Stef's Wonderful World of Geology

Research

Undergraduate Research

While at the University of Pittsburgh, I started some research under the supervision of Dr. Mark Evans, now at Central Conn. University.

Our research was focused on Appalachain Sandstone in West Virginia and Maryland. Existing AMS data suggests different times of oxidation mineralization, some pre-tectonically, some syn-tectonically, and some post-tectonically.

I made thin sections of approx. 36 samples and made characterizations and we looked at selective samples with SEM. We didn't get as far as I had hoped, but plan on collaborating with Dr. Evans whenever he can find an undergraduate at Central Conn. State to help him out.

Microphotograph of a Lithanerite. Note the extensive Fe-Ti oxidation between grains.

Microphotograph of a kinked plagioclase grain. Sorry for the poor lighting.

Microphotograph of another lithanerite. Note the lineation of muscovite and flattening of quartz.

Microphotograph of two quartz grains in plain light. There is possible dissolution between these grains. Also notice the extensive oxidation between grains.

Graduate Research

AGU Joint Meeting Abstract - 2006

Eclogite is typically exhumed by either entrainment of large blocks in an accretionary mélange or by extensional unroofing of a regional eclogite-facies terrane. The Ashe Metamorphic Suite (AMS) in the Blue Ridge Mountains of North Carolina contains kilometer-scale eclogite blocks within what appears to be an accretionary wedge that has been metamorphosed to amphibolite facies. The eclogite-facies mineral lineation in the separate blocks are roughly parallel to each other, suggesting that these rocks were exhumed as a coherent eclogite-facies terrane rather than individual blocks in an accretionary mélange, where upward flow would disorient blocks. If the eclogite blocks were exhumed within a coherent eclogite-facies terrane, the intervening amphibolite-facies rocks would have once been at eclogite facies. To test this hypothesis we analyzed mineral inclusions in zircons from the intervening metasedimentary and metaigneous rocks using optical petrology, SEM-EDS and Raman spectroscopy. Zircons formed during peak metamorphism are frequently preserved during subsequent metamorphic events. Mineral inclusions in these zircons would preserve a record of peak metamorphism that is no longer evident in the bulk mineralogy. Previous work showed that zircons from eclogite and retrogressed eclogite contain inclusions of eclogite-facies minerals, including omphacite, rutile, and garnet. If the amphibolite-facies rocks surrounding the eclogite had experienced eclogite facies, some of the zircons from these rocks should preserve eclogite-facies minerals. In our work so far, we have not identified any eclogite-facies minerals in zircon from the AMS. Thus, there is no evidence that the AMS metasedimentary and metaigneous rocks ever reached eclogite facies. An exhumation model for the AMS must explain the alignment of large eclogite blocks, as well as, the absence of eclogite-facies metamorphism in the intervening metasedimentary and metaigneous rocks. Thus, the process by which the AMS eclogite blocks were exhumed was more complex than either of the typical exhumation models. Modification of preexisting models may explain these observations: 1) exhumation as a coherent eclogite-facies terrane followed by complete amphibolite facies recrystallization of portions of the terrane, possibly through channelized fluid flow, or 2) exhumation in an accretionary mélange under unique conditions such that extremely large eclogite blocks (kilometer-scale) are transported without significant disruption of their orientation. Continuing research of the metasedimentary and metaigneous rocks of the AMS will further test these two models.

PDF Version of Thesis Proposal (May 2005)

Photo of part of my field area, taken near Lick Ridge in Bakersville, NC. This particular area has many abandoned houses/shacks/trailers.