Applied
Magnetics  Geosciences 439
Spring Semester 2013: 1/30/2013: Introduction to the course, general concepts, basic Earth parameters; Montana geologic map.kmz (as .zip), aeromagnetic, combo  geology & magnetics). The shape of the Geomagnetic field (declination, inclination, magnetic elements, bar magnets). 2/1: Structure demo:(kmz: 1, 2; wmv); magnetic units (1, 2), bar magnets and the fluxgate demo. The geocentric axial dipole hypothesis, secular variation. 2/6: Magnetic potential, and the uniformly magnetized sphere (spherical coordinates, dv). The dipole equation  the fundamental equation of paleomagnetism. 2/8: More on the uniformly magnetized sphere and its flux pattern (Butler's derivation and a Geomagnetic Field applet). Inclination versus latitude(graph, map), early paleomagnetism excerpt: Collinson & Runcorn, 1960. Apparent polar wander paths and calculating them. 2/13: Problem set for next Wednesday. Stereonets, then spherical trig (see Butler's appendix) and solutions for the distance between two points on a sphere, epicenter determination, apparent pole positions, and the calculation of apparent pole positions; Pole to field mapping (D, I) <> VGP. (web bonus: dot product). 2/15: Self assessment  these abstracts should make sense: translations and rotations (1, 2, 3). APW paths, transforms (1, 2), 2D tectonics, relative velocity vectors. More transform faults (Isacks_Oliver_Sykes), Euler poles, YouTube San Andreas. 2/20: Discuss problem set, vector review, poles and apparent polar wander, hot spot tracks (1,2), hotspot reference frame(2), 2/22: My VGP spreadsheet; True polar wander(1, 2) and paleomagnetic Euler poles (figure 1, 2). 2/27: Assignment for 3/6: an Euler pole problem (the spreadsheet, Solver demo, xls); local paleomagnetic examples (Doughty, Jolly, Brunt, Sheriff). 3/1: Continue local paleomagnetic
examples (Doughty, Jolly, Brunt, Sheriff). Begin Curie
temperature, magnetic minerals,
3/6: Blocking temperatures, thermal magnetic cleaning, and a quick look at vector end point diagrams (vector mixing, components). 3/8: Hysterisis, coercive force, magnetic domains, and AF cleaning. 3/13: My APW answers; your presentations of structure/tectonics papers that use paleomagnetism. 3/15: Midterm 3/20: Midterm return: do as take home for scores below 40  due Friday 3/22. Magnetic exploration, anomalies with latitude. Buried dipole applet & NW Montana. Magnetic prospecting; Montana aeromagnetics (with geology, data, grid). Total field (scalar) anomalies, fluxgate, proton precession (2) and cesium vapor magnetometers  details from GEM Systems. Block models (pblock, pdike) relating magnetics and gravity. 3/22: Discuss midterm and more exploration; block models (pblock, pdike), simple models (from Berkeley) relating magnetics and gravity; Poisson's relation the Talwani algorithm, MAGCAD in DOSBOX (mount c c:\), and forward models. Software: pblock, pdike, (Cooper's Software, mine), experimental design. 3/27: Experimental design, sampling theorem (2) and a start on Fourier analysis and frequency filtering; (demo.ppt). Some good definitions & explanations: Fourier series and transforms; pretty good web 'book' on geophysical signal analysis. 3/29: Fourier series & Fourier transform (Fourier series applet  applied to high frequency filtering; Fourier transform applet) white noise (1/f^o), instrument precision, designing filters in the frequency domain  high pass, low pass, bandpass, notch, and threshold. 2D FFT applet; magnetics of a randomly magnetized layer (filter shape, with depth, radial averages {you could compare pblock}. 4/3  4/5: Spring Break 4/10: Again: 2D power/amplitude spectra, white noise (1/f^0), signal/noise, and signal stacking.xlsx. Equivalent layers, upward continuation. Think about the shape of these things. 4/12: More upward continuation (ppt, Jacobsen.pdf, Phillips_1996) Urquhart's frequency filtering of potential fields. Gridding & contouring (figure: 4 methods) with Surfer; the USGS extensions to Oasis Montaj. 4/17: Your turn: Separation filtering  with upward continuation (stone ring photo, data). 4/19: Reduction to pole (RTP with latitude, Blakely excerpt); pseudogravity (Blakely excerpt; Chicxulub 2010 (ref)). Public data (Geonet; MT_Geol.kmz; NW_Montana (dat, grd, kmz); Beaverhead (mag, grav); Assignment: data, Oasis Montaj, and the USGS extensions for continuation  due 4/26. 4/24: Montana mag, blanking files (LL, UTM)). Separation filtering: statistical methods; filter figures: random layer components, with depth, with thickness. PSmag 2D_sequence, 4/26: Power Spectrummag  Calculate the depths! Spector & Grant: (1, 2). Matched filtering (stepbystep, MYAP example.ppt 5/1: Decorrugation (define); matched filtering in Oasis/USGS: demo data from Yellowstone  remember to use safe mode (F8 on boot). Compare matched filter separation to that by upward continuation. 5/3: Making matched filter choices. Next, edge detection: first vertical and second vertical derivatives, HGM, analytic signal (low latitudes). Fabric analysis: compare 2VD, HGM, AS, TiltD; and disk w/ Montaj. Edge detection on models (ppt), using post maps for curvature maxima.
5/8: Great example from Grauch. Depth estimates: slope
halfslope (example). Euler deconvolution; the faulted dome (.grd) and Euler solutions on the faulted dome.ppt and some figures: 1, 2, 3. The magnetic
modeling of the faulted dome comes from using models
from Surfer and PFmag3D (program) from R.
Blakely in the USGS
DOS software collection. 5/10: Depth estimate finale: Euler: Stevi.wmv, then Werner
deconvolution: Stevi example. Depth estimates
from the analytic signal and horizontal gradient. Curvature/special
function depth analysis from Phillips et al., 2007 on curvature. Inverse examples: Philipsburg Batholith (Pburg.ppt, wmv, wmv2, Darby.wmv). Tuesday May 14  Final Exam; 3:20  5:20 your individual choice: Take home or inclass.
The Spring 2012 course The Spring 2011 course


Layout and Design by Brian W. Collins, updates and current content by Aaron Deskins ©2005/2008