If subsurface geologic data are available and reliable, compare with surface survey results. Is there a relation of subsurface mapping with surface geochemical features?
Check for topography and soil-type from surfical geological/ agricultural maps: Many SGE data is surface-type related. This does not necessarily imply complete uselessness of the survey; however, surface factors may strongly influence the SGE pattern in question, meaning that many “anomalies” could be false positive anomalies. Make sure you own or have access to the raw data. Raw data and machine data outputs can be re-evaluated later or independently. If you receive and accept processed data only, there is little or no chance to ground-truth field data. It is an open secret in this business that some methods built up smoke screen in order to confuse the issue and to prevent detailed raw data reconstruction.
