东海DC-1,DC-2孔古地磁研究

STUDY ON PALEOMAGNETISM OF CORES DC-1 AND DC-2 FROM EAST CHINA SEA

本文报道了东海DC-1,DC-2孔古地磁研究结果,表明DC-l孔26.9m岩芯及DC-2孔61.0m岩芯段均以正极性为主,属布容正极性世 (Brunhcs)。其中DC-l孔18.86-19.18m的反向磁化带(倾角为—49.29°),经^(14)C测年为距今115lO土570a;DC-2孔29.95—30.54m处反向磁化带(倾角为—40.5°),经^(14)C测年为距今10250±lOOa。可与哥德堡事件(Gǒthcnburg)对比。对比地磁年表,DC-2孔37.80—38.0m为反极性事件与蒙哥事件(Mungo event)相当,7l.20—74.44m划为布莱克事件(B1akc event)。据此计算全新世沉积速率为2.12—2.84m/1000a,晚更新世沉积速率为O.65一O.69m/1000a。

Measurement shows that the normal polarity appears above the depth of 26.90m in Core DC-1 and 61.00m in Core DC-2 belonging to 'Brunhes' normal epoch. There is reversal excursion (inclination:-49.2°) occurred at 18.86-19.80m depth in Core DC-1 14C dating aga is 11510±570a B. P. The other reversal excursion (inclination: -40.5°) occurred at 29.95-30.54m depth in Core DC-2. 14C dating aga is 10250±100a B. P. They are both relative to the 'Gothenburg event'. According to the paleomagnetic time scale, the reversal events occurred at 37.80-38.00m depth in Core DC-2 belonging to 'Mungo event' and at 71.20-74.44m depth belonging to 'Blake event'. The average deposit rate was calculated as follows: 2.12-2 88m/1000a in Holocene and 0.65-0.69m/1000a in the late Pleistocene.