I suggests the use of magnetometer with SQUID sensor. This equipment are very expansive, but presents high sensibility. I have the new system by Quantum Design (VSM-SQUID), The accuracy of this system is 10-8 emu.

I have taken a breif look at this manual and it appears to focus on very elementary manetostatic calculations with quantitative assesments extending only as far as the dipole approximation which is then supplemented by some qualitative sketches of field measurements for highly symmetric geological structures. In your question you state " I am looking to model magnetometer response, in order to constrain an actual magnetometer data set with different geologic scenarios." The most ambitions interpretation of this sentence is that you hope to combine several sweep measurements into a competed 2D contour slice of the field at the Earths surface and from this back out the geometry and/or magnetization of the geological structure. To do this, you must scale the problem from a known dipole result (that can easily be handled by a spreadsheet) to that of a more general Maxwell Equation problem (ie: you may need to pull out your PDE solver). Also, I doubt that a single 2D slice is sufficient to fully map out the deposit in question. However, assuming uninformitiy of the deposit with a known (linear) susceptibilty I think quite a bit of traction can be acquired. For one, homogenaity of the linear media will allow you to reduce this to a boundary value problem with a known general solution in the form of Legendre polynomials (this is effectively a full multipole expansion of the entire problem at hand, instead of a simplistic dipole assumption). I don't know what software is available for geological application, and I would not know the limitations and applicability of such software unless I began writing the software myself since my studies focus on static and dynamic magnetic fluctuation at the level of exchange between atomic sites in crystalline solids. To much better understanding of the maths needed can be gained from an introductory E&M book. For instance, read Ch.3, Ch 5, and Ch. 6 of Griffiths. Hope this helps, and pm me if you have any questions.

Gentlemen, Thanks for the answers. I am modeling epithermal gold-bearing veins, so I can assume (and document, in some surficial cases) a general geometry and moment. I know where the main veins are based on field mapping. I've got 15 1-3 km transsects all run at 12 meter spacing perpendicular to the general vein strike. Dips are near vertical. The general purpose of the mag survey was to identify additional veins locations--the purpose of the modeling is to better understand the mag response I'm seeing in the data. For instance, I'd like to understand if some responses may represent larger (5 m wide) single veins or wide swarms of thinner (

In Blakely, 1995 you will find a good and complete compilation of methods of interpretation. In addition, the book contains at the end listings of subroutine referred to in the text.

Blakely R.J., 1995. Potential theory in gravity and magnetic applications. Cambridge University Press. 435 pp.

There are a number of geophysical textbooks that have parametric models of thin sheets/dykes/prisms, which can be spreadsheet or MATLAB modelled (eg Telford et al and Parasnis are exploration focussed). To answer some basic thickness/depth matching of field data questions such analytic modelling will do - given the basic trade-offs with magnetic modelling. With respect to dedicated software I'm not familar with the free stuff as I usually use Modelvision; however, these are free:

Noddy (well known and used by professional explorers) http://www.tectonique.net/tectask/index.php?option=com_content&view=article&id=23&Itemid=70

and

CHRISDBF (that past geophysics students have used) http://www.chrisdbf.com.au/

They are all "black box" in that the specific algorithms are not disclosed, but the algorithms used to model potential field data isn't really that complex or prone to arcane artifacts. Just model some textbook examples and verfy that the code matches the analytic response if you have doubts.

You will need to guess the susceptibility of the materials or have some sample measurements. Telford et al has fairly comprehensive tabulated data to begin with the starting values and these can be refined by trial and eror quickly if your structures come to the surface. If your veins don't come close to the surface then your initial guess will be more important as there are too many variations that will fit the data.

For free modeling software that is easy to use go to:

http://www.wits.ac.za/academic/science/geosciences/research/geophysics/gordoncooper/6511/software.html

You can refer to the Geological Society of India's Memoir entitled "Gravity and magnetic interpretation in exploration geophysics" written by Dr. I. V. Radhakrishna Murthy for basic theories of modelling and inversion of gravity and magnetic anomalies along with some functions and subroutines written in FORTRAN language for many of geophysical models.

the function TSHEET for modelling sheet/vein like bodies from magnetic anomalies and TSHEETIN for modeling the same by inversion are most useful for your purpose.

http://www.vectornav.com/support/library/magnetometer