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DOI	10.1016/j.epsl.2019.115949
	The seawater Sr/Ca ratio in the past 50 Myr from bulk carbonate sediments corrected for diagenesis
	Zhang S.; Zhou R.; DePaolo D.J.
发表日期	2020
ISSN	0012821X
卷号	530
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.
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
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203004
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
推荐引用方式 GB/T 7714	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],2020,530.
APA	Zhang S.,Zhou R.,&DePaolo D.J..(2020).The seawater Sr/Ca ratio in the past 50 Myr from bulk carbonate sediments corrected for diagenesis.Earth and Planetary Science Letters,530.
MLA	Zhang S.,et al."The seawater Sr/Ca ratio in the past 50 Myr from bulk carbonate sediments corrected for diagenesis".Earth and Planetary Science Letters 530(2020).