Research

Chugach Mountains rising out of the Prince William Sound in south central Alaska

Overview

My research focuses on the processes and products of the vertical motion of Earth's surface and underlying rocks, typically at Quaternary and Tertiary time scales.  This research involves both the uplift of rocks, the exhumation of once deeply buried rocks, and basin development.  These rocks are generally, but not always, in mountain belt settings such as the Wasatch Mountains in Utah, the mountains of southern California, or the huge mountains of Alaska.  My students and I use basic field methods, low-temperature thermochronometry, landform analysis, dating of surficial deposits, and geophysics to evaluate uplift and/or exhumation events.

To see a list of publications on these research topics, go to my CV.

If you are a student interested in this type of exciting research, please email me at parmstrong@fullerton.edu or call me at (657) 278-3169.

For more detail on the types of projects and the areas where I have worked, am presently working, or hope to work soon, scroll down a bit.

 

Fission-track Lab:

I maintain a fission-track lab here at Cal State Fullerton whereby my students and I measure fission-track ages and other parameters and prepare samples for Uranium-Thorium-Samarium-Helium  dating. 

Mineral separations: My lab contains full mineral separation facilities including jaw crushers and pulverizing mill, Wilfley table, Franz magnetic separator, and heavy liquid facilities. 

Fission-track measurements: I use an Olympus BX50 optical microscope with digitizing tablet, stage driver, and FTStage software system (supplied by Trevor Dumitru at Stanford) for fission-track measurements.  Irradiations of samples are done at the Oregon State Triga reactor, though I am considering new laser ablation techniques that allow direct determination of uranium in samples without having to irradiate.

(U-Th-Sm)/He: For (U-Th-Sm)/He dating we pick mineral grains (generally apatite) on a modified picking scope with cross polarizing capabilities.  After grains are picked, they are loaded into platinum tubes and carried to Caltech where we collaborate with Dr. Ken Farley for mass spectrometry work. 

 

 

Other Research Facilities:

Computing facilities: In my lab, I maintain two Windows work stations for student work and another for dedicated use with our fission-track scope.  These machines have full suites of software including graphics, plotting, and GIS packages.  In addition, our department maintains a state-of-the-art 32-station windows computer lab and a 16-station iMac computer lab.  Our department is very proactive on maintaining these computers with up-to-date versions of common word processing, spreadsheet, graphics, and GIS software. 

Geophysics and GPS equipment: Our department maintains a suite of geophysics equipment for research and course work, including a Scintrex CG-5 gravimeter, SuperSting resistivity meter, and Bison 24-channel seismometer.  We have two Topcon GB-1000 receivers with antennas with post-processing capabilities for precise GPS surveys. 

 

Projects:

Alaskan Tectonics.  Over the last couple years I have become very interested in understanding the tectonics of Alaska, in particular south-central Alaska.  I am trying understand the timing and processes of uplift of some of the large mountain in the area, in particular the Alaska Range, the Talkeetna Mountains, and the Chugach Mountains.  My students and I have been working with Dr. Peter Haeussler at the United States Geological Survey in Anchorage on evaluating uplift and exhumation of some key areas.  We have done some field work in all three mountain areas and have some low-temperature thermochronology ages (apatite fission-track and (U-Th)/He) - these are published in two abstracts so far - see CV.  Funding permitting, because it is expensive to do field work in AK, we hope to get back for more field work and sample collection soon.

 

Exhumation of the Wasatch Mountain, Utah.  My students and I have been working on the uplift and exhumation history of the Wasatch Mountains for about the last 10 years.  We've collaborated with Dave Chapman (Univ. Utah), Todd Ehlers (U. Michigan), Ken Farley (Caltech), Sean WIllett (ETH Zurich), and Peter Kamp (Univ. of Waikato in New Zealand).  Our goals were to (1) use low-temperature thermochronolgy techniques to pin down the exhumation history of the central part of the range (near the main ski areas of Alta and Snowbird) as a function of distance from the trace of the Wasatch fault at the range front; (2) use the ages to develop and refine thermo-kinematic models of exhumation in extensional settings; and (3) use the refined models to evaluate exhumation of the range front along different strands of the Wasatch fault along nearly 300 km of range length.   These results are published in a series of papers in Journal of Geophysics Research,  Physics of the Earth and Planetary Interior, and Geology (see CV)

 

Vertical tectonics of the eastern Los Angeles basin and Santa Ana Mountains.  This area is in our CSUF backyard, and I've been extremely interested in understanding the "ups and downs" of the main topographic features, such as the Puente Hills, San Jose Hills, San Joaquin Hills, and the Santa Ana Mountains.  MS student Christine Irwin is using thermochronology techniques to evaluate timing, rate, and magnitude of exhumation of these topographic highs.  We've extended this work a bit to the north and west to include the Verdugo Hills, with the hope of putting together a more coherent picture of the LA basin as a whole.  In the Santa Ana Mountains, student Aron Taylor (co-advised by Jeff Knott at CSUF) evaluated a flight of fluvial terraces in order to understand timing and rate of Quaternary uplift of this area.  To date, two MS and three undergraduate students have worked on various aspects of these projects.  Several abstracts and one guidebook paper have been published from this work to date.

 

Structures of the Lucerne Valley area.  In collaboration with colleagues here (Dr. Rich Laton and John Foster) and at the Mojave Water Agency, I've worked with MS student Tammy Surko (MS, Spring, 2006) and research scientist Vicki Langenheim (USGS) to evaluate the Lucerne Valley basement geometry.  Tammy performed a dense station gravity survey that she was able to interpret using GM-SYS and Oasis Montaj software packages to deduce basement topography and potentially hidden structures.  Two abstracts have been published on this work, and we plan to put together a paper soon.

 

Concentrated deformation along the San Andreas Fault in Joshua Tree National Park.  MS student Luke Sabala and I are working on a project to understand the effects of the San Andreas fault motion at Quaternary and Tertiary time scales in the southwestern part of Joshua Tree National Park.  We are doing low-temperature thermochronology analyses on samples collected along transects perpendicular to the fault in the Desert Hot Springs to Morongo Valley area.  In addition, Luke is doing geologic mapping and GPS-determined stream-gradient profiling to put together a picture of deformation associated with this bend region on the SAF.