New data on early Eocene diatom successions of the West Polar Urals margin: Biostratigraphic and paleogeographic implications

GFF ◽  
2000 ◽  
Vol 122 (1) ◽  
pp. 124-126 ◽  
Author(s):  
Tatiana V. Oreshkina
Keyword(s):  
Early Eocene ◽  
The West ◽  
Polar Urals

scholarly journals Tropical seaways played a more important role than high latitude seaways in Cenozoic cooling

2011 ◽  
Vol 7 (3) ◽  
pp. 801-813 ◽  
Author(s):  
Z. Zhang ◽  
K. H. Nisancioglu ◽  
F. Flatøy ◽  
M. Bentsen ◽  
I. Bethke ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Deep Water ◽  
Drake Passage ◽  
Central American ◽  
The Arctic ◽  
Early Eocene ◽  
High Latitudes ◽  
The West ◽  
Early Eocene Climatic Optimum ◽  
Tectonic Events

Abstract. Following the Early Eocene climatic optimum (EECO, ~55–50 Ma), climate deteriorated and gradually changed the earth from a greenhouse into an icehouse, with major cooling events at the Eocene-Oligocene boundary (∼34 Ma) and the Middle Miocene (∼15 Ma). It is believed that the opening of the Drake Passage had a marked impact on the cooling at the Eocene-Oligocene boundary. Based on an Early Eocene simulation, we study the sensitivity of climate and ocean circulation to tectonic events such as the closing of the West Siberian Seaway, the deepening of the Arctic-Atlantic Seaway, the opening of the Drake Passage, and the constriction of the Tethys and Central American seaways. The opening of the Drake Passage, together with the closing of the West Siberian Seaway and the deepening of the Arctic-Atlantic Seaway, weakened the Southern Ocean Deep Water (SODW) dominated ocean circulation and led to a weak cooling at high latitudes, thus contributing to the observed Early Cenozoic cooling. However, the later constriction of the Tethys and Central American Seaways is shown to give a strong cooling at southern high latitudes. This cooling was related to the transition of ocean circulation from a SODW-dominated mode to the modern-like ocean circulation dominated by North Atlantic Deep Water (NADW).

New Early Eocene mollusks from the Orocopia Mountains, southern California

1986 ◽  
Vol 60 (4) ◽  
pp. 851-864 ◽  
Author(s):  
Richard L. Squires ◽  
David M. Advocate
Keyword(s):  
New Species ◽  
North American ◽  
West Coast ◽  
Southern California ◽  
Submarine Canyon ◽  
North American Species ◽  
Early Eocene ◽  
Paris Basin ◽  
The West ◽  
South Central

Five new species of mollusks are described from the early Eocene Maniobra Formation, northeastern Orocopia Mountains, southern California. The new species are from the basal part of the formation, and the fauna is indicative of the West Coast provincial molluscan early Eocene “Capay Stage.” The mollusks are shallow-marine forms that were transported a short distance into slope/upper submarine-canyon deposits.Chedevillia saltonensis n. sp. and Eocypraea? maniobraensis n. sp. resemble Eocene species from Paris Basin, France. Phalium (Semicassis) louella n. sp. is the earliest North American species of Semicassis. Volutilithes orocopiaensis n. sp. is the earliest North American species of this genus and resembles V. muricinus from Paris Basin. Glossus (Meiocardia) susukii n. sp. is the earliest reported species of Meiocardia on the West Coast of North and South America.Galeodea gallica, a species previously only known from lower Eocene strata in the Anglo-Paris Basin, is tentatively identified from the Maniobra Formation. Campanilopa dilloni, previously only known from south-central California, is present in the formation. Supplementary descriptions and illustrations are given for these two species.The Maniobra species described have a close relationship to species characteristic of the Eurasian Tethyan paleobiogeographic province. The age of the Maniobra mollusks permits greater resolution of the timing of the westward migration of the Eurasian species, indicating that much of it occurred during early Eocene and/or late Paleocene time.

scholarly journals Tropical seaways played a more important role than high latitude seaways in Cenozoic cooling

2011 ◽  
Vol 7 (2) ◽  
pp. 965-996 ◽  
Author(s):  
Z. Zhang ◽  
K. H. Nisancioglu ◽  
F. Flatøy ◽  
M. Bentsen ◽  
I. Bethke ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Deep Water ◽  
Drake Passage ◽  
Central American ◽  
The Arctic ◽  
Early Eocene ◽  
High Latitudes ◽  
The West ◽  
Early Eocene Climatic Optimum ◽  
Tectonic Events

Abstract. Following the Early Eocene climatic optimum (EECO, ~55–50 Ma), climate deteriorated and gradually changed the earth from a greenhouse into an icehouse, with major cooling events at the Eocene-Oligocene boundary (~34 Ma) and the Middle Miocene (~15 Ma). It is believed that the opening of the Drake Passage had a marked impact on the cooling at the Eocene-Oligocene boundary. Based on an Early Eocene simulation, we study the sensitivity of climate and ocean circulation to the tectonic events such as the closing of the West Siberian Seaway, the deepening of the Arctic-Atlantic Seaway, the opening of the Drake Passage, and the constriction of the Tethys and Central American seaways. The opening of the Drake Passage, together with the closing of the West Siberian Seaway, and the deepening of the Arctic-Atlantic Seaway, weakens the Southern Ocean Deep Water (SODW) dominated ocean circulation and leads to a weak cooling at high latitudes, thus contributing to the observed Early Cenozoic cooling. However, the later constriction of the Tethys and Central American Seaways is shown to give a strong cooling at southern high latitudes. This cooling is related to the transition of ocean circulation from a SODW-dominated mode to the modern-like ocean circulation dominated by North Atlantic Deep Water (NADW).

Enumeration and Identification of Asbestos Fibres in Water

1974 ◽  
Vol 32 ◽  
pp. 526-527 ◽  
Author(s):  
O. Mudroch ◽  
J. R. Kramer
Keyword(s):  
Water Supply ◽  
Water Samples ◽  
Drainage Basin ◽  
Lake Superior ◽  
Research Work ◽  
List Type ◽  
The West ◽  
Asbestos Fibre ◽  
Amphibole Asbestos

Approximately 60,000 tons per day of waste from taconite mining, tailing, are added to the west arm of Lake Superior at Silver Bay. Tailings contain nearly the same amount of quartz and amphibole asbestos, cummingtonite and actinolite in fibrous form. Cummingtonite fibres from 0.01μm in length have been found in the water supply for Minnesota municipalities.The purpose of the research work was to develop a method for asbestos fibre counts and identification in water and apply it for the enumeration of fibres in water samples collected(a) at various stations in Lake Superior at two depth: lm and at the bottom.(b) from various rivers in Lake Superior Drainage Basin.

The fight to save Uganda’s White Rhino

1964 ◽  
Vol 2 (01) ◽  
pp. 6-12
Keyword(s):  
The West ◽  
West Nile ◽  
White Rhino

In the West Nile District of Uganda lives a population of white rhino—those relies of a past age, cumbrous, gentle creatures despite their huge bulk—which estimates only 10 years ago, put at 500. But poachers live in the area, too, and official counts showed that white rhino were being reduced alarmingly. By 1959, they were believed to be diminished to 300.

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