Applied
Magnetics - Geosciences 439
Spring Semester 2012: 1/23/2012: Introduction to the course, general concepts, basic Earth parameters; Montana (geologic, aeromagnetic, combo - geology & magnetics, geologic map.kmz) 1/25: Aeromagnetic SW Montana (kmz: 1, 2; wmv); near surface (ppt-TMI GPR), magnetic units (1, 2) and the fluxgate(2) demo. Geomagnetism, declination, inclination, magnetic elements, bar magnets, geocentric axial dipole hypothesis, secular variation. 1/30: Problem for Wednesday: for these data (Missoula (D, I,), .xls) calculate the x, y, & z components of each (D, I) pair then find the average (D, I) from the components - compare to the arithmetic average of the (D, I) pairs. Calculate field values,
magnetic potential, and the uniformly magnetized sphere (spherical
coordinates, dv). 2/1: Discuss the problem set; averaging vectors. More on the equation for a uniformly magnetized sphere (flux pattern, Butler's derivation and a Geomagnetic Field applet). The dipole equation - the fundamental equation of paleomagnetism; inclination versus latitude(graph, map), early paleomagnetism excerpt: Collinson & Runcorn, 1960. 2/6: Self assessment - these abstracts should make sense: translations and rotations (1, 2, 3). Spherical trig (see Butler's appendix) and stereonet (web bonus: dot product) 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. 2/8: Assignment; APW paths. Transforms (1, 2), 2D tectonics, relative velocity vectors. More transform faults (Isacks_Oliver_Sykes), Euler poles, hot spot tracks (1,2), hotspot reference frame, true polar wander(1, 2). 2/13: Vector review & Paleomagnetic Euler poles (figure). 2/15: Local paleomagnetic
examples (Doughty, Jolly, Brunt, Sheriff).
Then a quick: Curie
temperature & magnetic minerals.
Spring Semester 2011:
2/16: Buried dipole
applet & NW Montana, magnetic
anomalies vs latitude (1,
2,
3, 4).
Magnetic prospecting; Montana
aeromagnetics (with
geology, data, grid)
HRAM example Grauch
& Hudson, 2007 (field,
faults). Total field (scalar) anomalies, fluxgate,
proton
precession (2)
and cesium
vapor magnetometers - details
from GEM Systems. 2/23: Your presentations and problems for next week (the spreadsheet, Solver demo, xls) and a quick look at vector end point diagrams (vector mixing, components). 2/28: Poisson's relation, then 2D, 2.5D, and 3D modeling: Talwani algorithm, 3/2: Discuss the homework, a new problem set, then: Software: pblock, pdike, (Cooper's Software, mine). And maybe Fourier series and filters in the frequency domain - high pass, low pass, bandpass, notch, and threshold. (better images: Fourier_demo(.ppt). 3/7: Return problems; Euler Pole prob-xls; Fourier examples: my.ppt, Fourier series applet, Fourier transform applet, 2D power/amplitude spectra. Good definitions & explanations: Fourier series and transforms. 3/9: 2D power/amplitude spectra (the filters). Magnetics of a randomly magnetized layer (filters: depth,{you could compare pblock}), radial averages, upward continuation (ppt, pdf) & separation filtering (data). Frequency filtering of potential fields. 3/14: Separation of regional/residual and qualitative depth to source; magnetics of a random layer with slope~depth; radial averages. 3/16: Instrument precision & stacking (.xlsx, signal/noise);
separation of regional/residual;
statistical methods (Spector & Grant Figure (1,
2)). Applications: Acquisition,
gridding
& contouring (figure:
4 methods) with Surfer
(data); the
USGS extensions
to Oasis
Montaj: decorrugation (PowerLine),
upward continuation (Yellowstone
Lake#5), RTP, radial power spectra (MYAP data,
grid); 3/23:Public
data (Geonet;
MT_Geol.kmz; NW_Montana
(dat, grd,
kmz); Beaverhead
(mag, grav)).
3/28: MIDTERM - in class 3/30: Questions and some more lab stuff:
4/11: Edge detection: First vertical and second vertical derivatives, HGM, analytic signal (low latitudes), local wavenumber, tilt derivative. 4/13: More edge detection, fabric analysis: compare 2VD, HGM, AS, TiltD; and disk w/ Montaj.
4/20: Edges and enhancement - good Grauch .ppt. Depth estimates: slope half-slope (example). Euler deconvolution (figures: 1, 2, low latitude); least squares/simultaneous equations explained. Example - calculate for Stevensville grid and compare the inverse result. 4:/25: More Euler deconvolution - finish our solution on clipped grid then into Voxler; example figures:(sphere, combined solutions, low latitude); informational papers: 1, 2. 4/27: Euler results from an operational computer: Euler.dat, Stevi.wmv. Werner deconvolution (Stevi example). MAGCAD in DOSBOX (mount c c:\) - forward models! Models from Surfer. 5/2: Depth estimates from the analytic signal and horizontal gradient. Curvature/special function depth analysis; from Phillips et al., 2007 on curvature. Assignment: read for self assessment and discussion: Li et al., 2005. 5/4: Gridding-MacKenzie Dikes @ 100m_kmz; the grids (100m, 1000m), sampling/gridding.ppt, Stevi-Werner example. Magnetic modeling using models from Surfer and PFmag3D (program) from R. Blakely in the USGS DOS software collection; Faulted Dome (function, model, TMI). Using Phillip's Special Function Depth Analysis in Oasis. 5/10: Final Exam: 3:20 - 5:20, Tuesday 5/10 - we'll meet for discussion but the TAKEHOME EXAM is due Thursday at 6:00 PM by email (to allow color figures; you can print it if you'd rather). Recreational inverse solutions from UBC-GIF: Philipsburg Batholith (Pburg.ppt,.wmv, .wmv2, Darby.wmv) and then invert the faulted dome model (zipped). The Spring 2011 course
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