The SEG dictionary (Sheriff, 1991), spake thus:

1. A deviation from uniformity in physical properties; a perturbation from a normal, uniform, or predictable field.

2. Observed minus theoretical value.

3. A portion of a geophysical survey, such as magnetic or gravitational, which is different in appearance from the survey in general.

4. A gravity measurement which differs from the value predicted by some model, for example, a Bouguer or free-air anomaly (q.v.).

5. In seismic usage, generally synonymous with structure. Occasionally used for unexplained seismic events.

6. Especially, a deviation which is of exploration interest; a feature which may be associated with petroleum accumulation or mineral deposit.

7. An induced polarization anomaly is usually positive and greater than background (or the normal effect) to be economically interesting. In the frequency domain an anomalous region has a resistivity which decreases with frequency. An interesting re s i s t i v i t y anomaly is generally smaller than background.

Well, fine. These specific points are useful, as far as they go. But what do they add up to? Item 2 only seems to mathematize item 4, but 4 is unaccountably restricted only  to gravity surveys. And is an anomaly source generally a structure (item 5)? Is a geophysical anomaly the same as the geologic feature which is its source (items 1 and 5), or are these phenomena of different categories? Are only those anomalies deemed of exploration interest worthy of the title (item 6)? Why different anomaly definitions for different survey types?…”

Henry Lyatsky about it: http://www.cseg.ca/publications/recorder/2004/06jun/06jun-meaning-of-anomaly.pdf

In this 2010 year the program Targeted Geoscience Initiative (TGI-3) is finishing. The Government of Canada committed $25M over five years to extend the mission of the Targeted Geoscience Initiative Program with a focus on base metal reserves in established mining communities. And through the TGI-3 program, additional petrophysical data will be added to the database for the TGI study areas (Southern B.C., Cantral Manitoba-Saskatchewan, Central Newfoundland, Abitibi, Ontario-Quebec, Bathurst, N.B.).

The National Rock Properties Database (NRPD) has been in development since 1998 and was initiated through a partnership between Noranda, Falconbridge, the Geological Survey of Canada, Quantec Geoscience Ltd, and Mira Geoscience Ltd. The result of the original development was a fairly complete data model and interface for the maintenance and query of rock property data collected using wireline geophysical methods. Through a partnership between McMaster University, MIRA Geoscience, and the GSC through the CAMIRO Project in 2004-05, the NRPD data model was extended to include rock property data measured on rock samples, definitions of universal lithology and alteration classifications for geological description.

The NRPD resides in an Oracle database. The database currently contains over 5 million rock property data records. Key parameters of each dataset include location coordinates, so that data can be queried by region, as well as geological attributes. The parameters currently available for query are Caliper, Conductivity, Density, Gamma, IP, Magnetic Susceptibility, Neutron porosity, Potassium, Resistivity, Self potential, Self potential gradient, Uranium, Temperature gradient, Temperature, Thorium and Acoustic velocity.

Source: http://ess.nrcan.gc.ca