Petrology and Geochemistry of a Diorite from the EJB pluton, WhiteInyo Mountains, California Lindy S

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Petrology and Geochemistry of a Diorite from the
EJB pluton White-Inyo Mountains
CaliforniaLindy Straathof Ronald E. McNair
Scholars Program and Dr. David Matty
Department of GeologyCentral Michigan University
Introduction
Results Field Observations
Results XRF Data
This research project characterized a previously
unstudied diorite found in the Eureka
Valley-Joshua Flat-Beer Creek (EJB) composite
pluton located in Deep Springs Valley in the
White-Inyo Mountains of eastern California.
Magma Mingling
Brittle Contacts the darker diorite can be
visually put back together
Ductile Contacts
Field observations indicate that the diorite was
emplaced before the Beer Creek granite. Enclaves
of the diorite found within the Joshua Flat are
able to be visually fitted together showing that
the diorite was broken up by the emplacement of
the Joshua Flat pluton. Three different types of
contacts also indicate that the diorite had
cooled more in certain areas than in others by
the time the Beer Creek granite was intruded.
Results Petrography
Geologic map of Deep Springs Valley. The red
arrows represent the location of the diorite.
Average Percentage of Minerals in Collected
Samples
Discussion
Field observations and textural evidence leads to
the conclusion that the diorite was at least
partially cooled when the Beer Creek Granite was
intruded. The textures found in thin section
support this assumption indicating possible
magma mixing. Geochemical data also support some
degree of magma mixing although the diorites
themselves appear to have developed as a single
early magma.
The field area. The large diorite enclaves are
outlined in red the arrows indicate where
samples where taken.
Whats Next
Saussuritization
Deformed Plagioclase
Biotization
Several textures found indicate possible magma
mixing. These textures include saussuritization
biotization step-zoned plagioclase and
undulatory extinction and other forms of mineral
deformation.
Methods
More analysis need to be completed in order to
discover if there truly was magma mixing and to
what extent it occurred. Samples of the entire
EJB composite pluton will be analyzed with the
XRF spectrometer. The results of this research
will add to a larger project determining the
relative timeline of emplacement and interaction
of the entire EJB pluton.
Results for this project were collected through
field observations at Deep Springs Valley. Lab
analysis including thin section and geochemical
analysis preparation petrography and X-ray
Fluorescence (XRF) analysis were completed at
Central Michigan University.
Acknowledgements
I would like to thank the Ronald E. McNair
Scholars Program the Central Michigan Geology
Department and Dr. David Matty for his guidance.