کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4679332 1634879 2009 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Calibrating Mg/Ca ratios of multiple planktonic foraminiferal species with δ18O-calcification temperatures: Paleothermometry for the upper water column
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
Calibrating Mg/Ca ratios of multiple planktonic foraminiferal species with δ18O-calcification temperatures: Paleothermometry for the upper water column
چکیده انگلیسی

In order to consistently approximate the thermal vertical structure of past upper water columns, Mg/Ca ratios of eight planktonic foraminiferal species with different preferential calcification depths selected from 76 tropical Atlantic and Caribbean sediment-surface samples were calibrated with δ18O-derived calcification temperatures with an overall range of ≈ 8–28 °C. Extending the broad number of species-specific calibrations, which agree well especially with our shallow-dweller calibrations, this study presents new bulk calcite Mg/Ca vs. calcification temperature relationships for shallow-dwelling Globigerinoides ruber pink, thermocline-dwelling Globorotalia menardii, and deep-dwelling Globorotalia truncatulinoides dextral and Globorotalia crassaformis not separately calibrated before. The species-specific temperature sensitivities are relatively similar (≈ 7–11% increase in Mg/Ca per 1 °C), yet y-axis intercepts vary from 0.23–0.65 for the shallow and thermocline dwellers to 0.83–1.32 for the deep dwellers. Based on these differences, we established a ‘warm water’ calibration for temperatures > 19 °C (Mg/Ca = 0.29·exp(0.101·T); r = 0.90; shallow and thermocline dwellers) and a ‘cold water’ calibration for temperatures < 15 °C (Mg/Ca = 0.84·exp(0.083·T); r = 0.85; deep dwellers). These calibrations are offset by ≈ 8 °C. This may be significant for paleotemperature reconstructions, which are afflicted with the problem that similar Mg/Ca offsets are probably characteristic of extinct species used to calculate past temperatures.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 278, Issues 3–4, 25 February 2009, Pages 324–336
نویسندگان
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