Collaborative Research: Role of the Central Scotia Sea Floor and North Scotia Ridge in the Onset and Development of the Antarctic Circumpolar Current

学术价值：火地岛以南的德雷克海峡和西斯科舍海的开通，打破了一个完整的南极环极流（ACC）开始的最后大陆屏障。在33-34 Ma期间，ACC的开始与全球气温的急剧下降和南极冰盖的迅速扩张有关。导致德雷克通道形成的事件鲜为人知。了解中斯科舍海（CSS）和北斯科舍海脊（North Scotia Ridge）海底的构造演化是实现这一认识的关键。先前的研究表明，重叠的构造形成了一个火山弧，可能阻挡了从太平洋到大西洋的直接向东流动，通过开放的德雷克海峡门户，就像今天活跃的南桑威奇弧一样。pi提议进行一次巡航，以进一步有针对性地测绘和疏浚他们的CSS构造理论及其对ACC的发生和发展的影响，来测试、发展和完善。此外，他们还提议安装GPS接收器，以测试他们的古地理重建，并确定南乔治亚岛是否作为南美板块的一部分在移动。更广泛的影响：研究生将参与研究的所有阶段。本科生也将作为观察员参与其中。一名社区大学教师将参加这次巡游。pi将有一个网站，上面将有实际海底疏浚工作的图像。教师将通过PolarTREC提供网络和外展支持。古海洋学家、古气候建模者和古生物地理学家对这次航行的结果有广泛的兴趣。

Intellectual Merit: Opening of Drake Passage and the West Scotia Sea south of Tierra del Fuego broke the final continental barrier to onset of a complete Antarctic Circumpolar Current (ACC). Initiation of the ACC has been associated in time with a major, abrupt, drop in global temperatures and the rapid expansion of the Antarctic ice sheets at 33-34 Ma. Events leading to the formation of the Drake Passage gateway are poorly known. Understanding the tectonic evolution of the floor of the Central Scotia Sea (CSS) and the North Scotia Ridge is a key to this understanding. Previous work has demonstrated that superimposed constructs formed a volcanic arc that likely blocked direct eastward flow from the Pacific to the Atlantic through the opening Drake Passage gateway as the active South Sandwich arc does today. The PIs propose a cruise to test, develop and refine, with further targeted mapping and dredging, their theory of CSS tectonics and the influence it had on the onset and development of the ACC. In addition they propose an installation of GPS receiver to test their paleogeographic reconstructions and determine whether South Georgia is moving as part of the South American plate. Broader impacts: A graduate student will be involved in all stages of the research. Undergraduate students will also be involved as watch-standers. A community college teacher will participate in the cruise. The PIs will have a website on which there will be images of the actual ocean floor dredging in operation. The teacher will participate with web and outreach support through PolarTREC. Results of the cruise are of broad interest to paleoceanographers, paleoclimate modelers and paleobiogeographers.