Geologic setting and palynologic examination of the Vistulian sediments at Koźmin near Turek, central Poland

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Geological Quarterly, 1999,43 (1): 85-98

Geologic setting and palynologic examination of the Vistulian sediments at Kozmin near Turek, central Poland

Jacek FORYSIAK, Grazyna MIOTK-SZPIGANOWICZ, Joanna PETERA

Forysiak J., Miotk-Szpiganowicz G., Petera J. (1999) - Geologic setting and palynologic examination of the Vistulian sediments at Koimin near Turek, central Poland. Geol. Quart., 43 (I): 85-98. Warszawa

Several alternating organic-mineral and mineral beds of the Vistulian, accumulated by a braided river, are recorded from outcrops of the Adam6w open-cast mine. They have considerable lateral extension and are underlain by the Wartanian till. Sedimentary structures and lithologic analyses prove varying-energy conditions during formation of the mineral series. The organic-mineral series (organic silts and peats) is an effect of a low-energy flow. Palynologic examination does not allow to establish the age relationship between these sediments and particular warmings during the Vistulian.

Jacek Forysiak, Joanna Petera, L6di University, M. Sklodowskiej-Curie 11, 90-505 L6di, Poland; Gratyna Miotk-Szpiganowicz, Gdansk University, Dmowskiego 16A, 80-952 Gdansk, Poland (received: November 11,1998; accepted: January 26,1999).

Key words: central Poland, Late Pleistocene, Vistulian, fluvial deposits, organic deposits, pollen analysis.

INTRODUCTION

The Koimin outcrop in the Adam6w open-cast mine is located in an extensive alluvial plain in western part of the Uniej6w Basin, where a meridional segment of the Warta River valley flows into the Warsaw-Berlin Pradolina (Fig. 1).

The plain is occupied by numerous small streams that join the Kielbaska and Teleszyna Rivers; these in turn are the tributa- ries of the Warta River. The following Cainozoic deposits are displayed in the outcrop: the Tertiary series (about 20 m thick) with a brown coal bed, covered by sands and silts, and the Quaternary series (about 30 m thick), a composition of which is predominated by the Neopleistocene and the Holocene sediments. Investigations at Koimin have been conducted since 1995 by a team led by Professor Halina Klatkowa. Initial information, interpretation and stratigraphic suggestions ca- me outin 1996 (H. Klatkowa, 1996; H. Klatkowaetal., 1996).

The paper presents geologic records and results of palynologic analysis of organic-mineral deposits of the Yistulian (J.

Forysiak et al., 1998).

Outcrops at the Adam6w opencast mine, along with numerous geologic records, provided a base for a study con-

cerning geologic structure of the area surrounding Uniej6w and Turek. According to J. Czarnik (1972), the coal horizon in the vicinity of Turek is covered by the Pliocene grey-green clays, fine grey sands, grey clays with organic remains and grey-green clays. Among the Quaternary deposits, he noted relic tills of the South Polish Glaciation and two series of the Holsteinian Interglacial. The Middle Polish Glaciation was represented by varved clays, fluvioglacial sands and gravels, tills of the maximum stadial and interstadial deposits, followed by varved clays, glaciofluvial sands and gravels, and the Wartanian tills. During the maximum stadial, intensive gla- ciotectonic deformations occurred but they probably disappe- ared during the Wartanian. The Eemian Interglacial was represented by few phases of erosion and valley accumulation of vari-grained, mostly sandy deposits. During the Yistulian Glaciation, erosion and accumulation of glaciolacustrine and fluvial deposits occurred, accompanied by aeolian processes.

Geologic record at the Koimin outcrop is close to the sequence presented by J. Czarnik (1972), although his sequence presents a general picture of geology in the vicinity of Turek. The Koimin outcrop displays the Quaternary sequence, 30 m thick, predominated by the Neopleistocene and the Holocene sediments. The Tertiary deposits above the brown

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86 1. Forysiak, G. Miotk-Szpiganowicz, 1. Petera

D

Vistulian Pradolinas

Fig. 1. Location of the site Koimin against limits major of the last ice sheet and pradolinas (after S. Kozarski, 1988)

coal bed are glaciotectonically deformed. A subsequent sig- nificant erosive tendency is evidenced by truncation of these deformed deposits. The erosive surface is mantled with sandy and sandy-gravelly or silty deposits, or individual patches of the Wartanian tills. A till in the Kozmin outcrop is grey and is usually 2-5 m thick. In some profiles a till concordantly overlies the older, mostly the Tertiary deposits. Deposition of a till was followed by intensive erosion, which resulted in considerable reduction or even complete destruction of the till itself.

In a southern part of the Uniej6w Basin, within the Tele- szyna valley which adjoins the Warta valley, there are the Wartanian tills to over 20 m thick (H. Klatkowa, M. Zaloba, 1991). At Smulsko near Kozmin there are three tills, in total about 18 m thick (H. Klatkowa, 1992, 1993). The till in the Kozmin outcrop seems to correspond.to the Wartanian till at Smulsko. Petrographic coefficients O/K, KIW and AlB (after J. Rzechowski, 1991) for the till at Kozmin are equal to 1.51, 0.7 and 1.31, respectively, and content ofCaC03 is equal to 10.5-14.5% (Fig. 2). Values for a till from Smulsko are almost the same (H. Klatkowa, 1992, 1993). Long axes of clasts in tills have also a similar orientation. The Wartanian age of a till from Kozmin is confirmed by thermoluminescence dating at 160.1±24.0kaBP.

In the western part of the area, A. Mankowska (1980) noted glaciofluvial sands of the Vistulian. As an alternative opinion, these sands have been correlated by P. Klysz (1980, 1981), and P. Klysz and W. Stankowski (1986) to the Middle Polish Glaciation. The latter would agree with the idea ofB.

Krygowski (1975) that during maximum extent of the Vi stu- lian Glaciation (the Leszno Phase), the meltwaters flew wes- twards as far as possible and directly within a marginal zone;

otherwise, they flew through a pradolina. Most meltwater sediments remained in a marginal zone, and generated inside many various landforms. Hence, small alluvial fans in fore- land of the Leszno Phase ice sheet and small extent of glaciofluvial deposits southwards are typical. The present studies at Kozmin confirm a lack of glacio genic deposits of the Vistu- lian. Geological maps (A. Mankowska, 1980) and geomorp- hological sketches display terrace deposits of the Vistulian, cut by narrow belts of alluvia of the Holocene.

GEOLOGY AND PALYNOLOGY

Morphogenesis of the Vistulian is manifested in the vicinity of Kozmin by fluvial deposits, achieving a thickness of several metres. The Vistulian series is composed largely of sands, and is interbedded with numerous mineral-organic deposits with considerable lateral extent (a few square kilo- metres). The alternating mineral and organic beds are numbe- red from 5 to 9, and only these are a subject of the present study (Fig. 2); the others are of the Holocene age. However, due to a clear palynological individuality, the horizon 9 is presented for three separate sections (9/10, 9/A, 9/B).

The lowest part of the Vistulian sequence is composed of mineral-organic sediments, which fill an incision in sandy- gravelly series and in a till (Fig. 2: 9/10). Results of a pollen analysis indicate that pollen spectrum of the entire profile is slightly varied and characterized by considerable content of trees (AP equal to 80%): mainly Pinus, Betula, Alnus, Carpi- nus, Picea, Corylus and Quercus, also TWa, Ulmus and Salix.

Such pollen spectrum points out to a temperate warm climate, favouring development of forest habitats. On the other hand, relatively large and constant content of pollen of herbaceous plants (Rosaceae, Umbelliferae, Compositae, Cruciferae), in- cluding heliophilous ones (e.g. Helianthemum, Chenopodia- ceae), proves climatic deterioration in the early Vistulian.

However, a considerable content of the redeposited Ter- tiary material (Nyssa, Pterocarya, Neogenespores) suggests that some other pollen grains might have been redeposited as well. Hence, deposits in this profile should be associated with existence of a closed depression and therefore, it does not seem possible to determine the age of the studied basin (K.

Dyakowska, 1956). For this reason, a diagram of this profile is not attached to this paper.

Deposits of the series 9 and the profiles 9/A, 9/B have a considerable extension and, unlike the above described sediments, they are not confined to the basin. They form a conti- nuous series with a relatively constant thickness of about 2 m (PI. I, Fig. 1). These deposits are underlain by a thin series of

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Vistulian sediments at Koimin near Turek 87

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Fig. 2. Koimin, organic (3, 5, 7, 9A, 9B, 9110) and mineral (6, 8) series in the open-cast brown coal mine

A - Holocene and Vistulian organic and mineral series at the first exploitation levcl, B - the lowest organic horizon at the second exploitation level;

petrographic coefficicnts O/K, K!W and NB,long-axis azimuth of clasts and content of Cae03 in the Wartanian till

medium-grained sands and gravels. Flaster bedding is the most common sedimentary structure, with distinct alternating dark brown layers containing organic matter, and with lighter, more sandy layers, Such deposits are characteristic for deposition in a closed basin or an open basin with a limited water discharge. Infillings underwent cutting; afterwards, similar mineral-organic deposits were collected within intrenchments. Except for stratified structures, there is massive pac- king of structure-less material. Quartz-grain analysis by the method of A. Cailleux (1942) indicates that in fraction 0,6-0.8 mm, there is a similar content of grains RM and EL grains, equal to 20-24%, whereas M grains reach about 46-48%

(Fig. 3).

Within the lowest organic horizon, synsedimentary or post-sedimentary disturbances were found. Sometimes there are slightly undulated structures only, then again layers are more deflected. Elsewhere, deposits of the series 9 are deve- loped as folds, attaining a height of several centimetres.

Sediments from a top of the series 9 are TL dated to 1 02.8±15.4 ka BP, and radiocarbon dated to 32 ka BP. Pollen analysis of the profile 9A (Fig. 4) clearly points out to three individual parts. The lower one presents a high content of trees (AP), ca. 90%. There are abundant pollen of Pinus and Picea, whereas Alnus, Carpinus and Quercus are common. Herba- ceous plants are rare. This part of the diagram is similar to the profile 9110, however, a total of AP is higher, and there is no redeposited Tertiary material.

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88 J. Forysiak, G. Miotk-Szpiganowicz, J. Petera

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B - quartz grain abrasion of the grain size 0.63-0.80 mm after A. Cailleux (1942): RM - rounded mat, EL - rounded glittering, M - mat

An evident change in a palynologic record is connected with a shift from sandy deposits to silts with an organic admixture. Curves of deciduous trees visibly disappear, and contents of Pinus and Picea drops rapidly. A quantity of trees (AP) decreases to 30%, whereas a content of herbs (NAP) increases: mainly ofGramineae, Cyperaceae and heliophilous plants (Artemisia, Chenopodiaceae, Caryophyllaceae) as well as Compositae, Thalictrum and Umbelliferae. Such vegeta- tion changes indicate a climatic cooling. An increasing content of AP at the end of this period is due to more pollen of Betula, most likely Betula nana. Development of a treeless tundra in cool climatic conditions is also supported by occur- rence of plants as Helianthemum and Juniperus. A climatic cooling might have been referred to a stadial of the early Vistulian. Although the curves of trees are similar to the ones of the early Vistulian from Wladyslawow near Turek (K.

Tobolski, 1986), Zgierz-Rudunki (M. Jastrz~bska-Mamelka,

1985) and Imbramowice (K. Mamakowa, 1989), both too low values of NAP (K. Tobolski, 1991) and a further course of curves seem to exclude such interpretation from considera- tion.

Pollen-free sandy deposits at the top of the section are overlain by a thin (8 cm) peat layer, covered with mineral deposits. There is high content of Pinus (up to 76%), Betula (14-20%), and less Corylus and Alnus. There is sporadic polIen of other deciduous trees. At the top of the profile, polIen of trees almost completely disappears. There are great quan- tities of spores of Sphagnum and of polIen of herbs: mainly Gramineae, Cyperaceae and heliophilous plants. Such polIen composition indicates a slight climatic warming and development of an open pine-birch forest which, with progressing cooling, were replaced by peatbogs and a treeless tundra. High values of AP suggest that this climatic amelioration should be referred to the next interstadial than to an interphase rather.

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The picture that emerges from a pollen analysis of deposits in the section 9fB (Fig. 5) is completely different from the one for the profile 9/ A. Pollen spectrum of all samples contains more herbaceous plants (NAP 50-85%).

The lower NAP values were recorded in a middle part of deposits, where content of trees increases, i.e. mainly of Quercus, Alnus, Pinus and Betula. Higher content of Eri- caceae, Artemisia, Compositae and Caryophyllaceae was recorded at the bottom and at the top. Thus, both the bottom and the top ofthese deposits could have been formed under cooler climatic conditions than their middle part. However, particularly at the bottom, single grains of flex aquifolium and Hedera, which are "incompatible" with a general pollen spectrum, indicate contamination by extraneous matter. This is also supported by a type of deposits, containing well-pronounced layer disturbances. Thus, this picture reflects no climatic conditions in deposition of the studied sequence.

The surface between the organic-mineral series 9 and the overlying mineral series 8 reveals erosional features (Fig. 2; PL I, Figs. 1 and 2). Organic-mineral deposits are truncated, so a bottom of the series 8 occurs at more or less constant altitude, about 88 m a.s.L

The mineral series consists largely of sandy sediments.

Horizontal or low-angle tabular cross-bedding are prevai- ling usually at the bottom of the series. Above, sets of trough cross-bedding occur more frequently. Generally, all sorts of stratification which are typical for a high-energy environment of a braided river, can be observed there.

Occasionally, there are silty-sandy layers. A lack of erosional surfaces proves that probably erosion has not occurred. A quartz-grain analysis (Fig. 3) indicates a higher content ofRM (up to 30%) and EL (ca. 18%) grains than in the series 9. Such values may testify an increased supply of wind-abraded grains to a river system; furthermore, glacial debris could have been involved.

The next organic-mineral series 7 occurs at 90 m a.s.L (Fig. 2). Sands of the overlying mineral series are covered by peat, followed by sands and silts. These deposits com- prise the described series and are seriously deformed (PL II, Fig. 1). Downsinking caused undulations of organic sediments, the overlying silty material was in turn updo- med and resulting deformations frequently formed small diapirs. Sandy deposits beneath and above were involved in deformations, and their original sedimentary structures have been destroyed. The organic-mineral series was sampled to radiocarbon datings. The samples were collected wide apart, and gave the two different 14C dates of 24 200±300 and 28 600±260 years BP.

Pollen analysis of the series 7 (Fig. 6) indicates a small content of trees (AP 10-15%) at the bottom. Pinus is the most common tree. It seems, however, possible that in such a treelees environment, some pollen could have been derived from a long-distance transport. Among herbaceous plants there are mainly Cyperaceae, Gramineae, Caryop- hyllaceae and Thalictrum. Abundant spores of Equisetum and Pediastrum are common too. Thus, especially during growing of peat, there was a cool and humid climate.

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Vistulian sediments at Koimin near Turek 93

Pollen spectrum of the younger part of deposits points to presence of Betula; besides, there are some pollen of Alnus, Salix, Picea, Betula nana, Artemisia, Chenopodiaceae, Ra- nunculaceae, Helianthemum and other heliophilous plants.

Such spectrum might indicate slight warming, which is reflec- ted in development of treeless tundra communities with birch and dwarf willow, and with heaths in the youngest period.

Continued cool climatic conditions are indicated by occurrence of microspores of Selaginella selaginoides, which is an arctic-alpine species characteristic for a tundra. Deposition of this series should be associated with a warming during an interphase. The radiocarbon date of24 200±300 years BP for a peat at the bottom of the series, points out to an interphase of the Vistulian Glaciation.

This organic-mineral series is covered with a mineral series 6 (Fig. 2). As the series 8, it is mostly composed of vari-grained sands, though it contains presumably more finer fractions (Fig. 3). There are common sedimentary structures, typical for sandy material deposited in an aqueous environment. Horizontal lamination as well as tabular and trough bedding appear. At the boundary with the neighbouring organic series, deformation caused failure of the original structure of sandy sediments. These deposits do not display any erosional surfaces. Quartz-grain analysis indicates more RM grains, from 25% at the bottom up to 46% at the top, whereas contents of EL grains decreases from 23 to 8%, respectively (Fig. 3).

Grain-size distribution supports varied sedimentary conditions.

The youngest organic series 5 that represents a decline of the Vistulian is located at 95 m a.s.l. It is composed of sand with organic admixture of peat and silt. This series is also seriously deformed. However, in this case, deformations are fashioned in different way. Drop structures, resulting from downsinking of organic deposit, become flat at certain depth, as if spreading over a flat surface below was impossible (PI.

II, Fig. 2). This boundary reveals no lithologic features - within a mineral series, where drop structures sunk, there is no change in the sediment. Presumably, the boundary coinci- ded with a permafrost table. Also crack structures, occurring in the Vistulian deposits and covering often the entire profile (Fig. 2), provide evidence for presence of permafrost. These structures were described by H. Klatkowa (1996) as syngene- tic ones. The youngest organic-mineral series of the Vistulian is radiocarbon dated to 10 200±430 years BP.

Pollen analysis indicates that open pine forest with a slight admixture of Betula occurred at the beginning of deposition (Fig. 7). It is supported by low content of AP (below 50%), and some pollen could have been derived from a long-distance transport. Vegetation was predominated by herbaceous plants, mainly Cyperaceae and Gramineae, and was subjected to a cool climate which has not favoured development of more compact forest communities. Abundant spores of Selaginella selaginoides also indicate such conditions.

Later on, pine forest was replaced by open birch forest with patches of heliophilous plants. These conditions are supported by occurrence of Artemisia, Cruciferae, Chenopo- diaceae and Ericaceae, and particularly by a rise of Betula and simultaneous drop of Pinus. In spite of poor preservation of pollen, distinction between Betula and Betula f. nana was impossible, yet it could be assumed that most grains represent a dwarf birch, therefore an increase of AP does not indicate forest expansion. This pollen spectrum is typical for a cool subarctic climate. Deposits of this series were probably pro- duced during a decline of the Vistulian, thus a radiocarbon dating gave somewhat a younger age.

The top of the series 5 displays an erosional surface which was formed probably in the Holocene. Abundant erosional intrenchments in the outcrop extend downwards to the series 6 and 7. Erosional intrenchments are filled up with sandy deposits, enriched in organic remains. Besides, the Holocene deposits are represented by peats, alluvia and vari-grained mineral sediments.

CONCLUDING REMARKS

Studies in the outcrop at Koimin prove that stratigraphic role of the Vistulian organic-mineral deposits is smaller than preliminary assumed. The present state of investigations ma- kes difficult a precise connect of the organic series with decided warmings. Exclusively, earlier ideas (H. KIatkowa, 1996; H. Klatkowa et al., 1996) on the early Vistulian age of the lowest organic-mineral series 9 have been supported.

However, lack of relations to the Eemian deposits as well as contamination by extraneous matter do not allow for a more precise dating of the sediment. Also, the phase of erosion which followed accumulation of this series does not enable a stratigraphic reconstruction. Pollen spectrum of the organic series 7 does not reveal features which would permit accurate determination of age of its development. Radiocarbon age estimations from this series indicate that it was formed during an interphase, prior to the ice sheet advance during the Leszno Phase of the Vistulian Glaciation. Pollen analysis and radiocarbon datings of the youngest organic series 5 indicate that it was formed during an interphase of the Vistulian decline.

Palaeobotanic and lithologic investigations as well as recorded erosional surfaces point out breaks in deposition during the Vistulian.

In spite of a lack of reliable stratigraphic data, the studies at Koimin provide a base for reconstruction of environmen- tal changes in the Uniejow Basin. Further examination which has been already started may give new information on geologic structure and sedimentary conditions of the Vistulian sequence.

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94 1. Forysiak, G. Miotk-Szpiganowicz, J. Petera

REFERENCES

CAILLEUX A. (1942) - Les actions eoliennes periglaciares en Europe.

Mem. Soc. Geol. France, 46.

CZARNIK J. (1972) - Palaeogeography of the environs of Turek in the Upper Tertiary and Pleistocene (in Polish with English summary). Studia Geol. Pol., 40.

DY AKOWSKA K. (1956) - Pollen spectra of ice-dammed lake deposits (in Polish with English summary). Biul. Inst. Geol., 100: 217-225.

FOLK R. L., WARD W. C. (1957) - Brazos River bar: a study in the significance of grain size parameters. 1. Sed. Petrol., 27 (I): 3-26.

FORYSIAK J., PETERA J., MIOTK-SZPIGANOWICZ G. (1998) - Neo- plejstocenskie osady okolic Turku. Mat. V Konf. "Stratygrafia plejstocenu Polski" (eds. S. Lisicki et al.): 78. Iznota.

JASTRZ~BSKA-MAMELKA M. (1985) - The Eemian Interglacial and Early Vistulian at Zgierz-Rudunki in the L6di Plateau (in Polish with English summary). Acta Geogr. Lodz., 53.

KLA TKOW A H. (1992) - Some indicators of glacial transport directions in Central Poland and their usefulness in defining facial and stratigraphic differences and palaeogeographical reconstructions (in Polish with Eng- lish summary). Acta Geogr. Lodz., 63: 39-80.

KLATKOWA H. (1993) - Some features of the Warta glacigenic deposits in Middle Poland (in Polish with English summary). Acta Geogr. Lodz., 65: 99-166.

KLATKOWA H. (1996) - Symptoms of the permafrost presense in Middle Poland during the last 150000 years. Biul. Peryglac., 35: 45-86.

KLATKOWA H., ZALOBA M. (1991) - The formation of the geological structure and relief of the southern margin of the Uniej6w Basin (in Polish with English summary). In: Przemiany srodowiska geograficznego obszaru Konin-Turek (ed. W. Stankowski): 33-44. UAM. Poznan.

KLATKOWA H., ZALOBA M., FORYSIAK J. (1996) - Nowy profil osad6w plejstocenskich i holocenskich w srodkowej Polsce. Mat. 1II Konf. "Stratygrafia plejstocenu Polski": 17.

KL YSZ P. (1980) - Remarks on the Pleistocene stratigraphy of the area between Konin, Kolo and Turek (in Polish with English summary). Bad.

Fizjogr. n. Pol. Zach., 33: 43-53.

KLYSZ P. (1981) - Morphogenesis of a sequence of marginal forms in surroundings of Konin, Kolo and Turek (in Polish with English summary). Geografia, UAM, 23.

KLYSZ P., STANKOWSKI W. (1986) - RisslWiirm organic series at the Wladyslaw6w test site in vicinity of Turek (in Polish with English summary). Bad. Fizjogr. n. Pol. Zach., 36: 95-105.

KOZARSKI S. (1988) - Origin of pradolinas: a discussion of mistaken ideas. Z. Gletsch. Glazialgeol., 24 (I): 75-92.

KRYGOWSKI B. (1975) - Einige Probleme aus der Morphodynamik des Grosspolnischen Tieflandes (in Polish with German summary). Bad.

Fizjogr. n. Pol. Zach., 27: 89-156.

MAMAKOWA K. (1989) - Late Middle Polish Glaciation, Eemian and early Vistulian vegetation at Imbramowice near Wroclaw and the pollen stratigraphy of this part of the Pleistocene in Poland. Acta Palaeobot., 29 (I): 11-176.

MANKOWSKA A. (1980) - Mapa geologiczna Polski 1:200 000, ark.

Konin, Wyd. A. Inst. Geol. Warszawa.

RZECHOWSKI 1. (1991) - Granulometric-petrographic properties of the till in the drainage basin of the Middle Widawka (in Polish with English summary). Biul. Inst. Geol., 254: 111-155.

TOBOLSKI K. (1986) - Paleobotanical studies of the Eemian Interglacial and early Vistulian, Wladyslaw6w in the vicinity of Turek (preliminary raport). Quatern. Stud., 7: 91-101.

TOBOLSKI K. (1991) - Biostratigraphy and palaeoecology of the Eemian Interglacial and the Vistulian Glaciation of the Konin region (in Polish with English summary). In: przemiany srodowiska geograficznego obszaru Konin-Turek (ed. W. Stankowski): 45-87. UAM. Poznan.

STRATYGRAFIA I ANALIZA PALINOLOGICZNA OSADOW ZLODOWACENIA WISLY W KOZMINIE KOLO TURKA

Streszczenie

Odkrywka Koimin KWB Adam6w znajduje si~ na rozleglej r6wninie aluwialnej w zachodniej cz~§ci basenu uniejowskiego (fig. 1). Powierzchniv r6wniny pokrywajq osady tarasowe vistulianu poci.;te wqskimi strefami aluwi6w holocenskich. W zachodniej cz.;sci obszaru A. Mankowska (1980) wyr6inita piaski glacifluwialne zlodowacenia wisly, natomiast P. Klysz (1981) i P. Klysz, W. Stankowski (1986) wiek piask6w wi'li'l ze zlodowace- niem srodkowopolskim.

Osady czwartorz~dowe odslaniajq si.; na dlugosci 30 m profilu. Domi- nuj'l utwory neoplejstocenu i holocenu. Podscielaj'lje zdeformowane glaci- tektonicznie anast~pnie sci.;te erozyjnie osady trzeciorz~dowe. Nad nimi leiq osady r6znofrakcyjne, m.in. izolowane platy gliny zwalowej zlodowacenia warty. Platy gliny zwalowej w odkrywce Koimin odpowiadajq dolnemu poziomowi gliny zlodowacenia warty z pobliskiego stanowiska Smulsko (H.

Klatkowa, 1992, 1993).

Osady vistulianskie reprezentowane Sq gl6wnie przez piaski, poprze- dzielane poziomami organiczno-mineralnymi, charakteryzujqcymi si~ zna- cznym rozprzestrzenieniem lateralnym (fig. 2, 3). Najniiszy kompleks organiczny 9 (tabl. I, fig. 1,2) rna najwi~kszl\ mi'liszose i w gl6wnej mierze sklada si~ z laminowanych faliscie, cz~sciowo zaburzonych piask6w i mul6w organicznych. Obraz palinologiczny (fig. 4, 5) nie pozwaIajednak na stwier- dzenie czy osady powstaly w pocz<jtkowym okresie vistulianu, czy tei moina je Iqczye z kt6ryms z p6iniejszych interstadial6w. Nadlegla seria osad6w

mineralnych (8) zbudowana jest z r6inofrakcyjnych piask6w warstwowa- nych horyzontalnie i przekqtnie (fig. 2). Wyiej zalega poziom osad6w mineralno-organicznych z torfem (7), zaburzonych postsedymentacyjnie (tabl. II, fig. I). Wyniki analizy palinologicznej wyraznie wskazujq, :i:e w czasie powstawania tej serii panowal klimat zimny, uniemoiliwiaj'lcy rozw6j las6w (fig. 6). Nalezy to Iqczye najprawdopodobniej z jakqs interfazq. Seri~

mineralno-organicznq przykrywajq osady piaszczyste i mulkowe, wykazujq- ce zr6inicowane warstwowanie. Najwyiszy poziom vistuliaIiski w stanowi- sku Koimin to seria osad6w organiczno-mineralnych (5) utworzonych z piasku, torfu i mulku. Wyniki analizy palinologicznej wskazujq, ze badane osady powstaly w zimnym interstadiale bqdi interfazie (fig. 7). Serie organiczno-mineralne 5 oraz 7 majq znacznie mniejsz<j miqiszose (tabl. II, fig. I, 2). Podlegaly intensywnym deformacjom 0 charakterze niestatecznego war-

stwowaniag~stosciowego. W obr~bie serii vistulianskiej rozwin.;ly si~ liczne struktury szczelinowe.

Przeprowadzone badania wskazujq, :i:e rola stratygraficzna osad6w vi- stulianskich jest mniejsza niz zakladano pierwotnie. Obraz palinologiczny nie pozwala naodniesienie poziom6w organicznych do konkretnych okres6w cieplych vistulianu, ale moze bye podstawq do rekonstrukcji ewolucji paleo- srodowiska basenu uniejowskiego. Kontynuowane S<j prace w celu okreslenia specyfiki osad6w oraz warunk6w ich sedymentacji w vistulianie i holocenie.

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Vistulian sediments at Koimin near Turek 95

EXPLANATIONS OF PLATES

PLATEr

Figs. 1, 2. Koimin. The lowest organic-mineral series 9, truncated and covered with mineral series 8; photo H. Klatkowa

PLATE II

Fig. I. Koimin. Organic-mineral horizon 7 with deformations; photo H.

Klatkowa

Fig. 2. Koimin. The uppermost Vistulian organic series 5 with deformations, underlain by the mineral series 6 and covered by the Holocene series 3; photo H. Klatkowa

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fLATf I Geol. Quart., 1999,43 (I)

Fig. I

Fig. 2

Jflcek F0RYSIAK, Grazyna MIOTK-SZPIGANOWICZ, Joanna PETERA - Gcological setting and palynological examination of the Vistulian sediments at Koimin near Turek, central Poland

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Geol. Quart., 1999,43 (1) PLATE II