The major-ion composition of silurian seawater

Brennan, Sean T.; Lowenstein, Tim

doi:10.1016/s0016-7037(02)00870-0

Cited by 98 publications

(65 citation statements)

References 34 publications

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“…One can see from the trends with age that seawater concentrations of Mg, Ca, and SO 4 have varied considerably during Phanerozoic time . Other more recent estimates by Brennan and Lowenstein (2002) Mg and SO 4 . The inverse behaviour of Mg and Ca has resulted in major changes in the dissolved Mg/Ca and SO 4 /Ca ratios of seawater during the Phanerozoic Eon .…”

Section: Evaporite Deposits and Fluid Inclusionsmentioning

confidence: 88%

The Marine Carbon System and Ocean Acidification during Phanerozoic Time

Mackenzie¹,

Andersson²

2013

geochempersp

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Section: Evaporite Deposits and Fluid Inclusionsmentioning

confidence: 88%

The Marine Carbon System and Ocean Acidification during Phanerozoic Time

Mackenzie¹,

Andersson²

2013

geochempersp

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“…Hardie's oceanic Mg/Ca model is further supported by synchronized transitions between MgSO 4 and KCl evaporites (Hardie, 1996), fluid inclusion data (Lowenstein et al, J. B. Ries: Effects of secular variation in seawater Mg/Ca on marine biocalcification 2837 , 2005Brennan and Lowenstein, 2002;Brennan, 2002;Horita et al, 2002;Brennan et al, 2004;Timofeeff et al, 2006), secular variation in the skeletal Mg/Ca ratio of rugose corals (Webb and Sorauf, 2002), echinoderms (Dickson, 2002(Dickson, , 2004Hasiuk and Lohmann, 2008), and abiogenic carbonates (Hasiuk and Lohmann, 2008); secular variation in the ratio of aragonite-to-calcite within bi-mineralic calcareous serpulid worm tubes (Railsback, 1993); secular variation in the Sr/Mg ratio of abiogenic marine carbonates (Cicero and Lohmann, 2001); the occurrence of higher seawater Sr/Ca ratios during predicted calcite sea intervals than during predicted aragonite sea intervals (Sr would be depleted in seawater during aragonite sea intervals because Sr is more readily incorporated in aragonite than in calcite; Steuber and Veizer, 2002); and secular variation in the Br concentration of marine halite (Siemann, 2003).…”

Section: Insight Into the Composition Of Organisms' Calcifying Fluidsmentioning

confidence: 91%

“…Phanerozoic (solid curve; Hardie, 1996;Demicco et al, 2005) and Precambrian (dashed curve; seawater Mg/Ca is calculated from hydrothermal brine-river water mixing models driven by rates of ocean crust production (Gaffin, 1987) and granite pluton data (Engel and Engel, 1970), respectively. Open circles correspond to Mg/Ca sw estimated from fluid inclusions in primary marine halite (Lowenstein et al, 2001Brennan and Lowenstein, 2002;Brennan, 2002;Horita et al, 2002;Brennan et al, 2004;Timofeeff et al, 2006). Horizontal line divides the calcite (Mg/Ca sw < 2) and aragonite -high Mg calcite (Mg/Ca sw > 2) nucleation fields in seawater at 25 • C (Leitmeier, 1910(Leitmeier, , 1915Lippman, 1960;Müller et al, 1972;Berner, 1975;Given and Wilkinson, 1985;Stanley and Hardie, 1999).…”

Section: Effect Of Mg/ca Sw On Polymorph Mineralogy and Mg Content Ofmentioning

confidence: 99%

“…Curve is molar Mg/Ca ratio of seawater (Hardie, 1996;Demicco et al, 2005) estimated using a mid-ocean ridge hydrothermal flux/river water mixing model driven by global rates of ocean crust production. Closed circles correspond to seawater Mg/Ca ratios estimated from fluid inclusions in primary marine halite (Lowenstein et al, 2001Brennan, 2002;Horita et al, 2002;Brennan and Lowenstein, 2002;Brennan et al, 2004;Timofeeff et al, 2006). Open circles are seawater Mg/Ca ranges estimated from the Mg content of fossil echinoids [recalculated from Dickson (2002) by Ries (2004) using available paleotemperature data and a nonlinear, empirically-derived Mg-fractionation algorithm].…”

Section: Introductionmentioning

confidence: 99%

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Review: geological and experimental evidence for secular variation in seawater Mg/Ca (calcite-aragonite seas) and its effects on marine biological calcification

Ries¹

2010

Biogeosciences

219

170

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Abstract. Synchronized transitions in the polymorph mineralogy of the major reef-building and sediment-producing calcareous marine organisms and abiotic CaCO 3 precipitates (ooids, marine cements) throughout Phanerozoic time are believed to have been caused by tectonically induced variations in the Mg/Ca ratio of seawater (molar Mg/Ca>2="aragonite seas", <2="calcite seas"). Here, I assess the geological evidence in support of secular variation in seawater Mg/Ca and its effects on marine calcifiers, and review a series of recent experiments that investigate the effects of seawater Mg/Ca (1.0-5.2) on extant representatives of calcifying taxa that have experienced variations in this ionic ratio of seawater throughout the geologic past.Secular variation in seawater Mg/Ca is supported by synchronized secular variations in (1) the ionic composition of fluid inclusions in primary marine halite, (2) the mineralogies of late stage marine evaporites, abiogenic carbonates, and reef-and sediment-forming marine calcifiers, (3) the Mg/Ca ratios of fossil echinoderms, molluscs, rugose corals, and abiogenic carbonates, (4) global rates of tectonism that drive the exchange of Mg 2+ and Ca 2+ along zones of ocean crust production, and (5) additional proxies of seawater Mg/Ca including Sr/Mg ratios of abiogenic carbonates, Sr/Ca ratios of biogenic carbonates, and Br concentrations in marine halite.Laboratory experiments have revealed that aragonitesecreting bryopsidalean algae and scleractinian corals and calcite-secreting coccolithophores exhibit higher rates of calcification and growth in experimental seawaters formulated with seawater Mg/Ca ratios that favor their skeletal mineral. These results support the assertion that seawater Mg/CaCorrespondence to: J. B. Ries (jries@unc.edu) played an important role in determining which hypercalcifying marine organisms were the major reef-builders and sediment-producers throughout Earth history. The observation that primary production increased along with calcification within the bryopsidalean and coccolithophorid algae in mineralogically favorable seawater is consistent with the hypothesis that calcification promotes photosynthesis within some species of these algae through the liberation of CO 2 .The experiments also revealed that aragonite-secreting bryopsidalean algae and scleractinian corals, and bacterial biofilms that secrete a mixture of aragonite and high Mg calcite, began secreting an increased proportion of their calcium carbonate as the calcite polymorph in the lower-Mg/Ca experimental seawaters. Furthermore, the Mg/Ca ratio of calcite secreted by the coccolithophores, coralline red algae, reef-dwelling animals (crustacea, urchins, calcareous tube worms), bacterial biofilms, scleractinian corals, and bryopsidalean algae declined with reductions in seawater Mg/Ca. Notably, Mg fractionation in autotrophic organisms was more strongly influenced by changes in seawater Mg/Ca than in heterotrophic organisms, a probable consequence of autotrophic organisms inducing a less controlled ...

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“…Such changes in seawater chemistry controlled the type and the order of potash minerals (Warren, 2006), with two potash endmembers, (1) calcium chloride and (2) Mg-sulphate brines. According to Brennan and Lowenstein (2002) and Lowenstein et al (2003), the seawater in the Early Cretaceous had a CaCl 2 -rich composition, which does not precipitate the MgSO 4 potash salts, but rather the sylvite, carnaillite, bishofite and tachyhydrite potash salts (Warren, 2006). This water chemistry has probably favored the presence of these evaporites in the Central segment, and may explain the absence of MgSO 4 salts.…”

Section: Climmentioning

confidence: 97%

The Aptian evaporites of the South Atlantic: a climatic paradox?

et al. 2012

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Abstract. For a long time, evaporitic sequences have been interpreted as indicative of an arid climate. Such systematic interpretations led to the suggestion that the Central segment of the South Atlantic (20-0 • ) was characterized by an arid climate during the upper Aptian. Indeed, synchronous to this period that corresponds to the rifting and to the opening of this part of the South Atlantic, a large evaporitic sequence spreads out from the equator to 20 • S. Using the fully ocean atmosphere coupled model FOAM, we test the potential for the Aptian geography to produce an arid area over the Central segment. Sensitivity to the altitude of the rift shoulders separating the Africa and the South America cratons, to the water depth of the Central segment and to the drainage pattern have been performed. Using seawater salinity as a diagnostic, our simulations show that the southern part of the Central segment is characterized by very high salinity in the case of catchment areas draining the water out of the Central segment. Conversely, whatever the boundary conditions used, the northern part of the Central segment remains humid and salinities are very low. Hence, we conclude that the evaporites deposited in the southern part of the Central segment may have been controlled by the climate favouring aridity and high saline waters. In contrast, the evaporites of the northern part can hardly be reconciled with the climatic conditions occurring there and may be due to hydrothermal sources. Our interpretations are in agreement with the gradient found in the mineralogical compositions of the evaporites from the North to the South, i.e. the northern evaporites are at least 4 times more concentrated than the southern one.

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The major-ion composition of silurian seawater

Cited by 98 publications

References 34 publications

The Marine Carbon System and Ocean Acidification during Phanerozoic Time

The Marine Carbon System and Ocean Acidification during Phanerozoic Time

Review: geological and experimental evidence for secular variation in seawater Mg/Ca (calcite-aragonite seas) and its effects on marine biological calcification

The Aptian evaporites of the South Atlantic: a climatic paradox?

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