Wednesday, April 9, 2014
Black Lab Pub, Churchill Room • 4100 Montrose Blvd.
Social 5:30 p.m., Dinner 6:30 p.m.
Cost: $30 Preregistered members; $35 non-members & walk-ups
Emeritus/Life/Honorary: $15; Students: FREE
To guarantee a seat, you must pre-register on the HGS website and pay with a credit card. You may walk up and pay at the door if extra seats are available. Please cancel by phone or email within 24 hours before the event for a refund. Online & pre-registration closes Wednesday, April 9, at 5:00 a.m.
Speaker: Mark T. Ford
Assistant Professor, Department of Physics and Geosciences
Texas A&M University – Kingsville
Using a Portable X-Ray Fluorescence (pXRF) Spectrometer for Lithogeochemistry Applications: Potential for Volcanic Stratigraphy and Shale Marker Beds
Lithogeochemistry is a method commonly used for mapping and correlating surface exposures of rocks. A new generation of portable X-ray fluorescence spectrometers (pXRF) has the potential to be used for this purpose. Under certain conditions, pXRF analyses can likely be extended to chemostratigraphy of core obtained during hydrocarbon exploration. One shortcoming, however, is that many of the commercially available devices only provide pre-set, often proprietary calibrations, that are suitable only for narrowly restricted uses, typically where the analyses do not have to be compared with commercially available chemical analyses or data gathered with pXRFs of different brands. Use of raw intensity data might provide acceptable correlation in some cases, but the data provide no quantifiable analytical concentration values.
The use of standard pre-set calibrations, which are often based on multi-variate analysis statistics, might show correlation between units, but parameters must be narrowly defined and there must be little to no variation in matrix elements. Even then, some of these calibrations are based on proxy elements and no physical reason supports the calibration corrections. Corrections for these matrix elements (called influence coefficient corrections) can be achieved with some Bruker model pXRFs, whereas users can define their own calibrations and apply these calibrations over a broad range of compositions (within limits). One can obtain concentrations that are reproducible with other, better characterized, methods such as inductively coupled plasma (ICP), Wavelength Dispersive X-ray Fluorescence (WDXRF), etc. While much of this work focuses on pumice chemistry and tuff correlation in Big Bend National Park, it should have applications in identifying shale marker beds.
Mark T. Ford is an assistant professor in the Department of Physics and Geosciences at Texas A&M University – Kingsville. He graduated from Alfred University in 1995 with a BA degree in geology and mathematics and then worked in the ceramics industry for Corning Incorporated. He returned to school earning his MS in geology from Idaho State University and a PhD in geology from Oregon State University in 2012. Over much of the past decade he has roamed the high places and “lava plains” of Oregon and Idaho, working on volcanic systems related to the Yellowstone Hotspot, Newberry Volcano, and Cascades Arc. During that time he also worked with a wide array of geoanalytical techniques to characterize the major, trace and isotopic compositions of igneous rocks and to understand better petrogenesis in igneous systems. He began work last year at Texas A&M University – Kingsville where he is expanding his research to include pegmatite mineralization in the Llano Uplift and volcanism in Big Bend National Park. One of the key tools he is utilizing in this research is a portable X-ray fluorescence (pXRF) spectrometer.