Collaborative Research: Late Cretaceous - early Cenozoic paleolatitude of the Walvis Ridge hotspot: Implications for true polar wander and hotspot geodynamics

合作研究：白垩纪晚期 - 新生代早期沃尔维斯海岭热点的古纬度：对真正的极地漂移和热点地球动力学的影响

• 批准号: 2232970
• 负责人: William Sager
• 金额: $ 38.87万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2232970&HistoricalAwards=false
• 关键词: Collaborative; Research; Late; Cretaceous; early

The Walvis Ridge is a volcanic ridge in the South Atlantic Ocean that was erupted on the African plate as it drifted over a hotspot, similar to the Hawaiian-Emperor seamount chain in the Pacific Ocean. Scientists are debating how accurately such hotspot tracks record plate motion. During the formation of the Emperor chain paleomagnetic data show that the hotspot moved southward by ~10-15°to its current location. This shift might be caused by movement of the hotspot. An alternate cause could be the shift of the Earth’s spin axis, or true polar wander (TPW). If TPW occurred, it should cause a consistent global shift: southward hotspot motion in the Pacific would be paired with northward hotspot motion in the Atlantic. This project will study volcanic rocks and sediments cored from Walvis Ridge during International Ocean Discovery Program Expedition 391 (December 2021-February 2022) to produce a record of paleolatitudes for comparison with Hawaii-Emperor paleolatitudes. The project supports several early career researchers.This project will analyze and publish studies of sediment and basalt core paleomagnetic data from IODP Expedition 391, with the object of developing a paleolatitude record for Walvis Ridge hotspot volcanoes for Late Cretaceous and early Cenozoic. IODP Expedition 391 drilled four sites, three on the Cretaceous Valdivia Bank plateau and one on a Paleocene guyot. Previous studies from Emperor and Louisville seamounts in the Pacific Ocean have been influential in studies of hotspot geodynamics. Prior to Deep Sea Drilling Project/Ocean Drilling Program (DSDP/ODP) drilling of Emperor seamounts, hotspots were considered fixed mantle markers, defining plate motions by seamount age progressions. DSDP/ODP cores showed that northern Emperor guyots were formed ~15° farther north than the current Hawaiian hotspot. IODP Expedition 330 cored coeval Louisville guyots, finding insignificant latitudinal motion, concluding that hotspot motion is the preferred explanation for inter-hotspot motion. Consequently, other explanations for hotspot latitude changes are not currently favored. One such phenomenon is true polar wander (TPW), the coherent shift of the entire mantle relative to the spin axis. TPW has been deemed insignificant for the past ~100 Ma, even though it is occurring at present and it has occurred deeper in the past. Hawaii and Louisville paleolatitude data show a small amount of mutual southward motion. If this results from TPW, the Walvis Ridge, almost antipodal to Hawaii and Louisville, should show the opposite paleolatitude change. This project will produce paleolatitude data for the Walvis Ridge using Expedition 391 cores (with data from DSDP Legs 72 and 74). A major objective is to test the hypothesis of Late Cretaceous-early Cenozoic TPW. This project hypothesizes that observed paleolatitude shifts are a combination of TPW and mantle flow. The project addresses important geodynamical problems that ultimately reflect mantle structure and convection. This project supports three early career investigators. In addition, the two faculty on this project will recruit undergraduate student workers from under-represented groups for internships that will help them advance in STEM education.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

沃尔维斯山脊是南大西洋的一座火山脊，在非洲盘子上爆发在一个热点上，类似于太平洋的夏威夷人民海洋链。科学家们正在辩论这样的热点跟踪记录板运动的准确性。在皇帝链的形成期间，古磁数据表明，热点向南移动约10-15°，直到其当前位置。这种转变可能是由热点的运动引起的。另一种原因可能是地球旋转轴的移位或真极徘徊（TPW）。如果发生TPW，则应引起一致的全球变化：太平洋中的南热点运动将与大西洋的北向热点运动配对。该项目将研究来自沃尔维斯岭（Walvis Ridge）的火山岩和沉积物在国际海洋发现计划探险计划391（2021年12月至20022年12月）中产生仿古的记录，以与夏威夷帝国的旧植物比较。该项目支持几个早期职业研究人员。该项目将分析和发布来自IODP Expedition 391的沉积物和玄武岩核心古磁数据的研究，其中的目的是为Walvis Ridge Hotspot火山创建古属式葡萄酒和早期的新生代。 IODP Expedition 391钻了四个地点，在白垩纪瓦尔迪维亚银行高原上进行了三个地点，另一个在古新世盖特上进行。太平洋皇帝和路易斯维尔海山的先前研究对热点地球动力学的研究产生了影响。在深海钻井项目/海洋钻井计划（DSDP/ODP）钻探皇帝的钻孔之前，热点被认为是固定的地幔标记，这通过Seamount Age Ademations来定义板块运动。 DSDP/ODP核心表明，北部皇帝的Guyots比目前的夏威夷热点北部〜15°。 IODP Expedition 330 COEVAL LOUISVILLE吉他发现了微不足道的纬度运动，得出的结论是，热点运动是零件间运动的首选解释。因此，目前对热点纬度变化的其他解释尚未受到青睐。一种这种现象是真正的极性流浪（TPW），这是整个地幔相对于自旋轴的相干移位。 TPW在过去〜100 mA中被认为微不足道，即使它目前发生并且过去发生了更深层次。夏威夷和路易斯维尔的古色数据显示了少量相互的向南运动。如果这是由TPW产生的，那么几乎反对夏威夷和路易斯维尔的沃尔维斯山脊就会显示相反的古色性变化。该项目将使用Expedition 391核心为Walvis Ridge生成古显着数据（并带有DSDP腿72和74的数据）。一个主要目的是检验白垩纪晚期的新生代TPW的假设。该项目假设观察到的古显着偏移是TPW和地幔流的组合。该项目解决了最终反映地幔结构和结构的重要地球动力学问题。该项目支持三名早期职业调查员。此外，该项目的两个教职员工将从代表性不足的团体中招募本科学生，以帮助他们进步，这将有助于他们进入STEM教育。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准通过评估来获得的支持。

项目成果

Preliminary Characterization of Submarine Basalt Magnetic Mineralogy Using Amplitude‐Dependence of Magnetic Susceptibility

利用振幅对磁化率的依赖性对海底玄武岩磁性矿物学进行初步表征

• DOI: 10.1029/2023gc011222
• 发表时间: 2024
• 期刊: Geosystems
• 作者: Yang, H.;Tikoo, S. M.;Carvallo, C.;Bilardello, D.;Solheid, P.;Gaastra, K. M.;Sager, W. W.;Thoram, S.;Hoernle, K.;Höfig, T. W.
• 通讯作者: Höfig, T. W.