| Popis: |
The following idealized formula relates the metal content of an anomalous stream sediment sample (Mea) and the upstream drainage area (Aa) with the grade (Mem) and the surface area (Am) of the mineralized area, provided the background (Meb) is known and constant: MemAm = Aa (Mea — Meb) + AmMeb In deriving the formula, the assumptions are made that within the area represented by the anomalous sample, erosion is uniform and there is no more than one anomalous source, no sampling error, no contamination, and no feedback of metal between sediment and water. The degree to which the ideal formula is approached in actual practice has been checked by field observations at four recently discovered porphyry copper deposits — Cerro Colorado, Casino, Chaucha and Rosemont. It is concluded that within reasonable limits, the assumptions are valid and that the formula has potential applications in the planning of sediment sample layouts, and in the interpretation of sediment sample data. |
