Annales Societatis Geologonim Poloniae (2015). vol. 85: 187-203. SUCCESSIVE STAGES OF CALCITIZATION AND SILICIFICATION OF CENOMANIAN SPICULE-BEARING TURBIDITES BASED ON MICROFACIES ANALYSIS, POLISH OUTER CARPATHIANS Marta BĄK1, Zbigniew GÓRNY2’1, Krzysztof BĄK3, Anna WOLSKA1 & Beata STOŻEK2 1 Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, Poland; email: martabak@agh.edu.pl " Institute of Geological Science, Jagiellonian University, Oleandry 2a, 30-063 Krakow, Poland 3 Institute of Geography, Pedagogical University of Cracow, Podchorążych 2, 30-084 Kraków, Poland Bąk. M.. Górny, Z., Bąk, K., Wolska, A. & Stożek, B., 2015. Successive stages ofcalcitization and silicification of Cenomanian spicule-bearing turbidites based on tnicrofacies analysis, Polish Outer Carpathians. Annales Societatis Geologonim Poloniae, 85: 187-203. Abstract: Mid-Cretaceous turbidites with large proportions of sponge spicules are widely distributed in the Silesian Nappe of the Outer Carpathians, giving rise to diversified types of sediments, from spiculites to spicule-bearing siliciclastics and calcarenites. Part of this succession, Middle-Late Cenomanian in age, was transformed into cherts. A microfacies study showed that these turbidite sediments underwent several stages of calcitization and silicification, which took place during Mid-Cretaceous times in different sedimentary environ- ments, i.e., on a northern shelf bordering the Silesian Basin and on a deep sea floor. The first diagenetic changes were related to changes to the biotic components of the turbidite layers, dominated by siliceous sponge spicules. This process, which took place in the spiculitic carbonate mud on the shelves, was related to the calcitization of sponge spicules. Calcareous clasts and calcified skeletal elements also were corroded by bacteria. After trans- portation down the slope, the biogenic and siliciclastic particles were deposited below the carbonate compensation depth. Taphonomic processes on the basin floor and alternating phases of carbonate and silica cementations, recrystallization and dissolution occurred in these sediments and were related to the diversification in composition of successive turbidite layers. Silicification was related to the formation of quartz precipitates as fibrous chalce- dony or microcrystalline quartz, which were derived from the earlier dissolution of amorphous silica, originating mostly from siliceous sponge spicules and radiolarian skeletons. However, a source of silica from hydrothermal vents was also possible. The initial silica precipitation could have taken place in a slightly acidic environment, where calcite was simultaneously dissolved. A number of silicification stages, visible as different forms of silica precipitate inside moulds after bioclasts, occur in the particular mrbidite layers. They were related to changes in various elements of the pore-water profile after descending turbidity-current flows. A very low sedimentation rate during the Middle-Late Cenomanian in the Silesian Basin may have favoured the sequence of initial calcitization and silicification stages of the turbidite sediments. Key words: calcitization, silicification, sponge spicules, spicule-bearing turbidites, cherts, Cenomanian, Outer Carpathians. Manuscript received 20 August 2014, accepted 4 March 2015 INTRODUCTION Spicule-bearing turbidites arc very characteristic sediments, accumulated during the Cenomanian in the Outer Carpathian basins of the Tethyan domain, spreading out along the southern edge of the European Platform (Sujkowski. 1933; Książkie- wicz, 1951,1956; Unrug. 1959; Alcxandrowicz, 1973). Sponge spicules arc the main components of medium- to thick-bcddcd turbidites in gaize, spiculite and chert layers in medium- to thick-bedded turbidites. The Middle-Upper Cenomanian sediments in the Silesian and Subsilesian nappes of the Outer Carpathians, named the Mikuszowicc Cherts, arc an example of such facies extending along the Outer Carpathians arc over a distance of more than 300 km (e.g., Burtanówna, 1933; Książkiewicz, 1951; Burtan and Skoczylas-Ciszewska. 1956; Koszarski and Nowak, 1960; Koszarski and Ślączka. 1973). The siliceous sponge spicules with radiolarians, foraminifcrs, and siliciclastic and calcareous material create a scries of fine-grained turbidites in this unit, intercalated with hemipe- lagic, non-calcareous clays (Bąk M. et al., 2011). This paper focuses on well developed and well exposed spicule-rich turbidites in the central part of the Silesian Ba- 188 M. BĄK ET AL. Fig. 1. Location of the study area. A. The Carpathians against the background of a simplified geological map of the Alpine orogeny and their foreland. B. Tectonic sketch map of the Western Carpathians with location of the Silesian and Sub-Silesian nappes. C. Location of the sections studied in the Silesian Nappe of the Outer Carpathians against the background of a contour map (Bryndal, 2014); boundaries of structural units after Oszczypko (2004): J - Bamasiówka-Jasieniea Quarry. OG - Ostra Góra Quarry, T - Trzemeśnia; BR - Barna- siówka Ridge. D. Example of succession of spicule-bearing turbidites (thick-bedded sandstone layer) in the upper part of the Mikuszowice Cherts (Upper Cenomanian) exposed in the Bamasiówka-Jasieniea Quarry. E, F. Example of a single spicule-bearing sandstone with a chert layer. sin of the Outer Carpathians (Fig. 1). Previous field and mi- croscope observations (Bąk M. el al2005, 2011) indicated that these sediments had undergone several stages of dia- genctic processes with carbonate and siliceous cementation, leading to the formation of numerous chert layers. The cherts occur as thin layers in the medium- to thick-bcddcd turbidite sandstones. Silicification events producing microcrystalline quartz through the transformation of biogenic amorphous opal-A was suggested by many authors with regard to various scdi- CALCITIZATION AND SILICIFICATION OF CENOMANIAN SPICULE-BEARING TURBIDITES 189 mentary rocks. Review articles related to this problem in- clude those by: Williams and Crcrar (1985), Williams et al. (1985), Hesse (1989). and Knauth (1994). The chemical and mineralogical changes occurring in this transformation pro- cess were presented on the basis of experimental investiga- tions (e.g., Mizutani. 1970) and commonly in relation to studies of oceanic sediments in the Deep-Sea Drilling Pro- ject (e.g., Calvert, 1971; Von Rad and Rösch, 1972, 1974; Hurd. 1973; Calvert, 1974; Wise and de Weaver, 1974; Keene, 1975; Riech and von Rad, 1979; Hurd et al., 1981; Baltuck, 1986; Cady et al., 1996), turbidite sediments (Elorza and Bustillo, 1989) and the chalk facies of epiconti- nental seas (e.g., Clayton, 1986; Zijlstra, 1987; Madsen and Stcmmcrik, 2010). The aim of this study is to elucidate the processes and en- vironment that led to the diagenetic transformations of bio- genic particles, which are components of the turbidites. and to determine the diagenetic history of the spicule-bearing sediments after their deposition in a deep-sea environment. This study is based on microfacics analysis, in conjunc- tion with SEM observations on the biogenic particles of silty/sandy turbidites and also the sequences of generation of cement and dissolution of various particles, which took place before their deposition and after their burial. GEOLOGICAL BACKGROUND The study area is located in the central part of the Sile- sian Nappe in the Outer Carpathians (Fig. 1A-C), in the Lanckorona-Żegocina tectonic zone (Książkiewicz, 1951; Koszarski and Ślączka, 1973). During the Cretaceous, the sediments of the Silesian Nappe accumulated in the north- ern part of the Carpathian basins, known as the Silesian Ba- sin, restricted to the south by the Silesian Ridge (cordillera) and to the north by the southern shelves of the West Euro- pean Platform or the Sub-Silesian submerged ridge (Książ- kiewicz, 1962). Mid-Cretaceous sedimentation of the spicule-bearing Uirbiditcs in this area began with the accumulation of the Albian-Lower Cenomanian Middle Lgota Beds (Książkie- wicz, 1951; Unrug, 1959) and came to an end during depo- sition of the Turanian Variegated Shale, with an interrup- tion during the uppermost Ccnomanian-lowermost Tura- nian, related to Oceanic Anoxic Event 2 (OAE2; Bąk, 2007a; Okoński et al., 2014). The detrital material was sup- plied by turbidite currents from the shelves and slopes of the West European Platform, as documented by the orientation of the flute casts of sandstone layers (Książkiewicz, 1962; Unrug, 1977). Numerous biogenic particles with large amounts of sponge spicules occurring in these turbidites originated from the growth and dcstniction of sponge com- munities, built of the rigid skeletons of sponges mostly of lithistids group, and formed on the same shelves. The detri- tal grains and biogenic particles of the turbidites correspond mostly to the Tb-d divisions of the classic Bouma sequence (Bąk M. et al., 2011). They are commonly graded, with sand/silt passing upwards into mud. The biggest particles are loose sponge spicules, with an average maximum di- mension ranging from 100 to 200 pm. Fig. 2. Stratigraphie logs of the Mikuszowice Cherts (MC) and the encompassing units at the Bamasiówka-Jasieniea, Bamasiówka- Ostra Góra and Trzemeśnia sections, with locations of the samples studied. Numbered samples are related to photographs in Figures 3-6. BRSF-Barnasiówka Radiolarian Shale Fonnation. The spicule-bearing turbidites studied belong to three lithostratigraphic units: the Middle Lgota Beds, the Miku- szowice Cherts (the so-called Upper Lgota Beds) and the Bamasiówka Radiolarian Shale Formation (Fig. 2). Gener- ally, all of them arc dominated by turbidite sandstones, mud- stones and claystoncs, with intercalations of non-calcareous, green to black shales. The Middle Lgota Beds (Aptian- Lower Cenomanian; Geroch et al., 1967; Bąk M. et al., 2005) consist mainly of thin-bedded turbidites with very thin, hemi- pclagic, partly siliceous clays. The most characteristic feature of the overlying Mikuszowice Cherts (Middle-Upper Ceno- manian; Bąk M. et al., 2005) is the occurrence of bluish chert layers in the middle and upper parts of medium- and thick - bedded, fine-grained sandstones (Fig. IE, F). In turn, the Bar- 190 M. BĄK ET AL. Fig. 3. The most characteristic microfacies of spicule-bearing turbidites occurring in the Middle Lgota Beds and Mikuszowice Cherts (A-C: plane light; D: crossed polars). A. Biomicrite with radiolarians (r) and planktonie foraminifer (pf); sample Bar-5. B. Biomicrite with benthic foraminifers (f) and sponge spicules (sp); sample Bar-5. C. Spiculitic sublitharenite; sample Bar-57. D. Sublitharenite with calcified spicules (sp); sample Bar-64. nasiówka Radiolarian Shale Formation (Upper Ccnomanian- lowermost Turonian; Bąk K. et al, 2001) consists of thin-bedded silty and muddy hirbidites, with thicker interca- lations of hcmipclagic, green to black claystones. The succes- sion of hirbidites directly precedes the uppermost Cenomanian black, organic-rich shales, representing the sediments of OAE2 (Bąk K., 2006. 2007a-c; Bąk M., 2011). MATERIAL AND METHODS Three sections including the spicule-bearing turbidites, which belong to the Cenomanian sediments of the lithostra- tigraphic units mentioned above, were sampled with micro- facies studies in mind. Two of them, the Bamasiówka- Jasieniea (Fig. ID) and the Barnasiówka-Ostra Góra are ex- posed in quarries at the Bamasiówka Ridge (2 km away), near Bysina and Jasienica villages, a few kilometres west of Myślenice town (Fig. 1C). A third one, the Trzemeśnia sec- tion, is exposed near the mouth of a right tributary of Za- sanka Creek, in Trzemeśnia village (Fig. 1C). The detailed location of the sections shidied and their relationship to the regional geology was presented by Bąk K. et al. (2001). The location of the samples used in this study (Fig. 2) is the same as that presented in papers by Bąk M. et al. (2005) for the Bamasiówka-Jasieniea and Barnasiówka-Ostra Góra sections, and by Bąk K. (2007a) for the Trzemeśnia section. The micro facies and microfossils were dctcimincd and ana- lysed in forty-six thin sections, made from eighteen samples of the sandstones. The replacement textures as well as silica and carbonate cementations observable in thin sections were descri- bed. These textures were interpreted with respect to the compo- sition of biogenic (carbonate and siliceous) sediment particles. Selected mineral constituents of the sponge spicules were studied by electron microprobe point analyses, using a Hitachi S-4700 SEM with a link Noran Vantage EDS (the data were corrected using the ZAF/PB programme). The sponge spicules used in this analysis were extracted from the turbidite sandstone layers. They came from pieces weighing about 200 g, which were treated with 3-5% hydrofluoric acid. The residues (1-3 g) were dried, weighed and washed through sieves with mesh diameters of 63-500 pm. Thin sections of the rock used in microfacies analyses and cells with sponge spicules are housed in the Faculty of Geol- ogy, Geophysics and Environmental Protection, at the AGH University of Science and Technology, Kraków, Poland. RESULTS General sedimentary features of turbidites A single turbidite layer in the successions studied repre- sents a sequence of various lithotypes, resulting from cur- rent sorting of particles with various shapes, weights and different specific gravities. One dcpositional turbidite event may contain successively (Fig. 3): (1) dctrital grains such as quartz and/or lithic grains, usually forming sublitharenite, which passes upwards into (2) sublitharenite with increas- ing content of biogenic particles such as sponge spicules and calcareous benthic foraminifers, (3) spiculitic sublitha- renite, (4) spiculitc, which usually passes into (5) lithotypes containing more micrite/sparite with increasing amounts of planktonie foraminifers and radiolarians. These sequences fi- nally pass into a hcmipelagite layer, corresponding to deep- water pelagic sedimentation and containing agglutinated ben- thic foraminifers and radiolarians, but devoid of calcareous micro-/nannofossils. The boundaries between the lithotypes mentioned above usually facilitated the later silicification process during the diagenetic remobilisation of silica. CALCITIZATION AND SILICIFICATION OF CENOMANIAN SPICULE-BEARING TURBIDITES 191 Distribution of microfacies in the lithostratigraphical units studied The Middle division of the Lgota Beds is composed of centimetres-thick, diagenetically altered beds (up to 25 cm thick) of fine- to medium-grained, dark grey and black sub- litharenites, siliceous shales and biomicrites, partly silici- ficd, in packages up to 20 cm thick. The coarser material in the turbidite layers generally represents sublitharcnitcs, in places containing calcareous benthic foraminifers and sponge spicules. The finest calcarenitic material corresponds to bio- intramicritcs and mudstones. The Mikuszowice Cherts are the main body of the spi- cule-bearing turbidites. They arc composed of centimetre- thick layers, which are fine-grained siliciclastics as sub- litharenites, mudstones and siltstones with biogenic admix- ture, and also calcarcnitcs to calcisiltitcs, usually silicificd. In some places, the siliciclastics pass into carbonate sedi- ments with variable detrital admixtures. The microfacies composition shows the following types: (1) fine- to me- dium-grained sublitharenite with calcitic matrix/cement, in places with a biogenic admixture, (2) sublitharenite with sponge spicules containing 5-10% of sponge spicules, (3) spiculitic sublitharenite, (4) spiculite containing up to 90% of sponge spicules, with rare foraminifers and radiolarians and very rare detrital grains which are quartz and glauco- nite. and (5) biomicrite/sparitc with radiolarians, planktonie and benthic calcareous foraminifers, and rare sponge spi- cules. Pure sublitharenites, sublitharenites with a biogenic admixture, and spiculitic sublitharenite are the most common microfacies in the upper part of the Mikuszowice Cherts. The lower part of the Barnasiówka Radiolarian Shale Formation is the unit, which marks the final occurrence of spicule-bearing nirbidites within the Cenomanian succes- sion. These sediments arc composed of centimetres-thick layers (up to 12 cm thick), in which fine-grained siliciclas- tics as sublitharenite, mudstones and siltstones occur, with a biogenic admixture, and calcarenites to calcisiltites, usually silicificd. Petrographie features of biogenic and inorganic components in turbidites The turbidites include mainly sponge spicules within the biotic components. Less common arc radiolarians, planktonie and calcareous benthic foraminifers, inoccramid prisms, and echinoderm ossicles. Chert layers in the turbi- dites display a similar composition of biogenic particles, al- though the siliceous microfossils arc much better preserved. Sponge spicules Spicules of sponges recognised in the material studied belong to two taxonomic groups of siliceous sponges in the class level as Dcmospongea Sollas 1875 and Hexactincllida Schmidt 1870 (Bąk M. et al., in press). Most spicules be- long to the lithistid dcmospongcs, which are classified as the polyphylctic (informal) group of class Dcmospongea, characterized by rigid skeletons composed of desmas spi- cules (e.g., Pisera and Levi, 2002). Spicules predominate among the biogenic components (Figs 3, 4). ranging from 10 to 60% of their total volume. They were originally made up of hydrated, amorphous, noncrystallinc silica (opal-A); however this did not occur in the material studied. The char- acteristic feature of the spicule was an open axial canal, cir- cular in outline (Fig. 4A, N). Spicules in the sediments stud- ied represent two main types of preservation. They arc (1) replaced by blocky calcite (Figs 41, J, O-R, 5) and (2) re- placed by various phases of silica (Fig. 4L, Ml, M2). (1) Replacement by blocky calcite represents the predo- minant type of preservation of spicules. Various cross-sec- tions and SEM observations including EDS measurements show that calcite very consistently replaced the whole spicule (Fig. 5). The axial canal of the spicule is usually obscured and filled in by the same type of calcitc cement as the outer part of the spicule (Fig. 5E). However, some of the calcified spicules display a well preserved open canal (Fig. 4N). (2) Spicules replaced by more stable silica phases are rare in the Lower-Middle Cenomanian part of the succes- sion studied and their numbers increase in the Upper Ceno- manian turbidites, where they predominate among the bio- genic clasts. They are composed of microcrystallinc quartz (Fig. 4D-H, K-M2) or fibrous quartz (Fig. 4E, M2). An axial canal has not been preserved in most of the spicules. Radiolarians Radiolarians are common in the turbidite layers, but poorly to moderately preserved (Fig. 6A-C). Only 15% of the skeletons arc identifiable. The number of individuals var- ies, depending on the type and derivation of the host-sedi- ment. They arc numerous in the sand fraction within the tur- bidites studied, even exceeding 10 000 individuals per 100 g of the rock sample. Their skeletons arc mostly rccrystallized or present as voids, cemented by calcite (Fig. 6B1, C). Foraminifers The content of calcareous (benthic and planktonie) foraminiferal tests ranges from 1 up to 10% of the entire microfacies content. Benthic foraminifers are usually pres- ent as voids, reduced in volume by infillings of calcite ce- ment (Fig. 6D-F). Their primary walls were replaced by fringe sparitc (Fig. 6D-F2). Some of them are empty, but usually they are filled with calcitic or siliceous cement (Fig. 6D-K). The tests of planktonie foraminifers were usually replaced by fringe sparitc (Fig. 6D) or a micritic envelope (Fig. 6I-K). Microborings Post-mortem microborings of carbonate bioclasts and some of carbonate intraclasts by bacteria arc also character- istic of the material studied. Many tests of planktonie and benthic foraminifers, and calcified demosponge spicules have a micritic halo (Fig. 6I-K) around their outer margins, which is a combination of the microboring process and the later infilling of the borings with cryptocrystalline calcitc. Pyrite framboids Spherical pyritc framboids are attached directly to the inner surfaces of foraminiferal tests, both planktonie and benthic (Fig. 6E-F2, I-K). They could be in contact with calcite cement, reducing the porosity of the test. Addition- 192 M. BĄK ET AL. CALCITIZATION AND SILICIFICATION OF CENOMANIAN SPICULE-BEARING TURBIDITES 193 ally, the framboids are located between calcite crystals, which partly replaced the foraminiferal test wall (Fig. 6K). Moreover, the pyrite framboids may infill the central part of a sponge spicule left after the primary stage of silica cemen- tation (Fig. 4E, G, FI). Matrix The content and composition of the matrix change along individual turbidite layers and differ between particu- lar turbidites within the succession studied. The matrix con- sists mostly of detritic clay minerals, micrite, rhombic dolo- mite crystals and organic matter in the turbidites of the Mid- dle Lgota Beds (Fig. 6B-D), with an increasing amount of carbonate and Fe-oxides in the underlying parts of the suc- cession studied. The carbonate matrix (primary micrite) is usually visible as recrystallized in the form of sparite and blocky calcite, or it was partly replaced by chalcedony and microcrystallinc quartz (Fig. 6Ü). Calcareous and siliceous cements Carbonate cement is represented by rhombic calcitc and dolomite crystals and as micrite, showing different degrees of recrystallization (Fig. 7C, D). Rhombic calcite-like crys- tals and rare dolomite crystals occur in a contact with micro- quartz and chalcedony, which fill in different types of poros- ity in the sediment. Calcitc crystals formed syntaxial over- growths on the calcified spicules of sponges (Fig. 5B-F). Silica cement usually filled in the earlier voids left after the dissolution of calcareous bioclasts and the calcified spi- cules of siliceous sponges. Some of these particles were pre- viously overgrown by syntaxial calcitc (Figs 7H, 8A-F), then fibrous chalcedony and microcrystalline quartz precip- itated in the voids (Fig. 7C, D. 1, J). Chalcedony and micro- quartz also replaced calcitc rhombohedra and the primary micritic matrix (Fig. 7G-K). Structures left after mechanical compaction Some of the internal structures in the turbidite layers remained after previous mechanical compaction. Silicificd rocks usually display load-cast structures, indicating silicifi- cation after early mechanical compaction. Other lines of evi- dence arc micro fracturing of some sponge spicules (Fig. 41), calcitc crystals (Fig. 8). sutured contacts between quartz and glauconite grains or individual carbonate grains (Fig. 9A, B), plastic deformation of lithic fragments (Fig. 9A) and defor- mation of mica flakes (Fig. 7B). Structures left after chemical compaction The main structures produced by chemical compaction arc seams and stylolitcs caused by pressure solution. Stylo- lites are present in the carbonate-rich beds that contained a predominantly carbonate matrix. The stylolites separate particles with an insoluble residue (clay minerals, iron ox- ides, and organic matter; Fig. 7E, F). Small stylolites occur usually in the biointramicrites, where quartz, silt and small opaque grains have accumulated as a residue after pressure dissolution. Occurrence and petrography of cherts The outstanding feature of these deposits is the occur- rence of light grey and bluish cherts in the Mikuszowice Cherts (Fig. IE, F), but they also arc present in the Middle Lgota Beds. The cherts form layers from millimetres up to several centimetres in scale, and account for up to 50% of the bed. The cherts are parallel-laminated, similar to the host sediment (Fig. IE, F). Thin sections show that the mor- phology of the chert layers is controlled by the primary sedi- ment composition, sedimentary structures and porosity. The cherts may have sharp contacts with the underlying sedi- ments and pass through the overlying one. Initially, silica re- placed very consistently carbonates in form of micrite and/or sparitc. Most of the silica is in the form of microcrystallinc minerals (microquartz, megaquartz, and chalcedony; e.g., Flessc, 1989; Flörke el al., 1991; Heaney, 1993). In the sediments studied, microquartz is characterized by mosaics of equal-sized crystals, up to 20 pm across, with undulatory extinction. Microquartz usually replaced car- bonate sediment, and bioclasts, and is the first cement gen- eration to fill primary intraparticle porosity. Megaquartz is --------------------------------------------------------------------------------------------------------------------------------------------------- Fig. 4. Various preservation stages of sponge spicules observable in thin sections of spicule-bearing turbidites. Outer Carpathians. A. Generalized morphology of a siliceous sponge spicule. B-F. Drawings showing the types of recrystallization and replacement of sponge spicules present in the material studied. G, H. The same photomicrograph under plane light (G) and crossed polars (II), showing succes- sive stage of silica crystallization in void after sponge spicule. The process started with partial overgrowing by microcrystalline silica (mq) from outside toward the inner part of the void. The pyrite crystals (py) grew in the emptiness left after silicification; sample TrzM-3. I. Spicule of siliceous sponge replaced by blocky calcite; sample TrzM-1. J. Close-up view of Figure I showing bacterial-size microborings (mb) present along the spicule outline. Outer spicule surface visible on cross-section possesses signs of dissolution (diss). Rounded shape of the voids indicates that this process took place when spicule was originally siliceous. K. Cross-section of benthic foraminifera test with original wall replaced and partly covered by sparite. The first stage of infilling involved calcite-like crystals, which grew attached to the inner wall. Quartz microcrystals grew during secondary cementation stage; Sample OsG-2. L. Another view of spiculite microfacies showing that most of spicule moulds are strongly corroded. Planktonie foraminifers (pf); sample Bar-12. Ml. Close-up view of Figure L under crossed polars, showing that moulds are completely filled by microcrystalline quartz (mq). M2. Another close-up view of Figure L showing cross-section through mould after spicule, which was formed during two stages of silica precipitation. First stage (1) left rim of microquartz grain along the outermost wall of a previous void. During second stage (2), an empty space left inside void and imitating the spicule axial canal, was infilled with chalcedony; sample Bar-12. N. Spicule of Hexactinellid sponge replaced by calcite crystals. The remnants of axial canal are visible inside the spicule; sample Bar-12. O-R. Photomicrographs of sublitharenite with spicules of sponges, showing different cross-sections of calcified, previously siliceous spicules, replaced by blocky calcite (sp); sample Bar-37. Q. Calcified spicules of previously siliceous sponge. Outer spicule surface possess semicircular, concave hollows, left after dissolution (diss). 194 M. BĄK ET AL. Fig. 5. Spicules of sponges, etched by weak solution of hydrofluoric acid from chertified spiculites. All spicules are preserved as moulds after the original silica, now filled in by calcite crystals. A-C. Phyllotriaene spicules. A. Broken part of the spicule indicates that inner part consists of densely packed calcite crystals. B. Close-up view showing outermost part of the mould after spicule, which consists of small cal- cite crystals (sparite), less than 10 pm across. Cavities in rhombohedral shape (arrows) left after syntaxial cement. C. Photomicrographs showing that spicule mould surface possesses cavities in rhombohedral shape (arrow) left after syntaxial cement. D. Flat dennal spicule pre- served as mould with several pores with rhombic shape (arrows) after syntaxial calcite cement overgrowth. E, F. General view of spicule mould (E) and close-up of calcite crystals with point of F.DS analysis. Specimens covered by Au coatings for analysis. All samples - Bar-36. CALCITIZATION AND SILICIFICATION OF CENOMANIAN SPICULE-BEARING TURBIDITES 195 Fig. 6. Bioclasts in spicule-bearing turbidites. A, B. Spiculitic sublitharenite with common radiolarian skeletons, which are recrystallized and usually filled in with microcrystalline silica; A - sample OsG-7d; B - sample OsG-12. B1. Close-up view of sample OsG-12 with crossed polars. showing fibrous microcrystalline silica filling in radiolarian test. C. Radiolarian species from genus Praeco- nocaryomma replaced and filled in with blocky calcite; sample OsG-7d. D. Original biomicrite with benthic (fb) and planktonie (fp) foraminifers. and rare glauconite (gl) grains after stages of calcitization and silicification. Foraminiferal calcareous tests are recrystallized into sparite. Micritic ma- trix was secondarily recrystallized into sparite or replaced by chalcedony and microcrystalline quartz. Planktonie foraminiferal tests are filled in with chalcedonie cement (ch) or microquartz. (mq); sample OsG-10. E. Calcareous benthic foraminifer from genus Gyroidinoides with test recrystallized by spar and partly covered by fringe calcite cement (fee - whitish crystals in external part of wall); sample OsG-2. Fl, F2. Cal- careous benthic foraminifer from genus Gavelinella/Lingulogavelinella with chamber walls micritized (mic) and filled in partly with sparite (spar) and microcrystalline quartz (mq); sample OsG-12. G-K. Different preservation states of planktonie foraminifers from genus Hedbergella, An original test recrystallized in sparite (G, II) and filled with microquartz (mq) (J). Inner chambers contain pyrite framboids (py), attached to chamber wall or calcite, which crystallized inside the chambers (K); II-K - sample OsG-11. characterized by mosaics of crystals up to 300 pm in diame- ter. It always occurs as a late cement after generations of microquartz and chalcedony and as the primary and second- ary fillings of voids after calcified spicules and foraminifc- ral chambers. It is also present as a secondary generation of pseudomorphs after rhombohedral-calcite-like crystals. The fibrous variety of quartz is less common. Chalcedony is present locally as a cement phase, mostly botryoidal. 196 M. BĄK ET AL. Fig. 7. A. Spicule of siliceous sponge in sublitharenite, which was replaced by blocky calcite. Micritic halo (nth) around outer margins of spicule, as a result of microboring, filled with cryptocrystalline calcite; sample Bar-30. B. Sublitharenite with matrix consisting of clay minerals (cm), and micrite (mic). Plastic defonnation of micas flakes (mi) formed after mechanical compaction; sample Trz-11. C, D. Spiculitic sublitharenite with moulds after originally siliceous sponge spicules, surrounded by two generations of cements (as micro- quartz) and micrite (mic); sample Bar-32b. E, F. Two photomicrographs of microstylolite under plane and crossed polars. Microstylolite was formed in layer with prevailing carbonate matrix (yellow buckle). It separates particles which consist of insoluble residue as clay min- erals, iron oxides, and organic matter; sample Bar-23. G. Cross-section of moulds after radiolarian test contains microquartz (mq) and cal- cite-like crystal inside fill of one quartz crystal (q). H. Void after previously siliceous spicule of sponge filled in with calcite cement. One small calcite crystal is attached to inner wall (c). I. Foraminiferal test filled with microquartz (mq) and fibrous quartz, which were precipi- tated in rhombic space (fq). CALCITIZATION AND SILICIFICATION OF CENOMANIAN SPICULE-BEARING TURBIDITES 197 Fig. 8. Time-spatial model of early diagenetic processes which took place in neritic and slope environments of the Silesian Basin DISCUSSION Taphonomic and early diagenetic processes during pre-depositional stage Numerous biogenic particles occurring in the Ccnoma- nian turbidite spicule-bearing sediments came from the northern shelves of the Carpathian basins. The position of these shelf areas is interpreted on the basis of palaeocurrent indicators (e.g., Książkiewicz, 1962). The composition of bioclasts, characterized by a large number of the fragmented (broken during transportation), calcified sponge spicules (Fig. 8) and calcareous benthic foraminifers, shows that they originated in the neritic zone of the shelves and on the upper slope of the Silesian Basin (summary in Bąk M. et al., in press). The original opaline silica of the spicules was re- placed by blocky calcite during the initial decay and/or early burial of the siliceous sponges, which had grown in the car- bonate mud (Fig. 9). The various dimensions of calcitc crys- tals. observable inside the moulds after the original spicules, display successive stages of crystallisation (Fig. 4B, C). Such calcitization of siliceous sponges concurrently with silica dissolution is a known phenomenon, documented mainly from modem and ancient shallow-water environ- ments, including spiculitic carbonate mud-mounds and reefs (Frogct, 1976; Land, 1976; Wicdcnmaycr, 1980; Rci- tner and Keupp, 1991; Reitner, 1993; Flammes, 1995; Reitneref al., 1995; Wamkc, 1995; Pisera, 1997; Neuwcilcr et al. 1999; Kauffman et al., 2000). The dissolution of the opaline silica of spicules and their replacement by calcium carbonate may have occurred both within the living sponge, and during its decay in the weakly cemented material, a few centimetres thick, associated with bacterial mats (Hartman, 1979; Pratt et al., 1986; Bavestrelloef a/., 1996). According to Fritz (1958), after the death of a sponge, the organic ma- terial putrefies. This process normally favours the precipita- tion of carbonate (calcite spar) within and around the sponge spicules. However, at the beginning, an initial tr ansformation from opaline to microquartz silica takes place within the spi- cules (e.g.. Hartman et al., 1980; Olóriz et al, 2003). The post-mortem microborings of carbonate bioclasts (foraminiferal tests and echinoid plates), visible as a micri- tic halo in thin sections of the rocks, have been made by 198 M. BĄK ET AL. Fig. 9. An example of sequences of sedimentary and diagenetic events, interpreted on the basis of microfacies. bacteria during taphonomic-early diagenetic processes, most probably in soft, poorly cemented carbonate mud (Bąk M. et al, in press). Such corrosion of calcareous grains, caused by bacteria, is known from various modem and an- cient environments (e.g.. Liittge and Conrad, 2004; Davis et al., 2007). The same effect of bacterial corrosion is visible on the calcified spicules of sponges (Fig. 41, J, O-R). Another early diagenetic process, related to the shelf-derived bioclasts of the turbidites was the formation of spherical pyrite framboids, attached to the inner surfaces of planktonie and benthic foraminiferal tests. In some exam- ples, growth of them took place also on the surfaces of the calcite rhombohedra inside the tests. The occurrence of such framboids is related to bacterial colonization, which may provide local nucleation sites for sulphides (e.g., Kaplan et al, 1963; Ferris et al, 1987; Kohn et al, 1998). Flowcvcr, the pyritization inside the empty spaces in foraminiferal tests also could occur after their redeposition on the deep-sea basin floor. This cannot be unequivocally identified, because the subsequent processes related to dis- solution of silica and calcitization also took place in the deep-sea environment. These calcified spicules are found mostly in the Tb and Tc parts of the turbidite layers as fragmented particles, which are associated with siliciclastic (mainly quartz) grains. All of them have similar dimensions and occur in the micrite/clay matrix (Fig. 9B). In some turbidite layers, calcified sponge spicules have been rcdcpositcd in carbonate clasts (Fig. 9A). This shows on the one hand various stages of cementation of the carbonate mud on the shelf, and on the other, the occur- rence of littoral currents on the shelf, which eroded the sea floor and transported the material toward the shelf break. It should be emphasized that among the rcdcpositcd sponge spicules, transported by littoral currents and nirbidity cur- rents, a large quantity of them were originally siliceous, but not those previously calcified in the shelf and uppcr-slope environments. Diagenetic processes at deep basin fluor The mechanism of processes, related to the transporta- tion of biogenic and siliciclastic particles from the shelf to the deep-basin floor, and the taphonomic processes on the basin floor are not discussed in this paper. However, it should be emphasised that the deposition of this material from turbidity currents took place most probably below the calcium compensation depth, as documented by the compo- sition of benthic foraminiferal assemblages in the hemipe- lagic layers, intercalated with the spicule-bearing turbidites. They are devoid of calcareous benthos and are dominated CALCITIZATION AND SILICIFICATION OF CENOMANIAN SPICULE-BEARING TURBIDITES 199 by dccp-watcr agglutinated forms. Calcareous foraminiferal plankton was found only in the turbidites (Bąk M. et al., 2005, 2011). The next phase of diagenetic processes, which is dis- cussed here, took place in the consolidated turbidite mate- rial, characterized by the occurrence of siliceous and calcar- eous bioclasts, siliciclastic grains, carbonate grains and mic- rite/clay matrix, related to the different compositions of the Uirbidites, giving rise to the various Bouma cycles. The ear- liest diagenetic process in such an environment was the dis- solution of silica from the siliceous bioclasts in highly alka- line conditions, followed by early calcitization with the for- mation of rhombic calcite-like crystals, mostly inside and around the spicules (Fig. 5), the radiolarian and foramini- fcral tests (Figs 4K, 7G, FI) and also in the micritic matrix. These crystals were formed in conditions of high water con- tent in the sediment, as was suggested previously by MiSik (1966, 1993), among others. The carbonate cementation was also related to the creation of spar crystals as an effect of micrite recrystallization. Such calcitization was descri- bed by many authors with regard to various environments (e.g.. Dietrich et al., 1963; Bustillo and Riuz-Ortiz, 1987; Gimcnez-Montsant et al., 1999). Most of the spicules pre- served in the bioarcnites, spiculitic sublitharenites and spi- culitcs were calcified during this early diagenetic process. It occurs as selective calcitization during the early diagenetic interaction between the silica-rich fluids and the host sedi- ment before later silicification. Phases of silica cementations Several phases of silica cementation occurred in these sediments after mechanical compaction and early calcitiza- tion (Figs 7G-K, 8C-F). The silicification was related to the creation of quartz overgrowths and precipitates as fibrous chalcedony (Fig. 71, J) or microcrystalline quartz (Fig. K), derived from amorphous soluble kinds of silica (Fig. 8D-F). During this process, various forms of silica precipitates par- tially replaced calcitc rhombohedra and micritic matrix, thus reducing the mouldic porosity after biogenic particles. Botryoidal chalcedony was formed in the initial stages (Fig. 8D), followed by microquartz (Fig. 8E) that enveloped the earlier material. The initial silicification could take place in an environment that was slightly acidic, where calcite could dissolve at the same time as silica was being precipitated, as was also discussed by Madsen and Stemmerik (2010) in a study of the diagenesis of flint and porccllanite in the Maa- strichtian chalk. According to these authors, the dissolution of carbonate and liberation of magnesium hydroxyl com- plexes promoted the flocculation of silica that happened near to or at the surface of the dissolving carbonate, result- ing in the silicification of microfossils, preserving their ex- ternal shapes. In this replacement, rhombic dolomite crys- tals could be formed. The number of silicification phases, visible as different forms of silica precipitates inside the spicules (Figs 4M, N, 7C, D, 9), vary in particular turbidite layers; they arc related to changes in many elements of the porc-watcr profile (sec discussion in Mizutani, 1970; Knauth and Epstein, 1976; Knauth. 1994; Madsen and Stemmerik. 2010), which are not discussed here. The periodic sedimenta- tion of turbidites containing different proportions of siliceous to carbonate particles might have changed, in a variety of ways, the conditions in the bottom and interstitial water, causing the re-establishmcnt of a pore-water profile after de- position of the next turbidite layer. Source of silica The recent global estimates of silica budgets consUuc- ted for the world ocean show various sources of silica in- cluding fluxes related to biogenic silica production and re- cycling, biogenic silica burial in coastal regions, output flu- xes related to reverse weathering in estuaries and to spon- ges, mineral weathering, dissolution of amorphous silica on ocean margins, and hydrothermal fluxes (e.g.. Nelson et al., 1995, Treguer et al., 1995; Treguer and Dc La Rocha, 2013). Taking into account the character of the deposition of the sediments studied, which took place from diluted silty/sandy turbidity currents, and the composition of the shelf-derived particles in these turbidites (enriched in sponge spicules and radiolarians), transported to the dccp-watcr basin floor below the calcium compensation depth, the authors suggest three main sources of silica in the bottom water. All of them re- sulted in the later silicification of these sediments. Two silica sources are related to the main biogenic components of the turbidites, i.e., to spicules of siliceous sponges and radiola- rian skeletons. The third source may be connected with si- lica-rich hydrothermal vents. A possible additional source might be diatom frustules. The occurrence of frustules has been documented in the claystone layers of these sediments (Bąk M„ 2011). Today, diatoms arc responsible for as much as 30-40% of the pri- mary production at the modem ocean surface (Buesseler, 1998), and could have been a subordinate source of silica in the Upper Cenomanian part of the succession studied (Bar- nasiówka Radiolarian Shale Formation). The radiolarian skeletons, initially composed of amor- phous opal-A, could have great significance as a silica source in the Upper Cenomanian sediments. The redepos- ited radiolarian assemblages are numerous there in the turbidites. However, they arc scarce in the hcmipclagites, where there is a predominance of thick-walled skeletons, re- sistant to dissolution, or as skeletons replaced by pyrite or ferrous oxyhydroxidcs. The radiolarians which occur in the bottom sediments had to be transported through the water column in fccal pellets (Gersondc and Wcfcr, 1987; Bąk M., 2011). The pyrizited radiolarians found in the hemipelagites may indicate that the pellets were formed in waters which could have been periodically undersaturated with respect to silica. The rarity of siliceous radiolarian debris in the hemi- pelagites and their characteristic state of preservation in this sediment might be evidence of the early decay of such pel- lets during their descent in the water column and the pro- gressive dissolution of the opaline radiolarian skeletons. The preservation and/or dissolution of opaline radiola- rian skeletons and sponge spicules might have been control- led by a few factors and processes (summary in DeMaster, 2003), including the variation in aluminium content (related to an occurrence of a thin dissolution-resistant, Al-rich opal layer in the siliceous skeletons; Van Cappelen and Qui, 1997a); changes in the specific surface areas of particles ex- posed to corrosive action during diagenesis; changes in pro- 200 M. BĄK ET AL. tcctive organic coatings on fresh pellets including radiola- rian skeletons in the water column; changes in bacterial type and their activity; differences in temperature and the degree of undersaturation; the effects of pH variations; and the sed- iment accumulation rate. The latter factor could have been important in the silica diagenesis of the sediments studied, because it controlled the time of exposure of siliceous spicules and radiolarian skeletons to low saturation levels near the sediment-water interface. The biogenic silica preservation efficiencies, cal- culated for modern oceans in relation to various biogenic sources (e.g., DeMaster et al., 1996) reveal large differen- ces. Sponge spicules redissolve into silicic acid at far slower rates than those known for diatom frustules (Maldonado et al, 2005). Similar data came from the laboratory analysis of the dissolution of radiolarian skeletons (Morley et al, 2013). In both cases, there is non-linearity of silica dissolu- tion with increasing depth, with the highest dissolution oc- curring at the watcr-scdiment interface (Van Cappellcn and Qui, 1997b; Gallinari et al, 2002). Consequently, a low sedimentation rate with a low frequency of turbidite cur- rents supplying siliceous bioclasts to the basin floor may fa- vour the dissolution of siliceous bioclasts. This suggestion was also presented for the interpretation of initial silica pre- cipitation in the North European epicontinental seas, where the occurrence of flint layers was correlated with omission surfaces and hardgrounds (e.g., Zijlstra, 1987). Following these observations and using data from similar chalk suc- cession, Madsen and Stemmerik (2010) suggested that the initial precipitation of silica occurred near the seafloor dur- ing periods of slow or declining sedimentation. A similar conclusion is presented for the initial calcitization of bio- clasts and precipitation of silica in relation to the sedimenta- tion rate in the Mikuszowice Cherts studied. On the basis of biostratigraphical data from this succession (Bąk M. et al, 2005; Bąk M., 2011), correlated with the chronostrati- graphy, an average annual sedimentation rate for consoli- dated sediments of the Mikuszowice Cherts is estimated as 0.025 mm/yr and about 0.1 mm/yr for soft sediment. These are very low sedimentation rates, compared to the present- day environments of turbidite deposition (e.g., Piper and Dcptuck, 1997). As mentioned earlier, another source of silica on the seafloor of the Silesian Basin during the Middle-Late Cenomanian could be related to hydrothermal vents. The source for silicon in modern high-tcmpcraturc (mid-ocean ridges) and low-temperaturc (ridge flanks) vents is sug- gested to have been a combination of seawater reaction with basalt and diffusive exchange with the overlying basal pore waters, which were in pseudo-equilibrium with amorphous silica (Wheat and McManus, 2005). In the modem oceans, the high-tcmpcraturc hydrothermal systems, which leach silicon from the oceanic crust, resulting in high-silicic acid hydrothermal fluids, have a higher significance in silicon fluxes (Treguer and Dc La Rocha, 2013). In this paper, the authors tentatively suggest that hydrothermal vents could be of some relevance in fluxes of dissolved silica to the sca- floor during the Middle-Late Cenomanian, on the basis of chemical data from the overlying uppermost Cenomanian- lowcrmost Turanian sediments (the top of the Barnasiówka Radiolarian Shale Formation), which contain two horizons of Fe-Mn layers (Bąk K., 2007b). The chemical composition of these Fe-Mn sediments, characterized by low amounts of Co, Cu and Zn, a low Co/Zn ratio, a low Rare Earth Elements content with their characteristic distribution pattern, and pro- portions of Mn, Fe and (Ni+Cu+Co) that are typical for hy- drothermal fields, may indicate a contribution of silicon from a hydrothermal source (Bąk K., 2006. 2007a-c). FINAL REMARKS The Cenomanian spicule-bearing turbidites in the flysch succession of the Silesian Nappe, in the Outer Carpathians, arc highly silicificd sediments, which contain numerous chert layers in the Middle-Upper Cenomanian part. They under- went several stages of diagenetic processes including the cre- ation of various generations of cement and the dissolutions of various types of particle, which took place both before and after their deposition, and after their burial. The first diagenetic changes, precluded by taphonomic processes, took place during the pre-depositional stage. These involved initial decay and/or early burial of sponge spicules and other microfossils within the spiculitic carbon- ate mud in the neritic zone of the northern shelves of the Outer Carpathian basins. In this environment, the calcitiza- tion of numerous siliceous sponge spicules and radiolarians took place. Opaline silica was replaced by blocky calcite and the skeletons of radiolarians and the tests of planktonie and benthic calcareous foraminifers were partly or entirely filled with calcite cements. Additionally, bacteria have cor- roded the calcified bioclasts. The pyrite framboids could have been formed on the inner surfaces of foraminiferal tests and voids after sponge spicules in small empty cavities with depleted oxygen content. However, this pyritization also could have been possible in a deep-sea environment. After the transport of biogenic and siliciclastic particles from the shelves to the dccp-basin floor below the CCD. and after taphonomic processes on this basin floor, later diage- netic processes of the bottom sediments were related to dif- ferences in the composition of successive turbidite flows. Before the cementation of particles, mechanical com- paction of the host sediment affected the spicule-bearing turbidites. After that, several alternating phases of carbonate and silica cementations, recrystallization and dissolution occurred in these sediments. During these phases, there was the formation of rhombic calcite-likc crystals, especially in- side of the calcareous or siliceous microplankton skeletons (tests), and the creation of spar crystals as an effect of mi- crite recrystallization. During silicification, various forms of silica precipitate replaced partially or entirely the calcitc rhombohedra and micritic matrix and caused a reduction in the porosity after biogenic particles. These stages of silica v\. calcite dissolution, mobilization and crystalization were related to periodic sedimentation of successive turbidite, containing different proportion of siliceous to carbonates particles. It might have changed conditions in the bottom and interstitial water, causing the re-establishment of the pore-water profile after deposition of a next turbidite layer. The initial calcitization and precipitation of silica occurred CALCITIZATION AND SILICIFICATION OF CENOMANIAN SPICULE-BEARING TURBIDITES 201 most probably near the seafloor, favoured by the low sedi- mentation rate, estimated as 0.1 cm/yr during Middle-Late Cenomanian. Biogenic sources of silica may have caused the silicifi- cation of the sediments studied, including dissolution of primary siliceous sponge spicules, radiolarian skeletons and diatom frustules. However, a source from silica-rich hydro- thermal vents was also possible, taking into account the pub- lished data on the uppermost Cenomanian-lowermost Tura- nian Fe-Mn sediments, which overlie the succession studied (Bąk K., 2006. 2007a-c). These vents were the sources of manganese and ferrous iron, precipitated on the basin floor and in the bottom sediments during that time. Acknowledgements We are grateful to Jozef Michalik, (Slovak Academy of Sci- ence, Geological Institute, Bratislava, Slovakia) and an anony- mous reviewer for their helpful comments on the manuscript. Special thanks are to Przemysław Gedl. Frank Simpson and Alfred Uchman for their editorial work. The work was supported by funds from the AGH University of Science and Technology to M. Bąk (DS-AGI1 WGGiOŚ-KGOiG No 11.11.140.173). and Pedagogical University of Cracow to K. Bąk (DS-UP-WGB-3). REFERENCES Alexandrowicz, S. W., 1973. Gaize-type sediments in the Carpa- thian flysch. Neues Jahrbuch für Geologie und Paläontolo- gie, Monatshefte, 1973(1): 1-17. Baltuck, M., 1986. Authigenic silica in Tertiary and Upper Creta- ceous sediments of the East Mariana Basin. Deep Sea Drilling Project Site 585. In: Moberly, R.. Schlanger, S. O. etal. (eds), Initial Reports of the Deep Sea Drilling Project, 89: 389-398. Bavestrello, G., Cattaneo-Vietti, R.. Cerrano, C. & Sarr, M., 1996. Spicule dissolution in living Tethya omanensis (Porifera: De- mospongiae) from a tropical cave. Bulletin of Marine Science, 58: 598-601. Bąk. K., 2006. Sedimentological, geochemical and microfauna! responses to environmental changes around the Cenomanian- Turonian boundary in the Outer Carpathian Basin; a record from the Subsilesian Nappe, Poland. Palaeogeography. Pala- eoclimatology, Palaeoecology, 237: 335-358. Bąk. K.. 2007a. Deep-water facies succession around the Cenoma- nian-Turonian boundary in the Outer Carpathian Basin: Sedi- mentary, biotic and chemical records in the Silesian Nappe, Poland. Palaeogeography, Palaeoclimatology, Palaeoecol- ogy, 248: 255-290. Bąk. K., 2007b. Organic-rich and manganese sedimentation during the Cenomanian-Turonian boundary event in the Outer Carpa- thian Basin, a new record from the Skole Nappe, Poland. Palaeo- geography, Palaeoclimatology, Palaeoecology, 256: 21—46. Bąk. K., 2007c. Environmental changes during the Cenomanian- Turonian boundary event in the Outer Carpathian basins: a synthesis of data from various tectonic-facies units. Annales Societatis Geologorum Poloniae, 77: 171-191. Bąk. K., Bąk. M. & Paul, Z., 2001. Barnasiówka Radiolarian Shale Formation - a new lithostratigraphic unit in the Upper Ceno- manian-lowermost Turonian of the Polish Outer Carpathians. Annates Societatis Geologonnn Poloniae, 71: 75-103. Bąk. M., 2011. Tethyan radiolarians at the Cenomanian-Turonian Anoxic Event from the Apennines (Umbria-Marche) and the Outer Carpathians: Palaeoecological and Palaeoenviron- mental implications. In: Tyszka, .1. (ed.). Methods and Appli- cations in Micropalaeontolog}’. Part II. Studia Geologica Polonica, 134: 7-279. Bąk. M.. Bąk. K. & Ciurej, A., 2005. Mid-Cretaceous spicule-rich flysch deposits in the Silesian Nappe of the Polish Outer Carpathians; radiolarian and foraminiferal biostratigraphy. Geological Quarterly, 49: 275-290. Bąk. M.. Bąk. K. & Ciurej, A.. 2011. Palaeoenvironmental signal from the microfossils record in the Mikuszowice Cherts of the Silesian Nappe, Polish Outer Carpathians. In: Bąk, M. Ka- minski, M. A. & Waśkowska, A. (eds), Integrating Micro- fossil Records from the Oceans and Epicontinental Seas. Grzybowski Foundation Special Publication, 17: 15-25. Bąk, M.. Bąk. K., Górny Z. & Stożek B., in press. Evidence of bacteriogenic iron and manganese oxyhydroxides in Albian- Cenomanian marine sediments of the Carpathian realm (Po- land). Annales Societatis Geologorum Poloniae. Bryndal, T., 2014. A method for identification of small Carpathian catchments more prone to flash flood generation. Based on the example of south-eastern pint of the Polish Carpathians. Carpathian Journal of Earth and Environmental Sciences, 9: 109-122. Buesseler, K. O., 1998. The decoupling of production and particu- late export in the surface ocean. Global Biogeochemical Cy- cles, 12: 297-310. Burtan. J. & Skoczylas-Ciszewska. K.. 1956. Szczegółowa Mapa Geologiczna Polski, 1:50000, arkusz Bochnia. Państwowy Instytut Geologiczny, Warszawa. [In Polish.] Burtanówna, J., 1933. Der geologische Bau der Umgegend von Myślenice westlich vom Raba-Fluss. Annales de la Societe geologique de Pologne, 9: 279-293. Bustillo, M. A. & Riuz-Ortiz, P. A., 1987. Chert occurrences in carbonate turbidites: examples from the Upper Jurassic of the Betic Mountains (southern Spain). Sedimentology, 34: 611— 662. Cady. S. L.. Wenk. H. R. & Downing. K. H., 1996. HRTEM of microcrystalline opal in chert and porcelanite from the Mon- terey Formation, California. American Mineralogists, 81: 1380-1395. Calvert, S. E., 1971. Composition and origin of North Atlantic deep sea cherts. Contribution to Mineralogy and Petrology, 33: 273-288. Calvert. S. E., 1974. Deposition and diagenesis of silica in marine sediments. International Associations of Sedimentologists. Special Publication, 1: 273-299. Clayton, C. J., 1986. The chemical environment of flint formation in Upper Cretaceous chalks. In: Sieveking G. de C. & Hart, M. B. (eds), The Scientific Study of Flint and Chert. Cam- bridge University Press, Cambridge, pp. 43-54. Davis, K. J., Nealson, K. II. & Luttge, A. 2007. Calcite and dolo- mite dissolution rates in the context of microbe-mineral sur- face interactions. Geobiology, 5: 191-205. DeMaster , D. J., 2003. The diagenesis of biogenic silica: chemical transformations occurring in the water column, seabed, and crust. In: Holland, H. & Turekian, K. (eds), Treatise on Geo- chemistry, vol. 7. Elsevier Ltd., Amsterdam, pp. 87-98. DeMaster, D. J., Ragueneau, O. & Nittrouer, C. A., 1996. Preser- vation efficiencies and accumulation rates for biogenic silica and organic C, N, and P in high-latitude sediments: the Ross Sea. Journal of Geophysical Research, 101: 18501-18518. Dietrich, R., Hobbs, C. & Lowry, W., 1963. Dolomitization inter- rupted by silicification. Journal of Sedimentary Petrology, 33: 646-663. Elorza. J. J. & Bustillo, M. A., 1989. Early and late diagenetic 202 M. BĄK ET AL. chert in carbonate turbidites of the Senonian flysch, northeast Bilbao, Spain. In: Hein, J. R. & Obradovic, J. (eds), Siliceous Deposits of the Tethys and Pacific Regions. Springer, New York, pp. 93-105. Ferris, F. G.. Fyfe, W. S. & Beveridge, T. J.. 1987. Bacteria as nu- cleation sites for authigenic minerals in a metal-contaminated lake sediment. Chemical Geology, 63: 225-232. Flörke, O. W., Graetsch, II., Martin, B„ Roller, K. & Wirth, R„ 1991. Nomenclature of microcrystalline and non-crystalline silica minerals, based on structure and microstructure. Neues Jahrbuch fur Mineralogie-Abhandlungen, 163: 19—42. Fritz, G. K., 1958. Schwammstozen, Tuberolithe und Schutt- breccien im Weissen Jura der Schwäbischen Alb. Arbeiten aus dem Geologisch-Palciontologisclien Institut Technische Hochschule Stuttgart, N.F., 13: 1-118. Froget, C., 1976. Observation sur 1’alteration de la silice et des sili- cates au cours de la lithification carbonatee (region Siculo- Tunisienne). Geologie Mediterraneenne, 3: 219-226. Gailinari. M., Ragueneau, O., Corrin, L., DeMaster, D. J. & Tre- guer, P., 2002. The importance of water column processes on the dissolution properties of biogenic silica in deep-sea sedi- ments I. Solubility. Geochimica et Cosmochimica Acta, 66: 2701-2717. Geroch, S., Jednorowska, A., Książkiewicz, M. & Liszkowa, J. 1967. Stratigraphy based upon micro fauna in the Western Polish Carpathians. Instytut Geologiczny, Biuletyn, 211: 185- 282. Gersonde, R. & Wefer, G., 1987. Sedimentation of biogenic sili- ceous particles in Antarctic waters from the Atlantic sector. Marine Micropaleontology, 11: 311—332. Gimenez-Montsant, J., Calvet, F. & Tucker, M. E., 1999. Silica diagenesis in Eocene shallow-water platform carbonates, southern Pyrenees. Sedimentology, 46: 969-984. Hammes, U., 1995. Initiation and development of small-scale sponge mud-mounds, Late Jurassic, Southern Franconian Alb, Germany. In: Monty, C. L. V., Bosence, D. W. J., Bridges, P. H. & Pratt, B. R. (eds), CarbonateMud-Mounds: Their Origin and Evolution. International Associations of Sedimentologists Special Publications, 23: 335-357. Hartman, W. D., 1979. A new sclerosponge from the Bahamas and its relationship to Mesozoic stromatoporoids. In: Levi, C. & Boury-Esnault, N. (eds), Biologie des Spongiaires - Sponge Biology. Colloques Internationaux du Centre National de la Recherche Scientijique, 291: 467—474. Hartman, W .D.. Wendt. J .W. & Wiedenmayer, F., 1980. Living and Fossil Sponges: Notes for a Short Course. University of Miami, Miami, 274 pp. Heaney, P. J., 1993. A proposed mechanism for the growth of chalcedony. Contributions to Mineralogy' and Petrology, 115, 66-74. Hesse, R.. 1989. Silica diagenesis: origin of inorganic and replace- ment cherts. Earth-Science, Reviews, 26: 253-284. Hurd, D. C., 1973. Interactions of biogenic opal, sediment and sea- water in the central equatorial Pacific. Geochimica et Cosmo- chimica Acta, 37: 2257-2282. Hurd, D. C., Pankratz, H. S., Asper, V., Fugate. J. & Morrow, H., 1981. Changes in the physical and chemical properties of biogenic silica from the central equatorial Pacific: Part 111. Specific pore volume, mean pore size, and skeletal ultrastruc- ture of acid-cleaned samples. American Journal of Science, 281: 833-895. Kaplan, I. R.. Emery. K. O. & Rittenberg, S. C., 1963. The distri- bution and isotopic abundance of sulphur in recent marine sediments off southern California. Geochimica et Cosmochi- mica Acta, 27: 297-331. Kauffman, E. G., Herm, D., Johnson, C. C., Harries, P. & Efling, R. H., 2000. The ecology of Cenomanian lithistid sponge frameworks, Regensburg area, Germany. Lethaia, 33: 214— 235. Keene, J. B.. 1975. Cherts and porcellanites from the north Pacific, DSDP LEG 32. In: Larson. R. L. & Moberly. R. el al. (eds). Initial Reports of the Deep Sea Drilling Project, 32: 429-507. Knauth, L. P.. 1994. Petrogenesis of chert. Reviews in Mineralogy’, 29: 233-258. Knauth, P. L. & Epstein, S., 1976. Hydrogen and oxygen isotope ratios in nodular and bedded cherts. Geochemica et Cosmo- cliemica Acta. 40: 1095-1108. Kohn, M. J.. Riciputi, L. R.. Stakes, D. & Orange. D. L.. 1998. Sulfur isotope variability in biogenic pyrite: Reflections of heterogeneous bacterial colonization? American Mineralo- gist. 83: 1454-1468. Koszarski, L, & Nowak, W., 1960. Comments to age of the Lgota Beds. Kwartalnik Geologiczny, 4: 468—483. [In Polish, with English summary.] Koszarski. L. & Slączka, A., 1973. Outer (flysch) Carpathians. Lower Cretaceous. In: Pożaryski, W. (ed.). Geology of Po- land. Instynit Geologiczny, Warszawa, pp. 492-495. Książkiewicz, M., 1951. Objaśnienia do arkusza Wadowice. Szczegółowa Mapa Geologiczna Polski, 1:50 000. Państwowy Instytut Geologiczny, Warszawa, 283 pp. [In Polish.] Książkiewicz, M., 1956. Geology of the Northern Carpathians. Geologische Rundschau, 45: 396-411. Książkiewicz, M. (ed.), 1962. Geological Atlas of Poland: Strati- graphie and Facial Problems, vol. 13. Cretaceous and Older Paleogene in the Polish Outer Carpathians. Instytut Geo- logiczny, Wydawnictwa Geologiczne, Warszawa, 20 maps, 20 pp. explanatory notes. Land. L. S., 1976. Early dissolution of sponge spicules from reef sediments. North Jamaica. Journal of Sedimentary Petrology’, 46: 967-969. Liittge, A. & Conrad, P. G., 2004. Direct observation of microbial inhibition of calcite dissolution. Applied and Environmental Microbiology’. 70: 1627-1632. Madsen, H. B. & Stemmerik, L., 2010. Diagenesis of flint and porcellanite in the Maastrichtian chalk at Stevns Klint, Den- mark. Journal of Sedimentaiy Research, 80: 578-588. Maldonado, M., Carmona, M. C., Velasquez, Z., Puig, M. A., Cruzado, A., López, A. & Young, C. M., 2005. Siliceous sponges as a Silicon sink: An overlooked aspect of bentho- pelagic coupling in the marine Silicon cycle. Limnology’ and Oceanography, 50: 799-809. Miśik. M., 1966. Microfacies of the Mesozoic and Tertiary Lime- stones of the West Carpathians. Vydavatel’stvo Slovenskej Akademie Vied, Bratislava, 269 pp. Miśik. M.. 1993. Carbonate rhombohedra in nodular cherts: Meso- zoic of the West Carpathians. Journal of Sedimentaiy Re- search, 63:275-281. Mizutani, S., 1970. Silica minerals in the early stage of diagenesis. Sedimentology, 15: 419-436. Morley, J. J., Shemesh, A. & Abelmann, A., 2013. Laboratory analysis of dissolution effects on Southern Ocean polycystine Radiolaria. Marine Micropaleontology, 110: 83-86. Nelson, D. M., Treguer, P., Brzeziński, M. A., Leynaert, A. & Queguiner, B., 1995. Production and dissolution of biogenic silica in the ocean: revised global estimates, comparison with regional data and relationship with biogenic sedimentation. Global Biogeochemical Cycles, 9: 359-372. Neuweiler, F., Gautret, P., Thiel, V., Lange, R., Michaelis, W. & Reitner, J., 1999. Petrology of Lower Cretaceous carbonate mud mounds (Albian, N Spain): insights into organomineralic CALCITIZATION AND SILICIFICATION OF CENOMANIAN SPICULE-BEARING TURBIDITES 203 deposits of the geological record. Sedimentology, 46: 837- 859. Okoński, S., Górny Z., Bąk M. & Bąk, K., 2014. Lithistid spicules in the sediments of the Turonian Variegated Shale in the Silesian Nappe, Polish Outer Carpathians. Geology. Geophys- ics & Environment, 40: 33-48. Olóriz, F., Reolid, M. & Rodriguez-Tovar. F. J., 2003. A Late Ju- rassic carbonate ramp colonized by sponges and benthic mi- crobial communities (External Prebetic, southern Spain). Palaios, 18: 528-545. Oszczypko, N., 2004. The structural position and tectono-sedi- mentary evolution of the Polish Outer Carpathians. Przegląd Geologiczny, 52: 780-791. Piper, D. J. W. & Deptuck, M., 1997. Fine-grained turbidites of the Amazon Fan: facies characterization and interpretation. In: Flood, R. D. et al. (eds), Proceedings of the Ocean Drilling Program. Scientific Restdts, 155: 79-108. Pisera, A., 1997. Upper Jurassic siliceous sponges from the Swa- bian Alb: taxonomy and paleoecology. Palaeontologia Polo- nica. 57: 1-216. Pisera. A. & Levi. C. 2002. ‘Lithistid’ Demospongiae. In: Hooper, J. N. A. & Van Soest, R. W. M. (eds), Systema Porifera: A Guide to Classification of Sponges. Kluwer Academic/Ple- num Publisher, New York, pp. 299-301. Pratt, B., R., Bourque, P. A. & Gignac, H., 1986. Sponge-constructed stromatactis mud mounds, Silurian of Gaspe, Quebec; discus- sion and reply. Journal of Sedimentary Research, 56: 459-463. Reitner, J., 1993. Modern cryptic microbialite-metazoan facies from Lizard Island (Great Barrier Reef, Australia) - forma- tion and concepts. Facies, 29: 3-40. Reimer, J. & Keupp, H., 1991. The fossil record of the Haplo- sclerid excavating sponge Aka de Laubenfels. In: Reitner. J. & and Keupp, H. (eds). Fossil and Recent Sponges, Springer Verlag. Berlin, pp. 102-120. Reitner, J., Neuweiler, F. & Gautret, P., 1995. Modern and fossil automicrites: implications for mud-mound genesis. Facies, 32: 4-17. Riech, V. & von Rad, U., 1979. Silica diagenesis in the Atlantic Ocean: diagenetic potential and transformations. In: Tahvani, M.. Hay, W. & Ryan. W. B. F. (eds), Deep Drilling in the At- lantic Ocean: Continental Margins and Paleoenvironment. American Geophysical Union, Maurice Ewing Series, 3, pp. 315-340. Sujkowski, Z., 1933. Sur certains spongiolithes de la Tatra et des Karpates. Państwowy Instytut Geologiczny, Sprawozdania, 7: 712-733. [In Polish, with French summary.] Treguer, P., Nelson, D. M., van Bennekom, A. J., DeMaster, D. J., Leynaert, A. & Queguiner, B., 1995. The balance of silica in the world ocean: a re-estimate. Science, 268: 375-379. Treguer. P. J. & De La Rocha, C. L., 2013. The World Ocean silica cycle. Annual Review of Marine Science, 5: 477-501. Unrug, R., 1959. On the sedimentation of the Lgota beds. Rocznik Polskiego Towarzystwa Geologicznego, 29: 197-225. [In Pol- ish, with English summary.] Unrug, R.. 1977. Ancient deep-sea traction currents deposits in the Lgota beds (Albian) of the Carpathian Flysch. Rocznik Pol- skiego Towarzystwa Geologicznego, 47: 355-370. Van Cappellen, P. & Qui, L., 1997a. Biogenic silica dissolution in sediments of the Southern Ocean. II. Solubility. Deep-Sea Re- search II. 44: 1109-1128. Van Cappellen, P. & Qui, L., 1997b. Biogenic silica dissolution in sediments of the Southern Ocean. II. Kinetics. Deep-Sea Re- search U, 44: 1129-1140. Von Rad, U. & Rösch, H., 1972. Mineralogy and origin of clay minerals, silica and authigenic silicates in Leg 14 sediments. Reports of Deep Sea Drilling Project, 14: 727—751. Von Rad, U. & Rösch, H., 1974. Petrography and diagenesis of deep-sea cherts from the central Atlantic. In: Hsu, K. J. & Jenkyns H. C. (eds), Pelagic Sediments: On Land and Under the Sea. Blackwell Scientific Publications, Oxford, pp. 327- 347. Wamke, K.. 1995. Calcification processes of siliceous sponges in Visean limestones (counties Sligo and Leitrim, Northwestern Ireland. Facies, 33: 215-228. Wheat, C. G. & McManus, J., 2005. The potential role of ridge- flank hydrothermal systems on oceanic germanium and sili- con balances. Geochimica at Cosmochimica Acta, 69: 2021— 2029. Wiedenmayer, F., 1980. Siliceous Sponges-development through time. In: Hartman, W. D., Wendt, J. W. & Wiedenmayer, F. (eds). Living and fossil sponges. Notes for a short course. Sedimenta, 8: 55-85. Williams, L. A. & Crerar, D. A., 1985. Silica diagenesis: II. Gen- eral mechanisms. Journal of Sedimentaiy Petrology, 55: 312— 321. Williams, L. A., Parks. G. A. & Crerar. D. A., 1985. Silica dia-ge nesis: I. Solubility controls. Journal of Sedimentaiy Petrol- ogy, 55: 301-311. Wise, S. W. & de Weaver, F. M., 1974. Chertification of oceanic sediments. In: Hsu, K. J. & Jenkyns H. C. (eds), Pelagic Sedi- ments: On Land and Under the Sea. Blackwell Scientific Pub- lications. Oxford, pp. 301-326. Zijlstra, H. J. P., 1987. Early diagenetic silica precipitation, in re- lation to redox boundaries and bacterial metabolism in Late Cretaceous chalk of the Maastrichtian type locality: Geologie en Mijnhouw, 66: 343-355.