Madaras László – Szabó László – Tálas László szerk.: Tisicum - A Jász-Nagykun-Szolnok Megyei Múzeumok Évkönyve 8. (1993)

Sümegi Pál: A jászfelsőszentgyörgyi szunyogos felső-paleolit telephely üledékföldtani és sztratigráfiai elemzése

Fig. 4. Characteristic granuiometric composition curves the excavated sediments 3.0.2 - 0.3 m 5.0.4 - 0.5 m 7. 0.6 - 0.7 m 8. 0.7 - 0.8 m 10. 0.9 - 1.0 m 13. 1.2 - 1.3 m of . ábra A feltárt üledékrétegek jellegzetes szemcseösszetételi görbéi 3. 0.2 - 0.3 m 5. 0.4 • 0.5 m 7. 0.6 • 0.7 m 8. 0.7 • 0.8 m 10. 0.9 - 1.0 m 13. 1.2 - 1.3 m investigated region. This made also the finer dust to be bound and a band of finer granuiometric composition had been developed (Fig. 3. 0,7-0,8 m). The sediments of the fluctuation level with their carbonate content (4-18 %) are well distinguishable from underlying drift sand free of carbonate. The higher carbonate content of the formations covering the dune sand is most probably caused by a more intensive biogene produciton (Figs. 4 and 5). The level 3. is between 0,3 and 0,6 m in the investigated profile. Sediment statistical parameters suggest that the energy of the settlement medium had decreased and a poorly sorted carbonate (15-19 %) brownish yellow (5Y 7/3) loessy finegrained sand with coarse-grained silt deposited. The sedimentary level 4. is a greyish brown (10YR 5/2) solified fine-grained silt with coarsegrained silt (Figs. 3 and 4). This soil level is at a depth of 0,3 m below the surface. Originally the sediment was a sandy loess but during soil formation processes the granuiometric composition had changed to be finer. Because of tillage this level is highly disturbed. Sedimentary geological investigations were completed by 18

0 and 13

C isotope investigations made on the undisturbed carbonate sediment samples of the sequence (Figs. 3 and 5). The results demonstrate that the section between 0,3 and 0,8 m of the profile had been developed under relatively homogeneous paleoecological conditions. At the same time the isotope displacement (

13

C) of carbonates which came to light from soil differs considarably from this, first of all because of the biogene C0

2 production since one of the prerequisites of soil formation is the appearance of a considerable surplus amount of C0

2 which is the result of an increased activity of edaphic organisms due to favourable ecological conditions. We may confirm the abovementioned facts by presenting our data on a MANZE diagram (Fig.5) displaying also genetic relations. It is clear that loessy sand, sandy loess and loess samples are accumulated in the range of Central European loesses while the data of two soil samples are in the range of soil formed over loess. Having a koowledge of Brunnacker, K. et. al.'s (1980) isotope displacement data for loesses in Hungary it is also clear from the diagram that the loessy sediment at Jászfelsőszentgyörgy was deposited under a cool climate, though not in the coldest climatic phase. Most probably this climate was more humid, because as regards the 13

C factor it differs from data yielded by loesses for68