GEOLOGIA CROATICA 45 115 -126 12 Fig. ZAGREB 1992 UDC 553.492.1:551.736 (497.13+497.15) Scientific paper Origin and Depositional Environments of the Evaporite and Carbonate Complex (Upper Permian) from the Central Part of the Dinarides (Southern Croatia and Western Bosnia) Josip TIŠLJAR Key words: Evaporites, Gypsum, Anhydrite, Early­ diagenetic dolomites, Terrestrial breccias, Coastal Sabkha and Playa environments, Upper Perm ian, Dalmatia, Lika, Bosnia, Dinarides The Upper Perm ian sedim en ts from central part of the Dina ride s contain three main facies : 1.- carbonates; 2.- evaporites with early­ diagenetical dolomites and 3.- clastic rocks (siltstones and sandstones) and one special rock type- carbonate cavity breccias. The carbonate facies include lagoonal and intertidallimestone, evaporite facies contain gypsum (originated by hydration of anhydrites), early-diagenetical dolomites and anhydrites deposited in coastal sabkha environment. The clastic rocks were deposited either fore-shore or playa to salt­ lake playa environments. The carbonate cavity breccias are interpretated as a terrestrial features, i .e. secondary surface products of physical and chemical weathering oftectonically disrupted carbonate-evaporite sediments. The Upper Perm ian evaporites and carbonates of the central Dinarides are sediments deposited in evaporitic conditions arround the edges of an epeiric marine basin which existed in conditions of a general regressive tendency and permanent coastal seawards progradation. The Upper Permian evaporites of central Dina ride s af!: comparable with evaporites from the Bellerophon Formation from the Southern Alps, Italy. l. INTRODUCTIQN The"Permo-Triasic"evaporites and accompanying sediments from the central part of the Dinarides (central and northern Dalmatia, and the neighbouring region between Lika and SW Bosnia- Fig. l) have been a subject of extensive.geological investigations. The purpose of the investigations was to determine the age of evaporites and accompanying sediments, superposition and tectonic relationships with the surrounding rocks, minei=alogy, petrology and chemical composition, and also to define their depositional condi.tions and environments. This paper deal s oni y with the results of petrological and sedimentological investigations of carbonates and evaporites together with the interpretation of their origin, depositional environments and conditions. It is also a natural extention of the article written by ŠUŠNJA.~A et al.(l992) in this vol. and as such is a part of the presenta­ tion of syntesis of the above mentioned extensive geo­ logical investigations. 2. GEOl..OGICAL SETTING AND OUTLINE OF STRA TIG RAPHY The-age of the.evaporites and-r.ccompanying sed.iments from the central part of the Dinaride:: (central and northern Ključne riječi: Evaporiti, gips, anhidrit, ranodijagenetski do lomiti, terestičke breče, okoliši obalne sabkhe i pia je, gornji perm, Dalmacija, Lika, Bosna, Dinaridi Gomjopermski sedimenti središnjeg dijela Dinarida sadrže tri glavna facijesa: 1.- karbona te; 2.- eva~rite s ranodijagenetskim dolom i tima i 3.-klastične stijene (siltit i pJeŠčenjak) te jedan poseban tip stijena - šupljikave karbonatne breče. Karbonatni facijes uključuje laguna me i pl imske vapnence, a evaporitni facijes se sastoji od gipsa (nastalog htdratacijom anhidrita), ranodijagenetskih dolomita i anhidrita taloženih u okolišima obalnih sabkhi Klastične stijene su taložene ili u okolišima prednjeg žala i/ili u okolišima plaja do slanih jezera. Šupljikave karbonatne breče su interpretirane kao teres tičke tvorevine, tj . kao sekundarni površinski produkti fizičkog i kemijskog trošenja tektonski razdrobljenih karbonatno-evaporitnih sedimenata. Gomjopel'lnski evaporiti i karbonati središnjeg dijela Dinarida su sedimenti taloženi u evaporizacijskim uvjetima duž rubnog dijela epikontinentainog morskog bazena koji je postojao u uvjetima opće regresivne tendencije i stalne progradacije obale u smjeru mora. Po svojim sedimentacijskim značajkama ti se evaporiti mogu usporediti s evaporitima "Belerofon form acije" u gornjem permu Južnih Alpa, Italije. Dalmatia, Lika and SW.Bosnia) has been a subject of some dispute: namely these sedi ments have ages ascribed in range from the Permian (KATZER, 1921; 1925) to the Malm ian into the Early Cretaceous (ŠUŠNJ AR et al., 1965; ŠUŠNJAR, 1981). Although the prevailing view was that the "Perm o-Triassic" and Lower Triassic are the likely ages but there was no real paleontological eviden~e to support this argument. PODUPSKY (1963, 1973) regards that the deposition of evaporites occurred in the Permian in an epicontinental environment, and that they do not belong to the marine lagoonal1P.positional cycle. HERAK (1973, 1983) together with the presented arguments in favour of the Perm ian or "Perma-Triassic" a.se of the evaporites from Dalmatia and Lika, reflects to the possibility of their deposition in shall aw marine environments, although he does not exclude the possibility that the evaporite complex contains also units of different age associated with separated types diapiric movements. With the support of numero us palinological evidence ŠUŠNJARA et al.(l992) have succeeded to precisely determine that the evaporite complex with accompanying sediments from central Dalmatia belongs to the lower part-of the-Late.P-ermian .~md .in the .wide .reg-ion of.Sih in Lika to the middle stage of the Late Perm ian. Faculty of Mining, Geology and Petroleum Engineering- University of Zilgreb, Pierottijeva 6, P.O.B 186, 41000 Zagreb, Croatia - 116 Geologia Croatica 45 o SO km ~~---c==~--K==d BOSNIA and HERZEGOVINA ' ....... '· ) o Fig. l : Map showing the location of the studied area of the Upper Perrnian evaporite complex from the central part of the Dina ride s. Slika l: Karta područja istraživanja gomjoperrnskog evaporitnog kompleksa središnjeg dijela Dinarida. '· ...... --->\ r"'\ Tišljar: Origin and Depositional Environments .... 3. SEDIMENTOLOGICAL CHARACTERISTICS, ORIGIN AND SEDIMENT ARY ENVIRONMENTS OF THE UPPER PERMIAN EV APORITE COMPLEX The Permian sequences in Central and Northern Dalmati a, Lika and Western Bosnia (Fi g. l) contain three main types of facies: 1.- carbonate rocks (mainly limestones), 2.- evaporites (gypsum and anhydrite) and early-diagenetic dolomites and, 3.- clastic rocks, i.e. siltstones, sandstones, and very rarely conglomerates (see Figs. l, 2 and 3 in the atricleby ŠUŠNJARA et al., 1992, p. 96-99). Special facies type are carbonate cavity breccias or the so-called "rauhwacks" ("porous carbonate brec~ias"- ŠUŠNJARA et al.,(l992). The superposing succession of the three main faci es types and facies of carbonate cavity breccia equally developed on all locations and is often indistinct due to soil and vegetation covering and intensive tectonic disruptance of the sequences. In general, however, ŠUŠNJARA et al. (1992) state that evaporites are the o l dest facies and are succ~eded by clastic and/or carbonate facies and carbonate cavity breccias. Under the general name "evaporites" here is encircled evaporite facies, i.e. gypsum with no macroscopically visible dolomite and with dolomite laminas and vuggy dolomicrites (seciton 3.2). Outcrops with accurately determined direct synsedimentary contacts of carbonate and clast4: rocks were not observed due to soil cover and tectonical disturbances; this does not necessarily mean that these contacts and relationships do not exist. The relationship between evaporites and carbonate cavity breccias is more complex. Although the breccias regularly occur immediately above evaporites, and rarely in association with carbonate rocks, their stratigraphic position is dubious since they are a weathering product of tectonically disrupted and leached rocks of the evaporite and/or carbonate faci es , and they also occur during the course of different chronostratigraphic units (section 3.3). 3.1 PETROGRAPHY AND DEPOSITIONAL ENVIRONMENTS OF THE CARBONATE FACIES The Upper Permian carbonate facies consists of stratified, and in places horizontally laminated, dark-gray and black kerogenous mudstones, pellets-bearing and/or ostracods­ bearing wackestones, and crystalline (microsparite) limestones rich in organic matter and pyrite. Often they are more or less intensively late-diagenetically dolomitized or recrystallized. Rarely this facies contains dolomites resulting from late-diagenetically dolomitization of wackestones and mudstones. Sporadically are found dark­ gray kerogenous cryptocrystalline limestones, mudstones, and pelletoidal wackestones and packstones, rarely pelletoidal grainstones, which contain calcite pseudomorphs after anhydrite, or kerogenous ostracods-bearing mudstones/ wackestones with large, discoidal gypsum crystals (Fig. 2) or with molds of gypsum crystals which are now occupied by secondary minerals: opal, chalcedony and/or quartz. The gypsum was formed initially by displacive growth 117 Fig. 2: Thin-section photomicrograph of kerogeneous ostracoda wackestone with large, discoidal gypsum crystals formed initially by displacive growth in a intertidal-supratidal sabkha environment. Carbonate facies from Elerovac; width of photograph = 7,5 mm (crossed nicols). Slika 2 : Kerogenski ostrakodni vekston s krupnim, diskoidaln im kristalima gipsa nastalim rastom u mulju plimskog do natplimskog sabkha okoliša. Karbonatni facijes područja Elezovac; širina slike = 7,5 mm (ukriženi nikoli). in carbonate mud in the lateral marginal intertidal-supratidal zone of lagoon which gradually passes into sabkha, i. e during the early phase of the regressive sabkha cycle ("gypsum mush"- SELLEY, 1988). Limestones of the carbonate facies occurring in association with evaporites belong to sediments deposited in restricted shallow, hypersaline lag oo ns or in very shallow subtidal to intertidal environments of the regressive cycle. Here together with fine carbonate sediment, qui te a large quantity offinegrained organic matter was accumulated. A part of the limestone from this facies was probably deposited as a contemporary lateral or younger facies together with coastal sabkha and playa deposits in a generally regressive cycle on the margin of an epeiric sea (Fig. 3). In part they could have been deposited even after the coastal and terrestrial sabkhas ceased to exist, mainly laterally, in somewhat deeper, i.e. distant areas of an epeiric sea or a marine basin with a permanent narrowing tendency - a re gression cycle (Fi g. 3). The lagoons and shallow bays that existed there, due to the continuous fall of seawater, and its somewhat greater depth could not have been transformed into sabkhas, during the progradation of the coast or relative sea-level fall (Fig. 3). 3. 2 DEPOSITIONAL ENVIRONMENTS AND ORIGIN OF EV APORITE FACIES ln numerous outcrops, drill cores and gypsum guarries it r.as been observed that no significant quantities or mac•· )Scopically visible dolomite layers or laminae occur in the 1Jwer portions of the evaporite facies. While in the higher st>,quences of the evaporite facies the dolomite beds occur freqt..ently, and also evaporite beds alternated with dolomite beds (Fi g. 4 ), or tectonic dolomite-evaporite breccias which are not of synsedimentary origin (Fi g. 5). These breccias originate by intensive tectonical crushing of the dolomite-anhydrite thin layer alternation. - 118 SAL T LAKE PLAY A SLANO JEZERO PLAJA Geologia Croatica 45 COST AL SABKHA OBALNA SABKHA ---ll)loo~REGRESSIVE TENDENCY- REGRESIVNI SLIJED Fig. 3: Idealized drawing of the Upper Permian depositional environments: l and lA =carbonate facies; 2 and 2A = evaporite-dolomite facies and 3 = das tic facies. In some places may be ela s tic facies in l A and 2, too, and fan delta into the marine restricted shoals (not showing on the fig.). Slika 3: Shematizirani prikaz okoliša taloženja gomjopermskog karbonatno-evaporitnog kompleksa: l i lA= karbonatni facijes; 2 i 2A = evaporitno-dolomitni facijes i 3 = klastični facijes. Mjestimično lA i 2 može biti i klastični facijes, a deltne lepeze su mogle biti formirane i u morskom zaštićenom plićaku (nije prikazano na slici). Fi g. 4: Gypsum with laminated thin bed of tectonicaly crushed early­ diagenetic dolomite. Evaporite-dolomite facies from Sinj area. Slika 4: Gips s tankim slojem tektonski razlomljenog· laminiranog ranodijagenetskog dolomita. Evaporitno-dolomitni facijes područja Labrovića kuća kod Sinja. Fig. 5: "Dolomite-gypsum breccia" orip,inate by tectonicaly crushed thin-bedded dolomite-anhydrite (replacement by gypsum?) sabkha cycles. Evaporite-dolomite facies from gypsum deposit Mali Kuk or in the Kosovo polje. Slika5: "Dolomitno-gipsna breča" nastala tektonskim drobljenjem sabkha ciklusa sastavlJenih od tankoslojevitih izmjena dolomita i anhidrita (potisnutog gipsom?). Evaporitno-delomitni facijes, gipsolom Mali Kukor u Kosovu polju. Tišljar: Origin and Depositional Environments .... At some sites (for example, gypsum quany "Slane Stine", drill cores from Glavice, Sinjsko polje) the evaporites contain only dolomite fragments or relicts of dolomite-evaporite breccia which has resulted from either intensive tectonical crushing, diapirism, and/or replacement of dolomite by anhydrite. Often they contain, crumbledand broken, thin alternating laminae of dolomite and gypsum. Numerous outcrops contain dolomite carrying isolated gypsum nodules or dolomite with cavites and fissures filled with secondary gypsum which resulted from hydration of anhydrite or with anhydrite and secondary gypsum. Also gypsum occurs frequently em bedding dolomite layers, laminae, orrelics of laminated and strom atoli tic dolomite (Figs.6, 7 and 8). The evaporites consist of either gypsum or anhydrite Fig. 6: Gypsum bed with relics of thin beded, organic matter-rich dolomicrite. Gypsum origin by hydration of anhydrite that has replaced a dolomite mud stone host in coastal sabkha environment. Evaporite­ dolomite facies from Sinj; Thin-section (crossed nicols), height of photograph = 3,3 mm. Slika 6: Gipsni sloj s reliktima tankoslojevitog, organskom materijom bogatog dolom ik rita. Gips je nastao hidratacijom an hi drita koji je u sabkha uvjetima potiskivao dolomit. Evaporitno-dolomitni facijes Labrovića kuće kod Sinja; Visina slike = 3,3 mm (ukriženi nikoli). or both gypsum and anhydrite (Figs. 4-10). Normally, gypsum is bedded, internally thinly layered (3-8 cm) and consists of undulatory but roughly parallellaminae of light mosaic and dark gypsum. Often it is characterized with the "enterolithic" folds. The gypsum occurs on the surface or near the surface, while anhydrite is found in deeper sections of gypsum Fig. 7: Gypsum with thin laminae of dolomicrite (part of bed folded into an enterolithic structure). Gypsum is originated by hydration of sabkha anhydrite that have extensively replaced a laminated dolomite host. Evaporite facies from Kninsko polje, thin-section, width of photograph = 3,3 mm (crossed nicols). Slika 7: Gips s tankim laminama dolomikrita (dio sloja boranog u enterolitnu strukturu). Gips potječe od hidratacije sabkha anhidrita koji je u sabkha okolišu potiskivao laminirani dolomit. Evaporitni facijes Kninskog polja, širina slike = 3,3 mm (ukriženi nikoli). quarries and boreholes, due to the fact that the gypsum is, in general, a secondary mineral formed as a result of anhydrite hydration (Figs. 8 and 9). The hydration of anhydrite begins on the margins of anhydrite crystal cleavage planes and in tectonically disrupted and fissured zones, in shapes of fibrous gypsum veins. Advanced degrees of anhydrite hydration are characterized with gypsum crystals that poikilitically enclose anhydrite relics, or gypsum crystals produce an intersecting mass of oriented crystals which enclose and centripetally replace anhydrite (Figs.8 and 9). Fig. 8: Gypsum bed of the evaporite facies: thin-section showing more ·. relics of dolomicrite (dark) and anhydrite (blue-purpur grain) within the gypsum mass originated by anhydrite hydration. Bistrica area, width of photograph= 3,3 mm (crossed nicols). Slika 8: Sloj gipsa iz evaporitnog facijesa: mikroskopski izbrusak pokazo je više relikata dolomikrita (tamno) i anhidrita (plavoljubičasto) unutar gips ne mase nastale hidratacijom anhidrita. Područje Bistrice, širina slike = 3,3 mm (ukriženi nikoli). Complete hydration of anhydrite is manifested by homogeneous, fibrous gypsum crystals that sporadically contain isolated coroded anhydrite relics and very thin dark-grey, here and there yellow-brown laminae or bands of organic matter, pyrite or gypsum pigmented with Fe- - 120 Fig. 9: Thin-section of the evaporite facies anhydrite hydration in gypsum is more effective along cleavage plane; width of photogrph = 7,5 mm ( crossed nicols ). Slika 9: Mikroskopski izbrusak evaporitnog facijesa pokazuje hidrataciju anhidrita u gips koja je najintenzivnija duž pukotina kalavosti; širina slike= 7,5 mm (ukriženi nikoli). minerals. Fibrous gypsum crystal aggregates sporadically contain coarser authigenic calcite or/ and less frequently secondary dolomite, and commonly early-diagenetic dolomicrite relics (Figs. 6, 7 and 8). Anhydrite hydration is increased with temperature and salinity decrease of pore water in evaporites. It is even enhanced after anhydrite ispenetrated by circulation of fresh (meteoric) water (MURRAY, 1964). In our case the evaporites had been repeatedly intensively tectonically disrupted, crushed and faulted, and the hydration of anhydrite occlirred after their emplacement near or at the surface by tectonical and erosional processes. In other words they were subjected to the intensive influence of meteoric, surface and ground waters. Some evaporites contain macroscopically visible dolomite layers (Fig. 4 ). laminae or !amina relics and/or tectonically broken and brecciated thin layers of dolomite in shape of "dolomite-gypsum" breccia (Figs. 5 and 10), although in most evaporites these dolomites are not observed macroscopically; they are regularly present in thin sections of evaporites (Figs. 6, 7 and 8). Dolomite layers typically are lenticular, and may be laterally contiimous for no more than 3 - 10 meters and laminae no more than a few cm. The most striking structure of the dolomite are long narrow tabular cavities, lensoid to avoid vugs 0,5-2 mm in diameter. They appear to be linked to solution cracks or to leached tube. The observed dolomite texture, structure and composition define them as either dolomicrite, dolo­ pelmicrite or stromatolite with desiccation cracks and/ or shrinkage cracks. All of these dolomites are supratidal early-diagenetical dolomites or evaporite dolomites originated in the same sedimentary cycle as anhydrite, i.e. in regressive sabkha cycles (flfStly as mud accumulation _ in a shallow subtidal or restricted lagoon at the margin of a wide sabkha and then as early-diagenetic dolomiti­ zation at the supratidal environment). Evident alternating cycles of dolomite and gypsum (as a hydration product of anhydrite), have been preserved at many sites; although Geologia Croatica 45 the dolomite and gypsum (or anhydrite) beds and thicker laminae have been intensively tectonically brecciated. These cyclic alternations can be interpreted as B and C members of regressive sabkha cycle similar to sabkha cycles in Arab­ Darb Formation (WOOD & WOLFE, 1969). Evaporites without distinctly macroscopically visible dolomite layers and laminae ("pure evaporites") usually contain dolomite (observed in thin sections- Figs. 6, 7 and 8) in shapes of thin, broken and "folded" laminae, termed "enterolithic structure" or "enterolithic folds" (BOSELLINI & HARDIE, 1973) and irregular clusters or aggregates. Dolomite occurences in these evaporites are actually relics of dolomite layers and laminae belonging to the B member of the sabkha depositional cycle preserved after "~nterolithic folding" processes, i. e. by several periods of strain by hydration of anhydrite to gypsum and dehydration of gypsum to anhydrite. Diapiric uplift, and early-diagenetical anhydrite replacement of dolomite in sabkha environment is very strong and frequent (SHEARMAN, 1966). The processes qf tectonical fracturing and anhydrite and/or gypsum replacement of dolomite here must be also taken into account The relatively small amount of dolomite in "pure evaporites" can be the consequence of displacement and up lift of plastic evaporite strata by diapirsm, which separates them from the brittle undisplaced carbonate members of sabkha cycles. The essential evaporite characteristics together with the petrological and sedimentary interpretations of associated dolomi.:es, allow the interpretation of depositional environments of evaporites as follows. While evaporites associated with early-diagenetical dolomites exhibit principa! features of the origin coming from coastal sabkha depositional environments, the evaporites without macroscopically visible dolomite or with dolomite which occurs in shapes of thin broken laminae, pleated bands and relics, cannot be interpreted Fig. 10: Tectonicaly crushed dolornicrite replaced by veins of gypsum, respectively. Small relict of anhydrite (yellow) in dolomicrite point at sabkha cycle. Evaporite-dolomite facies from Bistrica area, thin­ section, width of photograph = 7,5 mm (crossed nicols). Slika l 0: Tektonski razdrobljen i dolomikrit po pukotinama in ten zi vno potiskivan žilama gipsa. U dolornikritu se nalaze i sitni relikti anhidrita (žuto) koji ukazuju na dolomitno-anhidritni sabkha ciklus. Evaporitno­ dolomitni facijes područja Bistrice, širina slike =7 ,5 mm (ukriženi nikoli). Tišljar: Origin and Depositional Environments .. .. unambiguously with respect to depositional' conditions and environments. The present surface gypsum evaporites (products of hydration of anhydrite), were deposited in evaporation conditions around the edges of an epeiric marine basin, i. e. in the large belt on desert carbonate-shoreline coastal sabkhas, which existed in the conditions of general regressive tendency and permanent coastal pro gradation originated by continua! sea-level fall (Fig. 3). These conditions ended with the development of long-lasting sabkha and playa environments, and finally with lake (either salty or brakish water), river and land environments. It is evident that the intertidal and supratidal zones (clastic and carbonate) have been prograding seawards, thus making the sediments of these facies diachronous (Fig. 3). In restricted shoals, lagoons and intertidal environ­ ments contemporaneous limestone deposition occurred, while on the fore-shore and shore-face with dominanting siliciclastic sediments (i. e. siliciclastic shore-lines), playas and lakes (salt, brakish and/or fresh water) with small deltas and rivers, clastic deposition prevailed (Fig.3). These clastic sediments, especially deposited in fore-shore, playa and salt lake environments, often contain cube molds ofleached hali te crystals which originally precipitated in dry periods of semi-arid or arid climate conditions. Although Upper Permian evaporite outcrops, with a complete "regressive sabkha cycle" (WOOD & WOLFE, 1969) were not found in the central Dinarides area, frequently B and C members, or A member succesion (section 3.1), of the sabkhacycle were observed. Thus, we can conclude that the evaporites which· contain earlydiagenetical dolomites were formed in coastal sabkha environments (Fig. 3). However, massive evaporites, which contain only dolomite relics, were probably formed in similar conditions of high evaporation on marginal parts of a shallow epeiric sea with a permanent regression tendency and development of long-lasting sabkhas. Namely, in these evaporites, in spite of their thickness (due to diapirism), absolutely no observation was made of laminated altemations of carbonates enrichment with organic matter, anhydrite and halite. The bulk of evaporites deposited in subtidal and deeper marine environments (lagoons, bays et e.) are either distinguished by previously mentioned regular thin laminated alternations inside a few hundred meters thick, continuous evaporite sequences or they belong to the "handed anhydrites" or "varve anhydrites" rich in organic matter, "Stinkenkarbonate", and altemations with hali te (RICHTER­ BERNBURG, 1955; SCHREIBER, 1986). As it is known, hali te deposits are uncommon or fail in carbonate-anhydrite sabkha evaporite sequences (SELLEY, 1988). Since, in our ·case such evaporite features have not been observed, this ex<;ludes the interpretation of their origin in subtidal or deeper marine environments. The comparatively small amount of dolomite and absence of complete sabkha cycles (A-phase: algallimestone - homogeneous, B-phase: laminar and bird's,- eye dolomite - algal mat dolomite, and C-phase: nodular anhydrite; WOOD & WOLFE, 1969) in the Upper Permian evaporites 121 of the central Dinarides, especially in deeper portions of evaporite sequences, can be interpreted as: - sabkha anhydrites have been deposited in long-lived sabkha environments with semi-arid to arid climate in the C-phase of the regressive sabkha cycle with high concentrations and influx of Ca-sulphates, and in which anhydrite more or less completely replaces dolomite formed in B-phase; - displacement by diapirism from the primary sabkha cycle succession of evaporite matter, without any significant up lift of carbonates, resulted in concentration of evaporite; - due to intensive tectonical activity the brittle carbo­ nate beds (i.e. B dolomite member of sabkha cycles) were severly disrupted and milonitized, and their remains were later more or less completely replaced by gypsum. Due to leaching of gypsum on the surface of outcrops, dolomite remains are repeatedly concentrated and formed either as "dolomite-gypsum breccias" or "rauhwackes"- cavity breccias. Thus we can assume that one, two or all the three processes had an important role in various periods of geological history of central Dinaric Upper Permian evaporites and associated sediments. 3.3 ORIGIN OF CARBON A TE CA VITY BRECCIAS Carbonate cavity breccias or the "rauhwackes" often go together with evaporites in various and somewhat indistinct relationships. Although the problem of their stratigraphical connection with the evaporite and carbonate facies remains un defined, due to more breccia generations ranging from the Late Permian and Pre-Neogene to the Quartemary (ŠUŠNJARA et al., 1992) and also to the type of their development, the observed features imply a similar or even identical origin. They are highly porous, cellular, full of small holes, cavity breccias, which macroscopically, here and there resemble travertine. Breccias contain various amounts of not sorted, angular fragments with corroded surfaces and edges, and also different amounts of cement (Figs. ll and 12). The fragments ofPemuan limestones, early-diagenetical dolomites and evaporites predominate. The dolomite fragments are usually more or less dedolomitized and evaporite fragments fully or partially leached (large cavities in breccia, Figs. ll and 12). The cement consists of cryptocrystalline to macrocrystalline laminar, pisoid-like or speleothem-like calcite accumulation pigmented with Fe-oxides and hydroxides, and impurites of siliciclastic material (Fig. 12). Not only did the leaching of evaporite fragments occur, but also dedolomite fragments from the latter, friable dedolomitized mass could have been mechanically and chemically removed, and the remained molds-vugs could be subsequently partialy or sometimes completely filled with calcite cement Mostly this was the reason why the breccia had cellular and cavity-like structures and why the leaching of rock fragments usually occured after they had been partially or completely cemented into breccia (Figs. ll and 12). The leaching usually had little or no - Figs. ll( above) and 12 (below) : Thin-sections of the carbonate cavity breccia: the evaporite and dolomite fragments and vu gs and m olds of leached fragments; microcrystalline and pisoid-like or calcrete cement around of the fragments and vugs. Sinjsko polje; width of photograph= 7,5 mm. Slika ll (gore) i 12 (dolje):Mikroskopski izbrusci karbonatnih šupljikavih breča: fragmenti evaporita i dolomita i šupljine nastale izluživanjem pojedinih fragmenata; mikrokristalasti i pizoidni kalcitni cement oko fragmenata i šupljina. Sinjsko polje, širina slike= 7,5 mm. effect on the cement (Fig. 12). Cavity breccias are definitly not of marine origin but they exhibit distinct terrestrial features. Their occurrence on elevated surfaces of hills, as well as their discordant overlapping of underlying evaporite or carbonate deposits, regardless of the position of footwall beds, composition and structure, imply that they are secondary products of physical and chemical weathering of tectonically disrupted Upper Permian evaporite and carbonate sediments. Whether it was due to a terrestrial phase at the and of Permian, or a post-Permian tectonical up lift and surface emplacement ofPermian evaporite and carbonate sediments, the sediments were weathered in terrestrial condition::-. The products of such weathering alterations were carbonate cavity breccias. The weathered products, beings either of semi-arid to arid climate with scarce rainfals and intensive evaporation, or meteoric and pore waters saturated with Ca-hydrosgen­ carbonate, were gradually cemented with crust-like to pisoid­ lik:e and speleo them-like calcite cement into more-or less compact breccia. Due to teaching of evaporite and dedolomite fragments, cavities develop in the breccia thus giving them cellular and/or cavity appearance. InteP.sive Geologia Croatica 45 dedolomitization is enhanced by high Ca content of pare solutions (i. e. low molar Mg/Ca ratio) which again is linked with dissolution and teaching of gypsum. This can also be an explanation why the cavity breccias or "rauhwackes" usually occur in association with the carbonate-evaporite facies. 4. DISCUSSION AND CONCLUSIONS Although there is a limited number of large and for study favourable outcrops that exhibit clear relationships between vertical succession and lateral transition of the three main Upper Permian facies, i. e. carbonate, evaporite and clastite facies, the interpretation of conditions and environments of deposition and origin of each individual facies and the existence of the general regressive cycle in the Upper Permian, allows for a general interpretation concerning tJ.!e conditions and environments·of deposition. The relation between the deposition of clastites and evaporite conditions is imp lied by occurrences of the hali te m olds inside clastite units from V rl ika and Knin (SĆA VNIČAR, B., 1973). On the basis of lithological characteristics of clastites from the surrounding areas of Drniš and Vrlika (central Dalmatia; IV ANOVIĆ et al.,l971), there is correlation with the top part of "the Groeden facies" (after Groedental =Val Gardena) from the wider region of the Dinarides. Taking into account the fact that during the Late Permian the general Permian regressive cycle was at its peak, and that narrowing of the epicontinental marine depositional basin was in constant progress, that the Upper Perm ian limestones belong to lagoonal and intertidal environments -often to the starting A member of the regressive sabkha cycles - that also the evaporite facies which major characteristics of sabkha sediments, and that the clastic facies exhibit transition from off shore, shore face, fore shore, over p laya and salt lake e:wiron-ments to alluvial environments, these characteristics show general depositional model on Fig. 3. In general, during the Late Pef!llian in the present day central parts of the Dinarides, assuming a more or less continuous regressive tendency, various deposition conditions and environments existed and were defined by the existence of a shallow epicontinental sea with a very differentiated coastline, bays and lagoons. Also, due to the general regressive tendency, this concerns wide zones of coastal sabkhas which gradually pass into playas and/ or salt lakes with or without alluvial sedimentation and which finally pass into terrestrial environments (Fig. 3). It appears that, simultaneously at different places, deposition of lagoonal and intertidal sediments (carbonate facies), supratidal and sabkha sediments (early-diagenetical dolomites and evaporites) was possible. This was also accompanied by clastic deposition in coastal environments, playa and salt lake environments with or without river mouths and deltas, and partially by river depositional environments (clastic facies) and the common terrestrial e'lvironments (Upper Perm ian cavity breccia). In case of a generally continuous regressive succession, exhibiting Tišljar: Origin and Depositional Environments .... probably with more or less positive or negative fluctuation, the normal facies succession would be: carbon te facies - evaporite and/or clastic facies (Fig. 3). Since depositiona1 environments are not oni y under the influence of the general regressive tendency, which plays an important part in development of large lateral differences of facies, but are also under the influence of rapid changes of deposition, of periodical sea-level fluctuations, global and local synsedimentary tectonics, autocyclicity, coast and tidal flat progradation, climate variation, alternation of semi­ arid to arid and rainy periods, various lateral and vertical facies succession from one locality to another have resulted. For example, in the central part of the Velebit Mt. (Oštarije near Gospić) in the Late Permian were deposited only peri tidal carbonates withour evaporites in the following succession: 1.- subtidal to lower intertidal fusuline-bearing limestones; 2.-supratidal dolomites; 3.- black organical­ rich mudstone,s and bioclasdc; packstones deposited as organical-rich mud in a restricted shallow bay and/or on the edge of a shallow lagoon between large supratidal areas, and 4 .- supratidal dolomites with reddish-brown or grey shale intercalations in the uppermost part (TISLJAR et al., 1991). From the presented data and schematic diagram (Fig. 3) it is evident that during the Late Permian in the wider region of the central parts of the Dinarides various deposition environments existed with both graduallateral and vertical sequence transitions. After and/or during shalow marine 11mestone and sabkha evaporite deposition together with associated early-diagenetic supratidal dolomites in the generally regressive regime and locally varying conditions of time, gradually ceased to exist shallow marine en v ironments with carbonate deposition and coastal sabkhas with dolomite and evaporite accumulation. These deposition environments were either gradually or abruptly replaced by clastic deposition in coastal, playa or (salt, brackish?) ephemeral lake or river environments, and finally, by terrestrial conditions. The latter were at their peak in the terminanting stages of the Perm ian. The reestablishment of the shallow marine deposition regime occurred at the beginning of the Triassic. The correlation of the Upper Perm ian evaporites from the central part of Dinarides compared to the similar northern and western European evaporites, for example "the Zechstein evaporites" from Poland, Germany, Netherlands and Denmark, due to lithological composition, depositional environments and conditions of Upper Permian evaporites from the Dinarides excludes the application of the first (Z-1) and second (Z-2) "Zechstein evaporite deposition cycle models". The third (Z-3) "Zechstein cycle" model of deposition (SCHREIBER, 1986), however, is partially applicable. To be more precise, the concluding sec;.uences of the third (Z-3) cycle including the deposition of evaporites in the evaporite basin, has a basin reducing tendency accompanied by shallowing. Only anhydrite and early­ diagenetical dolomite in sabkhas and limestone and gypsum in the sub tidal to intertidal zones developed here whereas halite and K-Mg-salt deposition are not present in these environments. 123 The lithological characteristics, sabkha cycles and general depositional environment of the Upper Permian evaporites from the Dinarides are quite similar to the Upper Permian evaporites of the Bellerophon Formation from the Southern Alps, Italy. The Bellerophon evaporite cycle is interpreted as a regressive cycle which was formed in an arid marginal marine environment by a prograding tidal flat building sea ward over a shallow subtidallagoon and leaving behind an exposed sabkha (BOSELLINI & HARDIE, 1973). ACKNOWLEDGEMENTS This work was partly supported by the enterprice INA­ NAFTAPLIN, Zagreb and the INSTITUTE OF GEOLOGY, Zagreb. The manuscript was read by Dr. Tadeus Peryt and his comments led to considerable improvement in the presentation. 5. REFERENCES BOSELLINI, A. & HARDIE, L.A. (1973): Depositional theme of a marginal marine evaporite. - Sedimento­ logy, 20, 5-27, Oxford. HERAK, M. (1973): Some tectonical problems of the evaporitic area in the Dinari des of Croatia. - G eo l. vjesnik, 26, 29-40, Zagreb. HERAK, M. (1983): Someideasanddilemmasconceming the genesis and tectonics of Adriatic and Peri-adriatic areas.- In: BABIĆ,LJ. & JELASKA, V.: Contri­ butions to sedimentology of some Carbonate and Clastic units of the coastal Dinarides.- I.A.S.41 h Regional Meeting Exurs. Guide-book, 7-11, Split. IV ANOVIĆ, A., SćA VNIĆAR, B., SAKAĆ, K. & GUSić, I. (1971) : Stratigrafski položaj i petrografske karakteristike evaporita i klas tita okolice Drniša i Vrlike u Dalmaciji. - Geol. vjesnik, 24, 11-33 , Zagreb. KATZER, F. (1921): Pregledna geološka karta Bosne i Hercegovine, list Banja Luka. M 1:200.000, Sarajevo. KA TZER, F. (1925): Geologie Bosnies und der Herzegovina - Geol. zavod Sarajevo, 1-480 (IH), 481-560 (liH), Sarajevo. KINSMAN, D.J.J. (1965): Gypsum and anhydrite of recent age, Trucial Coast, Persian Gulf.- In: RAU, J.L. (Ed.): Second Symposium on Salt, 1.- North Ohio geol. Soc., 302-326. KINSMAN,DJ.D. (1%9): Modesofformation,sedimentary association and diagnostic features of shallow­ water and supratidal evaporites.- Bull. Am. Assoc. Petrol. Geol., 53, 830-840, Tulsa. MURRAY, R.C. (1964): Origin and diagenesis of gypsum and anhydrite.- J. Sediment. Petrol., 34, 512- 523, Tulsa. PATTERSON,R.J. & KINSMAN, D.J.J. (1981): Hydro­ logic framework of a sabkha along the Persi an Gulf.- Bull. Am. Assoc. Petrol. Geol., 65, 1457- 1475, Tulsa. 124 PODUBSKY, V. (1963): Regionalne karakteristike geneze i geotektonskog položaja gips-anhidritskih ležišta zapadne Bosne i Hercegovine i Hrvatske. - Geol. glasnik, 7, 161-167, Sarajevo. PODUBSKY, V. (1976): Gips i anhidrit.- U: Mineralne sirovine Bosne i Hercegovine, Knj. II, Ležišta nemetala, 328-338 - Geoinženjering, Sarajevo. RICHTER-BERNBURG, G. (1955): Uber salinare Sedimentation.- Z. dt. Geol. Ges., 105, 593-645, Stuttgart. RICHTER-BERNBURG, G. (1957): Isochrone Warven im Anhydrit des Zechstein.- Geol. Rdsch., 49, 132-148, Stuttgart. SCHREIBER, B.C. (1986): Arid Shorelines and Evaporites. -In: READING, H. G. (Ed.): Sedimentary Environ­ ments and Facies.- Blackwells Publ., 189-228, Oxford. SELLEY, R.C. (1988): Applied Sedimentology.- Acad. Press,446 p. London San Diego, New York, Boston, SHEARMAN, D.J. (1966): Origin ofmarineevaporites by diagenesis.- Trans. Inst. Min. Metali., B., 75, 208-215. ŠĆAVNIČAR, B. (1973): Kalupi kristala kamene soli (halita) u klastitima na području Vrlike i Knina.­ Geol. vjesnik, 26, 155-157, Zagreb. ŠUŠNJAR, M. (1981): Genetski faktori i geološke Geologia Croatica 45 okolnosti mobili teta i dijapirizma s osvrtom na imobilna i mobilna stanja kalcijsko-sulfatnih naslaga u prostoru Dinarida.- Nafta,1-221, Zagreb. !iUŠNJAR, M., BUKOV AC, J., MARINČIĆ, S. & SAVIĆ, D. (1965): Stratigrafija gipsnih naslaga Unske doline i korelacija s poznatim evaporitnim naslagama i popratnim facijesima u Primorju, Dalmaciji, Lici i zapadnoj Bosni. - Acta geol., 5, 407-422, Zagreb. ŠUŠNJARA, A., SAKAČ, K., GABRIĆ, A. & JELEN, M. (1992): Upper Permian Evaporites and Associated Rocks of Dalmatia and Borderline Area of Lika and Bosna.- Geologia croatica, 45, 95-114, Zagreb. TIŠLJAR, J., VLAHOVIĆ, 1., SREMAC, J., VELIĆ, 1., VESELI, V. & STANKOVIĆ, D. (1991): Excursion A - Velebit Mt., Perm ian - J urassic. -In: VELIĆ, 1.& VLAHOVIĆ, I. (Eds.): Some Aspetcs of tlre Shallow Water Sedimentation on the Adriatic Carbonate Platform (Permian to Eocene). Excursion Guide-Book at the Second Int.Symp. on the Adriatic Carbonate Platform, Zadar, May 1991., l-50,Zagreb. WOOD, G. V. & WOLFE, M. J. (1969): Sabkha cycles in theArab/Darb Formation off the Trucial Coast of Arabia- Sedimentology, 12, 165-191, Amsterdam. Geneza i okoliši taloženja gornjopermskog karbonatnog i evaporitnog kompleksa središnjeg dijela Dinarida (južna Hrvatska i zapadna Bosna) J. Tišljar U ovom radu su prikazani rezultati petroloških i sedimentoloških istraživanja karbonatnih i evaporitnih sedimenata, interpretacija geneze, uvjeta i okoliša taloženja evaporita i pratećih sedimenata "permo-trijasa" središnjeg dijela Dinarida (srednja i sjeverna Dalmacija i granično područje između Like i jugozapadne Bosne -sl. 1). Po tome je ovaj rad normalni nastavak na rad ŠUŠNJARA et al. (1992) s kojim čini dio cjeline prezentiranja rezultata kompleksnih geoloških istraživanja "permo-trijaskog" kompleksa središnjeg dijela Dinarida. Rezultati se odnose na područja istraživanja prikazana na sl. l i na geološkim kartama sl. 2 i 3 u radu ŠUŠNJARA et al. (1992). Brojnim palinološkim dokazima ŠUŠNJARA et al. (1992) su utvrdili da "permo-trijaski" evaporitni kompleks s pratećim sedimentima središnje Dalmacije pripada gornjem permu (donji dio gornjeg perma), a ~ireg područja Srba u Lici srednjem katu gornjeg perma. Gornjopermski sedimenti središnje i sjeverne Dalmacije, Like i zapadne Bosne su zastupljeni s tri glavna facijesa: 1.- karbonatima; 2.- evaporitima (gips, anhidrit) s ranodijagenetskim dolomitima i 3.- klastitima, tj. pelitima, siltitima, pješčenjacima i vrlo rijetko konglomeratima (vidi sl. l, 2 i 3 u radu ŠUŠNJARA et al.,l992 str. 96-99). Poseban facijes su karbonatne šupljikave breče ("rauhwacke"). Superpozicijski slijed ta tri facijesa i šupljikavih breča nije svugdje isti, a niti potpuno jasan zbog pokrivenosti terena i intenzivne tektonske poremećenosti naslaga. Općenito su, međutim, najstariji evaporiti, a na njima leže klastiti i/ili karbonati ili karbonatne šupljikave breče (ŠUŠNJARA et al.,l992). Odnos evaporitnog facijesa i karbonatnih šupljikavih breča je složeniji jer su breče terestičke tvorevine nastale na površini zemlje u više različitih kronostratigrafskih jedinica. Nepostojanje većeg broja izdanaka s jasnim međusobnim vertikalnim slijedom i jasnim bočnim odnosima triju glavnih facijesa, kao i činjenica da uvijek ne postoji egzaktno utvrđeni odnos tih facijesa u vremenu i prostoru, stvara znatne poteškoće pri općoj interpretaciji uvjeta i okoliša taloženja gornjo-permskih sedimenata. Karbonatni facijes gornjeg perma se sastoji od dobro slojevitih, mjestimice horizontalno laminiranih, tamnosivih i crnih vapnenaca bogatih kero genom, uglavnom madston do vekston tipa. Nerijetko su manje ili više intenzivno Y.asnodijagenetski dolomitizirani ili rekristalizirani. Rjeđe se u tom facijesu nalaze i kasnodijagenetski dolomiti nastali dolomitizacijom vekstona i madstona. Vapnenci mjestimice Tišljar: Origin and Depositional Environments .... sadrže pseudomorfoze kalcita po anhidritu. Kerogenski ostrakodni madstoni koji sadrže krupne kristale gipsa (sl. 2) ili kalupne šupljine kristala gipsa, koji su se izluči vali u karbonatnom mulju u bočnim rubnim plinskim dijelovima laguna koje postupno prijelaze u sabkhe (sl. 3) i to u početnoj fazi regresivnog sabkha ciklusa ("gypsum much"- SELLEY, 1988), su tipični bočni ekvivalenti potplimsko-plirnske faze sabkha ciklusa, tj. član A sabkha ciklusa taloženog u plitkom potplimskom do plimskom okolišu s povišenim salinitetom i stalnom evaporizacijom. Dio vapnenaca tog facijesa je vjerojatno taložen kao istqvremeni bočni ili mlađi facijes sa sabkha i plaja sedimentima u istom, općem regresivnom ciklusu na rubnim dijelovima epikontinentalnog mora (slika 3). , Evaporitni facijes na mnogobrojnim izdancima, bušotinama i u gipsolomima pokazuje da se u njegovim dubljim dijelovima uglavnom nalaze evaporiti bez značajnijih pojava ili makroskopski vidljivih prosio jaka dolomita, a da se u vršnim dijelovima evaporitnog facijesa obično s evaporitima pojavljuju pro~lojci laminiranih dolomita (sl. 4), nekontinuirane tamine dolomita u evaporitu (sl. 6) ili dolomitno-evaporitn3 breče nastale naknadnim tektonskim, a ne sinsedimentacijskim procesima drobljenja proslojaka dolomita i evaporita (sl. 5 i 10). Najčešći su slojeviti i laminirani gipsevi u kojima se pojavljuju proslojci, tamine ili relikti laminiranih i stromatolitnih dolomita (sl. 6, 7 i 8) s tzv. "enterolitičkim boranjem" (BOSELLINI & HARDIE, 1973). Premda po obliku vrlo slična tektonskim deformacijama, ta su "enterolitička boran ja" ili tzv. "enterolithic folds" nastala kemisjkim promjenama volumena sedimenta uslijed 'stezanja i rastezanja proslojaka i slojeva evaporita pri procesima hidratacije anhidrita u gips i dehidratacije gipsa u anhidrik Naime, pri hidrataciji anhidrita u gips, tj. primanju vode, povećava se volumen za cca 38% što,jasno, izaziva snažna naprezanja posebice kad se taj reverzibilni proces više puta po~avlja tijekom geološke povijesti. Glede strukture i sastava dolomiti pripadaju dolomikritima, dolopelmikritima ili dolomitnim stro­ matolitima s desikacijskim pukotinama ili pukotinama stezanja (shrinkage cracks) te šupljinama otapanja. Kod evaporita u kojima makroskopski obično nije moguće zamijetiti dolomitne proslojke i tamine ("čisti evaporiti") dolomit je, kako to pokazuju mikroskopske analize, i tu redovito prisutan obliku tankih, raskinutih i plisiranih ("boranih") Jamina, gnijezda, grudastih relikata ili nepravilnih nakupina i agregata (sl. 5, 6 i 7). Sve su to ranodijagenetski ili evaporitni dolomiti nastali u istom sedimentacijskom ciklusu s anhidritom u rubnim dijelovima prostranih sabkhi koje su zbog sužavanja marinskogbazena progradirale preko potplimskih okoliša u smjeru mora (sl. 3). Usprkos snažnog tektonskog lomljenja u gipsevima se još mogu zapaziti cikličke izmjen'e'dolomit-gips koje odgovaraju članovima B i e sabkha ciklusa sedimentacije. Evaporiti su zastupljeni gipsom ili anhidritom ili gipsom i anhidritom (sl. 2-10). Gips se obično nalazi na površini ili blizu površine, a anhidrit u dubljim di jelo vima gipsoloma ili u bušotinama jer je gips pretežnim dijelom ovdje 125 sekundarni mineral nastao hidratacijom anhidrita, kako je to jasno vidljivo u mikroskopskim izbruscima (sl. 8 .i 9). Hidratacija anhidrita je uvjetovana opadanjem temperature i smanjivanjem saliniteta parnih voda sadržanih u evaporitima, osobito nakon što su anhidriti došli u doticaj sa slatkom oborinskom vodom. U našem slučaju gdje su evaporiti višekratno intenzivno tektonski lomljeni, drobljeni i rasjedani, očigledno je da je hidratacija anhidrita u gips nastupila nakon što su evaporiti tektonikom, dijapirizmom i erozijom dospjeli vrlo blizu površini ili na samu površinu gdje su bili izloženi jakom utjecaju oborinskih i slatkih površinskih i podzemnih voda. Evaporiti, koji su danas na površini zastupljeni gipsom nastalim hiđratacijom iz anhidrita, su taloženi u evaporitnim uvjetima u rubnim dijelovima epikontinentalnog marinskog bazena koji je zbog opće regresivne tendencije i permanentne progradacije oba:Ie, odnosno stalnog povlačenja mora, završavao formiranjem i duže vremena održavanjem sabkha i plaja uvjeta (sl. 3). Takvi okoliši su egzistirali na velikom prostoru duž prostran og i širokog područja uz stalne bočne migracije. Tu su u rubnim dijelovima mora mogle biti veće ili manje lagune, zatvoreni pličaci, sabkhe i slane bare s visokom koncentracijom ea-sulfata koje su općom tendencijom smanjivanja marinskog područja, tj. općom regresijom i progradiranjem obale prema moru, postupno prelazile u natplimske i priobalne sabkhe i vjerojatno kontinentalne sabkhe i slana jezera sa stvaranjem ranodijagenetskih dolomita i nodulamih anhidrita. Bočno u plitkim lagunama i plimskoj zoni tal oženi su vapnenci, a na prednjem žalu (foreshore) i obalnom licu (shore face) s prevladava jućim siliciklastičnim materijalom, kao i plajama\ i oslađenim jezerima, klastični sedimenti u ko jima se tijekom sušnih razdoblja izlučuje halit koji danas nalazimo u klastitima u obliku kalupa kubičnih kristala. Evaporiti, premda imaju veliku debljinu (dijapirizam, tektonika ?), nigdje ne sadrže debele pakete laminacijske izmjene karbonata, anhidrita i hali ta. Naime, većina evaporita taloženih u marinskim okolišima s nešto dubljom vodom (lagune, zatjevi i sl.) se odlikuje spomenutom pravilnom tanko lam~niranom izmjenom unutar kontinuirane debljine evaporitnih sedimenata od više stotina metara ili pak pripada tzv. "trakastim anhidritima", odnosno "V arven anhidritima" bogatim organskom supstancijom i izmjenom s halitima (RieHTER-BERNBURG, 1955; 1957; SeHREIBER, .1986). Kako takvi evaporiti u našem slučaju nisu nigdje nađeni, taj način njihovog mogućeg postanka je isključen iz ove interpretacije. Razmjerno mali udio dolomita i · nepostojanje kompletnih sabkha ciklusa: vapnenac-dolomit­ anhidrit u gornjopermskim evaporitima, osobito u dubljem dijelu evaporitnih naslaga, moguće je objasniti na slijedeći način: - sabkha anhidrjti su pretežno nastali u dugotrajno postojanim sabkha uvjetima e faze regresivnog sabkha ciklusa s visokom koncentracijom i donosom ea-sulfata u kojima je anhidrit manje-više potpuno potisnuo dolomit; - dijapirizmom su iz primarne sukcesije sabkha ciklusa bile kretane uglavnom samo evaporitne mase a ne i značajnije količine karbonata (vapnenci i dolomiti) što