Document Type
Thesis
Abstract
An unusual occurrence of a nodular rock exists within the Diana Mills pluton in the Piedmont Province of central Virginia. The rock consists of two separate assemblages: “nodules” and “matrix” material, each with a related, but distinct mineralogy. The nodules contain mostly serpentine and talc surrounded by a shell. These nodules range in size and shape from location to location, and contain mostly serpentine and talc, in addition to small amounts of amphibole and oxides ranging from magnetite to chromite. Matrix material is dominated by amphibole ranging from tremolite to actinolite, and chlorite, ranging from anomalous blue to tan varieties. Both rock types have high Mg numbers, and low SiO2 values, and their Ni and Cr values suggest that they are cumulates. The matrix material is magmatically linked to the chlorite amphibole rocks of the Diana Mills pluton, a relationship that provides a clue to the origins of these rocks. The preferred theory of the origins is that the nodules represent mantle xenoliths, which were emplaced into the pluton by a hydrous crystal mush. Alternatively, the nodules could be early ultramafic cumulates from the same magma as the matrix material, and chlorite amphibole rocks.
Date Awarded
2014
Department
Geology
Advisor 1
Brent E. Owens
Recommended Citation
Carter, Elizabeth Sanae, "The Field Characteristics, Mineralogy and Geochemistry of Mantle Xenoliths in the Diana Mills Pluton, Buckingham County, Central Piedmont, VA" (2014). Geology Senior Theses. William & Mary. Paper 307.
https://scholarworks.wm.edu/geologyseniors/307
