Trace elements in abyssal peridotite olivine record melting, thermal evolution, and melt refertilization in the oceanic upper mantle
Trace elements in abyssal peridotite olivine record melting, thermal evolution, and melt refertilization in the oceanic upper mantle
复制标题
DOI：
10.1007/s00410-023-02044-6
复制
发表时间：
2023-09
影响因子：
3.5
通讯作者：
Kuan-Yu Lin;Jessica M. Warren;F. Davis
中科院分区：
文献类型：
--
作者：
Kuan-Yu Lin;Jessica M. Warren;F. Davis
深海橄榄岩橄榄石中微量元素的含量为研究大洋岩石圈的形成和演化提供了重要的信息。我们提出橄榄石微量元素组成（铝，钙，钛，V，铬，锰，钴，镍，锌，Y，Yb）从深海橄榄岩调查部分熔融，熔体-岩石相互作用，和subsolidus冷却在洋中脊和洋内前弧。我们的目标是44个橄榄岩从快速（赫斯深，东太平洋隆起）和超低速（Gakkel和西南印度洋脊）扩展的山脊和汤加海沟，包括5个橄榄岩含有熔体静脉。我们发现，Ti，Mn，Co，和Zn的丰度增加，而Ni减少熔体脉状样品相对于裸露的样品，这表明这些元素是有用的示踪剂的熔体渗透。橄榄石中Al、Ca、Cr和V的丰度对温度敏感。利用橄榄石中的铝和钙的温度计显示温度为650-1000 °C，其变化对应于橄榄岩在不同构造环境中经历的对比冷却速率。最后，我们证明了一个两阶段的模型，橄榄石Y和Yb丰度反映部分熔融和亚固相线再平衡。记录较低的铝和钙的橄榄石温度的样品经历了更高程度的扩散Y和Yb的损失在冷却过程中。总之，我们表明，橄榄石微量元素的文件高温熔融和熔体岩石相互作用事件，以及subsolidus冷却有关的折返和侵位到海底。这使它们成为研究与海底扩张和洋中脊构造有关的过程的有用工具。
Trace element concentrations in abyssal peridotite olivine provide insights into the formation and evolution of the oceanic lithosphere. We present olivine trace element compositions (Al, Ca, Ti, V, Cr, Mn, Co, Ni, Zn, Y, Yb) from abyssal peridotites to investigate partial melting, melt–rock interaction, and subsolidus cooling at mid-ocean ridges and intra-oceanic forearcs. We targeted 44 peridotites from fast (Hess Deep, East Pacific Rise) and ultraslow (Gakkel and Southwest Indian Ridges) spreading ridges and the Tonga trench, including 5 peridotites that contain melt veins. We found that the abundances of Ti, Mn, Co, and Zn increase, while Ni decreases in melt-veined samples relative to unveined samples, suggesting that these elements are useful tracers of melt infiltration. The abundances of Al, Ca, Cr, and V in olivine are temperature sensitive. Thermometers utilizing Al and Ca in olivine indicate temperatures of 650–1000 °C, with variations corresponding to the contrasting cooling rates the peridotites experienced in different tectonic environments. Finally, we demonstrate with a two-stage model that olivine Y and Yb abundances reflect both partial melting and subsolidus re-equilibration. Samples that record lower Al- and Ca-in-olivine temperatures experienced higher extents of diffusive Y and Yb loss during cooling. Altogether, we demonstrate that olivine trace elements document both high-temperature melting and melt–rock interaction events, as well as subsolidus cooling related to their exhumation and emplacement onto the seafloor. This makes them useful tools to study processes associated with seafloor spreading and mid-ocean ridge tectonics.