Exploring the Formation of Listwänite in the Semail Ophiolite in Oman

The term “listwänite” was first coined in the mid-1800s to describe ultramafic rocks that have been completely carbonated. Carbonation cannot happen in the lower crust or mantle – where ultramafic rocks form – due to the lack of CO2, so the process must occur after the rocks are obducted near to the surface. Therefore, listwänite is usually found in ophiolite, assemblages of deep crustal rock and mantle rock thrust near to the surface. Lately, geologists have spent more time researching listwänite and other carbonated rocks because of their ability to sequester carbon from the atmosphere. Understanding how the Semail Ophiolite became carbonated may be useful in removing human-released CO2 out of the atmosphere. Though more geologists have been researching listwänite, there are a limited number of models for how it forms, particularly in the Semail Ophiolite Assemblage in northern Oman.

In January, I spent three days in the field in Oman, where I collected samples and made structural measurements of the listwänite and associated faults over a 20 km traverse. Through mineralogical analysis of the samples and structural analysis of the measurements, I will to create a geologic map of the area, create a series of diagrams that display structural information and patterns within the faults, and determine the role of the Tertiary-age faults in the formation of the listwänite.