Comprehensive Study of the Lu-Hf Radiogenic Isotope Systematics of Normal and Hotspot Affected Mid-Ocean Ridge Basalts

将对来自URI疏浚岩石收集的洋中脊玄武岩玻璃的176 Hf/177 Hf同位素比值变化进行全面的记录和研究。该系列的重点是受附近热点和底层地幔柱影响的异常升高的洋中脊段。 将对来自大约300个不同采样地点的大约300至400个样本进行研究。 可能的相关性，或去耦，将寻求放射性Lu-Hf同位素系统与Pb，Sr，Nd和He同位素系统，和其他地球化学参数先前建立在同一玄武岩玻璃。这项研究应提供新的制约因素，说明受热点影响的洋中脊段下石榴石的融化深度和方式以及石榴石的参与程度，这些热点包括大西洋的扬马延、冰岛、亚速尔群岛、塞拉利昂、圣赫勒拿岛和特里斯坦-达库纳、太平洋的加拉戈斯和复活节以及亚丁湾-红海区域的阿法尔。 还应该获得更多的见解，对海洋下地幔地球化学，长度尺度的不均匀性，地幔动力学。 该研究将与法国巴黎里昂的Janne Blichert-Toft博士和弗朗西斯Albarade博士合作完成，在URI分离Hf后，将通过等离子体源多收集器质谱法测量176 Hf/177 Hf比率。

A comprehensive documentation and study of 176Hf/177Hf isotope ratio variation of mid-ocean ridge basalt (MORB) glasses from the URI dredge rock collection will be conducted. The collection focuses on unusually elevated mid-ocean ridge segments affected by nearby hotspots and underlying mantle plumes. About 300-400 samples from some 300 different sampling localities will be studied. Possible correlations, or decoupling, will be sought between the radiogenic Lu-Hf isotope system with that of Pb, Sr, Nd, and He isotope systems, and other geochemical parameters previously established on the very same basalt glasses. The study should provide new constraints on the depth and mode of melting and extent of garnet involvement beneath mid-ocean ridge segments affected by hotspots such as Jan Mayen, Iceland, Azores, Sierra Leone, St Helena and Tristan da Cuhna in the Atlantic, the Galaggos and Easter in the Pacific, and the Afar in the Gulf of Aden-Red Sea region. Greater insights should also be gained on suboceanic mantle geochemistry, length scales of heterogeneities, and mantle dynamics. The study will be done in collaboration with Dr. Janne Blichert-Toft and Dr. Francis Albarede, from the Ecole Superieure de Lyon, France, where the 176Hf/177Hf ratio measurements will be made by plasma source multi-collector mass spectrometry, after Hf has been separated at URI.