Cenozoic boron isotope variations in benthic foraminifers

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• journal_title：Geology
• Contributor：Markus Raitzsch ; Bärbel Hönisch
• Publisher：Geological Society of America
• Date：2013-05-01
• Format：text/html
• Language：en
• Identifier：10.1130/G34031.1
• journal_abbrev：Geology
• issn：0091-7613
• volume：41
• issue：5
• firstpage：591
• section：Articles

摘要

<p id="p-2">The boron isotopic composition of seawater (δp>11p>B_sw) is a prerequisite for reliably estimating past variation of seawater pH from boron isotopes in marine carbonates (δp>11p>B_c). Here we compose a 50 m.y. stack of δp>11p>B_c from Atlantic and Pacific Ocean deep-sea sediments, and discuss the potential effects of deep-sea pH and δp>11p>B_sw on our record. Using model-based Cenozoic pH values, the inferred δp>11p>B_sw values suggest an ∼3‰ increase since the Late Eocene, superimposed on oscillating variations with amplitudes of up to 2‰. Our estimates match existing reconstructions of δp>11p>B_sw, but call into question published fluid δp>11p>B in halite as a recorder of δp>11p>B_sw. p>