November 1, 2017 at 8:00 pm

Geology Colloquium | Crystals as Archives into Igneous Systems and Processes, Nov. 17

Dr. Kenneth Brown

Dr. Kenneth Brown

The Geological Sciences Colloquium Series presents Kenneth Brown on “Crystals as archives into Igneous systems and processes: exploring potassium feldspar megacrysts in granites and granodiorites” on Nov. 17 at 4:10 p.m. in Clippinger 205.

Brown is a Teaching Assistant Professor of Geology at the West Virginia University Department of Geology & Geography.

Abstract: The formation of potassium feldspar megacrysts in granites and granodiorites has remained a controversial issue in igneous petrology for nearly half a century. These megacrysts have traditionally been interpreted as having a magmatic origin, whereby these large crystals represent primary phenocrysts that crystallized directly from an evolving melt. Alternative hypotheses, however, argue in favor of a subsolidus or near solidus origin. The main distinction between these two models is the timing of their formation. If megacrysts formed early, then they likely preserve a record of the physio-chemical processes operating within a crystallizing magma chamber (i.e. assimilation, fractional crystallization, and magma mixing). Conversely, if they form near the solidus, they overprint and obscure earlier textural and chemical relationships. Thus, the timing of megacryst formation bears on a fundamental issue in granite petrology, namely whether the textural and chemical features preserved within granitoid intrusions reflect primary magmatic processes or whether these features represent subsolidus modifications. To place new and important constraints on this problem, my students and I are investigating a suite of megacryst-bearing intrusions located within western North America. This talk will focus on the current research efforts being completed within one specific intrusion in northwestern Nevada (the Granite Peak stock).

Upcoming Colloquia

Lindsey Schafer on “Statistical analysis of mining parameters to create empirical models to predict mine pool formation in underground coal mines” and Fred Twumasi on “Modeling of hydrological data to predict mine pool formation and possible discharge locations in underground mines” on Dec. 1 at 4:10 p.m. in Clippinger 205. Both are Geological Sciences graduate students.

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