Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 82. (Budapest 1990)

Dulai, A.: The Lower Sinemurian (Jurassic) brachiopod fauna of the Lókút Hill (Bakony Mts., Hungary). Preliminary results

So the quantity size of brachiopods B I I I II 1 I I I I was resedimented into the basin along the slopes (GALÁCZ & VÖRÖS 1972). The examined sequence shows a basin-margin facies, resedimented to a great extent (Fig. 8a). By developing newer stepped faults, the source area gets more and more distant from the deposition area, in the B - C interval of the redeposited sediment, as well as the number and decreased, but the disintegration increased because of the longer transportation (Fig. 8b).In the D interval every tendency turns to the opposite. We could explain this fact that the area emerged again, but it can be seen in the sequence, that the first chert nodules appear immediately above the D interval (Fig. 2a), i.e. the area subsided further. Another possible explanation: a new emerging area appeared, that is a new source area in the neighbourhood, which increased again the degree of sediment transportation. (Fig

. Be

). This idea is supported by that examination, which shows the distribution of the most abundant species along the sequence (Fig. 9). It can be seen, that many species are found in all the four intervals, at the same time, some species enter only in the D interval (

Liospiriferina obtusa 2 , Prionorhynchia polyptycna

) or become frequent tHere (

Securina partschi

). . That is, the fauna of the new plateau slightly differs from the fauna of previously already existed plateau. The case of Cunei- rhynchia ? cartieri also demonstrates this difference, from which enough specimens were found to be worked up statistically (Fig. 10). On the diagram I described the width/convexity ratio of specimens in the function of the length. It can be seen, that with the exception of one point, the points construct two separated heaps. The almost round species in the A - B - C. intervals, levels out in the D interval. The possibility arises, that a ff I I I èiu 11 •! Fig. 9. Distribution of the m

ost abundant species along the sequence (tÊÊÊÊÊ species are found in all intervals, W2Z& species appearing or becoming frequent in the D interval )