Early Metamorphic History of the Oceanic Lower Crust

洋辉长岩的早期高温变质作用和变形记录了洋中脊附近下地壳的演化。事实证明，破译这些记录很困难，原因有二：(1)对变质作用的温度估计不精确；(2)矿物组合平衡状态的不确定性。本研究采用实验、分析和统计相结合的方法来解决这些问题。实验研究的重点是利用东太平洋隆起形成的天然变质辉长岩研究次生矿物组成的温度和时间依赖性。这个项目的岩石学和统计学组成部分将从蛇绿岩和洋中脊的一套辉长岩中确定变质矿物组成。这项研究将有助于更好地理解洋中脊附近下地壳过程的时间尺度和扩展速率依赖关系。

Early high-temperature metamorphism and deformation of oceanic gabbros record the evolution of the lower crust near mid-ocean ridges. Deciphering this record has proven difficult for two reasons: (1) imprecise temperature estimates for metamorphism, and (2) uncertainties about the equilibrium state of mineral assemblages. This study employs a combination of experimental, analytical, and statistical methods to address these issues. Experimental studies focus on the temperature and time dependence of secondary mineral compositions using natural metamorphosed gabbros formed at the East Pacific Rise. The petrologic and statistical component of this project will determine metamorphic mineral compositions from a suite of gabbros from ophiolites and mid ocean ridges. This study will yield a better understanding of the time scales and spreading-rate dependence of lower crustal processes near mid-ocean ridges.