SEA BAS IN MINERALS IN THE NORTH

takes place in two different diagenetic settings, deep burial and acidic weathering. These are characterized by different orders of mineral stability: apatite, chloritoid, garnet, sphene and spinel are less stable in acidic weathering than in deep burial, whereas the reverse is true for andalusite, kyanite and sillimanite. Heavy-mineral dissolution patterns, therefore, do not follow one single order of stability but several, depending on the diagenetic environment i which the dissolution occurs. It seems from this that the relative order of stability for detrital heavy minerals i controlled by the chemistry of the interstitial waters, whereas the limits of persistence depend on pore-fluid temperature, ate of water throughput, and geological ge. Because different diagenetic environments lead to differing orders of mineral stability, it may prove possible to elucidate certain aspects of the diagenetic history of a sandstone by heavy-mineral dissolution patterns. Prior to 1940, heavy-mineral nalysis was the most frequently employed technique in the petrological study of sands and sandstones, with heavy-mineral suites used as correlative tools and as direct indicators of the nature of sediment source areas. Little regard was paid at this stage to the pioneering work of Edelman (1931) and Edelman & Doeglas (1931, 1934) which demonstrated clearly that many detrital heavy-mineral species are not stable in the diagenetic environment. In the early 1940s, however, the stability of detrital heavy minerals in sandstones was questioned openly, with the virtually simultaneous publicatio