DOI: 10.1016/j.epsl.2019.115949
论文题名: The seawater Sr/Ca ratio in the past 50 Myr from bulk carbonate sediments corrected for diagenesis
作者: Zhang S. ; Zhou R. ; DePaolo D.J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 530 语种: 英语
中文关键词: carbonate diagenesis
; marine sediments
; Ocean Drilling Program
; seawater Sr/Ca
英文关键词: Calcite
; Carbonate minerals
; Carbonation
; Deposition
; Diffusion in liquids
; Infill drilling
; Oceanography
; Seawater
; Sedimentology
; Sediments
; Submarine geology
; Sulfur compounds
; Weathering
; Carbonate deposition
; Effective partition coefficients
; Marine sediments
; Ocean drilling programs
; Pore fluid chemistry
; Reactive transport modeling
; Sediment measurements
; Sulfate concentrations
; Strontium compounds
; calcium
; carbonate sediment
; Cenozoic
; chemical oceanography
; concentration (composition)
; diagenesis
; error correction
; isotopic ratio
; marine sediment
; Ocean Drilling Program
; paleoceanography
; reaction kinetics
; reactive transport
; reconstruction
; seafloor
; seawater
; strontium isotope
; Ontong Java Plateau
; Pacific Ocean
; Anthozoa
; Foraminifera
英文摘要: The strontium/calcium (Sr/Ca) ratio in paleoseawater is important for evaluating the global fluxes of continental weathering products and carbonate deposition in the oceans. Existing reconstructions of the paleoseawater Sr/Ca ratio using different methods give conflicting results. We use a modeling approach to estimate paleo-Sr/Ca for the past 50 million years that uses pore fluid chemistry and bulk sediment measurements of carbonate ooze and chalk from the Ontong Java Plateau as input. The effects of diagenesis in modifying the Sr/Ca ratio recorded in bulk carbonate sediments are estimated using a reactive transport model, and those effects are accounted for in determining the initial Sr/Ca ratio of the biogenic carbonate sediments. The Sr/Ca of the paleo-oceans is calculated based on an effective partition coefficient (KSr bio=0.198) inferred from Sr/Ca in modern sediments. The model simulates deposition of sediments on the seafloor, reactions between pore fluid and solid (dissolution and precipitation of calcite), and diffusion within the pore fluid. Measured pore fluid Sr, Ca and sulfate concentrations provide input for the Sr model. This approach, applied to four Ocean Drilling Program (ODP) sites (803, 805, 806, 807) that have long Cenozoic records of carbonate deposition, indicates that the Sr/Ca ratio of seawater has increased slowly over the past 50 million years from a value of about 8 mmol/mol to the modern value of 9.4, with fluctuations of about ±1 over 10 Myr periods. This result is consistent with previous estimates based on foraminifera and coral aragonite, but differs from recent estimates obtained with other approaches. The near-constant seawater Sr/Ca over the past 50 million years is consistent with likely weathering sources to the oceans. The fluctuations suggest that there were modest shifts in the aragonite/calcite ratio of marine carbonate. © 2019 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165382
Appears in Collections: 气候变化与战略
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作者单位: State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing100084, China; Department of Geography and Geology, Sam Houston State University, 1905 University Avenue, Huntsville, TX 77340, United States; Energy Geosciences Division, Lawrence Berkeley National Laboratory, United States
Recommended Citation:
Zhang S.,Zhou R.,DePaolo D.J.. The seawater Sr/Ca ratio in the past 50 Myr from bulk carbonate sediments corrected for diagenesis[J]. Earth and Planetary Science Letters,2020-01-01,530