Evidencias, causas y patrones de los eventos de extinción en el Cretácico Superior y Terciario Inferior con foraminíferos

Resumen

Three major foraminifera extinction events at the Cretaceous/Tertiary boundary, Paleocene/Eocene boundary and Eocene-OIigocene transition reveal different patterns o f extinction, whichimply different causes. The sudden catastrophic mass extinction pattern o f 70% o f the plankticforaminifera species at the end o f the Cretaceous is very compatible with the catastrophic effecto f an asteroid impact, which generated global cooling (impact winter). The extinction o f morethan 50 % o f the small bathyal and abyssal benthic foraminifera at the end o f the Paleocene isvery consistent with intensive volcanism and changes in oceanic water circulation, generating agreenhouse effect, global warming, deep sea anoxia and rapid eustatic sea-level rise. Thegradual extinction o f more than 50% o f planktic foraminifera during the Eocene-OI igocenetransition is compatible with the plate tectonic movement that produced the isolation o f Antarctica,generating the development o f a circum-Antarctic circulation, global cooling, growth o f icesheet and thermohaline circulation