BOSITRA LIMESTONES – A STEP TOWARDS RADIOLARITES:
CASE STUDY FROM THE TATRA MOUNTAINS
Re nata JACH
In sti tute of Geo logi cal Sci ences, Jagiel lo nian Uni ver sity, Ole an dry 2a, 30- 063 Kraków, Po land; e- mail: jach@ing.uj.edu.pl
Jach, R., 2007. Bosi tra lime stones – a step to wards ra dio larites: case study from the Ta tra Moun tains. An nales So cie ta tis Ge olo go rum Po lo niae, 77: 161–170.
Ab stract: Bosi tra lime stones of Aalenian–Lower Batho nian age crop out in the Krížna unit in the West ern Ta tra Moun tains (Po land). They are sand wiched be tween pe lagic red lime stones and ra dio larites and dis play lat eral fa cies varia tion. Four fa cies were dis tin guished: (i) Bosi tra pack stones/grain stones, (ii) cri noi dal pack stones/ grain stones, (iii) Bosi tra-cr ino idal pack stones, and (iv) Bosi tra-r adi ola rian wacke stones. The Bosi tra pack stones/ grain stones were laid down in high- energy set ting, while Bosi tra-r adi ola rian wacke stones in calm con di tion. Cri noi dal pack stones/grain stones rep re sent den sity cur rent de pos its. Bosi tra-cr ino idal pack stones re sulted from in tense bio tur ba tion and mix ing of cri noi dal pack stones/grain stones with back ground Bosi tra-rich de pos its. To po graphic gra di ent af fected the lat eral fa cies varia tion. Tapho nomic fac tors strongly con trolled by en ergy of the sedi men tary en vi ron ment, eco logi cal fac tors which caused domi na tion of Bosi tra bi valves in ben thos as sem blage and dis so lu tion elimi nat ing non- calcitic bio clasts could re sulted in for ma tion of the Bosi tra lime stones. The eutrophi ca tion of wa ter col umn and re mod ell ing of the Krížna Ba sin, which fi nally led to depo si tion of ra dio larites seem to be of con sid er able im por tance. Hence, Bosi tra lime stones can be re garded as the rec ord of the in ter me -di ate stage of the ba sin evo lu tion to wards ra -dio larite for ma tion.
Key words: thin- shelled bi valves, Mid dle Ju ras sic, Krížna Ba sin, Car pa thi ans, West ern Te thys. Manuscript re ceived 16 June 2007, ac cepted 14 Sep tem ber 2007
IN TRO DUC TION
The Ju ras sic de pos its com monly con tain thin- shelled bi valves. These spe cific de pos its are rep re sented by vari ous fa cies, such as organic- rich shells, car bon ate tur bid ites or pe lagic lime stones. Bosi tra bu chii, for merly known as Po si
do nia or re garded as al gal fila ments, com monly oc cur in de
-pos its of the Toar cian–Ox for dian age. Thus, the thinshelled bi valve bear ing de pos its are tra di tion ally named as Bosi
tra, Po si do nia or fila men tous fa cies. How ever, the pres er
-va tion of thin- shelled bi -valves of ten hin ders their pre cise taxo nomi cal po si tion. Sev eral de tailed in ves ti ga tions of Ju -ras sic thin- shelled bi valves led to rec og nize, be sides widely known Bosi tra bu chii, some new tax ons (Kuhry, 1975; Conti & Mon ari, 1992).
Thin- shelled bi valve bear ing de pos its are world wide dis trib uted. They were no ticed among oth ers from the Te thyan do main, South ern An des, Kenya and Can ada (Jef fer -ies & Min ton, 1965; Ber noulli & Jenkyns, 1974; Clap ham
et al., 2002). Apart from clas si cal and fa mous Lower Toar
-cian black shales, an other Bosi tra-bea ring com mon fa cies
are thin shelled bi valve bear ing lime stones. They are char ac ter ized by patchy ge ome try and lim ited lat eral range (Ber -noulli & Jenkyns, 1974). In the clas si cal sec tion of the Trento pla teau, where such lime stones are called Lu ma -chella a Po si do nia alpina, they oc cur be tween shal low wa ter lime stones and red nodu lar lime stones of the Rosso Am -monitico Veron ese. These de pos its fill nep tu nian dykes there (Sturani, 1971; Win terer et al., 1991). Bosi tra lime -stones form also bio clas tic in ter ca la tions within the Rosso Am monitico Veron ese (Mar tire, 1996). In the Marche re gion the lime stones with Bosi tra, called here Cal -cari a Po si do nia, over lay red nodu lar lime stones (Mon aco & Morettini, 1997). Thin- shelled bivalve- bearing fa cies are of ten suc ceeded by ra dio larites, for ex am ple in the North ern Alps, Cen tral Ap en ni nes and Ta tra Moun tains (Le feld et al., 1985; Böhm, 1986; Gal luzzo & San tan to nio, 2002). As so cia tion of Bosi tra lime stones with ra dio larites de mands de -tailed sedi men to logi cal analy sis, which al lows to rec og nize en vi ron mental re la tions of these two fa cies.
The main pur pose of this pa per is to dis cuss the ori gin of the thin- shelled bivalve- bearing fa cies from the Ju ras sic de pos its of the West ern Ta tra Moun tains, and to de fine their sig nifi cance in the re con struc tion of the Krížna Ba sin de vel -op ment in the early Mid dle Ju ras sic times. Con cen tra tions of thin- shelled bi valve shells can be a use ful tool in fa cies analy sis, es pe cially in an in te grated ap proach com bin ing sedi men to logi cal and pa laeoe co logi cal data. Since this kind of skele tal con cen tra tion is rela tively fre quent in the Mid dle Ju ras sic de pos its of the West ern Te thys, the pres ent re sults would have im pli ca tions for un der stand ing de po si tional pro cesses and the evo lu tion of other Ju ras sic ba sins of the Te thyan do main.
GEO LOG I CAL SET TING
The Mid dle Ju ras sic thin shelled bivalve bearing lime -stones, here af ter called Bosi tra lime -stones, crop out in the Pol ish part of the West ern Ta tra Moun tains. They be long to the Krížna unit, which in this part of the Ta tra Moun tains is rep re sented by a large slab, called the Bo brow iec unit, ho -mo cli nally dip ping to the north (Fig. 1; Bac- Moszaszwili et
al., 1979). The unit com prises Lower Tri as sic through
Lower Cre ta ceous de pos its.
A 100 m thick com plex of spot ted lime stones and marls (Fleck en mer gel) of the Late Si ne murian–Early Pli ens ba -chian age oc curs in the lower part of the sec tions (Fig. 2; Uch man & Myc zyñski, 2006). This com plex is cov ered by up to 20 m thick Domerian spicu lites (Jach, 2002). In the east ern part of the stud ied re gion, spicu lites are cov ered by Lower Toar cian cri noi dal grain stones, while in the west ern
part by al ter nated lime stones and marls (Jach, 2005). Lo -cally, man ga nese de pos its of hy dro ther mal ori gin oc cur above cri noi dal grain stones (Jach & Dudek, 2005). The over ly ing 1–4 m thick suite is com posed of red nodu lar Ad -net type lime stones and marls be long ing to the lower part of the Kliny Lime stones Mem ber of the Hu ciska Lime stone For ma tion (Fig. 2; Le feld et al., 1985). Red de pos its com -prise di ag nos tic am mon ites for Bi frons zone (Myc zyñski & Le feld, 2003; Jach & Myc zyñski, 2006). Bosi tra lime stones be long to the up per part of the Kliny Lime stones Mem ber (Le feld et al., 1985). Their age is not pre cisely de ter mined due to lack of di ag nos tic fauna, how ever they are usu ally as -cribed to Aalenian (Bu jnovský & Polák, 1979; Le feld et al., 1985). Bosi tra lime stones are cov ered with red, pink ish lay -ered ra dio lar ian lime stones and ra dio larites of the Late Batho nian–Early Kim me rid ian age (Polák et al., 1998). Av -er age thick ness of these de pos its is es ti mated as 15–25 m (Le feld, 1974).
METH ODS
Nine sec tions have been stud ied in the west ern part of the Krížna unit in the West ern Ta tra Moun tains (Fig. 2). For the sake of sim plic ity, sec tions are num bered as fol lows: 1 – sec tion lo cated in the up per parts of the D³uga Val ley (Dolina D³uga), 2 – sec tion on the north ern slopes of the D³uga Val ley, 3 – sec tion at Grzeœ hill in the D³uga Val ley, 4 – sec tion on the south- western slopes of the Hu ciañski Klin crest, 5 – sec tion at slopes of Poœred nia Kopka, 6 – sec -tion at Œwi ñska Tur nia, and 7 – sec tion on the west ern slopes of G³ad kie Up³az iañskie. Fa cies and sedi men tary
162
R. JACHFig. 1. Geo log i cal sketch map of the Pol ish part of the West ern Tatra Moun tains (af ter BacMoszaszwili et al., 1979; sim pli fied) show -ing lo ca tion of stud ied sec tions; sym bols of the sec tions ex plained in the text
. 2 . gi F /r e w o L e ht f o s g ol c i h pa r git art s o hti L e ht ni ti n u a nž ír K e ht f o st i s o pe d ci ss a r uJ e l d di M dl ef e L re tf a( s t M art a T nr et se W .l a t e ;)t fe l ; 5 8 9 1 , e ht f o s n oi t ce s l ac i g ol o hti l ar ti s o B e ht ni se n ot se mil n oi t a c ol n oi t ce s ;)t h gi r( s ni a t n u o M art a T nr et se W 1 . gi F ee s
struc tures were stud ied and dis tin guished in the field. The sec tions were ana lysed bed- by- bed with de tailed sam pling. The ob ser va tions were sup ple mented by rock slabs and mi -cro fa cies analy sis.
RE SULTS
Bosi tra lime stones are grey and well bed ded, only at the
base they are more grey pinkish and more cherty. Domi nat -ing com po nents are dis ar ticu lated Bosi tra shells. Elon gated si li ceous lenses up to a few cen ti me tres thick oc cur in the lower part of the sec tions. The thick ness of Bosi tra lime -stones ranges usu ally from 0.5 to 4 m (Fig. 2). How ever, one may as sume that their to tal thick ness is slightly greater be cause out crops are not com plete. The con tact of Bosi tra lime stones with un der ly ing red lime stones is very sharp and marked by change in col our and de crease in a fine frac tion con tent. The con tact most proba bly dis plays char ac ter of an omis sion sur face. Four fa cies types are dis tin guished mainly by means of thin sec tion analy sis: (i) Bosi tra pack -stones/grain stones, (ii) cri noi dal pack -stones/grain stones, (iii) Bosi tracr ino idal pack stones, and (iv) Bosi trar adi ola -rian wacke stones. The fa cies dis tri bu tion is pre sented in Fig. 2.
Fa cies de scrip tion and in ter pre ta tion
Bosi tra pack stones/grain stones con tain Bosi tra shells and rare cri noid frag ments. Shells are very thin (30–40 µm) and ap proxi mately 3.5 mm in length, but maxi mally reach 6 mm. They are flat tened and hori zon tally ori ented (Fig. 3A, E). The dis tinc tive fea ture of this fa cies is a grain- supported tex ture. Shells are usu ally so densely packed that the rock ex hib its fit ted fab ric (Fig. 3E). Only lo cally, shells are re ori -ented due to bio tur ba tions (Fig. 3F). Bio clasts are very well se lected and re crys tal lized. Bosi tra grain stones dis play com mon sty lo lites (Fig. 3E).
Bosi tra pack stones/grain stones dis play ing a good se
-lec tion of bio clasts were laid down in rela tively high- energy set tings. How ever, the Bosi tra shells were not crushed com -pletely, what in di cates rather mod er ate cur rent ac tion. Fit ted fab ric within Bosi tra grain stones sug gests that early ce men -ta tion was in sig nifi cant (see Clari & Mar tire, 1996).
Cri noi dal pack stones/grain stones con tain, be sides cri noi dal frag ments, rare fo ra mini fer tests and crushed Bosi
tra shells (Fig. 3B, C). Cri noids show over growth of syn
-tax ial ce ments. Nor mal grad ing and good sort ing of ma te rial are com mon in this type of sedi ment. In some sec tions this fa cies is in ter lay ered with thin lay ers of marls. Frag ments of
cri noids, fish teeth, rare fo ra mini fer tests (Len ticulina sp.) and glau cony domi nate in these marls. In such beds the cri -noi dal frag ments are of ten filled with glau cony. Cri -noi dal pack stones/grain stones oc cur usu ally in the lower part of the stud ied sec tions (sec tions 2, 3; Fig. 2). These beds are sev eral cen ti me tres thick, whereas marls are few cen ti me -tres thick.
This type of fa cies forms in ter ca la tions within Bosi tra lime stones. These in ter ca la tions sug gest the trans port of cri -noi dal ma te rial by den sity cur rents, proba bly of tur biditic char ac ter. Pri mary po ros ity of cri noi dal ma te rial de ter mines its hy dro dy namic be hav iour and makes the trans port pos si -ble on long dis tances, even by weak cur rents (Blyth Cain, 1968). Thin marls with glau cony over lay ing cri noi dal in ter -ca la tions, seem to rep re sent back ground pe lagic sedi ment with some ad mix ture of fine ma te rial of tail of grav ity flows.
Bosi tra-cr ino idal pack stones are characterized by high con tent of cri noi dal de bris and crushed Bosi tra shells (Fig. 3D). This type of fa cies oc curs in lower parts of the sec tions. Fo ra mini fer tests and sponge spic ules oc cur spo radi cally. Se lec tion of bio clasts is low. Bio clasts are re ori -en tated due to bio tur ba tion. Traces of dis so lu tion in the form of sty lo lites and dis so lu tion seams oc cur com monly within these fa cies.
Bosi tracr ino idal pack stones rep re sent bio tur bated tur
-bid ites mixed with back ground Bosi tra-bea ring de pos its. Cri noi dal de bris and proba bly ma jor ity of Bosi tra shells were trans ported. Bio tur ba tions in di cate oxic con di tions within the bot tom sedi ment.
Bosi tra-r adi ola rian wacke stones are fine- grained and struc ture less sedi ments (Fig. 3G). Lo cally they con tain sponge spic ules of rhax type. Bosi tra shells up to 1 mm in length are crushed and do not dis play sort ing. Ra dio lar ian tests are cal ci fied. Lo cally the Bosi trar adi ola rian wacke -stones dis play dis so lu tion seams.
Bositra-radiolarian wackestones were de pos ited in
lower-en ergy set tings. It is proved by the oc cur rence of large amount of micrite as well as nu mer ous radio lar ians. Prob a bly radio lar ians, as the el e ment eas ily put in mo tion, were re placed by cur rents from el e vated parts of the bas ins and ac cu mu lated in ad ja cent, calm de pres sions (Baumgart-ner, 1987). Thus, this fa cies were laid down in local depre-ssions.
Lat eral fa cies vari a tion
Bositra lime stones ex hibit dis tinct lat eral fa cies vari a -tion. Bositra-radiolarian wackestones oc cur in the sec tion 1 and 7, but only in the first one they con tain com mon sponge
164
R. JACHFig. 3. Facies of the Bositra lime stones: A. Bositra grainstone dis play ing densely packed flat tened Bositra shells; weath ered sur face of the rock sam ple; sec tion 3; B. Crinoidal grainstone with nor mal grad ing ho ri zons; pol ished sec tion; sec tion 3; C. Crinoidal grainstone with syntaxial ce ment; thin sec tion; sec tion 3; D. Bositra-crinoidal packstone show ing crushed bioclasts; thin sec tion; sec tion 3; E. Fit ted fab ric in Bositra grainstone; stylolite cut ting the shells are vis i ble; thin sec tion; sec tion 4; F. Bositra grainstone; lo cally re ori ented shells of Bositra may be ef fect of bioturbation; thin sec tion; sec tion 4; G. Bositra-radiolarian wackestone; thin sec tion; sec tion 7
spicules of rhax type (Fig. 2). Sec tions 2 and 3 are char ac -ter ized by the oc cur rence of crinoidal grainstones/pack-stones in their lower parts. In sec tions 4 and 5 Bositra-crinoidal packstones dom i nate in their lower parts, which are grad u ally re placed up ward by Bositra packstones/ grainstones. Lower part of the sec tion 6 con tains 60 cm thick in ter val of slump con glom er ates (Fig. 2), which com -prise intraclasts of Bositra packstones/grainstones where the Bositra wackestones form the ma trix. The spatial ar -range ment of Bositra lime stone fa cies mir rors the fa cies vari a tion of underlying deposits (Jach, 2003).
DIS CUS SION
Fac tors con trol ling con cen tra tion of Bositra shells The main char ac ter is tic of Bositra lime stones is the great abun dance of Bositra shells con sti tut ing the pre dom i -nant rock-build ing com po nent. There are sev eral pos si ble rea sons of such con cen tra tion. One can list: (i) taphonomic fac tors, (ii) eco log i cal fac tors, and (iii) dis so lu tion fac tors. How ever, the above de scribed dis tri bu tion of bi valve shells is hardly ex plained only by one of the listed fac tors. There -fore, it seems that sev eral fac tors af fected sed i men ta tion of
Bositra limestones.
Taphonomic fac tors
Af ter a long last ing dis cus sion on the ecol ogy of
Bositra their ben thic life has been fi nally proved (Etter,
1996; Röhl et al., 2001). The above con clu sion con cerns also other Ju ras sic thin-shelled bi valves (Conti & Monari, 1992). Wignall (1993) and Röhl et al. (2001) claim that
Bositra pre ferred soft muddy sub strate. Thus, ac cu mu la tion
of Bositra shells in the form of grainstones and packstones as ob served in the stud ied case may be a cur rent or win -nowed con cen tra tion (sensu Fürsich & Oschmann, 1993). The rel a tively good pres er va tion of frag ile Bositra shells let us rule out the for mer pos si bil ity (see Kuhry, 1975). The lat -ter pos si bil ity de pends on in tense re moval of fine-grained car bon ate frac tion and bioclasts char ac ter ized by the low pro por tion of weight to vol ume lead ing to the con cen tra tion of Bositra shells that, in con se quence, be came al most the only one autochthonous el e ment (Martire, 1992; Fürsich & Oschmann, 1993). Win nowed con cen tra tions can pro ceed in var i ous ways. How ever, in the stud ied case the most prob a ble one is the action of weak currents (cf. Fürsich & Oschmann, 1993).
Eco log i cal fac tors
An other pos si ble ex pla na tion of Bositra shell con cen -tra tion in vokes gen er ally ac cepted facts that Bosi-tra were oligotypic fauna. They were op por tu nis tic or gan isms, rep re sent ing ex treme rstrat e gists, there fore they in creased rap idly in num ber un der fa vour able con di tions. Hence, the con -cen tra tion of the shells may be the ef fect of en vi ron men tal stress. It is well known that Bositra tol er ates low ox y gen con tent (Oschmann, 1993; Röhl et al., 2001). How ever, no
proof for ox y gen de ple tion has been given for the stud ied de pos its. By con trast, some parts of Bositra lime stones bear the ev i dence of in tense bioturbation, which sug gests that ox y gen content in the pore water allowed infaunal coloni-zation.
A close re la tion ship ex ists be tween Bositra blooms and events of high or ganic pro duc tiv ity, since Bositra-bear ing shales, es pe cially those of Toarcian age, have high or ganic mat ter con tent (Röhl et al., 2001 and ref er ences quoted herein). It may not be ex cluded that Bositra were able to tol -er ate toxic el e ments or as sim i late nu tri ents in an un usual way (cf. Kauffmann, 1976). Ex tremely low biodiversity may re flect paleoenvironmental stress con di tions ow ing to high in put of nu tri ents (Bartolini & Cecca, 1999). High den -sity of oligotypic fauna, in the stud ied case rep re sented by
Bositra, is of ten re lated to eutrophication (Bartolini &
Cecca, 1999). This phe nom e non af fected the West ern Tethys dur ing Mid dle Ju ras sic time, which was re flected in sed i men ta tion of radiolarites and in the cri sis of car bon ate pro duc tion (Bartolini & Cecca, 1999). Hence, the con cen -tra tion of Bosi-tra in the stud ied deposits may be an effect of eutrophication of the wa ter column.
Dis so lu tion fac tors
An other rea son of high con cen tra tion of Bositra shells could be dis so lu tion of ar agon ite in the wa ter col umn. This con cept as sumes that ar agon ite com po nents were dis solved by ag gres sive bot tom wa ters which led to rel a tive en rich ment in cal cite com po nents. Sim i lar mech a nism was com -monly in voked to ex plain the de po si tion of Tethyan Ju ras sic radiolarites (Bosellini & Winterer, 1975; Winterer & Bosellini, 1981).
Al though the stud ied lime stones are com posed al most ex clu sively of bi valve shells, it is dif fi cult to state their pri -mary min er al ogy. Bositra shells were built of an outer calci- tic-sim ple pris matic layer cou pled to a na cre ous-aragonitic one (Conti & Monari, 1992). How ever, the stud ied shells are pres ently heavy recrystallized, there fore no rel ics of pri -mary struc ture are vis i ble. Hence, it is dif fi cult to find if these shells dis played sin gle-lay ered or dou ble-lay ered microstructure dur ing burial. The Bositra lime stones may be a con cen tra tion of cal cite lay ers of the orig i nally bi-mineralic shells ow ing to ar agon ite dis so lu tion be low the ar agon ite com pen sa tion depth (see also Böhm, 1986). In such a case they rep re sent dis so lu tion fa cies (sensu Bose-llini & Winterer, 1975). How ever, dis so lu tion alone can not ex plain for ma tion of Bositra lime stones, be cause one can ex pect more other calcitic com po nents, such as bel em nite guards and aptychi which occur even in overlying ra dio-larites (G¹siorowski, 1959).
To pog ra phy of the Krížna Ba sin dur ing de po si tion of Bositra lime stones
The de po si tion of Bositra lime stones took place in the ba sin with con sid er able top o graphic gra di ent, what plau si -bly ex plains the dis tinct lat eral fa cies vari a tion of Bositra lime stones as well as changes in their thick ness. The Krížna
Ba sin com prised pe lagic car bon ate plat forms (sensu Sant-an to nio, 1993) Sant-and ad join ing bas ins (Jach, 2003). SSant-antSant-an- Santantonio et al. (1996) and Galuzzo and SantanSantantonio (2002), fol -low ing the study of the drowned Pa cific atolls (Winterer, 1991), have sug gested that thick ness of pe lagic plat form de -pos its de creases to ward the edges, which is caused by the an gle of re pose and more in tense cur rent ac tion at the mar -ginal parts of the plat form. Galuzzo and Santantonio (2002) com pared such fa cies ge om e try of the pe lagic car bon ate plat form to the fa mous Mil a nese cake pan et tone. The pro -posed model fits well for Bositra fa cies dis tri bu tion in the Krížna unit. In the de pres sions and in the in te rior of the el e vated horsts Bositraradiolarian wackestones were de pos -ited (sec tions 1, 5, 6), while at the mar gins of the el e vated parts of the ba sin the de po si tion of well-sorted Bositra packstones/grainstones took place (sec tions 2, 3 and 4; Figs 2, 4). The best se lected Bositra-bear ing sed i ment formed along the mar gins of the pe lagic car bon ate plat form (sec tion 2, 3 and 4) due to more intense action of currents (cf. Galuzzo & Santantonio, 2002; cf. Baumgartner, 1987).
The thick ness of the stud ied de pos its dif fers from that of Galluzzo and Santantonio’s (2002) model. Bositralime stones reach the max i mum thick ness in sec tion 3, whose po si tion in di cates lo ca tion at the edge zone of the pe lagic car bon ate plat form (Jach, 2003). It may be ex plained by the ex -is tence of a small de pres sion of a perched ba sin type near the edge of the plat form (see Santantonio, 1993). The ac -com mo da tion space cre ated there, en abled for ma tion of a thick se quence of Bositra limestones.
Some ev i dence, like the oc cur rence of crinoidal turbidites, points to grav ity trans port and in di cates a con sid er able top o graphic re lief of the seabot tom. This kind of de po si tion was lim ited only to mar gins of the sub ma rine el e -va tions (sec tions 2 and 3). How ever, some mass move ments took place in the cen tral parts of the el e va tions, which is ev i -denced by intraformational slump con glom er ates, and might re flect synsedimentary tectonic activity (Jach, 2003). Top o graphic gra di ent af fect ing the de po si tion of
Bo-sitra lime stones was in her ited from Early Toarcian time,
since the spa tial ar range ment of the Lower Toarcian crinoi-dal tempestites and spotty lime stones is con cor dant with the dis tri bu tion of the dis cussed Bositra lime stone fa cies (cf. Jach, 2003, 2005). The top o graphic gra di ent per sisted dur -ing the de po si tion of radiolarites as well, and prob a bly caused the diachronicity of their lower bound ary, which was observed by B¹k (2001).
Sig nif i cance of Bositra lime stones for depositional his tory of the Krížna Ba sin
Pro gress ing deep en ing of the Krížna Ba sin through the Mid dle Ju ras sic was tra di tion ally ac cepted. This pro cess com menced af ter the de po si tion of crinoidal tempestites (Jach, 2005) and was con tin ued dur ing the sed i men ta tion of the red lime stones of Adnet type (Gradziñski et al., 2004). One can pre sume that the trend con tin ued to wards the de po -si tion of the over ly ing radiolarites which rep re sent ba-sinal and rel a tively deep-wa ter de pos its (Lefeld, 1974;
Wieczo-rek, 1988). Such a trend, com monly rec og nized in the Tethyan de pos its, is in ter preted as an ef fect of deep en ing of the ba sin, which fi nally gave rise to the or i gin of radiola-rites, de pos ited be low the ACD or even the CCD (Winterer & Bosellini, 1981). How ever, the de po si tion of the dis -cussed Bositra lime stones, es pe cially well-sorted Bositra grainstones/packstones, sandwiched be tween the red pe -lagic limestones and radiolarites, needs some additional comments.
The in flu ence of taphonomic fac tor and dis so lu tion pro -cesses of ar agon ite on the de po si tion of Bositra lime stone must have been as so ci ated with the in ten si fi ca tion of cur -rent ac tiv ity. It en abled a win now ing and re moval of fine car bon ate frac tion and led to the for ma tion of Bositra packstones/grainstones on the plat form edges. Such tex tural fea ture may in di cate fall of the sea level (Martire, 1992). De po si tion of the dis cussed lime stones may be a re sponse to Aalenian re gres sive ep i sode re corded within a gen er ally ob -served Mid dle Ju ras sic transgressive trend (Hal lam, 2001). How ever, it is dif fi cult to cor re late the Bositra lime stones with the global sealevel changes due to the lack of strati -graphi cal mark ers. More over, the Krížna Ba sin dur ing the Early/Mid dle Ju ras sic was a tec toni cally mobile area, what could overprint the global sea-level changes.
An other ex pla na tion of in ten si fi ca tion of cur rent ac tiv -ity is re lated to re mod ell ing of the bas ins, which caused palaeogeographic changes and which, in turn, were re lated to rift ing in the West ern Tethys dur ing Mid dle Ju ras sic time. In this case cur rent ac tiv ity in deeper set tings can be ex pected ow ing to an open ing of new seaways. The cur rents could es pe cially be ef fec tive in nar row bas ins. Now a -days, cur rents of ve loc ity ex ceed ing 30 cm/s are re corded at the depth down to sev eral hun dred metres in the bas ins sep -a r-at ing the Ryukyu Is l-ands (Tsuji, 1993). It is very prob -a ble that the Krížna Ba sin ex hib ited a nar row and elon gated shape in the Mid dle Ju ras sic time. It was bor dered from the north by the up lifted Tatricum do main, which was emerged un til the Bajocian (£uczyñski, 2002), while from the south by the Veporicum, where shal low pe lagic deposition took place (Kozur & Mock, 1996; Plašienka, 1999).
The or i gin of Ju ras sic radiolarites, the Bositra lime -stones are as so ci ated with, were tra di tion ally linked with deep-sea con di tion. How ever, some pa pers stress that other
fac tors led to their for ma tion. Ac cord ing to the new mod els, the de po si tion of the radiolarites is as cribed to the lack of di lu tion by ei ther terrigenous clastics or autochthonous car -bon ates along with the eutrophication of a wa ter col umn, which in turn cut down an autochthonous car bon ate fac tory (Baumgartner, 1987; Bartolini et al., 1996; Cobianchi & Pi-cotti, 2001). Nev er the less, the radiolarites are still re garded as rel a tively deepwa ter sed i ments formed in pe lagic con di tion, as proved by Kiessling (1996) af ter quan ti ta tive anal y -sis of si li ceous micro fauna from sev eral Tethyan sec tions. There fore, the bloom of Bositra lead ing to de po si tion of the stud ied Bositra lime stones was prob a bly fa cil i tated or even caused by the changes in trophic con di tions of the pe lagic wa ter-col umn. Fur ther eutrophication and deep en ing of the bas ins led to de po si tion of over ly ing radiolarites. Hence, the de po si tion of both fa cies mir rored changes in trophic con di -tions of the sea-wa ter dur ing Mid dle Ju ras sic in ter val. The changes were in turn caus ally con nected with in creas ing cli mate hu mid ity af fect ing the vig or ous runoff from the con ti nents (Cobianchi & Picotti, 2001). Thus, the Bositra lime -stones of the Krížna unit rep re sent the in ter me di ate stage of ba sin evo lu tion be tween red lime stones de pos ited in oligo-trophic con di tions (Gradziñski et al., 2004) and radiolarites, which or i gin was re lated to in crease of nu tri ents amount in the wa ter col umn. It is note wor thy that sim i lar tem po ral re -la tion ships were de scribed also from other sec tion of the West ern Tethys, that is from the Umbria-Marche re gion in It aly (Conti & Monari, 1992; Bartolini & Cecca, 1999), the Subbetic area in Spain (Kuhry, 1975; Rey, 1998), and the Luèatín Unit in Slovakia (Soták & Plašienka, 1996). Thus, the above pos tu lated ge netic re la tion ship between Bositra limestones and radiolarites can have universal significance.
CON CLU SIONS
Sed i men ta tion of Bositra lime stones be gan in the Late Toarcian or more prob a bly in Early Aalenian time and con -tin ued un til the Early Bathonian. Three fac tors might have con trolled the for ma tion of these lime stones: (i) taphonomic fac tors strongly con nected with en ergy of the sed i men tary en vi ron ment, which led to win now ing of finegrained car bon ate ma te rial and con cen tra tion of Bositra shells, (ii) eco -log i cal fac tors which caused dom i na tion of Bositra bi valves in benthos as sem blage and (iii) dis so lu tion fac tors which elim i nated noncalcitic bioclasts. The eutrophication of wa ter col umn and re mod el ling of the Krížna Ba sin, which fi -nally led to de po si tion of radiolarites, seem to be sig nif i cant. There fore, Bositra lime stones can be re garded as an in di ca -tor of the in ter me di ate stage in the evo lu tion of the bas ins to wards radiolarite for ma tion. The Krížna Ba sin dur ing the de po si tion of Bositra lime stones was com posed of a range of pe lagic car bon ate plat forms and ad join ing de pres sions. Well sorted Bositra packstones/grainstones were laid down near edges of plat forms, while Bositra-radiolarian wacke-stones in depressions.
Ac knowl edg ments
The au thor ity of the Tatra Na tional Park is grate fully ac knowl edged for pro vid ing per mis sion for the field work. The pa -per is the ex ten sion of a part of the au thor’s PhD the sis su -per vised by Al fred Uchman, who is thanked for in tro duc tion into ge ol ogy of the Tatra Moun tains. Con struc tive crit i cism of ASGP re view ers Tadeusz Peryt and Joachim Szulc is kindly ac knowl edged.
REF ER ENCES
Bac-Moszaszwili, M., Burchart, J., G³azek, J., Iwanow, A., Jaro-szewski, W., Kotañski, Z., Lefeld, J., Mastella, L., Ozim-kowski, W., Roniewicz, P., Skupiñski, A. & Westwalewicz-Mogilska, E., 1979. Mapa geologiczna Tatr Polskich 1:30000. (In Pol ish). Wydawnictwa Geologiczne, Warszawa.
Bartolini, A., Baumgartner, P. O. & Hunziker, J. C., 1996. Mid dle and Late Ju ras sic car bon sta ble – iso tope stra tig ra phy and radiolorite sed i men ta tion of the UmbriaMarche Ba sin (Cen -tral It aly). Eclogae Geologicae Helvetiae, 89: 831–879. Bartolini, A. & Cecca, F., 1999. 20 My hi a tus in the Ju ras sic of
Umbria-Marche Apennines (It aly): car bon ate cri sis due to eutrophication. Comptes Rendus de l’Académie des Sciencies Paris, Sci ence de la Terre et des PlanÀtes, 329: 587–595. Baumgartner, P. O., 1987. Age and gen e sis of Tethyan Ju ras sic
radiolarites. Eclogae Geologicae Helvetiae, 80: 831–879. B¹k, M., 2001. Promienice z kompleksu radiolarytów œrodkowej i
górnej jury jednostki reglowej dolnej Tatr – ich znaczenie biostratygraficzne. (In Pol ish). In: Trzecie Ogólnopolskie Warsztaty Mikropaleontologiczne, Zakopane, 31.05-2.06. 2001, Akademia Pedagogiczna w Krakowie, pp. 50–53. Bernoulli, D. & Jenkyns, H. C., 1974. Al pine, Med i ter ra nean and
Cen tral At lan tic Me so zoic fa cies in re la tion to the early evo -lu tion of the Tethys. In: Dott, R. H. & Sharer, R. H. (eds), Mod ern and An cient Geosynclinal Sed i men ta tion. So ci ety of Eco nomic Pa le on tol o gists and Min er al o gists, Spe cial Pub li -ca tion, 19: 129–160.
Blyth Cain, J. D., 1968. As pects of the depositional en vi ron ment and palaeo ec ol ogy of the crinoidal lime stones. Scot tish Jour -nal of Ge ol ogy, 4: 191–208.
Böhm, F., 1986. Der Grimming: Geschichte einer Karbonat plat -form von der Obertrias bis zum Dogger (Nördliche Kalk-alpen, Steiermark). Fa cies, 15: 195–232.
Bosellini, A. & Winterer, E. L., 1975. Pe lagic lime stones and radiolarites of the Tethyan Me so zoic: A ge netic model. Ge ol -ogy, 3: 279–282.
Bujnovský, A. & Polák, M., 1979. Korelácia mezozoických lito-stratigrafických jednotiek Malej Fatry, Vel'kej Fatry a sz. èasti Nízkých Tatier. (In Slo vak). Geologicke Práce, Správy, 72: 77–96.
Clap ham, M. E., Smith, P. L. & Tip per, H. W., 2002. Lower to Mid dle Ju ras sic stra tig ra phy, ammonoid fauna and sed i men -tary his tory of the Laberge Group in the Fish Lake syncline, north ern White horse Trough, Jukon, Can ada. In: Emond, D. S., Weston, L. H. & Lewis, L. L. (eds), Yu kon Ex plo ra tion and Ge ol ogy 2001. Ex plo ra tion and Geo log i cal Ser vices Di -vi sion, Yu kon re gion, In dian and North ern Af fairs Can ada, pp. 73–85.
Clari, P. A. & Martire, L., 1996. In ter play of ce men ta tion, me -chan i cal com pac tion, and chem i cal com pac tion in nod u lar
lime stones of Rosso Ammonitico Veronese (Mid dle-Up per Ju ras sic, north east ern It aly). Jour nal of Sed i men tary Pe trol -ogy, 66: 447–458.
Cobianchi, M. & Picotti, V., 2001. Sed i men tary and bi o log i cal re -sponse to sea-level and palaeoceanographic changes of a Lower-Mid dle Ju ras sic Tethyan plat form mar gin (South ern Alps, It aly). Palaeo ge ogra phy, Palaeoclimatoogy, Palaeo ec -ol ogy, 169: 219–244.
Conti, M. A. & Monari, S., 1992. Thin-shelled bi valves from the Ju ras sic Rosso Ammonitico and Calcari a Posidonia For ma -tions of the Umbri an-Marchean Apennine (Cen tral It aly). Paleopelagos, 2: 193–213.
Etter, W., 1996. Pseudoplanktonic and ben thic in ver te brates in the Mid dle Ju ras sic Opalinum Clay, north ern Swit zer land. Palaeo ge ogra phy, Palaeoclimatology, Palaeo ec ol ogy, 126: 325–341.
Fürsich, F. T. & Oschmann, W., 1993. Shell beds as tool in ba sin anal y sis: the Ju ras sic of Kachchh, west ern In dia. Jour nal of the Geo log i cal So ci ety, Lon don, 150: 169–185.
Galuzzo, F. & Santantonio, M., 2002. The Sabina Pla teau: a new el e ment in Me so zoic palaeogeography of Cen tral Apennines. Bolletino della Societ´ Geologica Italiana, Vol ume Speciale, 1: 561–588.
G¹siorowski, S. M., 1959. On the age of radiolarites in the Sub-tatric Se ries in the Tatra Mts. Acta Geologica Polonica, 9: 221–230.
Gradziñski, M., Tyszka, J., Uchman, A. & Jach, R., 2004. Large mi cro bialforaminiferal oncoids from con densed LowerMid -dle Ju ras sic de pos its: A case study from the Tatra Moun tains, Po land. Palaeo ge ogra phy, Palaeoclimatology, Palaeo ec ol -ogy, 213: 133–151.
Hal lam, A., 2001. A re view of the broad pat tern of Ju ras sic sealevel changes and their pos si ble causes in the light of cur -rent knowl edge. Palaeo ge ogra phy, Palaeoclimatology, Palaeo ec ol ogy, 167: 23–37.
Jach, R., 2002. Lower Ju ras sic spiculite se ries from the Križna Unit in the West ern Tatra Mts, West ern Carpathians, Po land. Annales Societatis Geologorum Poloniae, 72: 131–144. Jach, R., 2003. Rozwój facjalny utworów prze³omu jury dolnej i
œrodkowej w jednostce kri¿niañskiej Tatr Zachodnich. (In Pol ish). Un pub lished Ph.D. The sis, In sti tute of Geo log i cal Sci ences, Jagiellonian Uni ver sity, Kraków, Po land, 121 ms. pp.
Jach, R., 2005. Storm-dom i nated de po si tion of the Lower Ju ras sic crinoidal lime stone in the Krížna Unit, West ern Tatra Moun -tains, Po land. Fa cies, 50: 561–572.
Jach, R. & Dudek, T., 2005. Or i gin of a Toarcian man ga nese car bon ate/sil i cate de pos its from the Krížna Unit, Tatra Moun -tains, Po land. Chem i cal Ge ol ogy, 224: 136–152.
Jach, R. & Myczyñski, R., 2006. Nektonic fauna from the Toar-cian–Aalenian red de pos its of the Krížna unit in the West ern Tatra Moun tains, Po land. Scripta Facultatis Scientarum Naturalium Universitatis Masarykiana, Brunensis, 33–34 [for 2003–2004]: 38–40.
Jefferies, R. P. S. & Minton, P., 1965. The mode of life of two Ju -ras sic spe cies of ‘Posidonia’ (bivalvia). Palae on tol ogy, 8: 156–185.
Kauffmann, E. G., 1976. Deep-sea Cre ta ceous macrofossils: Hole 317A, Manihiki pla teau. Ini tial Re port of the Deep Sea Drill -ing Pro ject, 33: 503–535.
Kiessling, W., 1996. Fa cies char ac ter iza tion of Mid-Me so zoic
deep-wa ter sed i ments by quan ti ta tive anal y sis of the si li ceous microfaunas. Fa cies, 35: 237–274.
Kozur, H. & Mock, R., 1996. New paleogeographic and tec tonic in ter pre ta tion in the Slovakian Carpathians and their im pli ca -tions for cor re la -tions with the East ern Alps. Part I: Cen tral West ern Carpathians. Mineralia Slovaca, 28: 151–174. Kuhry, B., 1975. Ob ser va tions on fil a ments from the Subbetic of
SE Spain. Revista Española de Micropaleontología, 7: 231– 243.
Lefeld, J., 1974. Mid dle-Up per Ju ras sic and Lower Cre ta ceous biostratigraphy and sedimentology of the SubTatric Suc ces -sion in the Tatra Mts. (West ern Carpathians). Acta Geologica Polonica, 24: 277–364.
Lefeld, J., GaŸdzicki, A., Iwanow, A., Krajewski, K. & Wójcik, K., 1985. Ju ras sic and Cre ta ceous litostratigraphic units in the Tatra Mts. Studia Geologica Polonica, 84: 7–93.
£uczyñski, P., 2002. Depositional evo lu tion of the Mid dle Ju ras sic car bon ate sed i ments in the High-Tatric suc ces sion, Tatra Moun tains, West ern Carpathians, Po land. Acta Geologica Polonica, 52: 365–378.
Martire, L., 1992. Se quence stra tig ra phy and con densed pe lagic sed i ments, an ex am ple from the Rosso Ammonitico Vero-nese, north east ern It aly. Palaeo ge ogra phy, Palaeoclimato-logy, Palaeo ec ol ogy, 94: 169–191.
Martire, L., 1996. Stra tig ra phy, fa cies and synsedimentary tec ton -ics in the Ju ras sic Rosso Ammonitico Veronese (Altopiano di Asiago, NE It aly). Fa cies, 35: 209–236.
Mo naco, P. & Morettini, E., 1997. Marl-lime stone rhythmites and event beds in the Toarcian–Aalenian “Calcari e marne a Posidonia” unit of Fiuminata (Pioraco, cen tral Apennines). Bolletino del Servizio Geologica d’Italia, 116: 31–52. Myczyñski, R. & Lefeld, J., 2003. Toarcian ammonites (Adneth
fa cies) from the Subtatric Suc ces sion of the Tatra Mts (West -ern Carpathians). Studia Geologica Polonica, 121: 7–50. Oschmann, W., 1993. En vi ron men tal ox y gen fluc tu a tion and the
adap tive re sponse of ma rine ben thic or gan isms. Jour nal of the Geo log i cal So ci ety, Lon don, 150: 187–191.
Plašienka, D., 1999. Tektonochronológia a paleotektonický model jursko-kriedového vývoja Centrálnych Západných Karpát. (In Slo vak). Veda, Vydavatelstvo Slovenskej Akadémie Vied, Bratislava, 125 pp.
Polák, M., Ondrejièková, A. & Wieczorek, J., 1998. Lithostrati-graphy of the Ždiar For ma tion of the Krížna nappe. Slo vak Geo log i cal Mag a zine, 4: 35–52.
Rey, J., 1998. Extensional Ju ras sic tectonism of an east ern Subbetic sec tion (south ern Spain). Geo log i cal Mag a zine, 135: 685–697.
Röhl, H.-J., Schmid-Röhl, A., Oschmann, W., Firmmel, A. & Schwark, L., 2001. The Posidonia Shale (Lower Toarcian) of SW-Ger many: an ox y gen-de pleted eco sys tem con trolled by sea level and palaeoclimate. Palaeo ge ogra phy, Palaeoclima-tology, Palaeo ec ol ogy, 165: 27–52.
Santantonio, M., 1993. Fa cies as so ci a tions and evo lu tion of pe -lagic car bon ate plat form/ba sin sys tems: ex am ples from the Ital ian Ju ras sic. Sedimentology, 40: 1039–1067.
Santantonio, M., Galluzzo, F. & Gill, G., 1996. Anat omy and palaeobathymetry of a Ju ras sic pe lagic car bon ate plat form/ ba sin sys tem. Rossa Mts, Cen tral Apennines (It aly). Geo log i -cal im pli ca tions. Palaeopelagos, 6: 123–169.
Soták, J. & Plašienka, D., 1996. Up per Tri as sic–Lower Ju ras sic sed i ments of the Luèatín Unit in the North ern Veporicum: fa
cial di ver sity and tec tonic stack ing. Slo vak Geo log i cal Mag a -zine, 96: 273–277.
Sturani, C., 1971. Ammonites and Stra tig ra phy of the “Posidonia Alpina” Beds of the Ve ne tian Alps (Mid dle Ju ras sic, mainly Bajocian). Memorie degli Instituto di Geologia e Mineralogia dell’Universit´ di Padova, 28: 1–190.
Tsuji, Y., 1993. Tide in flu enced high en ergy en vi ron ments and rhodolith-as so ci ated car bon ate de po si tion on the outer shelf and slope off Miyako Is lands, south ern Ryukyu Is land Arc, Ja pan. Ma rine Ge ol ogy, 113: 255–271.
Uchman, A. & Myczyñski, R., 2006. Stop B3.14 – Lejowa Val ley: east ern of the Polana Huty Lejowe Alp – Up per Sinemurian– Lower Pliensbachian spot ted lime stones. In: Wierzbowski, A., Aubrecht, R., Golonka, J., Gutowski, J., Krobicki, M., Matyja, B. A., Pieñkowski, G. & Uchman, A. (eds), Ju ras sic of Po land and Ad ja cent Slovakian Carpathians, Filed Trip Guide book of 7th In ter na tional Con gress on the Ju ras sic Sys tem, Po land, Kraków, Sep tem ber, 618, 2006. Pol ish Geo log i -cal In sti tute, War saw, pp. 114–116.
Wieczorek, J., 1988. Maiolica – a unique Fa cies of the West ern Tethys. Annales Societatis Geologorum Poloniae, 58: 255– 276.
Wignall, P. B., 1993. Dis tin guish ing be tween ox y gen and sub -strate con trol in fos sil ben thic as sem blages. Jour nal of the Geo log i cal So ci ety, Lon don, 150: 193–196.
Winterer, E. L., 1991. The Tethyan Pa cific dur ing Late Ju ras sic and Cre ta ceous times. Palaeo ge ogra phy, Palaeoclimatology, Palaeo ec ol ogy, 87: 253–265.
Winterer, E. L. & Bosellini, A., 1981. Sub si dence and sed i men ta tion on Ju ras sic pas sive con ti nen tal mar gin, South ern Alps, It -aly. Amer i can As so ci a tion of Pe tro leum Ge ol o gists Bul le tin, 65: 394–421.
Winterer, E. L., Metzler, C. V. & Sarti, M., 1991. Nep tu nian dykes and as so ci ated brec cias (South ern Alps, It aly and Swit zer -land): role of grav ity slid ing in open and closed sys tem. Sedimentology, 38: 381–404.
Streszczenie
WAPIENIE BOSITROWE – KROK W STRONÊ RADIOLARYTÓW: PRZYK£AD Z TATR
Renata Jach
Wapienie bositrowe wczesnego aalenu–wczesnego batonu, które ods³aniaj¹ siê w jednostce kri¿niañskiej w Polskich Tatrach Zachodnich znajduj¹ siê w profilach pomiêdzy pelagicznymi czerwonymi wapieniami a radiolarytami (Fig. 1, 2; Lefeld et al., 1985; Gradziñski et al., 2004). Wapienie te wykazuj¹ wyraŸne facjalne zró¿nicowanie. Wydzielone zosta³y nastêpuj¹ce facje: (i) bositrowe pakstony/greinstony, (ii) krynoidowe pakstony/grein-stony, (iii) bositrowo-krynoidowe pakstony i (iv) bositrowo-ra dio- lariowe wakstony (Fig. 2, 3). Bositrowe pakstony/greinstony powsta³y w œrodowisku o stosunkowo wysokiej energii, a bosi-trowo-radiolariowe wakstony w warunkach niskiej energii. Kry-noidowe pakstony/greinstony s¹ interpretowane jako osady pr¹dów gêstoœciowych, a bositrowo-krynoidowe pakstony jako osady pr¹dów gêstoœciowych zbioturbowane i zmiksowane z osa-dami t³a depozycyjnego. Zró¿nicowana morfologia basenu wp³y-nê³a na oboczn¹ zmiennoœæ facjaln¹ omawianych wapieni i prze-strzenny rozk³ad facji (Fig. 4). Powstanie wapieni bositrowych by³o warunkowane przez czynniki natury tafonomicznej, zwi¹-zane z energi¹ œrodowiska sedymentacji, natury ekologicznej decyduj¹ce o dominacji bositr w zespole bentosu i procesy rozpuszczania eliminuj¹ce nie kalcytowe bioklasty. Postêpuj¹ca eutrofizacja wód (Bartolini & Cecca, 1999; Cobianchi & Picotti, 2001) i przemodelowanie basenu kri¿niañskiego zwi¹zane z pro-cesami ryftingu Zachodniej Tetydy, które ostatecznie dopro-wadzi³y do depozycji radiolarytów, wydaj¹ siê mieæ zasadniczy wp³yw na powstanie wapieni bositrowych. Tak wiêc, wapienie bositrowe reprezentuj¹ przejœciow¹ facjê poprzedzaj¹c¹ w czasie powstanie tetydzkich jurajskich radiolarytów.
