Petrology of Serpentinites and Rodingites in the Oceanic Lithosphere

Abstract

Serpentinization, steatitization, and rodingitization are consequences of seawater reaction with lithospheric mantle. These processes take place coevally within the oceanic lithosphere and are related to circulation pathways, lithologic makeup of rocks along the flow path, fluid flux, and temperature. While the boundary conditions are set by the history of magmatic and tectonic accretion of the lithosphere, fluid-rock equilibria determine what reactions take place and where in the system. Petrologists are challenged to determine the fundamental phase relations and fluid-rock interactions in order to better understand how the physical properties of the oceanic lithosphere develop and how the water-rock interactions contribute to providing energy for deep-sea microbial ecosystems independent of photosynthesis. How is hydrogen formed during serpentinization? How much of it is formed? Why are some gabbroic veins rodingitized, while others are not? What is causing steatitization? These are basic questions in oceanic petrology that have not been comprehensively addressed. The purpose of this thesis is to change this.