Geochemia wapieni oolitowych najniższego triasu zachodniej Polski (otwór Gorzów Wielkopolski IG 1)

Geochemical analyses performed using the Cameca SX100 electron microprobe included 10 uncoated thin sections of oolitic limestones selected for their microfacies representativeness in the entire section. These involved various carbonate components including primarily calcite components such as ooid nuclei and their cortexes, various generations of cements, stromatolite laminae and (post)biogenic calcite (skeletons/bioclasts), as well as small secondary dolomite inclusions that replaced the calcite components during diagenesis. In general, the individual components of the oolitic limestones show slight differences in the content of the subordinate elements studied (Mg, Sr, Mn, Fe, Na, K, Si, Al). The calcitic components are composed exclusively of low-Mg calcite (ca. 0.5wt % Mg), usually with a small admixture of Sr (400-1500ppm). It seems that the diagenetic processes led to homogenization of the chemical composition of the limestones. Synsedimentary calcite components (ooids, fine-crystalline cements, skeletons of organisms) probably originally contained more magnesium, which, when released during diagenesis, contributed to small-scale dolomitization. Differences in Sr, Mg, Fe, Mn contents are the result of changes in the solution chemistry during sedimentation and different stages of diagenesis. Changes in the content of elements such as Al, Si, or K can be correlated with the presence of admixture of aluminosilicate minerals, such as clay minerals. Ooids are enriched in these elements and the products of later diagenesis, such as blocky cements, are depleted.