Scher Howie D, Martin Ellen E
Department of Geological Sciences, University of Florida, Gainesville, FL 32611, USA.
Science. 2006 Apr 21;312(5772):428-30. doi: 10.1126/science.1120044.
Age estimates for the opening of Drake Passage range from 49 to 17 million years ago (Ma), complicating interpretations of the relationship between ocean circulation and global cooling. Secular variations of neodymium isotope ratios at Agulhas Ridge (Southern Ocean, Atlantic sector) suggest an influx of shallow Pacific seawater approximately 41 Ma. The timing of this connection and the subsequent deepening of the passage coincide with increased biological productivity and abrupt climate reversals. Circulation/productivity linkages are proposed as a mechanism for declining atmospheric carbon dioxide. These results also indicate that Drake Passage opened before the Tasmanian Gateway, implying the late Eocene establishment of a complete circum-Antarctic pathway.
德雷克海峡开通的年龄估计在4900万至1700万年前，这使得对海洋环流与全球变冷之间关系的解释变得复杂。阿古拉斯海岭（南大洋，大西洋区域）钕同位素比值的长期变化表明，约4100万年前有浅层太平洋海水涌入。这一连接的时间以及随后海峡的加深与生物生产力增加和气候突然逆转相吻合。环流/生产力联系被认为是大气二氧化碳减少的一种机制。这些结果还表明，德雷克海峡在塔斯马尼亚海峡之前开通，这意味着晚始新世建立了完整的环南极通道。
