979 resultados para N stable isotopes
Resumo:
Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.
Resumo:
Downcore records of magnesium/calcium, strontium/calcium, manganese/calcium, and oxygen and carbon isotopes of planktonic and benthic foraminifers from Ocean Drilling Program (ODP) Site 1237 on the Peru-Chile margin provide critical information regarding the history of climate in the region over the past 6 m.y. Specifically, these records can be used to infer the sea-surface temperature (SST) and sea-surface salinity (SSS) history of a region that today is associated with substantial wind stress curl-driven upwelling (Shipboard Scientific Party, 2003, doi:10.2973/odp.proc.ir.202.108.2003). This report provides data tables and other supporting information for measurements made on planktonic and benthic foraminifers from Site 1237. Items included in this report are (1) oxygen and carbon isotopic measurements of planktonic and benthic foraminifers and (2) Mg/Ca, Sr/Ca, and Mn/Ca ratio measurements of planktonic foraminifers from Holes 1237B, 1237C, and 1237D.