Formy występowania skupień minerałów ciężkich na plażach Pomorza Zachodniego

Abstract

OCCURRENCE FORMS OF HEAVY MINERAL ASSEMBLAGES IN BEACHES OF WEST POMERANIASummary The article deals with the results of the observations carried on in 1967 within certain selected parts of beaches at the Polish Baltic sea shores. Described are the occurrence forms of the enrichments found in beach deposits at Ustka, Darłówek, Mielno, Ustronie Morskie, Dźwirzyn, Niechorze and Trzęsacz. The process of formation of placers is presented, and the results of granulometric and mineralogic analyses made of concentrated and non-concentrated sands are given. Analysed was the fraction from 0.25 to 0.1 mm. According to numerous authors, the formation of placers is mainly a result of dynamic influence of waves, and, to a small degree, also of wind activity on sea shore. It is possible, too, that enrichments can occur within the Littorina cliff zone, as well. The size of an enrichment is a function of the enrichment processes closely related to the dynamics of the sea shore processes. The authors line to an opinion that the areas characterized by more intense enrichment are found within the abrasion areas, whereas the accumulation areas are poorer. The mineral composition of the series enriched in heavy minerals also depends upon the course of writing process. However, the authors are of the opinion that along the Polish sea shore no regional mineralogic differences may be observed in the series considered. The types of the enrichment observed are shown in Tables I-VI. Both grain size and mineral composition are illustrated in Tables 1 and 2. The enrichments in heavy minerals found to occur in the beaches of Polish Baltic sea shore appears as small lenses of sands, only several ten to several hundred metres in length, about 30 cm in thickness, and 3-5 m in breadth. It seems that these dimensions are typical of small, closed basins without outlet.