2014


Diana Rattanasith

Diana Rattanasith


Years participated in RESESS:
2014
2013


Poster
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An Overview

Major: Earth Sciences
Academic Affiliation: University of California - Santa Cruz
Research Mentors: Kevin Mahan
Communication Mentor: Yuri Springer


Biography

Born and raised in the Bay Area of California, Diana grew up enjoying visits to the California Academy of Sciences from which her initial interests in science began. Her curiosity and love for nature have led her to study Earth Science at the University of California, Santa Cruz. As a recent graduate and a returning RESESS intern this summer, she looks forward to continuing relationships with her peers and mentors at CU Boulder. By studying monazites both qualitatively and quantitatively from Big Thompson Canyon of northern Colorado she hopes to correlate two separate metamorphic events.


Abstract

Characterization study of monazite from Big Thompson Canyon, northern Colorado with implications for geochronology and timing of Proterozoic tectonic processes

The Precambrian tectonic evolution of Northern Colorado and the Northern Front range is a complicated story of perhaps multiple tectonothermal events, which despite years of study, remains relatively unconstrained. Big Thompson Canyon is a fruitful location to continue to unravel the complex geologic past of the region. The canyon is considered an excellent example of regionally zoned metamorphism that consists of an arcuate pattern of metamorphic isograds that mark east to west, biotite-chlorite to migmatite grade rocks that may be the result of multiple phases of metamorphism and deformation over the hundreds of millions of year timescale. The motivation for this study was to collect and use electron microprobe data on monazites to date the growth of multiple staurolite generations in samples that contain both retrogressed and fresh staurolite in hopes of a correlation to two separate metamorphic events.

Here, we report the results of a preliminary investigation into the possibility of a 1.4 billion year old-overprinting event that may be preserved in the pelitic schists exposed in the Big Thompson Canyon region. These metapelites are generally thought to be ~1.7 billion years old and experienced peak metamorphism around that time. Monazites present in samples collected from Bob Cat Ridge were found and imaged using an electron microprobe and QEMSCAN. Several monazite grains were found in staurolite psuedomorphs, garnet and muscovite porphyroblasts. Resulting U-Th-total Pb data on monazites can be used to quantify the timing of crystallization of the fresh staurolite in the samples and thereby estimate the age of a second possible metamorphic event. The timing of the fresh staurolite formation allowed for inferences to be made about the geochronology and timing of Proterozoic tectonic process within Big Thompson Canyon and the northern Front Range as a whole.


Presentation