Delayed climate cooling in the Late Eocene caused by multiple impacts: high-resolution geochemical studies at Massignano, Italy

摘要: Abstract High-resolution studies (δ13C, δ18O, and elemental abundances) were done in rocks at below the GSSP for Eocene/Oligocene (E/O) boundary Massignano, Italy. In addition to an earlier known Ir anomaly 5.61 m, which is possibly linked Popigai impact event, we confirm presence of two additional anomalies intervals from 6.00 6.40 m 10.00 10.50 with maximum values 259±32 ppt 6.17 149±24 10.28 respectively. The lower might be derived Chesapeake Bay whereas other one no event known. Similar δ13C δ18O trends related indicate that also into a continental shelf, similar event. decrease high layers −1.16‰ −1.17‰, respectively, which, together negative shifts Ir-rich levels, warm pulse superimposed on general Late Eocene cooling trend characterized by ranging between −0.6‰ −0.4‰. release methane hydrate after shelf or seafloor, impacts 12C-rich comets during 2.2-million-year-long comet shower, could produce these more carbon oxygen excursions compared continuously decreasing over whole Massignano section.