Annales Societatis Geologorum Poloniae (2007), vol. 77: 147–159.
EARLY JURASSIC DINOFLAGELLATE CYSTS FROM THE KRAKÓW-SILESIA MONOCLINE,
SOUTHERN POLAND: A RECORD FROM THE BLANOWICE FORMATION AT MRZYG£ÓD
Prze mys³aw GEDL
In sti tute of Geo logi cal Sci ences, Pol ish Acad emy of Sci ences, Senacka 1, 31- 002 Kraków, Po land;
e- mail: ndgedl@cyf- kr.edu.pl
Gedl, P., 2007. Early Ju ras sic di no flag el late cysts from the Kraków- Silesia Mono cline, south ern Po land: a rec ord from the Bla nowice For ma tion at Mrzyg³ód. An nales So cie ta tis Ge olo go rum Po lo niae, 77: 147–159.
Ab stract: A 3-m thick sec tion of the Bla nowice For ma tion ex posed in an aban doned clay- pit at Mrzyg³ód (Kraków- Silesia Mono cline, south ern Po land) yielded rich paly no logi cal ma te rial. Be sides domi nat ing land- derived phy to clasts and sporo morphs organic- walled di no flag el late cysts (dino cysts) oc cur. Pres ence of Luehn dea spi nosa al lows con sid er ing time of depo si tion of stud ied de pos its as Late Pli ens ba chian–ear li est Toar cian.
Quan ti ta tive fluc tua tions of main groups of palyno fa cies ele ments sug gest vari able sedi men to logi cal con di tions of depo si tion within the south ern part of the Pol ish epi con ti nen tal ba sin. Domi nance of large- sized cu ti cle re mains and lack of dino cysts oc curs in sedi ments de pos ited in con ti nen tal con di tions. Oc cur rence of dino cysts and other aquatic paly no morphs takes place in sedi ments that have origi nated dur ing ma rine in gres sion.
Key words: dino cysts, palyno fa cies, Lower Ju ras sic, Po land, bi os tra tigra phy, pa laeoen vi ron ment.
Manu script re ceived 8 September 2006, ac cepted 1 August 2007
IN TRO DUC TION
The epicontinental Lower Ju ras sic of Po land was de - pos ited mainly in con ti nen tal en vi ron ments. Nev er the less, dur ing the Early Ju ras sic few short- termed ma rine in gres - sions en tered into the Pol ish ba sin. The traces of these sea-floods can be traced in north- western Po land where de - pos its with ma rine fauna oc cur (e.g., Kopik, 1964; Dad lez
& Kopik, 1972); in re main ing, pe riph eral parts of the Pol ish ba sin, the ma rine in flu ences were much weaker gradu ally pass ing into brack ish fa cies. These pa laeoen vi ron men tal con di tions are re flected in gen eral scar city of fos sils ex cept of sporo morphs, which be came the most im por tant bi os tra - tigraphi cal tool in the Lower Ju ras sic in Po land (e.g., Mar- cinkiewicz, 1962, 1971; Ro gal ska, 1976). How ever, sporo - morphs do not al low pre cise da ta tion (e.g., Marcinkiewicz et al., 1960). It was Ro gal ska (1976) who pre suma bly was the first who noted the pres ence of aquatic paly no morphs (pos si bly also dino cysts) in epi con ti nen tal Lias of Po land;
she re garded their oc cur rence as re flec tion of ma rine in flu - ences dur ing the Early Ju ras sic. Later stud ies of organic- walled Di no flag el late cysts (dino cysts) from Lower Ju ras sic epi con ti nen tal de pos its of Po land (Bar ski & Le on owicz,
2002; Gedl & Pieñkowski, 2003) show their high ap pli ca - bil ity as a biostratigraphic tool in de pos its that usu ally lack age- diagnostic fos sils. Moreo ver, dino cysts and palyno fa - cies analy sis al low re con struc tion of pa laeoen vi ron men tal con di tions of stud ied de pos its. Dis cov ery of rich dino cyst assemblage from the Bla nowice For ma tion ex posed at Mrzyg³ód al lows age de ter mi na tion of this lithostratigra- phic unit in this area. It shows high ap pli ca bil ity of dino - cysts as bi os tra tigraphic tool in stud ies of Lower Ju ras sic of Po land, which strata are widely be lieved to con tain very few fos sils of stra tigraphi cal value. Pres ence of dino cysts com - bined with palyno fa cies analy sis al lows re con struc tion of ori gin of de pos its in ques tion.
GEO LOG I CAL BACK GROUND
Meso zoic de pos its of the Kraków- Silesia Mono cline con sist of Tri as sic and Ju ras sic strata that mono cli nally dip at an an gle up to 2° north- east (Fig. 1). This area rep re sents the south ern most, pe riph eral lim its of the Early Ju ras sic epi - con ti nen tal ba sin in Po land. The Lower Ju ras sic strata in this area con sist mostly of con ti nen tal de pos its char ac ter -
ized by fre quent fa cies changes and usual lack of age- diagnostic fos sils – the old est fau nis ti cally docu mented Ju - ras sic ma rine de pos its in this area are the Mid dle Ju ras sic (Aalenian–Bajocian), the so-called Koœcielec sand stones (Mos soczy, 1949; Ró¿ycki, 1953; Kopik, 1967). Among them, a range of la cus trine, flu vial to near- shore ma rine de - pos its with fre quent in ter ca la tions of coal lay ers of un cer - tain age has been dis tin guished in this area. Their stra tigra - phy bases mainly on su per po si tion, cor re la tion with fau nis - ti cally docu mented coe val de pos its from more north ern central- basin fa cies, and sporo morph bi os tra tigra phy. The old est Ju ras sic de pos its in this area are be lieved to be the so- called Po³omia beds (Fig. 2). How ever, the Lower Ju ras - sic (Het tan gian?) age of this in for mal stra tigraphi cal unit is highly ar bi trary and based on su per po si tion only (e.g., Zno - sko, 1955) since the Po³omia beds con tain al most no fos sils (Mos soczy, 1961). These sandy- gravelly de pos its oc cur as an iso lated rock- body that cuts older sub stra tum. Zno sko (1955) de scribed the Po³omia beds as younger than the sub- coal beds (the Up per He lenów beds sensu Zno sko, 1955) and older than the Bla nowice coals. How ever, re cently, there are no out crops avail able where the Po³omia beds would be cov ered by de pos its other than Qua ter nary. Gen - er ally, well docu mented Het tan gian and Si ne murian de pos - its are miss ing in the Kraków- Silesia Mono cline.
The age of younger sedi ments, de spite of fos sil (sporo - morph) oc cur rence has not been pre cisely de ter mined yet.
The ba sal sandy- loamy com plex with gravel in ter ca la tions was dis tin guished as the so- called sub- coal beds (Rut - kowski, 1923; Mos soczy, 1961), whereas the over ly ing dark- coloured loamy de pos its with coal lay ers and in fre - quent sand stones were known as the so- called Bla nowice coals [both in for mal stra tigraphic units were for mally de - scribed as the Bla nowice For ma tion by Pieñkowski (2004;
Fig. 2)]. Thick ness of this com plex does not ex ceed 40 me - tres. The age of the so- called sub- coal beds was be lieved by Mos soczy (1961) as Toar cian, whereas Dad lez (1978) re - garded them as Up per Pliensbachian. Pieñkowski (2004) as signed the Bla nowice For ma tion to the Pli ens ba chian.
The Bla nowice For ma tion is cov ered by over 40- metres thick com plex of muddy- loamy de pos its of brack ish or i gin, the so- called lower £ysiec beds (sensu Zno sko, 1959) or the so- called Esthe ria beds (sensu Mos soczy, 1961). The low er - most Toar cian age of these in for mal lithos tra tigraphic units was based mainly on cor re la tion with sedi ments from north- western part of Pol ish ba sin (Dad lez, 1978). Higher up, the de pos its passes into more sandy- loamy com plex – the so- called Up per £ysiec beds rep re sent ing pre suma bly Up per Toar cian (Zno sko, 1959; Deczkowski, 1962). Its vari able thick ness reaches up to 35 me tres.
Fig. 1. Sim pli fied tec tonic sketch-map of the Kraków-Silesia Monocline (from Dadlez et al., 2000) with lo ca tion of the study area (ar - rowed)
MA TE RIAL
The studied out crop is situ ated in an aban doned clay- pit at Mrzyg³ód (Fig. 3), where clays were ex ploited up to the end of the 20th cen tury. It is lo cated at the west ern bank of a lake that fills dumped pit (Fig. 3A, B; GPS co or di nates: N50 31 27.1, E19 21 20.9; 332 m a.s.l.). Stud ied sec tion rep re - sents the top most part of sev eral me tres thick Bla nowice For ma tion suc ces sion once ex posed here dur ing clays ex - ploi ta tion. It con tains nearly 3-m thick pro file of dark- coloured non- calcareous clays with a sin gle 10- cm thick coal seam in its up per part (Fig. 4). Ba sal 2 me tres of the sec tion con sists of dark brown clays with rhyth mic lami na - tion of very thin (up to 0.1 mm), un dis turbed silt lami nas.
Higher, a 10- cm thick coal seam oc curs. It is un der lied by a 15- cm thick layer of grey clay with abun dant co ali fied plant de tri tus. The coal seam is cov ered by black ish clays de void of that clear lami na tion as in the lower part of the sec tion.
Three sam ples were taken from the stud ied ex po sure.
Sam ple Mrz1 was taken 12–15 cm above the coal seam, sam ple Mrz2 was taken 10 cm be low it from grey ish clays,
whereas sam ple Mrz3 was col lected 1.2 m be low the coal seam from strati fied ba sal dark- brown clays (Fig. 4).
METH ODS
The sam ples were proc essed fol low ing stan dard paly - no logi cal pro ce dure in clud ing 38% hy dro chlo ric acid (HCl) treat ment, 40% hy dro flu oric acid (HF) treat ment, heavy liq - uid (ZnCl2+HCl; den sity 2.0 g/cm3) sepa ra tion, ul tra sound for 10–15 s and siev ing at 15 µm on a ny lon mesh. No 100%
fum ing ni tric acid (HNO3) treat ment was ap plied. Mi cro - scope slides were made us ing glyc er ine jelly as a mount ing me dium. The quan tity of rock proc essed was 20 g for each sam ple. The rock sam ples, paly no logi cal resi dues and slides are stored in the col lec tion of the In sti tute of Geo logi cal Sci - ences, Pol ish Acad emy of Sci ences, Kraków.
Dino cysts from sam ple Mrz3 were counted up to a to tal of 300. In case of sam ple Mrz1, which con tains very rare dino cysts, all speci mens from two slides were counted. Pa- lynofacies ra tio was cal cu lated on the base of 1000 counts.
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Fig. 2. Lithostratigraphic di vi sion and cor re la tion of epicontinental Lower Ju ras sic of Kraków-Silesia Monocline and west ern sur - round ings of the Góry Œwiêtokrzyskie Mts, Po land (from Pieñkowski, 2004)
RE SULTS
All sam ples con tain very rich paly no logi cal ma te rial. It con sists in over whelm ing ma jor ity of land- derived par ti - cles: large- sized cu ti cle frag ments, vari ously pre served land- plant de bris, sporo morphs and amor phous or ganic mat ter (Figs 5 and 6). Dino cysts have been found in sam ples Mrz1 and Mrz3 (Figs 7–9). They oc cur sub or di narly, es pe - cially in sam ple Mrz1 be ing very strongly dis persed by ter - res trial ele ments. Al though palyno fa cies of all stud ied sam - ples shows over whelm ing domi nance of ter res trial ele - ments, there are some quali ta tive dif fer ences (Fig. 5A).
Low er most sam ple Mrz3 col lected from lami nated dark- brown clay stones con tains palyno fa cies domi nated by pol - len grains (Fig. 5C), which con sti tute over 50% of to tal palyno fa cies (spores con sti tute up to 7%). Cu ti cle and wood de bris do not ex ceed 38% and these are mainly small- sized cu ti cles and black opaque phy to clasts. An other char ac ter is - tic fea ture of paly no logi cal con tent from this ba sal sam ple is an oc cur rence of rela tively fre quent dino cysts that oc cur up to 2% of the palyno fa cies (Fig. 5A). These are mainly rep re -
sen ta tives of the ge nus Nan nocera top sis – over 99% (see chap ter Dino cyst as sem blages); sin gle speci mens of Men di - cod in ium spi no sum, Luehn dea spi nosa and Batia cas phaera sp. also oc cur. Ad di tion ally, very rare speci mens of Tas - mani tids (pre suma bly cysts of green al gae rep re sent ing Pra - si no phyceae) were found. These are two spe cies dif fer ing by thick ness and struc ture of the wall (Fig. 9M–O).
A dif fer ent palyno fa cies was re corded in sam ple Mrz2 taken from grey ish clay stones with fre quent co ali fied plant de bris. It is domi nated by large- size cu ti cles (80%); pol len grains oc cur as 16% of the palyno fa cies whereas amor phous mat ter does not ex ceed 7% (Fig. 5A). This sam ple con tains no dino cysts.
Very rare dino cysts (less than 1%) rep re sented by the ge nus Nan nocera top sis have been found in the sam ple Mrz1 taken above the coal seem (see chap ter Dino cyst as - sem blages). Its palyno fa cies con sists chiefly of large- and middle- sized cu ti cles (up to 40%) and pol len grains (30%;
Fig. 5A, B). Amor phous or ganic mat ter (ap proxi mately 15%), which oc cur in this sam ple con sists of very small- sized, strongly dis persed par ti cles and larger, rela tively Fig. 3. Lo ca tion of study area: A – lo ca tion of aban doned clay-pit at Mrzyg³ód (ar rowed); B – view on the stud ied sec tion at the west - ern bank of the lake fill ing the ex ca va tion (ar rowed); C – close up at the higher part of the sec tion
thick cloaks (Fig. 6). Woody de bris (elon gated and equidi - men sional) rep re sents up to 10% of the palyno fa cies.
Dinocyst as sem blages
Dino cysts were found in two sam ples: Mrz1 and Mrz3.
In both sam ples their as sem blages are domi nated by the ge - nus Nan nocera top sis. De spite this, these two as sem blages dif fer quan ti ta tively and, less dis tinc tively, quali ta tively (Fig. 5A).
Dino cyst as sem blage from sam ple Mrz1 is com posed en tirely of rep re sen ta tives of the ge nus Nan nocera top sis.
Speci mens are rare be ing strongly dis persed by land plant tis sue re mains. They rep re sent Nan nocera top sis glo bi - formis (Fig. 7A, B) and N. rauns gaar dii (Fig. 8A, B) that oc cur in ap proxi mately the same ra tios; very rare speci mens of N. tri ceras were also found (Fig. 9A–C). No other dino - cyst spe cies were found in this sam ple.
Sam ple Mrz3 con tains dino cyst speci mens, which are much more fre quent than in sam ple Mrz1. The ge nus Nan - nocera top sis, which rep re sents over 99% (Fig. 5A) of the whole as sem blage, is much more taxo nomi cally di ver si fied than in sam ple Mrz1. The most fre quent spe cies are N.
rauns gaar dii (Fig. 8C–M) that con sti tute over half of the
as sem blage and N. glo bi formis (over 20%; Fig. 7C–K). Be - sides N. tri ceras (Fig. 9B, C) that was found also in sam ple Mrz1, few other spe cies of this ge nus oc cur ex clu sively in this sam ple. These are N. spicu lata (over 10% of the as sem - blage; Fig. 8N, O), Nan nocera top sis sp. A (Fig. 7L–P), and very rare N. rid ingii (Fig. 9D) and N. de flandrei subsp. se - nex (Fig. 8P). Ad di tion ally, very rare speci mens of Batia - cas phaera sp. (Fig. 9E–G), and sin gle speci mens of Men di - cod in ium spi no sum (Fig. 9H, L) and Luehn dea spi nosa (Fig. 9I–K) were found.
Dino cysts found in the Mrzyg³ód sam ples are char ac - ter ized by thin and deli cate cyst wall. This con cerns speci - mens of Batia cas phaera sp. and all Nan nocera top sis spe - cies ex cept of N. de flandrei subsp. se nex. These dino cysts have very thin aut ofragm, which is de void of any traces of even low re lief – it is smooth or very faintly mi cro punc tate.
They show very pale (pale yel lowish) col ou ra tion of the walls. The only ex cep tion is sin gle speci men of N. de - flandrei subsp. se nex, which cyst wall is rela tively thick.
Sin gle speci men of Luehn dea spi nosa shows, in con trast, much darker (dark yel low) col our of rela tively thick cyst wall.
An other no tice worth fea ture of the Mrzyg³ód dino cysts is the loss of epi cyst in many speci mens of Nan nocera top sis
EARLY JU RAS SIC DINOFLAGELLATE CYSTS
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Fig. 4. Li thol ogy of stud ied sec tion of the Blanowice For ma tion ex posed at Mrzyg³ód clay-pit and po si tion of col lected sam ples: A, B – li thol ogy of up per (A) and lower (B) part of the sec tion (ham mer length – 32 cm); C1-4 –de tailed lithologies of the shales from the lower part of the sec tion show ing un dis turbed lam i na tion
Fig. 5. Palynofacies and dinocyst as sem blages in stud ied sam ples (A). Ex am ples of palynofacies from up per part of sec tion (B) dom i - nated by large-sized phytoclasts, and (C) lower part with fre quent pol len grains and small-sized phytoclasts
(e.g., Fig. 7C–F, J, M; Fig. 8A, C, E). This fea ture, noted also by other authors (e.g., Evitt, 1961; Gocht, 1964; Fen - some, 1979) was ex plained by the lat ter author as a re sult of weak en ing of par ac in gu lum due to loss of a mid- dorsal par - ac in gu lar para plate (i.e., the ar chaeopyle for ma tion; Fen - some, 1979).
AGE OF STUD IED DINOCYST AS SEM BLAGE
Al though the Mrzyg³ód dino cyst as sem blage is taxo - nomi cally un di ver si fied, it con tains dino cyst spe cies that are good age in di ca tors al low ing rela tively pre cise sug ges tion of its age. Luehn dea spi nosa, found as sin gle speci men in sam ple Mrz3, ac cord ing to sev eral author has range that spans Late Pli ens ba chian (Mar ga ri taus Am mon ite Zone) through ear li est Toar cian (Tenui cos ta tum Am mon ite Zone;
e.g., Rid ing & Tho mas, 1992). This age- range can be ap - plied to the sedi ment in ques tion be cause the other dino cysts (e.g., Men di cod in ium spi no sum – Late Pliensbachian–
Aalenian ac cord ing to Buce falo Pal li ani & Rid ing, 1997), have much wider stra tigraphic ranges.
The ge nus Nan nocera top sis, the domi nat ing one in stud ied ma te rial, is known to have ap peared ex clu sively dur ing Ju ras sic rang ing from Early Pli ens ba chian through Ti tho nian, be ing a very fre quent ele ment of dino cyst flora mainly dur ing Late Pli ens ba chian to Ba jo cian. Al though rela tively long- ranging as the ge nus, par ticu lar spe cies have much shorter stra tigraphic ranges. N. gra cilis and N. de - flandrei subsp. se nex, the old est known spe cies, ap peared for the first time dur ing Early Pli ens ba chian (e.g., Buce falo Pal li ani & Rid ing, 1997). But the main ra dia tion of this ge - nus took place dur ing Late Pli ens ba chian when sev eral spe - cies ap peared for the first time. Among those found in Mrzyg³ód, N. rid ingii, N. rauns gaar dii and N. tri ceras ap - peared for the first time then (N. rid ingii ap peared till Toar - cian whereas two re main ing spe cies ap peared till Ba jo cian).
PALAEOENVIRONMENT
Com bi na tion of sedi men to logi cal ob ser va tion and paly - no logi cal analy sis may pro vide im por tant clues for pa - laeoen vi ron men tal re con struc tion. The most out stand ing fea ture of paly no logi cal con tent of the Mrzyg³ód sam ples is over whelm ing domi nance of land- derived phy to clasts and paly no morphs, and al most mono spe cific dino cyst as sem - blage of Nan nocera top sis. The lat ter fea ture must re flect re - stricted con di tions in the photic zone dur ing for ma tion of stud ied de pos its. Nan nocera top sis is con sid ered by sev eral authors to be a eury ha line ge nus (e.g., Rid ing, 1983; Buce - falo Pal li ani & Rid ing, 1997). Also the oc cur rence of Tas - mani tids in sam ple Mrz3 may in di cate low- salinity con di - tions (see Rid ing, 1983). Pra si no phycea are known to ap - pear in wide range of en vi ron ments, from ma rine to brack - ish, be ing most fre quent in near- shore ma rine en vi ron ments (e.g., Tap pan, 1980; Guy- Ohlson, 1996). Prauss & Riegel (1989) con sid ered cli ma to logi cal and palaeo geo graphi cal causes re spon si ble for their dis tri bu tion. Ac cord ing to these authors, pra si no phycean al gae might have fa voured cold- water low- salinity en vi ron ments.
High amount of ter res trial or ganic mat ter points at in - tense sup ply and ac cu mu la tion of land- derived or ganic par - ti cles from sur round ing land ar eas. This, com bined with a low- salinity sig nal con cluded from dino cyst as sem blage com po si tion sug gests that stud ied sec tion, rep re sent ing a part of the Bla nowice For ma tion, was de pos ited in a proxi - mal area un der brack ish con di tions. How ever, fluc tua tions of palyno fa cies and dino cyst as sem blage composition (Fig. 5) show on change able con di tions, re flect ing sa lin ity changes. In ter vals with coal seams and closely sur round ing de tri tal sedi ments were de pos ited dur ing pe ri ods of more in - tense sup ply of ter res trial or ganic mat ter as so ci ated with more dis tinct sa lin ity drop caused by fresh wa ter in flux.
Clayey in ter vals, in turn were ac cu mu lated dur ing pe ri ods of more in tense ma rine in flu ences re sult ing in brack ish con - di tions fa vour able for Nan nocera top sis and Tas mani tids.
EARLY JU RAS SIC DINOFLAGELLATE CYSTS
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Fig. 6. Amor phous or ganic mat ter from the Blanowice For ma tion at Mrzyg³ód (sam ple Mrz1)
De com po si tion of high amounts of or ganic mat ter, sup - plied into the ba sin dur ing depo si tion of the Bla nowice For - ma tion, de pleted oxy gen con tent in bot tom wa ters. Pre sum - ably, anoxic con di tions at the ba sin floor can be sug gested on the base of pri mary lami na tion in tact by bot tom dwell ing or gan ism ac tiv ity (Fig. 4C) and pres ence of amor phous or - ganic mat ter (Fig. 6). High amount of the lat ter is usu ally as - so ci ated with bac te rial de cay of or ganic mat ter in an oxic en - vi ron ments (e.g., Ty son, 1987). The rela tively low amounts of amor phous or ganic mat ter in Mrzyg³ód sam ples may re - sult from high ac cu mu la tion rate, which may pre vent its more wide spread for ma tion.
DIS CUS SION
The Blanowice For ma tion rep re sents de pos its ac cu mu - lated in the south ern most ar eas of the Pol ish epicontinental ba sin dur ing the Early Ju ras sic. The hith erto con ducted stud ies of this lithostratigraphic unit (and its for mer coun - ter parts) con cluded with rel a tively im pre cise age, based mainly on lithostratigraphic cor re la tion with de pos its from north ern ar eas of the ba sin with faunistically doc u mented age. Ac cord ing to Rogalska (1954), the coals from the Bla- nowice For ma tion rep re sent Lias a (i.e., Hettangian and lower Sinemurian), Mossoczy (1961) sug gested their Toar- cian age, and Dadlez (1976) be lieved them to rep re sent the Upper Pliensbachian. The re sults of pres ent study show that at least the up per part of this lithostratigraphic unit was de - pos ited dur ing the Late Pliensbachian through ear li est Toar- cian. Pieñkowski (2004) sug gested sig nif i cant re gres sive event in the area of study dur ing Late Pliensbachian, which pre sum ably re sulted in ap pear ance of en vi ron men tal con di - tions fa vour able for coal seam for ma tion (i.e., the sedimen- tation of the ex “Blanowice coals”). This pe riod was fol - lowed ac cord ing to Pieñkowski (2004, fig. 71.11) by ma rine trans gres sion dur ing the Early Toarcian. Dinocyst assem- blage found in the Mrzyg³ód out crop is pre sum ably a re sult of ma rine in flu ences as so ci ated with that trans gres sion.
Simi lar dino cyst as sem blages were found by Bar ski (in Bar ski & Le on owicz, 2002) in the Ciecho ci nek For ma tion ex posed in the Kraków-Silesia Mono cline north- westwards from the Mrzyg³ód area. These ap proxi mately coe val as - sem blages (oc cur rence of Luehn dea spi nosa) from the Ciecho ci nek Beds are also domi nated by Nan nocera top sis spe cies. Moreo ver, Bar ski noted simi lar re la tion be tween dino cyst as sem blage com po si tion and palyno fa cies: sam - ples with higher amounts of large- sized woody de bris con - tain mono spe cific Nan nocera top sis as sem blages, whereas those sam ples, which con tain palyno fa cies with higher ra tio of sporo morphs con tain also Luehn dea spi nosa. This points at simi lar, re stricted con di tions dur ing Late Pli ens ba - chian–ear li est Toar cian time in Pol ish epi con ti nen tal ba sin, which rep re sented mar ginal area of the north west Euro pean epi con ti nen tal ba sin. It was a shal low ba sin with high, but vari able rate of ter res trial ma te rial in put. A con se quence was fluc tu at ing sa lin ity level, rang ing from fresh wa ter con -
di tions when coals ac cu mu lated, to re stricted ma rine (=brack ish) en vi ron ments with mono spe cific blooms of Nan nocera top sis. In more cen tral ar eas of this ba sin, i.e. in the Brit ish Isles (e.g., Rid ing, 1984, 1987; Rid ing et al., 1991), Ger many (e.g., Mor gen roth, 1970; Wille & Gocht, 1979; Wille, 1982; Prauss, 1989) or Den mark (Poulsen, 1992), the late Early Ju ras sic dino cyst as sem blages, al - though con tain fre quently nu mer ous speci mens of Nan - nocera top sis (e.g., Rid ing, 1982) are more di ver si fied re - flect ing ma rine palaeoenvironments.
SE LECTED TAX ON OMY
Di vi sion DINOFLAGELLATA (Bütschli 1885) Fensome et al. 1993
Sub di vi sion DI NO KARY OTA Fen some et al. 1993 Class DI NO PHYCEAE Pascher 1914 Sub class DI NO PHYSI PHY CI DAE Möhn 1984
ex Fen some et al. 1993
Or der NAN NOCERA TOP SIA LES Piel et Evitt 1980 Fam ily NAN NOCERA TOP SI ACEAE Gocht 1970
Ge nus Nan nocera top sis De flandre 1938 emend. Poulsen 1992
Type spe cies: Nan nocera top sis pel lu cida De flandre 1938 Nannoceratopsis sp. A
(Fig. 7L–P)
De scrip tion. A subtriangular to rounded subtriangular spe cies of Nannoceratopsis hav ing two rel a tively short and of equal size and shape, pointed antapical horns. Con cav ity be tween these horns has tri an gu lar out line: the in ner edges of the antapical horns are straight lines, which cross at the an gle of 110–140°. The auto- phragm is rel a tively thin and its sur face is microperforate to mi - crore tic u late. The sagittal band is not thick ened. The epicyst is fre - quently miss ing.
Di men sions:
length of the cyst: 38–48 µm (with epicyst at tached);
width of the cyst: 36–42 µm.
Com par i son. This spe cies dif fers from all Nannoceratopsis spe - cies that have two antapical horns by the shape of con cav ity be - tween these horns. It has tri an gu lar shape cre ated by two straight in ner mar gins of the horns.
CON CLU SIONS
1. Up per part of the Bla nowice For ma tion ex posed at Mrzyg³ód con tains dino cysts. Pres ence of Luehn dea spi - nosa sug gests Late Pli ens ba chian–ear li est Toar cian age of stud ied as sem blages. Thus, dino cysts ap pear to be good age in di ca tors in epi con ti nen tal Lower Ju ras sic strata of Po land, which usu ally lack age- indicative fos sils (see also Bar ski &
Le on owicz, 2002).
2. The stud ied sec tion of the Bla nowice For ma tion at Mrzyg³ód is char ac ter ized by vari able palyno fa cies con tent
re flect ing un sta ble en vi ron mental con di tions dur ing their for ma tion. Lami nated black ish clays ex posed in the ba sal part of the ex po sure yielded rela tively rich dino cyst as sem - blage, which re flect pe riod of ma rine in flu ence. The ex - posed higher up grey clays with abun dant co ali fied de tri tus that un der lie a 10- cm thick coal seam con tains ter res trial palyno fa cies com posed chiefly of large- sized phy to clasts.
This sec tion in ter val was thus de pos ited dur ing fresh wa ter (la cus trin?) con di tions. Oc cur rence of rare dino cysts rep re - sented by mono spe cific as sem blage above the coal seam sug gests grad ual turn ing into brack ish en vi ron ment.
3. Palyno fa cies analy sis, sup ported by dino cyst as sem - blage analy sis ap pears to be a valu able tool for pa laeoen vi - ron men tal re con struc tions of Lower Ju ras sic epi con ti nen tal
EARLY JU RAS SIC DINOFLAGELLATE CYSTS
155
Fig. 7. Dinocysts from the Blanowice For ma tion at Mrzyg³ód. A–K – Nannoceratopsis globiformis: A, B – Mrz1, C–K – Mrz3 (note the pres ence of epicyst in spec i men at pho to mi cro graph A, K – the re main ing spec i mens of N. globiformis are de void of epicyst); L–P – Nannoceratopsis sp. A: all spec i mens from sam ple Mrz3. Scale bar in (A) re fers to all other pho to mi cro graphs
de pos its of Po land. Sedi ments de pos ited in ter res trial en vi - ron ment con tain palyno fa cies com posed en tirely of land- plant re mains, fre quently large- sized. Ma rine in flu ences are re corded in the sedi ment by usu ally smaller di men sions of phy to clasts, higher fre quences of sporo morphs (par ticu larly pol len grains) and oc cur rence of dino cyst as sem blages. The com po si tion of the lat ter show grad ual pas sages from monospe cific Nan nocera top sis as sem blages re flect ing pre - suma bly brack ish con di tions into more di ver si fied ones as - so ci ated with ma rine en vi ron ment.
Ac knowl edge ment
I would like to thank Dr. Mariusz Paszkowski (In sti tute of Geo log i cal Sci ences, Pol ish Acad emy of Sci ences, Kraków) for in tro duc tion into ge ol ogy of study area, as sistance in sam ple col - lec tion and dis cus sion dur ing this study. I also thank M. Barski (Fac ulty of Ge ol ogy, War saw Uni ver sity) for crit i cal read ing the manu script and valu able com ments. K. B¹k (In sti tute of Ge og ra - phy, Ped a gog i cal Uni ver sity, Kraków) is ac knowl edged for ed i to - rial proof.
Fig. 8. Dinocysts from the Blanowice For ma tion at Mrzyg³ód. A–M – Nannoceratopsis raunsgaardii (A, B – Mrz1, C–M – Mrz3); N, O – Nannoceratopsis ?spiculata: both spec i mens from sam ple Mrz3; P – Nannoceratopsis deflandrei subsp. senex (Mrz3). Scale bar in (A) re fers to all other pho to mi cro graphs
EARLY JU RAS SIC DINOFLAGELLATE CYSTS
157
Fig. 9. Dinocysts and Tasmanitaceae from the Blanowice For ma tion at Mrzyg³ód. A–C – Nannoceratopsis triceras (A – Mrz1, B,C – Mrz3); D – Nannoceratopsis ridingii (Mrz3); E–G – Batiacasphaera sp. (all spec i mens from sam ple Mrz3; F, G – the same spec i men, var - i ous foci); H, L – Mendicodinium spinosum (Mrz3; the same spec i men, var i ous foci); I–K – Luehndea spinosa (Mrz3; the same spec i men, var i ous foci); M–O – Tasmanitaceae: M, N: the same spec i men of a spe cies (Tasmanites? sp.) with thick wall per fo rated by reg u larly dis - trib uted pores (N); O: spe cies with thin ner wall (Tytthodiscus suevicus?). Scale bar in (A) re fers to all other pho to mi cro graphs
AP PEN DIX
An al pha bet i cal list ing of dinocyst taxa found in the Mrzyg³ód sec tion is pro vided be low. Tax o nomic ci ta tions are given in Wil liams et al. (1998). Num bers in pa ren the ses re fer to the ap pro pri ate pho to mi cro graphs in Fig ures 6 to 8.
Batiacasphaera sp. (Fig. 9E–G)
Luehndea spinosa Morgenroth 1970 (Fig. 9I–K)
Mendicodinium spinosum Bucefalo Palliani, Rid ing & Torricelli 1997 (Fig. 9H, L)
Nannoceratopsis deflandrei subsp. senex (van Helden 1977) Ilyina 1994 (Fig. 8P)
Nannoceratopsis globiformis Bucefalo Palliani & Rid ing 1997 (Fig. 7A–K)
Nannoceratopsis ridingii Poulsen 1992 (Fig. 9D) Nannoceratopsis ?spiculata Stover 1966 (Fig. 8N, O) Nannoceratopsis triceras Drugg 1978 (Fig. 9A–C) Nannoceratopsis sp. A (Fig. 7L–P)
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Streszczenie
WCZESNOJURAJSKIE DINOCYSTY Z KRAKOWSKO-ŒL¥SKIEJ MONOKLINY, POLSKA PO£UDNIOWA: ZAPIS Z FORMACJI
BLANOWICKIEJ W MRZYG£ODZIE
Przemys³aw Gedl
Epikontynentalna dolna jura w Polsce wykszta³cona jest w wiêkszoœci w facjach kontynentalnych. We wczesnej jurze zaznaczy³o siê jednak kilka ingresji morskich na teren dzisiejszej Polski, których najbardziej kompletny zapis znany jest z Polski pó³nocno-zachodniej. W pozosta³ych, peryferyjnych obszarach basenu zapis ingresji jest znacznie s³abiej udokumentowany z uwagi na brak skamienia³oœci. Z tego powodu, jednostki litostra- tygraficzne epikontynentalnej dolnej jury tej czêœci Polski (Fig. 1, 2) s¹ czêsto pozbawione precyzyjnych datowañ biostratygra- ficznych. Podjête w ostatnich latach badania organicznych cyst Dinoflagellata (dinocyst) z epikontynentalnej jury Polski pokazuj¹ du¿¹ ich przydatnoœæ dla biostratygrafii oraz, wraz z analiz¹ palinofacji – dla rekonstrukcji œrodowiska sedymentacji tych osadów. Takie badania, podjête w dolnojurajskim profilu formacji blanowickiej w nieczynnym wyrobisku cegielni w Mrzyg³odzie (Fig. 3), s¹ prezentowane w niniejszym artykule.
Blisko 3 metrowy profil (Fig. 4) ods³ania ciemne i³owce z za- chowan¹ pierwotn¹ laminacj¹, przechodz¹ce ku górze w jasno- szare i³y z licznym uwêglonym detrytusem roœlinnym, które podœcielaj¹ 10 cm pok³ad wêgla. Powy¿ej ods³aniaj¹ siê ponownie ciemno zabarwione i³y. Z profilu pobrano 3 próbki, które poddano standardowej maceracji palinologicznej.
Wszystkie próbki zawieraj¹ bardzo bogaty materia³ palinolo- giczny zdominowany przez roœlinne elementy pochodzenia l¹do- wego. W próbce Mrz2 najliczniej wystêpuj¹ du¿ych rozmiarów fitoklasty (Fig. 5); podobnie w próbce Mrz1, gdzie pojawiaj¹ siê jednak nieliczne dinocysty z rodzaju Nannoceratopsis. W próbce tej zaznacza siê równie¿ udzia³ organicznej materii amorficznej (Fig. 6). Dinocysty najliczniej wystêpuj¹ w próbce Mrz3, gdzie stanowi¹ blisko 2% palinofacji. Próbka ta charakteryzuje siê równie¿ du¿ym udzia³em sporomorf (Fig. 5). Zespó³ dinocyst jest wyraŸnie zdominowany przez przedstawicieli rodzaju Nanno- ceratopsis (Fig. 7, 8, 9). Jedynie w próbce Mrz3 pojawiaj¹ siê pojedynczy przedstawiciele innych gatunków: Batiacasphaera sp., Luehndea spinosa, Mendicodinium spinosum.
Obecnoœæ Luehndea spinosa wskazuje, ¿e badane osady re- prezentuj¹ górny pliensbach-najni¿szy toark. Analiza palinofacji wskazuje na zmienne warunki sedymentacji osadów z badanego profilu. Najni¿sza jego czêœæ powstawa³a w warunkach morskich, których odzwierciedleniem jest obecnoœæ dinocyst. Wy¿sza czêœæ profilu, w obrêbie której wystêpuje wêgiel, powsta³a zapewne w œrodowisku l¹dowym (jeziorzyskowym?). Pojawienie siê nie- licznych dinocyst w stropowej partii profilu wskazuje na stop- niowy powrót warunków morskich (brakicznych?) w trakcie jego powstawania.
EARLY JU RAS SIC DINOFLAGELLATE CYSTS
