Episodes of volcanic activity and their environmental effects in the Okinawa Trough during the last 150 ka

摘要: A piston core Z14-6 was used in this study. The core, 896 cm long, collected from eastern slope of the Okinawa Trough (27°07′N, 127°27′E, water depth 739m). δ18O and δ13C values sediment bearing planktonic foraminiferaG. sacculifer andN. dutertrei were determined; abundance volcanic glass analyzed. content high occurred early stage polar ice-sheet growth period, or beginning cold climate periods corresponding to Milankovitch cycles (Peak I, II V are beginnings oxygen isotopic stages 2, 4 6, Peak III IV matching 5b–5d.). It might be possible that episodes changes responding orbital forcing late Quaternary. difference betweenN. andG. shows no clear correlation high, which suggests eruptions did not influence structure upper column. However, low betweenG. is coeval with sub-high content. This fact reduction vertical nutritional gradient carbon cycle process mechanism huge quantity ash dust had weakened light intensity, resulting photosynthesis reduction, productivity decrease, biological pumping.