A Lu-Hf Isotopic Investigation of the Origin and Evolution of the Indian Ocean Mantle Domain

印度洋地幔域起源与演化的Lu-Hf同位素研究

• 批准号: 0221368
• 负责人: Philip Janney
• 金额: $ 4.47万
• 依托单位: Field Museum of Natural History
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0221368&HistoricalAwards=false
• 关键词: Lu; Hf; Isotopic; Investigation; Origin

Under this award, the PI will attempt to constrain the evolution and origin of the unusual Indian Ocean mantle domain by determining the initial hafnium isotope compositions and Lu and Hf concentrations of old oceanic crustal basalts from 21 DSDP/ODP drill sites and two Tethyan ophiolite complexes already studied for Sr, Nd and Pb isotopes. Establishing the Hf isotopic composition of old Indian Ocean and Tethyan crust will help to determine when and where this isotopic signature first appeared in the Indian Ocean mantle domain, and if it was present in the composition of Tethyan crust produced before the opening of the Indian Ocean basin. It will also help to determine whether the distinct composition of the Indian Ocean mantle domain is primarily derived from subducted, deeply recycled components that have undergone extensive mixing and homogenization in the mantle, or whether it more likely derives from shallow contamination via the foundering of local Gondwanan continental lithosphere, which has evolved in isolation from the convecting mantle for billions of years.

根据该奖项，项目负责人将尝试通过确定来自 21 个 DSDP/ODP 钻探点和两个已经研究了 Sr、Nd 和 Pb 同位素的特提斯蛇绿岩杂岩的古老洋壳玄武岩的初始铪同位素组成和 Lu 和 Hf 浓度，来尝试限制不寻常的印度洋地幔域的演化和起源。建立旧印度洋和特提斯地壳的Hf同位素组成将有助于确定该同位素特征首次出现在印度洋地幔域的时间和地点，以及它是否存在于印度洋盆地打开之前产生的特提斯地壳的组成中。它还将有助于确定印度洋地幔域的独特成分是否主要源自俯冲的、深度再循环的成分，这些成分在地幔中经历了广泛的混合和均质化，或者是否更有可能源自当地冈瓦纳大陆岩石圈的沉没造成的浅层污染，该岩石圈是在与对流地幔隔绝的情况下演化了数十亿年的。