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Now showing items 21-30 of 34
Age, composition, and origin of the lower continental crust, northern Tanzania
(2008)
Granulite xenoliths from the East African rift in Tanzania sample the lower continental crust beneath both the stable Tanzanian craton and the adjacent, polymetamorphic Mozambique belt. Protoliths of surface rocks in both ...
A Stable Isotope Investigation of Precipitation Nitrate
(2005-08-15)
The isotopic composition of precipitation nitrate reflects the processes involved in its formation. Silver nitrates prepared from Maryland precipitation were thermally decomposed to gases for mass spectrometric analyses. ...
Isotope and Organic Geochemistry of a Unique Proterozoic, Postglacial Succession: The Lapa Formation, Vazante Group, Brazil
(2007-05-09)
This study is the second to investigate biological characteristics associated with Proterozoic glaciation via molecular fossils from organic matter preserved in shale. In the Vazante Group, Minas Gerais, Brazil, the Serra ...
Highly Siderophile Element and Tungsten Systematics of Hawaiian Picrites
(2009)
A suite of Hawaiian picrites (MgO > 13 wt.%), and associated basalts, that represent some of the most primitive melts from the Hawaiian mantle source regions were analyzed for their W, highly siderophile element (HSE: Os, ...
Timing of Orogenesis in the Southern Brasília Belt
(2009)
The Neoproterozoic-Cambrian Brasília Orogeny records suturing of the passive margin on the western side of the São Francisco Craton with magmatic arcs and the Paranapanema Block in the south or the Amazon Craton in the ...
Scales of Bank Roughness and Their Relationship to Bank Erosion Processes
(2009)
Stream bank erosion rates and the stabilization of channel width are poorly understood processes. There have been two distinct approaches to the study and prediction of bank erosion rates in natural streams. In order to ...
THE P-T-t HISTORY OF A BARROVIAN SEQUENCE IN DUTCHESS COUNTY, NEW YORK, AND THE ADJACENT PART OF CONNECTICUT
(2009)
The P-T-t history of a Barrovian sequence in Dutchess County, New York and the adjacent part of Connecticut was studied. Using the average P-T mode in THERMOCALC, the following P-T results were calculated for the garnet, ...
Melting and Phase Relations in Iron-Silicon Alloys with Applications to the Earth's Core
(2009)
Experiments were performed on iron-silicon alloys to determine their suitability as analog compositions for the Earth's core. Starting compositions with 9 wt.% silicon and 16 wt.% silicon were compressed in diamond anvil ...
EFFECTS OF BAR FORMATION ON CHANNEL STABILITY AND SEDIMENT LOADS IN AN URBAN WATERSHED
(2009)
This study investigates channel adjustment due to urbanization in the Little Paint Branch creek of the Anacostia River watershed. In the past 15 years, large gravel bars have formed in the channels, more than doubling the ...
LITHIUM ISOTOPIC SYSTEMATICS OF THE CONTINENTAL CRUST
(2005-12-05)
In order to fully utilize Li isotopes as a geochemical tracer, it is necessary to characterize the Li isotopic compositions of different geological reservoirs, and quantify the magnitude of isotopic fractionations for ...