Abstract:

In the paper the histroy of spreading of Darke Passage and its effects on Antarctic circumpolar current are discussed basing on the geophysical data obtained during first Chinese Antarctic Expedition. The spreading direction of Drake Passage is NW-SE. The spreading process could be distinguished into three stages: first stage was in 28-24 Ma B.P., the second in 24-16 Ma B.P. and the third in 16-8 Ma B.P. The spreading rates are 2.5cm/a, 1.8cm/a, and 1.0 cm / a repectively. The West Antarctica was separated form the South America by the spreading of Drade Passage. It is the last important geological event in Gondwanaland fragmertation. The Antarctic circumpolar current was formed in 24 Ma B.P. The development of the current was restrited by Shackleton Fault Zone. The current prevents warm current from Equator. Thus, it is the main cause for that the temperature of Antarctic continent became very cold.