planktic foraminifera, the stable isotope curve and its correlation with marine sections and sequence stratigraphy. Sediments of the transgression/regression cycles were derived from physical and chemical-weathering processes of basaltic rocks as indicated by the different geochemical proxies. Carbon isotope analyses of bivalve shells and organic matter reveal a negative excursion that is correlative with the global Early Eocene excursion. The presence of fish bones, fish teeth and organic matter can be related to the Early Eocene climatic optimum. Clay mineral data from the Naredi Formation indicate variably hot humid to arid climate conditions.
Regional and Standard Stratigraphic Classifications and Correlation in India Available to Purchase
Benthic Foraminiferal Biostratigraphy of Middle to Late Jurassic Sequence, Ler Dome, Kutch Available to Purchase
Abstract: Jurassic sediments of Ler Dome near Bhuj, Kutch, belonging to Chari Formation yielded forty-two benthic foraminiferal species from thirty-three samples. Thirteen species are reported for the first time from this region. All the species are benthic comprising calcareous hyaline and agglutinated forms. Callovian to Oxfordian age is suggested for the studied sequence. An attempt is made to mark the Callovian-Oxfordian boundary in the Ler Dome section.
Terminal Maastrichtian Age Calcareous Nannofossils Preceding K/T Mass Extinction from Aladi Formation, Vridhachalam Area, South India Available to Purchase
Abstract: A moderately diversified, well preserved, low frequency nannofossil assemblage with over twenty species is recorded from one (S-13) calcareous marl sample of the Ariyalur Formation situated north of the village Aladi. The assemblage includes the latest Maastrichtian index species Micula prinsii. Preservation is good and although specimens are overgrown, no dissolution effects are apparent. The assemblage is of late Maastrichtian age CC 26b (Perch- Nielsen, 1985) correlative with UC 20d TP (Burnett, 1998). The range of Micula prinsii , a low latitude marker, is indicative of the latest Maastrichtian magnetochron C29r below the K/T boundary that spans approximately the last 500,000 years of the Maastrichtian. In addition, high abundance of Petrobrasiella? bownii in both very small and large sizes (3-4 μm to 10 μm diameter) along with Ceratolithoides aculeus, C. kamptneri, Arkhangelskiella maastrichtiana, Calculites obscurus attests to this zonal placement. The high latitude Maastrichtian genus Nephrolithus , represented by N. miniporus , is also present in the assemblage and indicates a cold water current in the southeastern part of India during latest Maastrichtian. Reworked Campanian species represented by Nannoconnus spp. and Haqius circumradiatus are also present in the assemblage. Further study of this locality may provide a record of the K/T boundary.
Deccan Continental Flood Basalt Eruption Terminated Indian Dinosaurs before the Cretaceous-Paleogene Boundary Available to Purchase
Abstract: Late Cretaceous-Early Paleogene sediments associated with Deccan Continental Flood Basalt (DCFB) sequences of central and western India record the timing of the introduction and extinction of Late Cretaceous dinosaurs in India based on magnetostratigraphy and magnetic susceptibility stratigraphy. Current taxonomy indicates that only two genera of titanosaurs (e.g., Isisaurus and Jainosaurus), at least four species of large-bodied abelisauridae theropods (e.g., Rajasaurus narmadensis, Rahiolisaurus gujaratensis, Indosuchus matleyi and Indosaurus raptorius) and a small-bodied theropod Laevisuchus inhabited India during the Maastrichtian. Their stratigraphic and geographic distribution suggests that these dinosaurs were dominated by titanosauriforme and abelisauridae that first appeared before the advent of Deccan volcanism in the magnetochron C30n and were well established with the acme of breeding and nesting during C30n to maastrichtian C29r. Their decline in diversity and abundance coincides with initiation of DCFB eruptions when most of the early taxa were terminated and only a few titanosauriforme sauropods survived becoming extinct at about 350 kyr before the Cretaceous-Paleogene boundary (KPB). Dinosaur extinction in India is thus directly tied to Deccan volcanism with no evidence of an asteroid impact.
Biostratigraphy and Foramiferal Paleoecology of the Early Eocene Naredi Formation, SW Kutch, India Available to Purchase
Abstract : The Naredi Formation in southwestern Kutch overlies the last Deccan Trap deposited during the early Paleocene. The lower part of the Naredi Formation (2.8-4.2 m from base) is of early Eocene (Ypresian) age (SBZ8, E4) based on larger foraminifera and rare planktic foraminifera, whereas the upper part (9.3-11 m, including the Assilina limestone) is of late early Eocene age (SBZ11, E6). There is no age control for the basal 0-2.8 m and between 4.2-9.3 m because microfossils are rare or absent. Small benthic and rare planktic foraminifera are common in three short intervals and indicate deposition in a brackish to normal marine inner shelf environment (SBZ8, E4), brackish environment (middle of section, no age control) and inner shelf to marginal marine environment (SBZ11, E6). Two phases of marine transgressions can be identified with the maximum transgressions in each phase coincident with the lower and upper foraminiferal assemblages. A paleosol indicated by root traces and burrows (5.9 m) represents a regression and possibly sequence boundary. This study is dedicated to Dr. Lukas Hottinger (1933-2011), who passed away before this study was completed. We remember him for his invaluable contributions to the biostratigraphy, taxonomy and paleoecology of larger Foraminifera and his generous ever cheerful willingness to teach, advise and share his immense knowledge and expertise. We will miss him.
Distribution of Benthic Ostracoda in surface and subsurface backwater sediments of Ernakulam, Kerala, Southwest coast of India: Microenvironmental Implications Available to Purchase
Abstract: Fourteen surface and two core sediment samples were collected from the backwaters of Cochin, Kerala, southwest coast of India, in order to study the systematics and distribution of Recent Ostracoda. The ostracod taxa were separated from the sediments applying standard micropaleontological techniques. A total of 20 Ostracod species belonging to 17 genera and 8 families were identified. Sediment parameters such as CaCO 3, organic matter and sand-silt-clay ratio were estimated for the surface as well as core samples in order to determine the relationship between substrate and Ostracoda populations, and to evaluate the favoured substrate of dominant species populations. The down core distribution of sediment parameters and ostracod assemblages is presented. Based on this data we determine that ostracods favour silty-sandy substrate environments. The rate of sedimentation was determined based on the ratio between the carapace and open valves of Ostracoda. The benthic ostracod fauna recorded is characteristic of a tropical, brackish to epi-neritic environment and few warm, shallow marine species occur in the backwaters of Cochin, may be due to the tidal influence.
Palaeocene to early Eocene Planktonic Foraminifera of the Pondicherry area, South India Available to Purchase
Abstract: Planktonic foraminifera from several outcrops and sections in the Pondicherry area, South India, were analyzed to determine their age. Preliminary analysis of the samples collected from various outcrops and sections of Pondicherry area yielded abundant well preserved planktonic foraminifera belonging to Globoanomolina, Parasubbotina, Subbotina Praemurica, Igorina, Acarinina, Morozovella, Pseudohastigerina and Astrorotalia occurring in part of the sequence in association with abundant Discocyclinids. Fifty-two planktonic foraminiferal species of these genera are recorded from and interval spanning from the early Palaeocene zone P1b to the early Eocene zone P9. The stratigraphic distribution of the planktonic foraminifera from these samples do not allow identification of individual biozones, undifferentiated zone intervals can be recognized, including P1b-P2, P3a-P5 and P6-P9. Species are illustrated based on SEM microphotographs. More detailed biostratigraphic work is needed and will be carried out to identify individual zones and determine the completeness of the sections.
Strontium Isotope Stratigraphy of the Naredi Formation, Kutch Basin, India Available to Purchase
Abstract: The Naredi Formation records the first marine transgression of the Cenozoic era in Kutch. Its age has remained equivocal and various workers have assigned different ages ranging from Late Palaeocene to Early and Middle Eocene. In this study we carried out strontium isotopic analysis of the foraminiferal shells of the Naredi Formation to determine its numerical age in order to resolve this controversy. The measured 87 Sr/ 86 Sr ratios, lying between 0.707727 and 0.707816, have been compared with the standard strontium isotope variation curve for the Cenozoic. Biostratigraphically, the formation ranges from shallow benthic zone SBZ 6 to SBZ 11 corresponding to planktonic foraminiferal zones P5 to P9 (Serra-Kiel et al., 1998). The biostratigraphically constrained Sr isotopic values indicate that the Naredi Formation is of Early Eocene age spanning from 50 to 55Ma.
Effect of Temperature and Salinity on Stable Isotopic Composition of Shallow Water Benthic Foraminifera: A Laboratory Culture Study Available to Purchase
Abstract : Quantitative estimation of past climatic parameters from stable isotopic composition of foraminifera relies on estimating the precise relationship between stable isotopic composition of the species analyzed and the physico-chemical factors of the seawater. This relationship can be established either on species collected from surface sediments or in plankton tows. Another method to establish such relationships is by subjecting the foraminiferal species to known physico-chemical parameters in the laboratory. In the present work, shallow water benthic foraminiferal species, Rosalina sp. and Pararotalia nipponica were subjected to different combinations of seawater temperature (25°C to 35°C) and salinity (25 psu to 37 psu) in the laboratory to assess their stable oxygen isotopic composition and its applicability in determining seawater temperature and salinity. The stable isotopic ratio of the species shows no consistent relationship with salinity. The relationship between δ 18 O foraminifera and seawater temperature is more consistent for P. nipponica than for Rosalina sp. Salinity appears to have less control on δ 18 O foraminifera as compared to the seawater temperature, within the studied salinity and temperature range. The study shows that the changes in δ 18 O of P. nipponica can be used effectively to infer past seawater temperature changes.
Palaeoenvironmental Significance of Rectilinear Benthic Foraminifera in the Middle Eocene section of Matanomadh Sub-basin, Kutch Available to Purchase
Abstract : A lignite-bearing section at Matanomadh (N23°30′; E68°55′) in Kutch was examined for its foraminiferal assemblage. The section consists of lignite and carbonaceous shale in the lower part and mudstone in the upper part. The mudstone is characterized by a low diversity and moderate abundance of dwarf foraminifera. The presence of Halkyardia minima, Linderina kutchensis and Lockhartia alveolata suggests its correlation with Fulra Limestone exposed in the adjoining regions of Kutch. The smaller benthic foraminifera mainly include the species of Brizalina, Bulimina, Trifarina, Cibicides, Discorbis and Guttulina. The Rectilinear Benthic Foraminifera morphogroup (RBF) constituting up to 60% of the foraminiferal assemblage are characterized by large pores. These are typical characteristics of foraminiferal assemblages from low oxygen environment. The peak abundance of RBF occurs consistently at co-eval levels in several sections of Kutch. It is suggestive of dysoxic conditions in late Middle Eocene, corresponding to planktonic foraminiferal zone P13.
Micropalaeontological response to mid–late Cretaceous Oceanic Anoxic Events: 50 th Anniversary Tribute to the Pioneering Work of R.P.S. Jefferies Available to Purchase
Abstract : In the early 1960s, R.P.S. Jefferies conducted an investigation of the microfossils found in the Actinocamax plenus Marls of Southern England. This was the first investigation of its kind, using closely-spaced samples and providing a detailed analysis of a relatively short interval of geological time. The Plenus Marls Member, as it is now known, is the on-shore representation of Oceanic Anoxic Event ll (=Bonarelli Event or Cenomanian/Turonian Boundary Event [CTBE]). Jefferies’ detailed analysis of the changes over this major extinction event in Earth history has provided the foundation for much later research. Anoxic events – including the CTBE – characterise the mid-Late Cretaceous interval and all are associated with stable isotope excursions, geochemical changes and distinctive patterns of both extinction and appearance of various taxa. Some of these (e.g., calcareous dinoflagellates, radiolaria) are now regarded as ‘disaster taxa’ and their appearance, in variable numbers, from a range of locations can be used to inform judgements about the nature of these events.
Early Paleocene Planktic Foraminifers and Stratigraphy, Jaisalmer Basin, Rajasthan Available to Purchase
Abstract: Early Paleocene planktic foraminifera (Zones P1c to P4) from well sections (Sanu, Sam, Tanot, Ram-1, GTF-1) are reported from the Jaisalmer Basin. The Subzone P1c is characterized by the hemipelagic early Danian species Globoconusa daubjergensis, Eoglobigerina edita, Praemurica pseudoinconstans, P. inconstans, Parasubbotina pseudobulloides, Subbotina triloculinoides and Globanomalina compressa. Zone P2 is identified by the total range of Praemurica uncinata and Eoglobigerina spiralis and Zone P3 by the occurrence of Igorina pusilla in association of Morozovella angulata and M. conicotruncata. Larger benthic foraminiferal species, such as Assilina dandotica , are abundant in the interval identified as Zone P4 characterized by Globanomalina pseudomenardii , Morozovella velascoensis, Igorina albeari, I. tadjikistanensis, Subbotina velascoensis, S. triangularis, Acarinina soldadoensis , and Parasubbotina varianta . This indicates a lower P4 stratigraphic range for Assilina dandotica , which was assumed to appear in Zone P5 (= Standard benthic foraminiferal Zone 5). The Paleocene-Eocene boundary was identified based on Acarinina africana and A. sibaiyaensis marking the Zones P5 to E1 interval.
Distribution of Recent Benthic Ostracoda off Rameswaram, Palk Strait, Tamil nadu, South East Coast of India Available to Purchase
Abstract: An investigation to record spatial and seasonal distribution of recent benthic ostracoda was carried out along two transects (East and Northeast) off Rameswaram island of Tamil Nadu coast, India. Thirty sediment and bottom water samples were collected during January 2011 and April 2011 and analysed for various physico-chemical and sediment characteristics using standard procedures. The top 4 cm sediment was preserved in 10% formaldehyde and later in the laboratory the live and total population of Ostracoda was determined using the rose Bengal stain technique. Faunal frequencies for benthic ostracods were computed and correlated with physico-chemical and sediment characteristics. The correlation reveals that ostracod frequency has a positive correlation with sandy substrate and negative correlation with clay substrate and OM%. Faunal frequencies increased by 3 times during summer (April 2011) although values of physico-chemical and sediment characteristics do not show considerable variation from January 2011. The east transect is proximal to the coral reef and characterized by sandy substrate in both seasons, supports high populations and therefore is more congenial for ostracod proliferation. Finally, environmental variables have been correlated with those measured three decades ago to understand the causes for variations.
Middle Cenomanian to Middle Turonian Planktic Foraminiferal Assemblages from Scattered Outcrops in the Karai - Kulakkalnattam Area, Uttattur Group, Southern India Available to Purchase
Abstract: The purpose of the present study is to record the planktic foraminiferal fauna present and to determine the Cenomanian-Turonian boundary based on the planktic foraminifera of the Karai – Kulakkalnattam Traverse of Uttattur Group, East coast of India. For this study one hundred ninety five sediment samples were systematically collected from the Karai - Kulakkalnattam traverse. Foraminifers were separated out by using standard micropaleontological techniques. Five Species of planktic foraminifera were identified and studied. In the present study area the Cenomanian-Turonian boundary (C/T) is placed in the upper most part of the Whiteinella archaeocratacea Partial range zone. The distribution of foraminifera and stratigraphic importance of this species are discussed.
Aquilapollenites Pollen from Deccan Intertrappean Sediments: Age Implications Available to Purchase
Abstract: Palynological studies of Deccan volcanic associated sediments of the Sahyadri Group of Nand-Dongargaon basin of Maharashtra, Amarkantak Group of Chhindwara and unclassified Deccan Trap sequences of Saurashtra show the presence of Aquilapollenites pollen. The overall data on this genus from the Indian Late Cretaceous-Early Paleocene indicates that the genus was widely distributed during the Late Cretaceous. A notable decline in abundance in the Early Paleocene may be related to the climatic and environmental changes brought about by the Deccan volcanism.
Sediment Characteristics and Foraminiferal Distribution in the Bet Zone of the Great Rann of Kachchh, Western India Available to Purchase
Abstract : Based on geomorphological characteristics, the vast, flat saline tract of the Great Rann of Kachchh is considered as a raised floor of a former gulf that was connected to the Arabian Sea in the west. In general, the Rann exhibits a unique supratidal environment complicated by alternating periods of marine and freshwater inundation and extreme dryness. The Great Rann is divisible into four distinct geomorphic domains – the Banni plain, the Linear trench zone, the Great barren zone and the Bet zone. Contrary to the rest of the Great Rann, the Bet zone shows distinct variations in elevation due to the presence of bets (islands) and is dotted by several vegetated elevated areas, seasonal short distance channels and local depressions. The present study attempts to characterize the environmental conditions of the Bet zone comprising the northwestern part of the Great Rann. Surface sediment samples were collected by digging small pits in the Rann surface at several locations along ESE-WNW and roughly N-S oriented transects (transect 1 and 2). The samples were subjected to detailed grain size analysis and micropalaeontological analysis for determining foraminiferal assemblage. Overall, the sediments of the Bet zone are of sandy-silty to clayey-silty in nature. The grain size was found to vary in accordance with the microgeomorphic setting of the stations. The foraminiferal assemblages recorded along the two transects belong to twelve genera (Ammonia, Elphidium, Bolivina, Nonian, Bulimina, Cibicides, Helenina, Brizalina, Globigerinella, Globigerina, Globorotaloides Gallitellia). Presence of some reworked foraminiferal tests suggests the transport of foraminifera from the Arabian Sea water surges under the influence of strong SW monsoon winds. However, the relatively higher diversity near the open ocean gets reduced in the Great Rann due to the typical hypersaline conditions, submergence patterns, mixing by fresh water (runoff, fresh water influx), and the microenvironments created by variations in the elevation of the Rann surface. The diversity is limited to the few tolerant taxa which can survive through such large scale changes in the environmental parameters.