کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6438114 | 1638000 | 2015 | 17 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Sulfur isotope fractionation in modern euxinic systems: Implications for paleoenvironmental reconstructions of paired sulfate-sulfide isotope records
ترجمه فارسی عنوان
تجزیه ایزوتوپ های گوگرد در سیستم های مدرن اکسینیک: اثرات تجدید ساختار پالئوی محیطی سوابق ایزوتوپ سولفات سولفید
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
The sulfur (S) isotope difference between sulfates and sulfides preserved in sedimentary rocks (Î34S) has been utilized to reconstruct ancient marine sulfate levels with implications for oxygenation of the Earth surface and biogeochemical cycling. S isotope data from modern, low-sulfate euxinic systems illustrate that preserved Î34S values are positively correlated with sulfate concentration. However, absolute constraints on the range of low-sulfate levels over which preserved Î34S values vary with sulfate concentration remain poorly constrained. Here, we present a compilation of S isotope data for modern euxinic systems demonstrating that preserved Î34S values increase with sulfate concentration at low sulfate levels and approach values that are similar to in situ S isotope fractionation values from microbial sulfate reduction at high sulfate levels. We compare these results to a closed system model of S isotope cycling in a euxinic ocean in order to evaluate when the size of the sulfate reservoir is sufficiently small that Rayleigh fractionation affects the preservation of S isotope signatures. We conclude that the reservoir effect places constraints on Î34S values deposited in euxinic settings at sulfate concentrations <5Â mM. Thus, over this range, Î34S values can be used to evaluate ancient sulfate levels. At higher sulfate levels (>10Â mM), Î34S values are similar to the kinetic isotope fractionation due to microbial sulfate reduction and therefore provide information about biological and environmental controls on sulfate reduction rates and location of pyrite formation. The results of this compilation provide an improved model for the use of Î34S records to evaluate paleoenvironmental conditions in euxinic depositional environments.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geochimica et Cosmochimica Acta - Volume 157, 15 May 2015, Pages 39-55
Journal: Geochimica et Cosmochimica Acta - Volume 157, 15 May 2015, Pages 39-55
نویسندگان
Maya L. Gomes, Matthew T. Hurtgen,