Uranium, thorium isotopic analyses and uranium-series ages of calcite and opal, and stable isotopic compositions of calcite from drill cores UE25a 1, USW G-2 and USW G-3/GU-3, Yucca Mountain, Nevada

1985 ◽  
Author(s):  
B. J. Szabo ◽  
T.K. Kyser
Keyword(s):  
Yucca Mountain ◽  
Uranium Series ◽  
Isotopic Compositions ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Drill Cores

Stable isotopes in planktonic and benthic foraminifera from Arctic Ocean surface sediments

1988 ◽  
Vol 25 (5) ◽  
pp. 701-709 ◽  
Author(s):  
A. E. Aksu ◽  
G. Vilks
Keyword(s):  
Surface Water ◽  
Arctic Ocean ◽  
Sea Water ◽  
Ocean Surface ◽  
The Arctic ◽  
Size Fractions ◽  
Isotopic Compositions ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Surface Water Salinity

Oxygen and carbon isotopic analyses have been performed on the tests of Planulina wuellerstorfi and three size fractions of sinistral Neogloboquadrina pachyderma recovered from 33 Arctic Ocean surface-sediment samples. Stable isotopic compositions of N. pachyderma are found to be dependent on the test size: larger specimens show considerable enrichment in both δ18O and δ18C. The difference between the isotopic compositions of the 63–125 and 125–250 μm size fractions in N. pachyderma can be explained by biogenic fractionation effects during foraminiferal test growth. Larger (250–500 μm) N. pachyderma displayed accretions of secondary calcite, i.e., the outermost shell contained significant amounts of inorganically precipitated magnesium calcite. Thus, larger foraminifera may not be suited for down-core stable isotopic studies. There is a difference of ~2‰ between δ18O values of surface samples from the eastern and western Arctic Ocean, reflecting large differences between surface-water salinity in these regions. Therefore, oxygen isotopic data may have limited use as a chronostratigraphic tool in down-core studies in the Arctic Ocean, but we can use them to infer past variations in surface-water salinities. Planulina wuellerstorfi also showed depletions of both δ18O and δ18C in its calcite tests relative to calcite precipitated in isotopic equilibrium with ambient sea water; these depletions ranged from −0.8 to −0.9‰ in δ18Oand −1.2 to −0.9‰ in δ18C. This taxon is found to deposit its shell very close to the δ18C of ΣCO2 of bottom waters.

scholarly journals Uranium-Series Constraints on Subrepository Water Flow at Yucca Mountain, Nevada

2006 ◽  
Author(s):  
L.A. Neymark ◽  
J.B. Paces ◽  
S.J. Chipera ◽  
D.T. Vaniman
Keyword(s):  
Water Flow ◽  
Yucca Mountain ◽  
Uranium Series

Stable isotopic compositions of hydrothermal vent organisms

1989 ◽  
Vol 102 (2) ◽  
pp. 257-263 ◽  
Author(s):  
C. L. Van Dover ◽  
B. Fry
Keyword(s):  
Hydrothermal Vent ◽  
Isotopic Compositions ◽  
Stable Isotopic
Sign in / Sign up

Export Citation Format

Share Document