Three aspects of magna dynamics: Granite partial melting, experiments on laccolith emplacement, and effects of xenocryst re-equilibration.

摘要

The texture and mineralogy of an igneous rock is the story of magma. The story tells where the magma comes from and how it came to be where it is now, a rock in the field. Many igneous petrologists are concerned with where the magma came from, its magmatic source, which is important, but unfortunately misses most of the story. The rest of the story is the path. The path magma takes through crust; slow or fast; convoluted or simple; to the surface or trapped abyssally; all alter the end product. Heat transfer, entrainment or sealing of crystals, and mixing of disparate magmas are all processes that skew magmas both texturally and chemically. Magmatic origins are static, but magma transport is dynamic--this is the part of the story with which this research is concerned.;This dissertation is the culmination of varied studies concerning processes that occur during and as a result of the transport of magma. It is divided into three parts, each representing one of the fundamentals of geology---field work, experimentation, and theory.;Part 1 is the study of a melt zone in the host rock surrounding a magmatic sill. Field work was completed in the McMurdo Dry Valleys of Antarctica, a magmatic plumbing system unparalleled for its extent of exposure.;Part 2 concerns a new experimental method that recreates magmatic sills, but it does so via a table-top sized apparatus. The sills solidify and can be handled afterwards, or cut in any direction, allowing the user, rather than Nature, to choose where the exposure is.;Part 3 considers the effects of a magma entraining foreign crystals. These xenocrysts, out of equilibrium with the magma, re-equilibrate by exchanging chemistry between crystal and liquid. The result is a potential significant change in the chemistry of the carrier magma that may alter the saturation point of sulfur, and thus become a fundamental factor in the formation of certain ore deposits.