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Geology and Geological Engineering Dr. Gokce UstunisikExperimental Petrology, Planetary Geochemistry: |
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Meet the teamThe unifying goal of my research is to understand the physics and chemistry of processes effective in solar nebular environments that may have modified magmas ranging from chondrule precursor melts to the primary compositions of the planetary magma oceans.My research team focus on sorting out the geochemical signals that are imparted by various differentiation processes (crystallization, mixing, recharge, decompression and degassing) and evaluating their relative roles and timing in different magmatic systems. Evidence of these processes is less apparent in the bulk chemistry of lavas, than in the minor, trace, and isotopic characteristics of the phenocrysts and melt inclusions within eruptive/cooling units. Therefore, detailed analysis of melt inclusions, zoning in phenocrysts, development of reaction rims becomes powerful tools for us petrologists in establishing magmatic conditions (pressure, temperature, volatile content, composition) and timescales which are the key to understand ?how explosive volcanoes work and ultimately predict volcanic eruptions?. We use a variety of microanalytical techniques to analyze major and trace elements and volatile abundances of minerals and melt inclusions in igneous rocks. Combined with the compositional information on minerals and melts, we apply numerical modeling (phase equilibria and thermodynamic) to constrain phases; estimate pressures, temperature, and residence times; and eventually construct a picture of magma assembly and dynamics. In planetary sciences, in contrast to the Earth, the largest challenge is the limited time-space systematics in sampling that is essential for representative bulk composition of magmas. Martian meteorites, although they are igneous basaltic rocks that could provide a window into the interior the planet, come from random sites. Apollo samples are only from limited areas of the Moon. Furthermore, what we have is small in size, either dust or loose sediments, or cumulates and a vast majority is coming under 25 km deep regolith. Even pristine samples are coming from a top surface which was reworked over and over with heavy meteor bombardment. Chondrules represent the oldest materials in the Solar nebula, yet their precursor materials were exposed to extensive heating and melting processes. In order to relate anything from the surface to the planetary interior or to understand how the planetary processes affect the chemistry of these planets and formation of first solids, and molten (liquid) rock droplets and the volatile abundances of their source regions or precursor melts, we need laboratory experiments. Therefore, my research group design experiments that mimic the interior of planetary conditions to provide the interpretations for the analytical and geological data of the planetary materials brought to the surface by volcanoes, erosion or impact cratering. In conjunction with various experimental techniques (piston cylinder, gas-mixing and quench furnaces), we use simple numerical modeling not only to guide the design of specific experiments but also demonstrate the implications of our results for natural systems. Current Graduate Students:
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contact: Dept. of Geology and Geological Engineering, 501 E. Saint Joseph St., SDSMT, Rapid City, SD 57701 phone: (605)394-2461 / fax: (605)394-6703 / email: Gokce.Ustunisik@sdsmt.edu |