Some geological problems of the Southern Baltic Basin

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acta geologlca

polon-Ic~

Vol. 24, No. 1 Warszawa 1974

RYBZARD DADLEZ

Some geological problems of the Southern Ba]tic Basin

.A.BS':lmAACT: On the basis of seismic ;results in the Polish of'fshore sector and of geological knowledge at the surroun'CliDg countries, a -general outline of -the-- geoklgy of the Southern. Bailie Basin is given. Both tectoo.ic sttJcHv1Bion end straUgraphlc sequence are discussed as well as the m()6t imporlJa.n.t geological problems 80 far WlSd.'VIeId are erUnieIraIteid A ~ 'WIitJh 'the North Sea :s.J!n lis riJIIIde _ tib.e

eoncluslon..

An intensive seismic surveying was carried out from 1964 until-1967 in the Southern Baltic Basin in a belt c. 50 km Wide along the Polish coast.

More than 4.400 kIn of profile lines were measured by use of reflection method. Almost Whole sedimentary cover has been mvestigated in the- eastern part of the area studied, with the main reflectors in the Upper Permian (or, partially, at the top of Silurian) and in the Ordovician (Fig. la). In the western part, due to the deterioration of the reflections below the Upper Penman (Zechstein), only the upper part of the sedimentary -cover has been penetrated. Several marker horizons have been traced within this cover (Fig. lb, c).

No deep well has been so far dri1led offshore, nor any other geo- physica!!. method has been applied. The geological interpretation of seismic results must have been based upon the data from adjoining land areas as well

8s

upon dbservations of the dynamic character of seismic horizons.

In view of considerable variabiRty of both the geological sequences and the fades on the southern slope of the Baltic Shield, this interpretation_ remains, however, very hypothetical (Figs 2-4).

In spite of these deficiencies th~ seismic results, together with the numerous geophysical andg~ologica1 onshore data, have conspicuously enlarged our knowledge of theSotithern Baltic-Basin. It is evident that,

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262 BYSZARD D.ADLEZ

apart ~om the explanation of some problems, there has appeared at least the same number of new questions which wait for solution. The bulk of

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b, c) in the owestem part of the area. ~ ref1ectora: P - Ion the ZecbBteiD, E - at the top of Lower BUntsandBteln, D - in dle lIof.uaChe'lkalk. c -- at the boaDdBry Keuper/Rhaetle.

B - at 1be tqp or TdaliSlo

;Map 1IboW. the area of .elImlc IJUrvey

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SOME GEOLOGlCAIL PBOBLJ:lIIS OF 'IlHE SOtJ'TBEBN BAlII'lC BASIN 263

them is of essenltial impol"tance for the possilble exPloration for hydro- carbons. This paper is an attempt to' Compile the data so far received. as well as to outline the aims of the future geological studies in thiS area.

Reference is made to a few Polish papers on the same subject (Dadlez

& MJynarski 1967, 1972; Poi:aryskl. 1970; "Zardecka 1973).

The Southern Ba!ltic Basin .belongs to two tectonic units of the first order. Its greater, central and eastern part constitutes without doubt a fragment i5f the East European Precambrian Platform. The tectonic pOsiotion of the smaller, western part as well as the question of the bo- Undary between 'both parts remaln disputable. That is the most important

probl~ of the area in question.

The siJtuationof the south-western boundary of the Precambirican Platform has 'beE1n extensively discussed in the European geological literature of the last two decades. It is beyond the scope of this paper to review this discussion. It should be only stated here that the majority of POlish authors .(Znosko 1964, 1966; Modliilski -1968; PoZaryski 1969; Teller 1969) is. 'of" opinion' that· the well known Tornqumt-Teisseyre Line (or, more exactly, Tornquist~eisseyre Zone): at least in the territory of Western Pomerania, is generally an equivalcmt of the discussed boun-

darY.

The preSent author shares this opinion (Dadlez 1967'b, 1973)."' - . - BetWeen Koszatin and Ohojnice (Western Pomerania) the TornqUist- -Teisseyre Zone can -be easily traced in" the configuration of high velocity refraction horizons. Along. this zone the strongly disturbed Ordovician and Siluriari strata have been encountered in ·numerous deep wells. These strata, consisting of shales and 9iJ:tstones, occasionally interlayered by . sandstones, are believed to be several thousand 'metres thick. On account

" of the facies, thickness and the high degree of tectonic disturbance these beds a1'e regarded as the miogeosynclinai sediments of the south-eastern branch of the Caledonides. The direct extension of this zone has been in all probability proved by the deep wells in the northernmost Riigen (Jaeger 1967), although the sequence revealed there is interpreted in a different way by some German authors (Franke 1967).

North-east of the supposed folded 'belt the epicontinental sediments of the youngest Precambrian and Cambro-Sil~n are ·known in the area of the Leba Uplift. These sediments spread northwestward through south- -western Bornholm as far as Scania ,(Gry 1960, RegnelI 1960). The Lud- lovian deposits show particularly great thickness in this zone, thus indi- cating a rapid subsidence and quick (synorogenic?) sedimentation in the external, moma.e belt of the Precam!brian Platform.

Taking these facts into consideration it can be a-ssumed that the south-western boundary of the Precambrian Platform runs offshore

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towards WNW ()f Kasza1!in 'and farther about midWay, .between 'ROgeIl and. Bornholm (Fig. 2). However, this assumpti()n is not·yet corifirmed by

the g~ophysical investigations.

The tectonic·~vision.cif. tbe19outh-westem. part of the area is only partly recognized,; mainly due to' the lack of' 'seismic information 'from below the base of the Zechstein. In the Zechstein-Mesozoic 'COver (Fig.' 3).

a complex system of faults exists with <:llsplacements up to 1,500 m (DadIez & Mlynarski 196'1). The prinCipal faUlt zones (SwinoujScie, Ka- mien, Trzebiat6w and Koszalin) divide the. area into ~our·lblocks (WoIin.

Gryfice, KoJ:obrzeg and Dadowo). These fault zones cut .the whole Zech- stet.n-Me~ozoic . cover, Hence. we "may' infer' that they were definitely formed in the Latest Cretaceous or post;-Cretaceous. times .. Nevertheless, these zones, or ~.t" least .some segments oftbem, originated much earlier.

It results, for instance, from the essentiaidiffereI).ce in the .onshore pre- -Zechstein sequences at the both sides Qfthe IS:oszaun fault zone as well . as from the distinct influence ,thi~ zone had on' the rate.of sedimentation in the Zechsteiri and Mesozoic times.

The problem of northern and north-western· continuation' of all these. fault zones is not quite clear as yet (Fig. 3) .. Judging. from the Me':""

sozoic sequences, the· Koszalin fault zone runs fairly. dose to Bornholm . . The faults of the .western and south-western part of this island may be directly. connected with this. zone. The Trzebiat6w fault zone. seems to continue in the faults .wl).ich cut off tbe external horstsof the Pre- cambrian basement in Seania '(Romeleasen horst - Magnusson 1958).

Finally, the Kamien fault zone runs undoubtedly east of Riigen. The regional trend of the discussed fault zones is generany oblique to the presumed boundary of the Precam'brian Platform. This trend reflects the compar;tively young mavelments which have caused the complex pattern of faulted blocks at the auter edge of the Platform; so . distinctly ·visible in the Scania area.

Due to the post-Cretaceous' movement6 which have deeply obli- terated the course of earlier tectonic events, the reconstruction of older faults is extremely difficult. Their directions ate probably nearly W -E.

Late Variscan fault systems of such directions have recently been proved to exist on 'Riigen (.Mbre·cht 1967). They .throw down the pre-Zechstein formations' BOuthwaxds. It seems reasonable to assume that these fault systems continue east of Rilgen. The traces

at

the same regional trend may be represented offshore by an almost W-E strike of some apparently subordinate faults in the Gryfice and Kolobrzeg Blocks (Mrzezyno and Mielno fault zones - Fig. 2). A complicated arrangement of the tectonic blocks consisting of various Devonian and Carboniferous strata, similar to that revealed in the onshore part of the Kolobrzeg Block, is probably characteristic for this part of the 'basin. The mterpretation of these pre- -Zechstein blocks (Figs' 2, 4a, b) is necessarily based mainly upon the

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Fig. 2

Outline geol~cail ma:p IOIf the pre-Zechstein formaltions

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madn f.eu(w aDd fault _ (1 - &wlnouj§c1e, :I - Kamled, 3 - T·rzeblat~, " - Ko82laUn, 11 - Mrzetyno, " Mielno, '1-Gardoo, 8 - Smol- ~ dziIno, 11 -- l.eba; 10 - Bta!og6ra, 11 - oB~e)., U reolog\eal bOundaries, la contours of tbe top of the crntalllne b~t in metres (11--...13

dulled when .~OIIed), I. contours of the aefanlo reflector k1 the 0rd0v1e1«n ~n metre., 16 teGtanic blocIaI (I - 'WOlln, D - Trent, III _ Arlkona. IV - Oryfice, V - <KalQllx'RC. VI - <Dar1owo. VlI - ~-U.tlr.a), U Unel cC crOll aecUOII8 ehQWU on P'iI.'.

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266

tectonic features of the Zechstein-Mesozoic cowr, supposing their posth-

·umous nature.

In the Zechstein-Mesozoic cover of the· area so far discussed no manifestations of the salt tectonics have been MCertained. Block anti- . dines appear 'along the faults (Fig. le). Some of -these anticlines are

~ntirely or partly 'buried, owing their origin to the vertical, contempora- neous with sedimentation, movements of· the pre-Zechstein basement.

·Strong moveme~ts of the Latest Cretaceous and Early Tertiary times, followed by denudation, 'have caused the various Jurassic and Triassic :stages to apPear at the pre-Cainozoic surface on the creSts of anticlines .Fig.3).

The tectonic SIl'bdivdsion of the central and eastern parts of .the basin is fairly simple. In the east the central depression of the Peribaltic Sy- neclise extends from the Gdairs'k Bay northwards along the coast of the

"Baltic Soviet Republics, ThiCkness of the sedimentary cover exceeds 4,000 m near Gdansk (Fig. 2). In the north-west the crystalline rooks oIf the Feamoscandian Shield crop

Out

ontbe coasts of Southern Sweden :and Bornhohn. A broad and gently tilted slope spreads between these outcrops and the central depression mentioned above, the sedimentary .cover .thickening grndually towaros south and south-east. The crystalline basement of this slope is probaJ):;J.y broken ·by the faults of various strikes {Gcilub & Sidorov 1971, see also Fig. ·4e). In the Polish offshore area :several faUlt zones have been ascertained in the Ordovician seismic horizon (Fig. la), their throw ,being generally not more than 250 m. The Rozewie fault zone r'epresents presumably the western border of the central depression ·of the Perlbaltic Syneclise (fig. 2). Very flat anticlines .adjacent to the faults have also been found. They are of post-Si1urian - pre-Zechstein age. The existence of 'buried anticlines of Camlbrian or pre-

·-Ordovician age can not be excluded since BUch anticlines, connected with . mobile blocks of the Precambrian basement, are known on the southern and eastern slope of the Peribaltic Syneclise (Goldberg & Rukhovetz 1970;

Balaszow, Knieszner & Poleszak 1972; Tyski 1973).

The question of south-eastern extension of the Bornholm horst remains unsolved as yet. An uplift of crystalline basement along the line Bornholm-Ustka (Fig. 2) may be probably indicated by the configuration of the Ordovician reflector. This reflector is, however, fragmentary and . problematic in this region.

The Zechstein..,Mesozoic cover of the Precam'brian Platform is very gently cUsturbed. Some of .the· f~ults observed in the Early Palaeozoic horizons may pass upwards either in posthumous faults or in monoclinal folds with displacements of not more than some scores of metres. An e'longated uplift (Shlpsk"'Rozewie, Fig. 3), extending W -E along Polish coast, is of regional importance. The base of the Mesozoic cover lies on its crest at the depth of about 250 m.

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Oubline g~oCal m.8,p of the p.e-Caioozoilc.:formations

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268.

PcA.I...A.EOG®6GAPEIC iPROBTIIllMS

Fundamentai .problems· of the Early Palaeozoic pa1.a:eogeography are dbviously closely related to the problems of the Precambrian Platform bOQlldaTy as well as of the transition zone between epicontinental and midgeosynclinai .:lacies. These !problems have .been diS'CUSSed above.

Epicontinenta'l deposits in the area of the Precambrian Platform. begin with the cong!iomerates, sandBtones and all"koses regarded as. the youngest Precambrian (Vendian?). They crop out on Bornholm (Gry 1960}

and are revealed by' drilling on the f.eba Uplift (Lendzion 1970, Bednar-, czyk 1972), their thickness varying between 30 and 150' m. These sedi-

Iilen~ are 'believed ,to wedge out 'Offshore nor,th of the line: He! Penin- sula - Bornholni.

The 'Cambrian sediments are develope4, in the whole area in an almost homogenous sandy-silty facies and reach their maximum thickness of about 500 m on the f.eba Uplift (Lendzion 1970, Bednarczy'k 1972)~

The question, whether the thiCkness increases gradually southwards of Blekinge and Oland or is reduced locally on the buried anticlines mentioned above, seems to be very essential.

TheOrdawcian on Gotland conSits of limestones whereas in the zone of Scania-Bornholm-l.eba Uplift it is represented by shales, marls and limestones (Sorgenfrei 1969a, ModliDSki. 1973). Their thickness does

not exoeed 100 m. . .

A total of 300 m of Silurian shales and lftnestones occur on Gotland while in the zone of Scania-l.eba Uplift ·the shales prevail in the sequence, their thickness being much more greater, up to 2,000 m in the Leba area (Tener 1969). According to the offshore seismic cross sections the reduotion in thickness northwards of the Polish coast is gradual (Fig. 4c).

In spite of the unconformity at the top of the Silurian, it may be mostly the primary reduction since the sequence both on Gotland and on the f.eba Uplift includes all the Silurian stages. Offshore cross sections also prove that the Silurian thickness increases remarkably towards the central depression of the Peribaltic Syneclise as well as towards the margin of the Precambrian Platform.

The principal probiem of the Omovician-Silu!l"ian palaeogeography in the offshore area lies in the examination of a transition zone between calcareou'S and clayey facies and in detecting of the possible reef barriers.

The. Devonian is developed in Western Pomerarua in two main lacies, the formation thickness exceeding 1,100 m (Fig. 4a. b). The succession in the neritic facies (western

Vcwt

d.f tl1.e Kolobrzeg Block) consists entirely of claystone, roarls and 1i~eston-e8. The near-shore facies (in the Koszalin zone) is represented. by sandstones, shales, limestones (partly reef limestones) and dolomites. The sedimentary record is particularly complete in this very zone, the variegated deposits of Old Red. type

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ACTA GEOI.<XaCA POLONICA, VOL. 24 B. DAD'LEZ, FIG. ~

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o L' ______ ¹⁰~' ______ ~,~ ²⁰____ -L, ______ ³⁰ ^"0~' ______ ~I ^50itJr/

HypothetieaJ. cross sections thr.ough Ithe South Baltk Basin (situation shown of fig_ 2)

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1 Precambrhm. crystall1ne !l'oclai, Z Uppermost Precambrian (Vendia'nT) sedimentary rocltB, 3 Cambrian, 4 Ordovician, 5 Sdlurian, 6 folded Qrd.ovicilllll and Slluria-n, 'I Devonian, 8 Lower Carboniferous, g Upper Car- bonife!l'OUs, 10 Lower Permlan volcanic rocks, 11 Lower Permian sedimen.tuy rocks, 12 upper PeNIlian Zechste.in, l!f Triassic, 14 Lower Jurassic, :IS Middle and Upper Jurasal,c, 16 CretaceoUs, 17 faults

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SOME GEOLOGICAL .PROBLEMS. OF .~ SOtlTSERN BALTIC BASIN 289

including. The boundary b~tween-these facies zones crosses the coastline near KolO'brzeR and runs offshore probably towards WNW.

Simflar facies differentiation is marked in the Carboniferous sediments. Lower Carboniferous sequence on Riigen (Kniipfer & Weyer 1967) consists of claystones, marls and limestones while in Western Pomerania it includes layers of coarse greywackes, arkoses, quartz sandstones, oolitic limestones and anhydrites. Finally, the Upper Carboniferous series in Western Pomerania displays much more amount of sandstones than on Riigen (Host & Schlimansky 1967).

The present north-eastern boundary of the Devonian and Catboni- :ferous is in Western Pomerania mo8tly of tectonic character. The thickness and facies distribution revealed· close to this bounda~ strongly supports such conclusion. Its erosional-tectonic nature· is then presumed also in the offshore area (Figs 2, 4a., b). It seems reasonalble to assume

. that the deposits of ·the fo:tmations discussed extended previously farther

northwards and north eastwards and were even probably connected (along the depression of the Peri'baltic Synec1ise?) with the area of the De- vonian - Lower Carboniferous occurrence in Lithuania and Latvia. This _. _. area adjoins at present the Baltic coast at a -length of about 300 km, the southernmost localities of the Devonian being known from the 'Sambia Peninsula (Suveizdis 1964). The Devonian is developed there in the Old Red clastic facies with more or less marine, liniestone-dolomite beda in the middle part ..

't ..

The problem of ,the western offshore lI'ange of the Lithuanian De- vonian as well as the details of development and of the northern boundary of the Devonian and Carboniferous between Riigen . and Koszalin (Fig. 2) - belOng to the most important problems involved.

The Lower Permian rocks occur merely in the south-western strip

. of the Southern· Baltic Basin, lava sheets prevailing in the sequence

(Fig. 4a. b). Superposed sedimeilts of this age are probably in general af small and varia-bIe thickness and belong to conglomeratic-sandy marginal fades. These assumptions are evidenced by drilling data from Riigen (Host &. Schimansky 19'67) and Wolin mock {PdkorSki & Wagoner 1972).

On the Kolobr.zeg · Blbck only the isolated occurrences of volcanic extrusives along the fault zones have been recognized ..

The timdamental problems· of the Zechstein palaeogeography in the western :Part of the area under consideration are difficult to solve on the ground

of

nothing but seismic data although the quality of these data above the Zechstein base is quite good. For that reason the extrapolation from the mown geology of the surrounding countries is ~gain necessary.

The fairly complete salt-beari!llg Zechstein sequences in the north- . eastern Medlclenbu'I'g and southern Riigen (Miinzberger, Rost & Wirth 1966} pass northwards into more reduced sulphate-carbonate sequences on

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central Riigen and, finally,intomarginal clastics of',doubtful '~~ on northern Riigen (Arkona Block). The similar trend of tne fac::ies; changes can beaSI;Jumed in going north along the Wolin. Block (Fig .. 3) .. The Arkona Block.·in ,turn may !be·connected· with. the Ringkebing.,.Fyn High (Sorgen-

·frei 1969b) which is devoid of: tile. Zechstein .. deposits and borders the North German Zechstein Basin from ,. the·.north~ . " .

Also farther east the Z~chstein. of -the onshore. part of the Darlowo .Block (pokorski & Wagner'1972) is either locally miSsing or developed as the near-shore carbonates, sulphate$ .and clastics (Fig. 3)~ On'

the.

offshore part of the Darlowo Block as well as of the northern part:of the :~Qlobrzeg Block the poor seismic results and the difficulties in cor-

relation of the supposed Zechstein reflectors are . noted. These facts'may h;tOicate the extension of the area ip which the Zechstein de"ppsi~s are

.reduced or absent. The question arises. whether the areas of the Arkona

and northern KoIobrzeg Blocks were linked together during the.;Upper Permian time, thus closing the Polish evaporite basin from the north~

In the intervening part of the Gryfice Block the dynamic features of the Zechstein reflectors do not, however, change northwards pointing to the .occurrence of the Zechstein deposits about40~OO m thick (Fig. 5b).

It may be· conoluded then that the positive area which was formed towards:

the close' of the Variscan time, was divided into .several separate swells.

A comparatively free connection may have existed -between the Danish Embayment and the Polish Basin along ,the narrow channel similar to that known from the North Sea Basin (Hinz,1968, Sorgenfrei·1969b).

East of the swell of the Darlowo Block the evaporite fades appears again (pokorSki & Wagner 1972). The.western boundary of this subbasin crosses the Ba1tic coast weS't of t.eba (Fig. 3) and then turns to the east t() come again onshore north of the Sambia Penin:sula (Suvei:zms 1963).

The discussed problem of reconstruotion of the Zechstein sea ooast- -line is an essential one because of fringing limestone/dolomite reefs which accompany this line at long distances and are perspective for oil and gas exploration.

. The direct contact between the Danish Embayment and the Polish Basin (Dadlez 1967a) seems to have 'been generally continuous during the Triassic, Jurassic and iLower Cretaceous times. Nevertheless, .this contact

was

rather restricted. It. happened along the same narrow strait which is believed to have existed in Zechstein i.e. along the Gryfice Block sens1,t- lato. This conclusion is based on the fact that no major changes of the

'Mesozoic thiclmess have .been aScertained off$ore in the zone disc~

'(Fig. 5b). thickneSs of the Triassicon' the island' of Sjaelland (1,1QO m-in

the Slagelse well - Sorgenfrei & Buch 1964) is only somewhat smaller

·than that on the Pomeranian coast (1,400-12600

m),

the facies being very

simiiar. Ciose relati:onship of the J;..iassic facies in Scania,Western Ponie- riUlia and on Bomholm (Dadlez 1969)

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CT,oss sections a'long the Wolin: (0,), G!'yfdee (b) and iKdobrzeg (c) BlocIk:s based UIPOIl seisln'~c data:

I lau11;11, PI Zechstein, T Trla.sslc, T1 Lower TrilUlllic (Bu1llt8andatel.n), TI-I Middle and tJ\pper Tr.i.all8l.c (Musche1ka.lk ant1 'Keuper), J Juranlc, Jl Low~ JurUlic, J , ... Middle 8IIId U~r J·un8.l.c,.lC c;re~!!c~

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272 RY~DAm&Z.

Middle and Upper Jurassic reported recently from Scania (Larsen 1966, Norling 1970) prove the same basinal pattern to continue in the Jurassic.

Lastly, the Lower Cretaceous series in these regions, though strongly reduced and developed mainly as continental beds, is thougbt likewise to have 'been deposited in the same basin.

On either side of the Gryfice Block the sedimentary record is quite different. Along the line joining Wolin and northern Riigen a considerable reduction in thickness is proved by drilling data. The sequence on the Arkona Block is characterized by the lack of the Jurassic _. Lower Cre- taceous strata and the strong redUction of the Triassic deposits. Similar trends c.an be easily recognized on the Wolin and Kolobrzeg Blocks (Fig. 5a, c) thanks to the offshore seismic data. These sequences may have resulted both from the primary wedging out of some formations and from the subsequent removal of another ones, the latter concerning above all the· Jurassic deposits in the Early Cretaceous time. The Lower and Midklle Triaasic reflectors become northwards less distinct and, finally, they can no longer be identified. It suggests the Muschelkalk limestone jacies as well as the Lower Buntsandstein clayey facies to disappear in this direction.

Northwards and northeastwards of the Koszalin fault zone a farther :reduction of the Mesozoic cover is observed. The most reduced sequence in the onshore part of the l.eba Uplift (Dadlez 1967a) consists merely of the Lower Triassic, Cenomanian and Turonian. Moreover, the Cretaceous sediments are believed to wedge out offshore near the coast (Fi·gs 3, 4c) . . In the Upper Cretaceous time the greater pal"t of the Southern Baltic Basin became again the area of sedimentation. An uniform series .of marls and limestones covers its south-western part, its thickness :reaching 2,000 m at places. In Scania and on Bornholm. sandstone beds .occur. 'On the l.elba Uplift the gla'll'Conitic sand and siltstones point also to the near-shore .environment.

~he Tertiary sediments play an unimportant role. They are developed probably only in a narrow and discontinuous belt along the -central and eastern part of the Polish cOflst. The Tertiary cover is thin and rests unconforma'bly on the various Mesozoic stages.

OONCUJIOONG RmMARIK'S

Some words of comparison between the South Baltic Basin and one of the most 8Jttractive prospective areas in Europe - the North Sea Ba'sin (Hinz 1968, Sorgemfrei 196'9b; Kent & Walmsley 1970) - seem necessary as a conclusion of this short report. It should 'be emphasiz'ed here that the 'both areas, in spite of their general relationship within the same Middle European Basin, reveal fairly di~erse palaeogeographic and

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80Mt GEOLOGICAL PROBLEMS OF"'I'Hl!i eOtTTBEBN BALTIC BASIN .273

tectonic "developments. Among the most significant differencestlte· fol·

!owingshotild be stressed:

- The positiori of the top. of crystalline basement is.in the South Baltic Basin generally b1.gher and thE! sedimentary cover less di.fferentiat- edthanin the. North Sea Ba'Sin.

- The South Baltic Basin was situated mostly in· the marginal zones of· the successive ^~entarybasins while. the North SE,!a Basin constituted often the central area of subsidence. The consequences of this difference for the oil·and gas prospects are obvious.· The negligible role of the Lower Permian sediments, the limited extent and umavo-urab'le fades of. the Jura.ssic and, finally, -the lack of the Tertiary subsidence may offer the best examples.

:- No evidence af salt flowage ha's been ascertainecL 1n tne South BaltiC aa:-ea. Hance the occurrence of neither salt structUres nor the local.

facies and thickness changes connected with salt movements are to be expected in the Zechstein-Mesozoic cover.

- The greater possibilities of the exploration of· the Early Pala- eozoic rocks in the eastern part of the area may be regarded as an ad-

vantage of the South Baltic Basin. .

- Thick sandstone and limestone formations of the Devonian and Carboniferous in the south-western part of the area also attract attention.

However,· modern and expensive seismic methods are need.ed to obtain an adequate picture of the 'tectonic framework of ·these formations.

Acknowledgements. The author is deeply indebted to Dr S. MJY!ll.arski, and Dr K. Jawor·owskiof the Geological Institute, Warsaw, for helpful dJscussiO!lls.

Laboratortl of the PoU8h Lowlands

G~ Institute .

02~51g. Wa:rsZQll.OO,ul. RakowiecJca.4 Way8la!W, Janv.aY'll1973

ALEIiBE'OHTrK. H. 196'7. ZurAusbildWlg. und zum ·geologischen Bau des Paliiozoikums aut R(lgen. - Ber. neut.&ch. Ges. Geol. Wiss., A, Geol Palll<lnt, Bd. 12, H. '1/2 . .Berlin.

BALAEIU.YW E. T., ~ L. & POLF.SZ.M{ E. 19'72. Rmwoj tektoniczny star-

IlZl!gO .pale.ozoiku w a,nekl:izie .perybaHycld.ej. (r~ic evolution at the older PaD.ae<J0Oioe 'Od' the iPedbaiti<: Synecllse). - Pnegll\d Gedl., R. 2(), nr 8/9. Wax- szawa.

BEDNIA:BmYIK W.·lm. PrekamJb.l' i kambr wy,liJesienia: !.eby, NW Polska (!'be Plreoambrian snd Cambr18n ^ofthe l.eba Elevation - NW Poland). - Acta

·.Gool Pd., wl 22, no. 4. Warszawa.

DAILm !R. ll96'7a.. ZUm p.~ .undeeinemUntergrund :In Nordwelt- iPOOen. - Ber. ·,Deu.1Isch. G.es. Geoi. Wiss., A, Geol. Palaont.,I5d. 12, H. 3/4.

Berlin.

11

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274 :RYSZARD. D.c\DLEZ

1967b. Najnowsze profile pod~o.Za cechsztynu w"p6lnocno.:zachodniej Palsce, komunikat wstQpny (New sections of the Zechstein substratum in Northwest Poland). - Xwartalnik Geol., t. 11, nr 3. Warszawa.

- . 1969. Stratygrafia liasu w Po.}sce zachodniej . (Stratigraphy of the Lias in Western !Pol.aJD.d). - Prace Inst Geel., -to 57. ·Warszawa.

il.9'1I3. TeCtonic !pOSition ^ofWe&tern Pooleramia(N01'fuwest Nand) tprior to UJ;JPe1' Permian. - ·Biul. Inst. Geol. (in PTess). Warszawa.

& .Mit..YNARSKI S. 1967. Wgl~a budowa geologiczna iPO(ilooa BaUyku na WBch6d ,od ujscia Odry'(Deep geological structure of the Baltic Sea subs'tratum east' of the Odra river mouth). Kwartalnik Geol., t. 11, nr 3. Wai:szawa.

& - 1M2. Wgl~bna budowa geologiczna poIskiego ohszaru szelfu baltyckiego. - Przew. 44 Zjazdu Pol .. Tow. Geel. Wydawn. Geol. Warszawa.

FRANKE:: D. 1967. Zu den Varisziden und 2IUlIl Problem der Kaledoniden im nord- lichen Mitteleuropa. - Ber. Deutsch. Ges. Geol. Wiss., Ai Geol. Palliont., Bd. 12,

. H. 1/2. Berlin. .

GOLDBERG I. S. & RUKHOVEC N. M. 1970. 0 vremeni formirovanya lokalnykh struktur i zaleZ'hej nefti v Baltijskoj sineklize. - Geol. Nefti i Gaza, 1. Moskva.

GOLUB D. P. & SIDOROV J. S. 1971. Stroenie poverkhnosti dokem:brijskogo funda- menta Baltijskogo morya (po dannym magnitnykh semoIt EIS ,;Zarya"): - Okeanalogya, 11, vyp. 2. Moskva.

GaY H. 1900. Geology of B01'lllholm. Guide to excursion No A45 and C40. Intern.

Gool. OOlIlgl"., 21 Sess.ion Norden. Copenhagen.

HIlNZ K. 1968. A .contrihution to the geology of the North Sea according to geophysical inwstigatiOllS iby tile IGeologica:I Survey of German Federal Republic.

Geol. <Xf Shelf Seas. Pro<:. '14th Jnteruniv. Geol. Con·gr. Oliver and Boyd. Ltd.

EcUnlburgh-LOndoo..

JAJOCHlIRH.llJ16'1. Ordoviz aui Riigen, Datierung undVergleich mit anderen Gebieten (vorlliufige iM:itt.eilung) .. -Ber. Deutsch. Ges. GeoL Wdss., A, oGeol. PaUiont., . Bd. 12, H. 1/2. Berlin.

DNT P. E. & WAlIJMSLEY P. J. 'lMO. North Sea progress. - Bull. Amer Assoc,

;Petrol. Geod., vol. 54, nr. l. Tulsa.

KNOPFtI!lR J. & WlEYlIDR D. 1967. VJOOUi.uf.ige MJittei1Uillg liber das Unlteii<karbOln dar Inse! Rilgen. - Ber. Deutsch. Ges. Geol. Wiss., A, Geol. Palliant., Bd. 12, H. 3/4.

,Berlin.

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Ksbenhavn.

LENlDZION K. H170. IF.okambr i kamIbr w otworze Zarnowiec IG-l (Eocambrian and

·Cambrdw

m

the lborehole Zarnowiec IG-'1). ' -.Przegllld"· Geol., R.

fa;

'nr 7.

·Warszawa.

MAGiN'USSIOI:N N. H. (Ed.). 1958. Karta over Sveriges Berggrund 1 : 1 000 000. Stock- holni;

M~ Z.1968. Ordowik na Pomorzu Zachodnim (Ordovician in West Po- memnia). - Kwarta[nik oGeol., t. 12, nr 3. Warszawa.

19'1'3. stratygrafia ii 'l'ozw6j ordowiru w p6h!()cno-wschodnie.j Pols'ce (Strati- graphy .and development of .. the Ordovician in North-Eastern. Poland). - iPraoe 'Inst. Geol.,. t. 72. Warszawa.

MUNZBERIGIER !E., ROST U. & WlRTH J:1966. Vergleichende DarstelLung der Sedi- menta'hionsverhAltnisse des Zechsteins von. Thiiringen 'mit denan' des Nordost- deutsChen. Flachlandes. Ber. Deutsch. ·'Ges. Geol.Wiss'J A, Geol. PaUlont.,

Bd. U,' B. l/2. Berlip. .

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SOME GEOLOGICAL PBOBLEMS OF-'1;'HE SOUTHERN BALTIC BASIN 275

NORL~NG E. 1970. Jurassic andLow~r Cre~ceousstratigraphy ·of the Rydeoock .- FortuDoa borings in southem Sweden; - Geol. Foren .. Stockh. "Forhanc:il., 92,

p~ 3.S~hobn. . .

POKORSK![ J.& WAGNER R. 197·2. Stratygrafia i paleogeografia permu.l!Il - Stratygrafia i paleogeografia permu, triasu' J jUl'y w Polsce ... - Biu!. Inst.

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F~., 19, H. 2. iKBbenhavn.

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Vopr. Geol. Litvy. Akad. iNaUlk: Lit. SSSR. ViLnlus.

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TYSKI S. 1973. Rozw6j strukburadno-tektonkzny ob6za'l'u .Zal'nowca (Spructufal- -tectonic developmeIllt of the Zamowiec area).·-' ·RrzegIJ.l4d . Geol., R. 21, nr 3.

Warszawa.

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. ZARDEClCA D. 19'73. Sejsmkzne badania .refleksyjne w morsk.iej .i 'l¥Iowej cz~soi

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.R,DADI,.EZ

NImroBE PROBLEMY GEOLOGICZNE W BASENIB POI.UDNIOWEGO BAf..TYKU .

(Stres~czenie)

Na ,tie wynik6w morsk.icll re:fileksyjnych badan sej,wni.cznych,· przeprowadzo- nych w lataeh I1MJ4-!1967 wzdhr!,pdlsld~gQ wytbrzeza, om6wiono problematyk~ bu- dowy geologkznej basenu poIudniowego Baltyoku, Przedstawiony zostal obecny stan

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278

m2l;PlJZiD8iBia pOaz-cmeg61n,ych ,HgaOOien oraz aformulowanezKdania 8I;oilice przed

·~ibadamallH,SZ'CzegOlnie ^'W8&pekcie~yw·~aftbltunWl6w.

SpairOd ,problem6w te'ktoIJi.cznyd,.· §ako najwa!niejszewydajll iSdr: by~ nastf:··

. Pu1_

^ee^!

-przebieg 1)OluodDiowo-zadlooruej grarucyplatformy ~j&ldej;

- ·przebieg i eharakte!" gran1cy dewonu i 'karobonu -w ·poIllIdnlowo-n.cbodIlliej

GZ'f:tci baSmu; . .'

- podzia~ poiud!Mowo-.zachodniej .ez~ uwenu nil 'biald ·tektonicme rui9zego rzti"du, a szezegMnie kwestla kieruni6w i ;przebiegu uakok6w wa'l"yscyjaklich oraz 'kwestill''OdhikHilania -'\:IiIIkook6w na ipl'Zelom:ie eryme7l0ZOi'CZnej i bnozoiICZnej;'

- fPOd'Zial -tedirtonic:z.n,.· l'O:lJlqfletG' zachoctniqo sMOnu synelk:ldzy ;pery.baUycldej ora ~tenjeo .,ogZ:Zebany.cll ant~ wiekukambr'y.j~ lUb-pokambryjsSdego;

- pn:eS1edzenie'J,'lOlwiJnioW'o-'w8chodni~ przecRUl!enia zrQbu .BomhQImu . . De·1Prdb1em6w·:paleogeograficzny.eh, wymagaj~h przede 1W'S2iys·tkimwyjd- . ni~a :0 1 . :

- Z86i~ uittwoc6w osadowych najmlodszego prekambru;

- :obadaft.ie strefy 1Ir'IIlIej&oia od fa~ wapiellSl~h do ilastych. w ordowilw ~ 6y- lUrze platf'lllll'mY ·prekambryjstd.ejoraz ,problem ewmtualnego WYSt~powania facji ra-

fawycll; .

- badanie w poNdniowo-za'C'hodniej czt:Sci akwenu stref przej8cia Od nery-

~ych iaeji w8jpienno-ma~istyeh do brzeinych facji wa}ii&ID.n~szoystO-:ilas

tych w dewonie i dolnym !kairbonie, jRk r6wn·iei od facji iauto-;muloW!eOWY'Ch do facji

piaszezysty.ch"W gbrnymkar'bonie; . '

- anmka zasd~ ku zachodo.wi utwor6w dew.onu i dolnegokarbonu znanycb

Z o"b5Zarow 'Utewslklieji ·l.ioItewI!Jdej ."sRR; .

- zaaif:g. i !feje seiii osadowycb deilnego pernlU oraz zagadnienie udzialu -i zna- cienia .'Sit&i w:Wk1micmych tego wieku na poludniowo-zacbodnim *awku obszaru;

- .rekonstJrukeja przebiegu lillii brzegowej morza cechszty6sktego i zwll4ZB.1lych :z;·nit)barier . \JJl1worOw ~D.owych;

- proIbleni . ~efJ miQdzy Dasenami p6}n0cnej Danii i !Il6InOClllo-zaIChodniej

Po1ski w oob'e6ie jury 1 dolnej klredy.

Na .tJle. tego.przeibldu zagadnien, z:i4ustrowe.nego mapami (.fIig. 2 i 3). oraz prze- larojami geologilCZO·ymi (fIlg. 4 ii' 5), przeprowadtono 'por6wn-anie z basenem Morza

"PMnocnego. stwierdzono mlaC2'Jllq, ~emia\~ budDWY gtiologiemej 1 hlliStorii rozwoju

geo1ogiCZlllelo baaeoo poludniowego Baityku, ktbra Slltowadza ai~ do nastlwujll- cych ceeh:

- ogMnie pIy1tsze. 'WY~poWanie podloria krystalieznego i lrinie'jsze m6tDico-

wmde

^polarywy'06adowej;

- usytuoweoie w trakcie' swej . bistorU gedlogicznej przewaZnie w brzei.nych

str~aeh basen6w 6edymentacyjnych;

- brak tektondkli solne:l w kompleksie·cechsozd;ymko-mez.ozoiiCZnym;

- ~ ~ penetracjl utworOw' staJrszego paleoeolku w obszarze

platformy prekambcy'js'kiej; .

- liuteresujltCe perapektywy badan komplebu dewtlflsko-kad>06skiego w PQ- lud'l'iliOWO-7.llChodruej ez~i 'ObIszaro. kt6re jednak wymagajll stosowania Ilowoczes- nydh'metod sejsmieznyCh.

Zaklad Geologi.i StrUktUT Wgl,bnych NUu 11'111J1tt1f;utu Geoklgtc:mego

02-519 WaT8za:wa, W. R4Jk~ 4 Wa,.~ to S't~niu 1913 r.