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Burns, S.J., Haudenschild, U. and Matter, A. (1994). The Strontium Isotopic Composition of Carbonates from the Late Precambrian (Approximate-to-560-540 Ma) Huqf Group of Oman. Chemical Geology 111(1-4): 269-282. |
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The strontium isotopic compositions of carbonates from the Huqf Group of Oman provide the first data on the Sr isotopic composition of seawater during the latest Precambrian. The data show that the isotopic composition of seawater was increasing relatively rapidly, from values of similar to 0.7082at similar to 560 Ma, to values of similar to 0.7090 at similar to 540 Ma. When combined with data from older carbonates, the data verify a large change in the isotopic composition of late Precambrian seawater, from <0.7070 at similar to 680 Ma, to greater than or equal to 0.7090 in the early Cambrian. Thus, late Precambrian seawater Sr isotope ratios should eventually prove to be useful for stratigraphic correlation. The causes of the increase in seawater Sr-87/Sr-86 are interpreted to be due in part to increased continental weathering associated with extensive tectonic activity of the Pan-African orogeny and the Varangian and Sinian glacial periods, which increased the riverine flux of Sr to the oceans and may also have increased the isotopic ratio of the riverine Sr flux. Mass-balance calculations suggest that the change must have also in part been caused by a decrease in the hydrothermal flux of Sr to the oceans. |
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Keywords
phanerozoic time, proterozoic carbonates, crustal evolution, sea-water, seawater, ocean, stratigraphy, tectonics, neogene, model |
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Publisher
Elsevier Science
P.O. Box 211
1000 AE Amsterdam
The Netherlands
(+31) 20 485 3757
(+31) 20 485 3432
nlinfo-f@elsevier.com |
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