Collaborative Research: Mantle Melting and Crustal Genesis at the Slowest Spreading Rate: A Petrological Investigation of Gakkel Ridge, Arctic Ocean

合作研究：最慢扩散速度下的地幔融化和地壳成因：北冰洋加克尔海脊的岩石学调查

• 批准号: 9912156
• 负责人: David Graham
• 金额: $ 6.74万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9912156&HistoricalAwards=false
• 关键词: Collaborative; Research; Mantle; Melting; Crustal

AbstractOPP-99-11795MichaelOPP-99-12162DickOPP-99-12156GrahamOPP-00-00389LangmuirThe Gakkel Ridge occupies a unique and important place within the global system of ocean ridges because it is: 1) the slowest spreading ridge; 2) the deepest ocean ridge; 3) the sole region where polar mantle compositions can be sampled directly; and 4) in a unique tectonic setting surrounded by continental lithosphere in close proximity. The Ridge's strike is perpendicular to spreading direction which results in very few transform offsets and it appears to be the ridge above the coldest upper mantle. This combination of characteristics permits a large number of hypotheses of ocean crust formation to be tested. The Gakkel Ridge has been unsampled petrologically, largely due the permanent ice cover of the Arctic Ocean that makes geophysical data difficult to obtain. This perennial ice cover over the Ridge will require two icebreakers working in tandem to mount a safe and effective expedition. Recent developments make a sampling expedition possible. The U.S. SCICEX bathymetry, sidescan and gravity data collected from a submarine provide the necessary background data to plan a good sampling program. German colleagues, in response to InterRIDGE planning efforts, have in place ice breaker, Polarstem, for a two-ship, 50-day international expedition dedicated to study of the Gakkel Ridge. The United States will also provide an icebreaker, the new USCG Healy. The Principal Investigators will sample basalts, peridotites, and related rocks along 600 km of the Gakkel Ridge. Detailed geochemical study of these rocks along with geophysical estimates of crustal and lithospheric thickness can be combined to generate quantitative models of oceanic crust formation under ultra-slow spreading conditions. Concurrently, with the basement sampling, a reconnaissance will be carried out as a hydrothermal survey using MAPR devices attached to the dredging (or coring) wire and rosettes. The survey would be designed to lay the groundwork for future hydrothermal and related biological studies along Gakkel Ridge. Finally, sampling along Gakkel Ridge and interpretation of the data will provide a basic understanding of the makeup of Arctic Ocean crust, and its influence on Arctic Ocean chemistry.

摘要OPP-99-11795MichaelOPP-99-12162DickOPP-99-12156GrahamOPP-00-00389LangmuirGakkel海脊在全球洋脊系统中占有独特而重要的地位，因为它是： 1）扩张最慢的海脊； 2）最深的洋脊； 3）唯一可以直接对极地幔成分进行采样的区域； 4）处于被紧邻的大陆岩石圈包围的独特构造环境中。 脊的走向垂直于扩张方向，这导致很少的变换偏移，并且它似乎是最冷的上地幔上方的脊。 这种特征的结合使得大量关于洋壳形成的假设得以检验。加克尔海脊尚未进行岩石学采样，这主要是由于北冰洋的永久冰盖使得地球物理数据难以获得。 山脊上的常年冰盖需要两艘破冰船协同工作才能进行安全有效的探险。 最近的发展使得采样考察成为可能。 从潜艇收集的美国 SCICEX 测深、侧扫和重力数据为规划良好的采样计划提供了必要的背景数据。 德国同事响应 InterRIDGE 的规划工作，部署了破冰船 Polarstem，开展为期 50 天的两艘船国际考察，专门研究 Gakkel Ridge。 美国还将提供一艘破冰船，即新的美国海岸警卫队希利号。 首席研究员将沿着 Gakkel Ridge 600 公里的范围对玄武岩、橄榄岩和相关岩石进行采样。 对这些岩石的详细地球化学研究与地壳和岩石圈厚度的地球物理估计相结合，可以生成超慢扩张条件下洋壳形成的定量模型。 同时，在进行地下室采样的同时，还将使用连接到疏浚（或取芯）线和玫瑰花结的 MAPR 设备进行水热勘察。 该调查旨在为未来加克尔山脊沿线的热液和相关生物学研究奠定基础。 最后，沿着加克尔海脊采样并对数据进行解释将提供对北冰洋地壳的构成及其对北冰洋化学影响的基本了解。