calcrete sampling, page-2

looks like the SA government has done its bit to develop this methodology:

http://www.pir.sa.gov.au/minerals/geological_survey_of_sa/geology/geological_provinces/gawler_craton/gawler_calcrete

Gawler Calcrete Re-Analysis Project

The use of calcrete sampling as a surface geochemical exploration technique developed from research conducted by AMIRA (Australian Minerals Industries Research Association Ltd), which was a collaboration between CSIRO and sponsoring mineral exploration companies.

The aim was to detect gold deposits concealed under cover or in deeply weathered environments. Research undertaken in the late 1980s and early 1990s demonstrated that calcrete is an important, readily identifiable sampling medium (Lintern 1997).