Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 99. (Budapest 2007)
Embey-Isztin, A. ; Dobosi, G.: Composition of olivines in the young alkali basalts and their peridotite xenoliths from the Pannonian Basin
Though in many cases the calculated equilibrium composition is nearly the same as the measured olivine phenocryst composition, there are rock samples where it is more basic, or on the contrary, considerably more evolved than the measured composition (Fig. 9). If there is coincidence between the two variables, it means that the olivine grains are genuine phenocrysts and the crystallization took place in a closed system. These rocks are not necessarily primitive, however the separation during the fractionation must have been complete, so that earlier formed grains are not represented in the present phenocryst population. According to our data set, the following basalts belong to this group: Halom-hegy, Hegyes-tű, Kovácsi-hegy, Szigliget, Tátika, Kab-hegy-Torma-rét, Uzsa, Zalahaláp in the Balaton region, Central Range; Ság-hegy in the Little Hungarian Plain; Pál-hegy in Burgenland; Selmecbánya, Dobra Niva and Brehy in Slovakia. In a few cases (Brehy and Konradovice), the composition of the most primitive olivines is similar to the composition of "mantle" olivines and at the same time, it corresponds to the calculated equilibrium composition as well (Fig. 9). Probably these rocks represent an unfracionated primary melt that could have been in equilibrium with mantle peridotite. Fig. 10 also shows those basaltic rocks in which the olivine phenocrysts are richer in iron than the calculated equilibrium composition. To this group belong the basalts of Klöch and Steinberg in Styria; Szilvás-kő and Podrecany in the Nógrád district. In these rocks the formerly precipitated olivine could have reached a new equilibrium - at least partially - with an already evolved melt phase, the composition of which is probably represented by the ground mass. Fo in olivine Fig. 9- Frequency distribution of forsterite (Fo) molecule content in the cores of olivine phenocrysts from different Pannonian alkali basalts
