The variation of the marine ratio during Phanerozonic time: interpretation using a flux model

Brass, Garrett W.

doi:10.1016/0016-7037(76)90025-9

Cited by 255 publications

(92 citation statements)

References 24 publications

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“…These non-radiogenic 87Sr/86Sr ratios are below the mean seawater isotope composition at the time span of nodule exhumation (0.70915-0.79020 during the late Pleistocene; McArthur et al, 2001). They could be attributed to a Levantine Intermediate Water-derived component in the MOW, mainly generated by the Nile River contribution, with an Sr isotopic composition of 0.706 (Brass, 1976;Albarede and Michard, 1987;Palmer and Edmond, 1992).…”

Section: Stage Two: the Influence Of The Mediterranean Outflow Water mentioning

confidence: 99%

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

et al. 2012

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Section: Stage Two: the Influence Of The Mediterranean Outflow Water mentioning

confidence: 99%

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

et al. 2012

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“…Silicate rocks generally have low strontium content and higher 87 Sr/ 86 Sr ratios while limestones are typically less radiogenic but with more strontium (Brass 1976;Wadleigh and Brooks 1985). Conversely mafic rocks have a markedly lower 87 Sr/ 86 Sr ratio.…”

Section: Strontium Isotopesmentioning

confidence: 99%

Geochemical evolution of uraniferous soda lakes in Eastern Mongolia

Linhoff

Bennett

Puntsag³

et al. 2010

Environ Earth Sci

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“…7) (Goldstein and Jacobsen, 1987); the Ganges and Brahmaputra data are similarly displaced due to geologically unusual circumstances associated with the Himalayan Orogeny (Palmer and Edmond, 1992). Data from Palmer and Edmond (1989 (Brass, 1976). In the following section we will consider specific paleoclimatic and geological conditions that could affect fluvial Sr derived from silicate weathering.…”

mentioning

confidence: 99%

Seawater strontium isotopes, oceanic anoxic events, and seafloor hydrothermal activity in the Jurassic and Cretaceous

Jones¹

2001

American Journal of Science

466

323

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ABSTRACT. There were three negative seawater strontium-isotope excursions (shifts to lower 87 Sr/ 86Sr values) during the Jurassic and Cretaceous that were of relatively short duration (5-13 my) and showed a relatively quick recovery to pre-excursion 87 Sr/ 86 Sr ratios. These excursions occurred in the Pliensbachian-Toarcian (Early Jurassic), Aptian-Albian, and Cenomanian-Santonian (Early and Late Cretaceous respectively). Each excursion coincided closely in time with an Oceanic Anoxic Event (OAE) marked by sediments unusually rich in organic carbon. The Jurassic OAE occurred at the end of the strontium-isotope excursion, whereas the two Cretaceous OAEs occurred at the onset of the accompanying strontium-isotope excursions.The possible causes of these excursions were evaluated by successively examining the changes in the riverine strontium fluxes, riverine 87 Sr/ 86 Sr ratios, or hydrothermal strontium fluxes required to produce each excursion. A range of seawater strontium budgets was used to encompass the uncertainties in modern and ancient cycles. To produce the excursions, we calculate that the riverine strontium fluxes would have had to decrease by 6 to 15 percent or the fluvial 87 Sr/ 86 Sr ratios by 0.00019 to 0.00046. The uncertainties largely stem from the assumed magnitude of the hydrothermal strontium flux at the onset of each excursion. Alternatively, increases in sea-floor hydrothermal activity of 7 to 104 percent could also have produced the strontium-isotope excursions. This large range is due mostly to uncertainties in the relative flux of strontium from axial high-temperature hydrothermal systems and low-temperature off-axis systems. Only a small portion of this range stems from uncertainties in the riverine strontium terms.The possible causes of the excursions were further evaluated by examining several geologic factors that could have affected riverine strontium, including climate change, sealevel, and the eruption of flood basalts. We conclude that neither variations in riverine strontium fluxes nor in 87 Sr/ 86 Sr ratios is the likely cause of the strontiumisotope excursions. The most probable explanation is increased rates of hydrothermal activity related to increased ocean-crust production at the mid-ocean ridges.The close correlation in time between the strontium-isotope excursions and the major Oceanic Anoxic Events (OAEs) is compatible with a causal linkage. We propose that increased ocean-crust production led to enhanced CO 2 outgassing and global warming, which in turn led to several processes that acted to make surface ocean waters more productive. However, because OAEs did not occur throughout the proposed periods of enhanced hydrothermal activity, it appears that these processes only preconditioned the oceans for the OAEs: sealevel rise may have been the final trigger. This model explains why all three OAEs did not occur at the same time relative to the onset of excess hydrothermal activity and why OAEs are not associated with every sealevel rise documented in the stratigraphic re...

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The variation of the marine ratio during Phanerozonic time: interpretation using a flux model

Cited by 255 publications

References 24 publications

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

Geochemical evolution of uraniferous soda lakes in Eastern Mongolia

Seawater strontium isotopes, oceanic anoxic events, and seafloor hydrothermal activity in the Jurassic and Cretaceous

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