Evaporites and the salinity of the ocean during the Phanerozoic: Implications for climate, ocean circulation and life

Hay, William W.; Migdisov, A. A.; Balukhovsky, A.N.; Wold, Christopher N.; Flögel, Sascha; Söding, Emanuel

doi:10.1016/j.palaeo.2006.03.044

Cited by 226 publications

(146 citation statements)

References 48 publications

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“…However, these values for f py come with a testable prediction. That is, that the isotopic composition of the sulfur input to the oceans δ in was much more depleted in 34 S than previously assumed, as shown in Fig. 2.…”

Section: Modeling From Metastratigraphic Datamentioning

confidence: 72%

“…When sulfate is particularly abundant, the organic sulfur is up to 40% depleted in 34 S compared with the sulfate, and this depletion is reduced as the sulfate becomes more limiting. These peats clearly show the influence of microbial sulfate reduction in supplying 34 S-depleted sulfide to the peat, and they also demonstrate that organic sulfur is enriched into the peat during early diagenesis (18,19,23). Similarly, for high-sulfate bogs from the western British Isles with a clear marine influence, Sphagnum moss is some 5-10 per mil depleted in 34 S compared with the isotopic composition of the rain supplying the sulfate to these sites (24).…”

Section: Isotopic Composition Of Sulfur In Coal Precursorsmentioning

confidence: 79%

“…There are also some indications for more 34 S-enriched coals, and thus more 34 S-enriched surface waters in the range of 11-12 per mil, during the Jurassic and Triassic periods (145-250 Ma). From a modeling perspective, this would generate lower values for f py (Fig.…”

Section: Isotopic Composition Of Coal Through Timementioning

confidence: 96%

“…The logic is as follows: Coal is composed of degraded and thermally matured aquatic plant material. If sulfate is limiting during plant growth, as is typical in terrestrial environments, then the sulfur in the growing plants is assimilated with an isotopic composition of only about 1.5 per mil depleted in 34 S on average compared with the isotopic composition of the surface waters providing the source sulfate (17). This sulfur is delivered further into the peats forming from the plants, and ultimately into the coal itself (18).…”

Section: Isotopic Composition Of Sulfur In Coal Precursorsmentioning

confidence: 99%

“…In this case, microbial sulfate reduction can supply 34 S-depleted sulfide to the peat. Enrichments in 34 S in peat sulfur are also possible. This is believed to occur during the late stages of sulfate reduction when sulfate is nearly depleted and the 34 S of the sulfide produced may also be 34 S-enriched (e.g., ref.…”

Section: Isotopic Composition Of Sulfur In Coal Precursorsmentioning

confidence: 99%

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Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle

Canfield

2013

Proc. Natl. Acad. Sci. U.S.A.

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Sulfate is the second most abundant anion (behind chloride) in modern seawater, and its cycling is intimately coupled to the cycling of organic matter and oxygen at the Earth's surface. For example, the reduction of sulfide by microbes oxidizes vast amounts of organic carbon and the subsequent reaction of sulfide with iron produces pyrite whose burial in sediments is an important oxygen source to the atmosphere. The concentrations of seawater sulfate and the operation of sulfur cycle have experienced dynamic changes through Earth's history, and our understanding of this history is based mainly on interpretations of the isotope record of seawater sulfates and sedimentary pyrites. The isotope record, however, does not give a complete picture of the ancient sulfur cycle. This is because, in standard isotope mass balance models, there are more variables than constraints. Typically, in interpretations of the isotope record and in the absence of better information, one assumes that the isotopic composition of the input sulfate to the oceans has remained constant through time. It is argued here that this assumption has a constraint over the last 390 Ma from the isotopic composition of sulfur in coal. Indeed, these compositions do not deviate substantially from the modern surface-water input to the oceans. When applied to mass balance models, these results support previous interpretations of sulfur cycle operation and counter recent suggestions that sulfate has been a minor player in sulfur cycling through the Phanerozoic Eon.

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Section: Modeling From Metastratigraphic Datamentioning

confidence: 72%

Section: Isotopic Composition Of Sulfur In Coal Precursorsmentioning

confidence: 79%

Section: Isotopic Composition Of Coal Through Timementioning

confidence: 96%

Section: Isotopic Composition Of Sulfur In Coal Precursorsmentioning

confidence: 99%

Section: Isotopic Composition Of Sulfur In Coal Precursorsmentioning

confidence: 99%

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Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle

Canfield

2013

Proc. Natl. Acad. Sci. U.S.A.

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Changing tectonic controls on the long‐term carbon cycle from Mesozoic to present

Mills

Daines

Lenton

2014

Geochem Geophys Geosyst

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Tectonic drivers of degassing and weathering processes are key long-term controls on atmospheric CO 2 . However, there is considerable debate over the changing relative importance of different carbon sources and sinks. Existing geochemical models have tended to rely on indirect methods to derive tectonic drivers, such as inversion of the seawater 87 Sr/ 86 Sr curve to estimate uplift or continental basalt area. Here we use improving geologic data to update the representation of tectonic drivers in the COPSE biogeochemical model. The resulting model distinguishes CO 2 sinks from terrestrial granite weathering, total basalt weathering, and seafloor alteration. It also distinguishes CO 2 sources from subduction zone metamorphism and from igneous intrusions. We reconstruct terrestrial basaltic area from data on the extent of large igneous provinces and use their volume to estimate their contribution to degassing. We adopt a recently published reconstruction of subduction-related degassing, and relate seafloor weathering to ocean crust creation rate. Revised degassing alone tends to produce unrealistically high CO 2 , but this is counteracted by the inclusion of seafloor alteration and global basalt weathering, producing a good overall fit to Mesozoic-Cenozoic proxy CO 2 estimates and a good fit to 87 Sr/ 86 Sr data. The model predicts that seafloor alteration and terrestrial weathering made similar contributions to CO 2 removal through the Triassic and Jurassic, after which terrestrial weathering increased and seafloor weathering declined. We predict that basalts made a greater contribution to silicate weathering than granites through the Mesozoic, before the contribution of basalt weathering declined over the Cenozoic due to decreasing global basaltic area.

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Biogeochemical sulfur cycling during Cretaceous oceanic anoxic events: A comparison of OAE1a and OAE2

2016

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Biogeochemical sulfur cycling has varied widely over geologic time, mainly in response to changes in primary productivity and organic carbon burial, volcanism, weathering, and evaporite deposition. Several of these processes are explicitly linked to discreet (<1.2 Ma) intervals of widespread organic carbon burial, termed oceanic anoxic events (OAEs). During the Cretaceous, there is a highly distinctive ~4‰ negative excursion in the sulfur isotope composition of seawater sulfate (δ34SSO4) that is bracketed by the two most prominent OAEs (OAE1a and OAE2). This excursion lasted for ~25 Ma and has been variously attributed to enhanced volcanism, changes in weathering, evaporite burial, and/or changes in modes of organic carbon remineralization. We present new high‐resolution carbon and sulfur isotope records from carbonate‐associated sulfate and pyrite for OAE1a and OAE2. OAE1a is characterized by a monotonic decrease in δ34SSO4 values. Both negative and positive δ34SSO4 excursions are associated with OAE2. To refine hypotheses for the observed changes in biogeochemical sulfur cycling associated with these events, we use a simple sulfur isotope box model. Both empirical and modeling results indicate that δ34SSO4 variability was dominated by input fluxes during OAE1a, whereas enhanced volcanism, weathering, and pyrite burial controlled δ34SSO4 records during OAE2. Our analysis supports the conclusion that Cretaceous marine sulfate concentrations were much lower than modern concentrations and indicates that increases in marine sulfate occurred at the onset of both events. We conclude that increases in marine sulfate from low background concentrations, in conjunction with other environmental characteristics, contributed to the development of OAEs.

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Evaporites and the salinity of the ocean during the Phanerozoic: Implications for climate, ocean circulation and life

Cited by 226 publications

References 48 publications

Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle

Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle

Changing tectonic controls on the long‐term carbon cycle from Mesozoic to present

Biogeochemical sulfur cycling during Cretaceous oceanic anoxic events: A comparison of OAE1a and OAE2

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