234 Th:238 U disequilibria within the California Current1
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چکیده
منابع مشابه
Control on ( 234 U / 238 U ) in lake water : A study in the Dry Valleys of Antarctica
The (U/ U) ratio in surface waters is generally higher than secular equilibrium due to nuclide recoil during alpha-decay of U. The size of the deviation from secular equilibrium contains information about the environment in which the water is found. This potential tool for environmental reconstruction has previously been studied in rivers, groundwater, and sediment pore-water. Here we conduct a...
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Constraining the history of seawater (234U/238U) is important because this ratio is used to assess the validity of U/ Th ages, and because it provides information about the past rate of physical weathering on the continents. This study makes use of U-rich slope sediments from the Bahamas in an attempt to reconstruct seawater (234U/238U) for the last 800 kyr. For the last 360 kyr, U/Th dating of...
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Lavas from the Puʻu ʻŌʻō eruption of Kīlauea Volcano are thought to partially bypass the shallow magma reservoir beneath the volcano's summit, and thus, provide a relatively direct “window” to the mantle. Here we use high-precision U-series isotope measurements of Puʻu ʻŌʻō lavas (1985–2001) to investigate the timing and mechanism of melt transport within the Hawaiian mantle plume. The lavas di...
متن کاملSeasonal and spatial dynamics of Th/U disequilibria in southern Lake Michigan
[1] Measurements of Th/U disequilibria were made on an approximately bimonthly basis over the course of a year in nearshore (10–40 m deep) and offshore (160 m deep) surface waters of the southern basin of Lake Michigan (18,100 km). The mean activity of U in Lake Michigan measured 230 ± 20 dpm m , approximately 1 order of magnitude lower than what is typically found in marine systems. Measured m...
متن کاملDehydration and partial melting in subduction zones: Constraints from U-series disequilibria
We present a critical reappraisal of U-series data from arc volcanoes to constrain slab dehydration and melting processes using a global subduction zone data set. There is no clear evidence for significant mobilization of Th or Pa in dehydration fluids while the source region of arc rocks is relatively oxidized and mobility of U is strongly enhanced. It is argued that along-arc U/Th and U/Pa is...
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ژورنال
عنوان ژورنال: Limnology and Oceanography
سال: 1985
ISSN: 0024-3590
DOI: 10.4319/lo.1985.30.1.0022