Heavy mineral composition of the Lanaittu Sandstone in Eastern Sardinia, Italy

Analyses of Lanaittu Sandstone (middle-upper Campanian, Eastern Sardinia, Italy), recovered from a geognostic well cored in 1989, permit reconstruction of the paleogeography of this area. Heavy mineral associations were analyzed in the 60-250 μm fraction of selected arenites. Samples were crushed and sieved to <4 mm, then disaggregated by etching with 10% hydrochloric acid to remove carbonate and apatite. For gravity separation, tetrabromoethane (density 2.967 g/cm³) was used. The ribbon method was used for quantitative analysis until 200 transparent grains were determined (Gazzi et al., 1973). The transparent heavy mineral assemblage includes rare glaucophane-crossite combined, up to 13% kyanite, and trace amounts of lawsonite, indicating a HP-LT metamorphic source.