The ASARCO Smelter in Ruston deposited heavy-metal-rich ash over a wide footprint in the south and central Puget Sound. Other processes such as pesticide application, however, may also have enriched local soils in heavy metals. Students Mike Cole, Jason Story, Rod Wells, and I are developing a mineralogical "fingerprint" of smelter contamination based on magnetic oxide minerals in smelter-derived materials. This will eventually allow us to quantify how much smelter ash was deposited in soils independent of the arsenic and lead concentrations.
This project may spin off some additional work on the magnetic
properties of zinc-bearing olivine (which is antiferromagnetic at low
temperatures) and other unusual magnetic minerals.
Sequences of windblown glacial dust (loess) deposits interspersed with fossil soils (paleosols) have provided a useful record of climate patterns in China. With collaborators Sian Davies-Vollum, Caroline Stromberg, Rick Madden, and Regan Dunn, along with students Scott Hopson and Aaron Beckner, I am examining the magnetic properties of Eocene to Miocene sediments from Argentina. I am hoping to extend my work to the Palouse loess in Washington as well. Like the Chinese loess, these magnetic records may provide valuable constraints on climate change.
The Stillwater Complex is one of the best-studied layered intrusions in the world. In spite of decades of study, however, some aspects of its origin remain poorly understood. In particular, we still do not completely understand the extent to which the textures and compositional layering in the Stillwater Complex are due to in-situ crystallization, crystal-laden density flows, compaction, or slumping. Magnetic anisotropy measurements can identify subtle textural features not visible in the field or in thin section. Along with former student Max Mousseau and collaborators Jeff Gee, Bill Meurer, and Josh Feinberg, I have been using anisotropy of remanence (AARM) and anisotropy of susceptibility (AMS) to examine fabric development in the Middle Banded Series of the Stillwater Complex. These observations help constrain the types and timing of magmatic processes responsible for the Stillwater's textural and compositional variations.
Italics indicate student authors
Selkin, P.A., J.D. Story, and M.P. Cole. 2011. Magnetic properties as a proxy for airborne smelter dust contamination, Tacoma, WA [poster]. Geol. Soc. Am. Abstracts with Programs, 43 (5): 284.
Selkin, P.A., J.S. Gee, W.P. Meurer, and S.R. Hemming. 2008. Paleointensity record from the 2.7 Ga Stillwater Complex, Montana. Geochem. Geophys. Geosyst., 9(Q12023), doi:10.1029/2008GC001950.
Selkin, P.A., E.T. Cline, and A. Beaufort. 2008. Integrating writing into an introductory environmental science curriculum: Perspectives from biology and physics [poster]. AGU Fall Meeting, December, 2008. ED31A-0587.
Becker, B.J. and P.A. Selkin. 2008. Marine Reserve Design: Simulating stakeholder options. Teaching Issues and Experiments in Ecology [online], 6, Experiment 3. http://tiee.ecoed.net/vol/v6/experiments/marine_reserve/abstract.html.
Selkin, P.A., J.S. Gee, and L. Tauxe. 2007. Nonlinear thermoremanence acquisition and implications for paleointensity data. Earth Planet. Sci. Lett., 256, 81-89.
Gee, J.S., W.P. Meurer, P.A. Selkin, and M.J. Cheadle. 2004. Quantifying three-dimensional silicate fabrics in cumulates using cumulative distribution functions. J. Petrol., 45, 1983-2009.
Selkin, P.A.. 2003. Archean Paleointensity from Layered Intrusions [PhD Thesis]. University of California, San Diego. 310 pp.
Selkin, P.A., J.S. Gee, W.P. Meurer, and L. Tauxe. 2002. Magnetic anisotropies at the mineral scale: Building magnetic fabrics from the ground up. Quaderni di Geofisica, 26, 157-158. [Extended abstract for the International Symposium on Fundamental Rock Magnetism and Environmental Applications, Erice, Italy, June 2002.]
Cronin, M., L. Tauxe, C. Constable, P. Selkin, and T. Pick. 2001. Noise in the quiet zone. Earth Planet. Sci. Lett., 190, 13-30.
Selkin, P.A., J.S. Gee, L. Tauxe, W.P. Meurer, and A.J. Newell. 2000. The effect of remanence anisotropy on paleointensity estimates: a case study from the Archean Stillwater Complex. Earth Planet. Sci. Lett., 183, 403-416.
Selkin, P.A. and L. Tauxe. 2000. Long-term variations in palaeointensity. Phil. Trans. Roy. Soc. Lond. A, 358, 1065-1088.