Dehydroxylation and diagenetic variations in diatom oxygen isotope values
نویسندگان
چکیده
منابع مشابه
Triple oxygen isotope variations in sedimentary rocks
Relatively large (P0.2&) O anomalies in the geologic record have been used to recognize atmospheric processes such as photochemical reactions and to trace changes in the partial pressures of O2 and CO2 in Earth’s atmosphere through time. However, recent oxygen isotope measurements of terrestrial rocks, minerals and waters also reveal common, smaller (but statistically significant) deviations fr...
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RATIONALE Potential post-mortem alteration to the oxygen isotope composition of biogenic silica is critical to the validity of palaeoclimate reconstructions based on oxygen isotope ratios (δ18 O values) from sedimentary silica. We calculate the degree of oxygen isotope alteration within freshly cultured diatom biogenic silica in response to heating and storing in the laboratory. METHODS The e...
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Direct measurements of snow accumulation at stakes near the South Pole over a 6-year period (1958-1963) provide an unusual opportunity to check the reliability of accumulation and annual-layer determinations by stratigraphic and isotopic methods. The results are gratifying. Agreement between interpretations based on stratigraphic and isotopic data is excellent, and both are consistent with accu...
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This chapter summarizes the oxygen isotope geochemistry of terrestrial basalts and their mantle sources, including the conceptual framework for interpreting such data and the phenomenology of known variations. In particular, the first section outlines the motivations for and first-order results of oxygen isotope studies of terrestrial and lunar basalts over the last 30 years; the second section...
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RATIONALE Current studies which use the oxygen isotope composition from diatom silica (δ(18) Odiatom ) as a palaeoclimate proxy assume that the δ(18) Odiatom value reflects the isotopic composition of the water in which the diatom formed. However, diatoms dissolve post mortem, preferentially losing less silicified structures in the water column and during/after burial into sediments. The impact...
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ژورنال
عنوان ژورنال: Geochimica et Cosmochimica Acta
سال: 2017
ISSN: 0016-7037
DOI: 10.1016/j.gca.2016.11.034