GEOCHRONOMETRIA Vol. 18, pp 35-40,2000 - Journal on Methods and Applications ot Absolute Chrof/ology

AGE OF GLACIOTECTONIC STRUCTURES ON THE IN THE LIGHT OF LITHOSTRATIGRAPHIC DATA AND RADIOCARBON DATING

2 RYSZARD K. BORÓWKA l, TOMASZ GOSLAR2 and ANNA PAZDUR 'Deparlmenl ofGeolog::; and Palaeogeography, Ins/iW/e of Manne Sciences, Universi/y, Felczaka 3a, PL-71-41 2 Szczecin, (e -mail: [email protected]) 2 Department of RadioisalOpes, Institule of Physics, Silesian University of Technology, Krzywoustego 2, PL-44-100 Gliwice, Poland (e -mail: [email protected][email protected])

Abstract. On the basis of Iithostratigraphie analysis of deposi ts forming lhe Wolin End Moraine as well as radioearbon dating of the intercalations of organie maner found amongst su eh deposils, the age of glaeioteetonie struetures existing in the area of morainie hills was determined. It is claimed that both th e glacioteetonie defor­ mations and the end moraine itself were formed during regression of the last gla­ eiation_

l. INTRODUCnON In this work the authors attempted to determine the age of the Wolin End Moraine and the glaciotectonie The age determination of glaeiotectonic structures deformations existing in its area by referring to some can be achieved up to date with either lithostratigraphic new litho- and biostratigraphical observations. These or morphostratigraphic method (Rotnicki, 1998). In the were also confronted with the results of radiocarbon first one, marked by a greater universality, the age of dating obtained for selected intercalations of organie glaciotectonic structures is derived indirectly by consi­ matter found in the sandy and silty-sandy exposures in dering the age of the you ngest deposits containing these the northern and central regions of the Wolin hills. structures and the age of the oldest deposits covering the perturbed formation_ The seeond one, most com­ 2. GEOMORPHOLOCY monly applied to young glacial areas, puts in relation the glaciotectonie perturbations with the correspond­ One of the most characteristic relief features of the ing marginal zon es which mark the ensuing glaciation Wolin Island are the so called Wolin hills (also known ar deglaciation stages of these areas. The accuracy of as the Wolin End Moraine), reaching the average sueh dating methods is usually not high and does not height of 60 m above sea level with the max.imum height even allow relating the glaciotectonic perturbation of 115 m. They stretch from the environs of Świ ę to u ść zones to given glacial periods. However, the accuracy to the north eastern part of the island, in the direction improves whenever there is a way of absolute dating of Międzyzdroje, to the south western part in the direc­ both the glacioteetonieally di sturbed deposits and for­ tion of Lubin (Fig. 1)_ Geological structure of these hills mations covering these deformations (Rotnieki, 1998). is in certain parts perfectly exposed in the cliffs devel­ Sueh a situation is eharacteristic of the Wolin Island, oped in the northern parts of the hills, on the coast of for whieh as early as in the beginning of this century Pomrneranian Bay, and in their southern parts towards the rafts of Mesozoic rocks were described and identi­ the Szczecin Transgression. The relief of these hills fied amongst the Quartenary deposits together with proves to be particularly interesting. It is composcd of a number of structures disturbing normallayout of bed more and less elongated and elosed depressions havi ng exposures in cliffs (Deecke, 1907). These structures the relative heights of a few tens of metres. The analys is classified by C. Heberman (1913), W. Hartnack (1926) of the Wolin hills relief carried out with a topographi­ and K. Keilhack (1930) as belonging to a group of cal map with scal ing of 1:10,000 allowed discovering glaciotectonic deformations were considered in rclation a elear orientation of these secondary forms (Michalak, with transgression of the last ice sheet (Karczewski, 1997)_ It was also 'concluded that in the northern part 1968) as well as older glaciations (Krygowska and of the island the axes of the forms are oricnted along Krygowski , 1965). the run directions of principal overthrusts_ The Wolin Age o[ glacioleClOnic slructures on [he Wolin !s/and .. .

BALTlC SEA

SZCZECIN BAY G§' 1'1- ~. E1J5 0 8 i::::;::;:;:;: 7 t·;.:-:-:18 1··:::::::::::1"0"

:':0]13 WrWl.. ('.ela" R'j.. o 11

Fig. 1. Geomorphological map of Wolin Island (after a manuscript by A. Karczewski, 1968): 1 - morainic plateau, 2 - eskers, 3 - end moraines, 4 - kames, 5 - melt-out depresions, 6 - scarps, 7 - outwash plains; 8, 9, 10, 11 - terraces o( Lower Odra Valley. 12 - erosional-denudative valleys, 13 - ice marginal valleys; 14, 15 - inland and coastal dunes, 16 - lakes and streams, 17 - research sites, 18 - location of Wolin Island. hills together with their numerous glaciotectonic struc­ glaciotectonic structures covered by f1uvioglacial depos­ tures constitute one of th e youngest marginal zones of its, which form the so called karne plateau, exist here the last glaciation period in Poland. They were usually (Krygowska and Krygowski, 1965; Krygowski, 1967; beLieved to originate from the Wolin-Gardno Phase Matkowska et al., 1977; Ruszał a et al., 1979). The second during which the ice margin is supposed to have run view is difficult to uphold in the light of recent geologi­ along the contemporary coast \ine (Galon, 1968; eaL research which shows that sa ndy series covering the Roszkówna, 1968; Boulton et al. , 1985). More recent re­ glaciotectonieally perturbed deposits is a eover of Late search of the marginal zones of north western Poland Glacial aeoli an sands intercal ated hy Alleród fossil soil seems to cóntrast this view (Lagerlund et al. , 1995; (Borówka et al., 1982, 1986) and that con tradiets the Kozarski, 1995; Mojski, 1995; Rotnicki and Borówka earlier belief which assumed a cover of f1uvioglacial 1995 a,b). The present view suggests that the marginal karne deposits. zone related to the Wolin hills was formed between 15,500 and 14,200 BP. The lower age limit of this mar­ 3. LITHOSTRATIGRAPHY ginaL zone is determined by the oldest swampy-Iacll s­ tfine deposits found at the bottom of the Pommeranian Thanks to the geological researcb and observations Bay and their radiocarbon dating falls in the range be­ carried out between 1996 on th e seaside cliff in the en­ tween 14,060±220 ahd 13,100±300 BP (Kramarska and virons of Grodno and Świętouść it was stated that the Jurowska, 1991). The upper age limit of the Wolin mar­ glacioteetonie exposures inc\ude the fo llowing deposit ginal zone is harder to determine, however it should not series (Fig. 2 and 3): go beyond 16,200 BP, that is the estimated age of the - Cretaceous marls (embedded as gla ciotectonic Pommeranian marginal zone (Pommeranian StadiaL) scales and rafts amongst Quaternary fo rmations); whieb in tum was calculated on the basis of the aver­ - glacial grey till, in some parts also brown; age rate of deglaciation of the last continental glacier - sandy series amongst which appears the marine start ing from its maxi mum reach (Kozarski, 1995). malacofauna characteri stic of Eemian sea (Borówka However, the genesis of the Wolin hills is open to et al., 1999); question. Some authors consider them as Moraine hills - sandy-silty series whieh sporadically feature interca­ thrust by glaciotectonic process (Hartnack, 1926; lations of organie matter and very rarely the lumps Ży nd a, 1962; Bryi, 1972; Borówka et al. , 1982) whereas of gravel with sparse boulders. others share the opinion that only old Pre-Vistulian

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The głac iot ec t onica U y pcrturbed formations might ous slructures charactcristic of dynamie contact with reach n ca rły up to the very hilltops, in partiClJ!ar in their lower Iying deposits are observed. elevation zones. In such locations they are oflen cove­ A series of glacioteclonically pcrturbed formations red by a thin łayer of brown gladal liII with a thickness and the youngest layer of glacial till are usually signifi­ of strata up to a few metres. In the underclay numer- cantly eroded (Fig. 2 and 3). Above this di scontinuity area the following might appear: Grodno - Gosań 1 Depositlonal Stratigraphy Lithology I environment

lłI ....,.... lIIn Gl ~ C Bo o eeoł l an :x::

....lIIn .

toi

....lIIn

g~

lluYiogIacill

ftUYlał (1)

C

. .. ~ aJ 1-----

25 GOO. 300 BP (G,H20S1)r- / 27 100 •. ,3400... BP (Gd-~) - - - > ~ 30 100.600 BP (Gd-12063) lllcualrine 31 ~. 2000 BP (Gd-10622) tIuv.1 !lO > 25 GOO BP (Gd-9933) morine (1) ~ > 26 100 BP (Gd-9948) > 29300 BP (Gd-11376) > 30 \ 700 BP (Gd-9927) ~-----1 > 35 -400 BP (Gd-1 1378)

gl..,;gone

~---

Fig. 2. Generalized Iithostratigraphic log (rom Wolin End Moraine-Grodno Site.

-37 - Age olgłaciol ee LOnie SlnlClUres on l ite Wolin Island ...

- covers of slope deposits; et al., 19R2). Taking into account the li tostratigraphic - deflational pavement; data it is safe to say that the perturbations described - trisectional cover of aeolian sands within which the formed between the Eemian Interglacial and the intercalations of two fossil soils commonly appear; Late Vistulian interglacial. The marine malacofaUlJa thc oldcr one has the features of poorly developed found in perturbed sandy series near Świ n oujści e tundra soi l of Usselo type and originates from (Borówka, Makowska and Cedro, 1999) dates from AlIerod period, whereas the yo unger one was al­ the Eemian Interglacial, whereas the oldest cover of ready forming during Holocene period (Borówka aeoli an deposits dates from the Late Glacial and more accurately from the Pre-Allerod period. ŚWIĘTOUŚĆ

Depositional 1·C Age Stratigraphy lithology environment

soWeeoIlen

aeollan

• 1880:65 BP -1OiLIbOg (Gd.1062)

aeolian

.11590:270BP lOiI/DOII (GcI-e31> eeoIian

~ ~ f-----

c: lU

::J nuvial II) GNdzi'Idz ....ii) VI ~ ~ Iacuotrine """;n8(1) &. > ~ .:-:- CI) ~ "O i-e ::J -=oII) . ~ ~~.~~--j: e ~ ~ . . ~ as E ...... ma" ... (?) CI) ..... O ~ ... W . . . _- ·c --...... _ . ł ...... O O

c: ·0 ·cal nuviogl..:ial as lU (5 1:: * C\l ~ glecigene

ł 'ł'I' ł

Fig. 3. Generalized lithostratigraphic log trom Wolin End Moraine-Świętouść Site.

-38 - R. Borówka et al.

4. RADIOCARBON CHRONOSTRATIGRAPHY the last glaciation period. A number of geologieal and geomorphologieal faets suggest though that the process The exposures in the Wolin e1iff sometimes eontain of glaeiotectonie slructures formation was rather interealations of organie Illatter whose age was de ter­ related to the period of deglaciation of last iee sheet. Illined with the me ans ofradioearbon dating (Table 1). The most important faets are as follows: Radioearbon age of the greatest number of sampies - a elear eonsistenee of orientation of surfaee elements was determined at Grodno station where amongst of end moirane relief (the longer hills axes and de­ perturbed sandy and si lty-sandy deposits numerous pressions with no outtlow) with the orientation interealations of organie matter were found. These of main glaeioteetonie stmetures of the last iee sheet; were usually the aeeumulations of flora debris within - eontinuation of som e disjunetive glaeioteetonie and the e1imbing-ripple eross lamination deposits. A1so thin relaxation struetures within the oldest series of organie laminae interlaeed with silty layers ean be some­ aeolian cover sands for which radioearbon dating times observed (FigA). yieJded an age beyond the Alleród period. Four out of nine deposit sampies taken from per­ The penetration of certain glaciotectonic reverse tu rbed series yielded definite radioearbon dates which fa ults up lo the upper Iying Pre-Alleród aeoli an sands fe li in the interval of 31,140±200 to 25,900±360 BP. (compare Borówka et al., 1982) suggests that the early However, the yo ungest date refers to a earbonate frae­ phase of their deposition still occurred during a term i­ tion. Nevertheless a general eonelusion ean be drawn nating stress, exerted by ice sheet on its underneath. that the si lty-sandy deposils with interealations of or­ The Wolin End Moraine seems therefore to have been ga ni e matter were at least partly aeeumulated during rather uplhrusted during iee sheet retreat (i nstead of advanee) at the end of the lasl glaeiation.

Fig. 4. Gosań profile. G/aciotectonically disturbed /acustrine 5. CONCLUSrONS si/ts with a interca/ations ot organie matter. ~~~~~----~ The litostratigraphic and ehronostratigraphie analy­ ses show that the Wolin End Moraine was formcd during the recession of the last glaciation. Perturbed depo­ sits with Eemian malacofauna as well as younger forma­ tions from the interpJenivistulian period are found in this area. The oldest dated series deposited in ullconformity on glaeioteetonic structures are lhe Pre-A1leród eolian series whieh were formed yet before the eomplete disap­ pearance of glacioteetonie tensions.

REFERENCES

Borówka R. K., Gonera P., Kostrzewski A. and Zwoliński Z., 1982: Origin, age and paleogeographic significance of cover sands in the Wolin end moraine aren , ~orth-\xre s t Poland. Quaestiones Geographicae 8: 19-36. Borówka R. K., Gonera P., Kostrzewski A., Nowaczyk B. and Gd-988227,100 +- 24003400 BP Zwoliński Z., 1986: Slratigraphy of colian deposits in Wolin Island and the su rrounding area, North-WCSl Poland. Boreas 15: 301-309. rabIe 1. Resu/ts ot radiocarbon dating.

Site "e Age [BPI Lab. No. Geologieal situation Aelerenees I Świętou ść K·35 1 880±65 Gd·I062 Aeol ian eover, aeeumulation horizon ol you nger lossil soil Borówka et al. (1 982) Swięt ou ść K·43 11 ,5 90 ±270 Gd·631 Aeol ian eover, aeeumulation horizon ol older lossil soi I Borówka et al. (1982) Grod no·Swidna Kępa 111/96 31.400 ±2000 Gd·l0622 Plant detritus in sand·si~ series, glaeiteetonieally disturbed Borówka et al. (1998 , 1999)

Grodno·Swidna Kępa (1 /981 > 30.700 Gd·9929 Plant detritus in sand·silt series, glaeileetonieally disturbed Thi s paper Grodno·Swidna Kępa 2/98 > 25,900 Gd·9933 Plant detritus in sand·si~ senes. glaeiteetonieally disturbed This pa per Grodno·Swidna Kępa 3/98 > 29,300 Gd·I1376 Plant detritus in sand·si~ series, glaeiteeton ieally disturb ed This paper Grodno·Gosań 0/97 25,9 00 ±360 Gd·12057 Organie layer (earbonate fraetio n) in sand·silt series, This paper glaeiteetonieally disturbed Grodno·Gosań 0/98 > 26,100 Gd·9948 Organie layer (orga nie fraetionl in Sand·silt series, This pap er glaeiteetonieally disturbed Grodno·Gosań 1/98 30,100±600 Gd·12063 Organ ie layer; sand·si~ senes, glaciteeton ieally disturbed This paper

Grodno·Gosań 2/98 + 3 400 Gd·9882 Organie layer; sand·si~ series, glaeileetonieally disturbed Borówka et al. (1998, 27.100 · 2400 1999) Grodno·Gosań 3/98 > 35,400 Gd·11378 Organ ie layer; sand·silt series, glaeiteetonieally disturbed This pa per

-39 - Age oj glacioteclOnic structures on the Wolin Island...

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