[Ca2+] and [SO2- 4] in Phanerozoic and terminal Proterozoic seawater from fluid inclusions in halite: the significance of Ca-SO4 crossover points

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dc.contributor.authorWeldeghebrial, MFen_AU
dc.contributor.authorLowenstein, TKen_AU
dc.contributor.authorGarcía-Veigas, Jen_AU
dc.contributor.authorCendón, DIen_AU
dc.date.accessioned2022-09-04T22:05:15Zen_AU
dc.date.available2022-09-04T22:05:15Zen_AU
dc.date.issued2022-09-15en_AU
dc.date.statistics2022-09-02en_AU
dc.descriptionThis research was supported by graduate student research grant funds from the: Society of Economic Geologists Foundation (2018), American Association of Petroleum Geologists Foundation (2018), and the Mineralogy, Geochemistry, Petrology, Volcanology (MGPV) Division of the Geological Society of America (2019) to MFW. Addi-tional funds came from the Binghamton University Mileur Faculty Development Grant to TKL. The Binghamton University LA-ICP-MS system was purchased using National Science Foundation (NSF) grant EAR-1463936. We thank V. M. Kovalevych, T. M. Peryt, and Juske Horita for providing samples and David Collins for LA-ICP-MS support. We thank Laurence Coogan and two anonymous review-ers for the careful review of the manuscript and comments that helped improve the paper.en_AU
dc.description.abstractChemical analyses of 2,618 (1,640 new and 978 published) fluid inclusions in marine halite were used to define paleoseawater [Ca2+] and [SO2- 4] over the past 550 million years (Myr). Three types of fluid inclusion brine chemistries were recognized based on measured [Ca2+] and [SO2- 4]: (1) SO4-rich with [SO2- 4] ≫ [Ca2+]; (2) Ca-rich with [Ca2+] ≫ [SO2- 4]; and (3) Ca-SO4 crossover points with [Ca2+] ≈ [SO2- 4]. The SO4-rich and Ca-rich fluid inclusion chemistries oscillated twice in the terminal Proterozoic and Phanerozoic. Transitions between SO4-rich and Ca-rich seas, here called "Ca2+ -SO2- 4 crossover points” occurred four times: terminal Proterozoic–Early Cambrian (544–515 Ma), Late Pennsylvanian (309–305 Ma), Triassic–Jurassic boundary (∼200 Ma), and Eocene–Oligocene (36–34 Ma). New fluid inclusion analyses using laser ablation-inductively coupled plasma-mass spectrometry better defined the [Ca2+] and [SO2- 4] in seawater at the Late Pennsylvanian and Eocene–Oligocene crossover points and the timing of the Triassic–Jurassic crossover point. Crossover points coincide with shifts in seawater Mg2+/Ca2+ ratios, the mineralogies of marine non-skeletal carbonates and shell building organisms (aragonite vs. calcite) and potash evaporites (MgSO4 vs. KCl types). Phanerozoic and terminal Proterozoic trends in seawater [Ca2+] and [SO2- 4] also coincide with supercontinent breakup, dispersal, and assembly cycles, greenhouse–icehouse climates, and modeled atmospheric ρCO2. Paleoseawater [Ca2+] and [SO2- 4] were calculated from the fluid inclusion data using the assumption that the [Ca2+] × [SO2- 4] ranged from 150 to 450 mmolal2, which is 0.5–1.5 times the [Ca2+] = 11 × [SO2- 4] = 29 product in modern seawater (319 mmolal2). Two additional end-member scenarios, independent of the [Ca2+] × [SO2- 4] = 150–450 mmolal2 assumption, were tested using constraints from fluid inclusion [Ca] and [SO4]: (1) constant [SO2- 4] = 29 mmolal as in modern seawater, and variable [Ca2+], and (2) constant [Ca2+] = 11 mmolal as in modern seawater and variable [SO2- 4]. Mg2+/Ca2+ ratios calculated from the three scenarios were compared to independent data on the Mg2+/Ca2+ ratios from skeletal carbonates (echinoderms and corals) and mid-ocean ridge flank calcite veins. Constant [Ca2+] of 11 mmolal is unlikely because this relatively low concentration generated unreasonably low seawater [SO2- 4] during most of the past 550 Myr and high Mg2+/Ca2+ ratios compared to independent data. Constant [SO2- 4] of 29 mmolal produced unreasonably high seawater [Ca2+] and lower Mg2+/Ca2+ ratios than those derived from fluid inclusions, echinoderms, corals, and calcite veins. Variable [Ca2+] and [SO2- 4] showed the best agreement with the Mg2+/Ca2+ ratios derived from fluid inclusions, echinoderms, corals, and calcite veins. © 2022 Elsevier B.V.en_AU
dc.description.sponsorshipThis research was supported by graduate student research grant funds from the: Society of Economic Geologists Foundation (2018), American Association of Petroleum Geologists Foundation (2018), and the Mineralogy, Geochemistry, Petrology, Volcanology (MGPV) Division of the Geological Society of America (2019) to MFW. Additional funds came from the Binghamton University Mileur Faculty Development Grant to TKL. The Binghamton University LA-ICP-MS system was purchased using National Science Foundation (NSF) grant EAR-1463936.en_AU
dc.identifier.articlenumber117712en_AU
dc.identifier.citationWeldeghebriel, M. F., Lowenstein, T. K., García-Veigas, J., & Cendón, D. I. (2022). [Ca2+] and [SO2− 4] in Phanerozoic and terminal Proterozoic seawater from fluid inclusions in halite: The significance of Ca-SO4 crossover points. Earth and Planetary Science Letters, 594, 117712. doi:10.1016/j.epsl.2022.117712en_AU
dc.identifier.issn0012-821Xen_AU
dc.identifier.journaltitleEarth and Planetary Science Lettersen_AU
dc.identifier.urihttps://doi.org/10.1016/j.epsl.2022.117712en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/13734en_AU
dc.identifier.volume594en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectSeawateren_AU
dc.subjectWater chemistryen_AU
dc.subjectHaliteen_AU
dc.subjectCalciumen_AU
dc.subjectSulfuren_AU
dc.subjectAragoniteen_AU
dc.subjectCalciteen_AU
dc.title[Ca2+] and [SO2- 4] in Phanerozoic and terminal Proterozoic seawater from fluid inclusions in halite: the significance of Ca-SO4 crossover pointsen_AU
dc.typeJournal Articleen_AU
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