Lithofacies Palaeogeography and Biostratigraphy of the Lowermost Horizons of the Middle Triassic Hallstatt Limestones (Argolis Peninsula, Greece)

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Journal of Palaeogeography 2013, 2(3): 252-274 DOI: 10.3724/SP.J.1261.2013.00030

Lithofacies palaeogeography andPalaeogeography sedimentology

Lithofacies palaeogeography and biostratigraphy of the lowermost horizons of the Middle Triassic Hallstatt Limestones (Argolis Peninsula, Greece)

Fotini A. Pomoni1, *, Vassilis Tselepidis2 1. Department of Geology and Geoenvironment, University of Athens, Panepistimiopolis 157 84, Athens, Greece 2. Institute of Geology and Mineral Exploration, Olympic Village, Acharnae, P.C. 13677 Athens, Greece*

Abstract Condensed ammonoid beds of the Hallstatt facies (Anisian-Ladinian) are widespread around the Ancient Theatre of Epidaurus, in the locality Theokafta of the Argolis Pen- insula (eastern Peloponnesus). The Hallstatt Formation in Argolis appears, generally, in the form of lensoid bodies of variable sizes, inclination and direction and is always found overlying a formation consisting of keratophyric tuffs. In fact, the contact of the keratophyric tuffs with the overlying limestones, specifically evidenced by anin situ brecciated zone, is stratigraphic and constitutes the base of the Hallstatt Limestones. The contact of the Hallstatt Limestones with the overlying radiolarites is stratigraphic as well. Lithofacies and biostratigraphic research has focused on the lowermost horizons of the Hallstatt Limestones of Anisian age (average thickness about 1.30 m), where a dense sampling has been performed, followed by detailed facies analysis. The lowermost horizons of the Hallstatt Limestones of Theokafta represent typical hiatus beds/concretions sensu Wetzel and Allia (2000), characterized by discontinuous sedimentation and erosion. They consist of red ammonoid-bearing hemipelagic limestones with calcium carbonate nodules floating in an enriched Fe-oxides matrix with dispersed lensoid/prismatic calcium carbonate crystals. This part of the section is characterized by condensed sedimentation, due to significant lowering of the rate of sedimentation and includes omission surfaces, firmgrounds and hardgrounds along certain horizons. Nine lithostratigraphic units have been distinguished in the lowermost horizons of the Hallstatt Limestones, including radiolarian packstones, volcaniclastic facies, packstones/floatstones with ammonoids and lag deposits. Tselepidis (2007) defined nine distinct ammonoid biozones from the Anisian to Ladinian, documenting deposition of the Hallstatt facies during a low depositional rate over nearly 5 million years (using the timescale of Gradstein et al., 2004). The biozones: Japonites/Parac- rochordiceras, Hollandites, Procladiscites/Leiophyllites, zoldianus, trinidosus, Reitziites/Par- akellnerites and the Nevadites (Anisian) and the biozone curionii (Lower Ladinian). Although sedimentation was very condensed, it didn’t reach the level of mixing fauna. Synsedimentary and early burrowing processes differentiated the primary texture characteristics of the deposited sediments. Multiphase diagenesis occurred not very deep below the sediment surface and includes boring and/or encrustation, burial and cementation. The deposition of the studied Hallstatt Limestones is considered to be due to anaerobic oxidation of organic matter, which provided excess alkalinity, inducing carbonate precipitation. Sedi-

* Corresponding author. Email: [email protected]. Received: 2013-03-30 Accepted: 2013-05-06 Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 253

mentation took place on differentially-subsided deep swells. After drowning, the swells were covered by pelagic carbonate deposits. Further slight rotation of blocks, along listric faults, may have led to additional differential subsidence of the blocks. Shelf bathymetry and third- order sea-level changes played a significant role in the formation of the Hallstatt beds. In terms of sequence stratigraphy, the studied hiatus concretions and beds are considered genetically linked to rising or high sea-level, formed at the initiation of transgressions, as well as during the time of maximum rate of transgression, in areas where the sediment input was strongly reduced (‘‘condensed section’’) . Taking into consideration the present location of the Hallstatt Formation, in the context of the Hellenides, an area suitable for the deposition of the Hallstatt Limestones, should be located between the sub-Pelagonian (western part of the Pelagonian zone) and Pindos geotectonic zones, which during the Triassic corresponded to a platform slope and a deep ocean, respectively. The widespread Middle Triassic Han Bulog Limestones (ammonoid-bearing pelagic limestones) from Triassic successions of the Eastern Alps (Dinarides, Hellenides) may have formed partly in similar slope environments.

Key words Middle Triassic, Hallstatt Formation, facies analysis, ammonoid biozonation, condensed pelagic sedimentation, palaeoenvironment, eastern Peloponnesus

1 Introduction not manifested as biostratigraphic gaps (e.g., Wilson, 1985). The hiatus beds, and specifically the hiatus concre- Ammonoid-bearing pelagic carbonate formations on tions are characterized by a multiphase diagenetic history top of platforms, following a significant stratigraphic that occurs not very deep below the sediment surface and break, are very common in Middle Triassic sequences of includes exhumation, boring and/or encrustation, burial the southern and eastern Alps (Assereto, 1971; Schlager and cementation (Savrda and Bottjer, 1988). and Schollnberger, 1974; Epting et al., 1976; Brandner, In terms of sequence stratigraphy, hiatus concretions 1984; Angiolini et al., 1992; Brack et al., 2007; Monnet et and beds are genetically linked to rising or high sea-level al., 2008). These formations are condensed, red, micritic, (e.g., Van Wagoner et al., 1988). They are thought to form sometimes nodular, rich in cephalopods, conodonts and during the initiation of transgressions (e.g., Voigt, 1968; molluscs, and are known as “Hallstatt-type limestones”. Fursich et al., 1991), as well as during the time of maxi- The Hallstatt horizons are of particular stratigraphic and mum rate of transgression in areas where sediment input geologic interest, as far as the relationship of the Hallstatt is strongly reduced (‘‘condensed section”). Similar depos- facies with surrounding formations and the determination its, considered to have formed during sea-level highstand, of the stratigraphic level that coincides with the beginning were also reported from drowned carbonate platforms by of Hallstatt facies deposition. Kendall and Schlager (1981). Hallstatt facies correspond to hiatus beds/concretions However, this simple sequence-stratigraphic interpreta- characterized by discontinuous sedimentation and erosion. tion of hiatus beds and condensed sections, is not always Hiatus concretions are hypothesized to form during early valid, because hiatus beds seem to form more frequently diagenesis by reworking of carbonate sediments, after a during times of tectonic activity than times of intense sea- break in sedimentation or seafloor erosion (Voigt, 1968; level changes (Wetzel and Allia, 2000). Other processes, Raiswell, 1987, 1988; Spears, 1989; Wetzel and Allia, such as a differential subsidence, may produce sediment 2000). A prerequisite for the growth of concretions is that starvation or seafloor erosion, providing the necessary they should remain for a considerable time within the sul- conditions for formation of hiatus concretions (e.g., Hes- fate reduction zone (7000 years; Coleman and Raiswell, selbo and Palmer, 1992). 1993). The identification of such horizons has a great The Hallstatt facies occur in the following areas of stratigraphic and sedimentologic value, as they indicate Greece: in Chios Island (Skythian-Lower Anisian; Bend- markers of significant interruption of sedimentation that er, 1970; Jacobshagen and Tietze, 1974; Gaetani et al., otherwise would not be noticed (Fursich and Baird, 1975; 1992; Mertmann and Jacobshagen, 2003), in Hydra Is- Baird, 1976). Such discontinuity surfaces are commonly land (Anisian-Carnian; Römermann, 1968; Angiolini et 254 JOURNAL OF PALAEOGEOGRAPHY July 2013 al., 1992), in Argolis Peninsula (Upper Anisian-Norian; analysis, extended the interval of Hallstatt facies depo- Renz, 1906a, 1906b, 1910a, 1910b, 1955; Sakellariou, sition from the lower Anisian to the lower Norian and 1938; Bornovas, 1962; Dercourt, 1964), in Crete (Lower considered that a submarine slide, in the frame of a syn- Carnian; Creutzburg et al., 1966), in Orthrys (Carnian- sedimentary tectonism, relocated the Hallstatt Formation Ladinian; Mitzopoulos and Renz, 1938), in Attica (Bend- in-between the radiolarites. On the other hand, Dürkoop et er, 1962), in Western Peloponnesus (Tsoflias, 1969) and in al. (1986), considered that the stratigraphic contacts of the Naxos (Dürr, 1975). Hallstatt facies with the underlying keratophyric tuffs, as For estimating the significance of this unique event, in well as with the overlying radiolarites, was stratigraphic, the context of the Tethyan realm, precise dating and cor- reaching up to the Upper Norian (Sevatian). relation is a necessary prerequisite. In the present paper, Red, micritic, ammonoid-bearing limestones of the new constraints on the lithofacies palaeogeography and Hallstatt facies are widespread around the Ancient Theatre biostratigraphy of the Middle Triassic ammonoid-bearing of Epidaurus, in the Argolis Peninsula (Figs. 1, 2, 3). De- pelagic formations (Hallstatt Formation) of the Argolis tailed sampling of the Hallstatt facies was conducted in Peninsula (NE Peloponnesus), are presented. one of the most spectacular sequences, which is situated in the broader area of Epidaurus, 600 m NW of the Ancient 2 Stratigraphic location and geologi- Theatre of Epidaurus, in the locality of Theokafta. cal setting of the Hallstatt facies in The Theokafta outcrop is composed of the following Argolis lithologic formations, from base to top: the keratophyric tuffs, the limestones of the Hallstatt facies, the radiolarites Hallstatt Limestones exposed in the Argolis Peninsula and the limestones with cherts (Figs. 4, 5). have been investigated since the start of the twentieth The formation of the keratophyric tuffs extends through- century. Renz (1906a, 1906b), first confined Hallstatt fa- out the broader area of Argolis, and is in contact with dif- cies to the Triassic at the Theokafta locality, following the ferent formations each time (e.g., the Hallstatt, the radi- discovery of the ammonite Joannites diffisus HAUER by olarites and the limestones with cherts), resulting in dif- Douvillé (1900), attributing to an Upper Anisian-Middle ferent age estimations. For instance, as substrata of the Carnian age. Hallstatt Limestones, the keratophyric tuffs should be con- In the Argolis Peninsula, the Hallstatt Limestones is sidered older than Lower Anisian, whereas as substrata of considered to overlie stratigraphically, volcaniclastic for- the formation of limestones with cherts, should be older mations consisted of keratophyric tuffs (Renz, 1910a, than Lower Ladinian. 1910b, 1939, 1955; Bender, 1962; Τselepidis et al., 1989). The Hallstatt Formation in Argolis appears, gener- Bender and Kockel (1963) attributed an Early Triassic age ally, in the form of lensoid bodies of variable sizes, in- to the keratophyric tuffs, suggesting that the Hallstatt faci- clination and direction and is found always overlying the es began in the upper Anisian. Jacobshagen (1967), Ban- keratophyric tuffs, although due to inversion tectonics the nert and Bender (1968) and Pelosio (1973) also refer to keratophyric tuffs appear in places, to overlie the Hall- Hallstatt facies as condensed horizons of Upper Anisian- statt Limestones (Bender et al., 1960; Jacobshagen, 1967; Carnian age that are normally deposited on the tuffic sub- Bannert and Bender, 1968; Pelosio, 1973; Bachmann strata. and Jacobshagen, 1974; Krystyn and Mariolakos, 1975; The Hallstatt facies is overlain by a radiolaritic forma- Tselepidis et al., 1989; Geol. Sheet Ligourio 1:25000 tion, although in places there appears to be a lateral tran- IGME). In fact, the contact of the keratophyric tuffs with sition between these two formations. However, according the overlying limestones, as evidenced by an in situ brec- to other authors, the whole lithostratigraphic series is re- ciated zone, is stratigraphic and constitutes the base of versed (Bender, 1962; Bender and Kockel, 1963), whereas the Hallstatt Limestones. Due to tectonism, the Hallstatt Baumgartner (1985) suggested that the contact of the radi- Formation has, in places, undergone fragmentation and olaritic sedimentary rocks with the Hallstatt facies, as well significant translocation. The outcrop studied, at the east- as with the keratophyric tuffs is tectonic, and suggested ern slopes of the Theokafta Hill (Fig. 2), which appears in that the Hallstatt Formation, in association with the kera- the form of a lensoid body with thickness reaching 82 m, tophyric tuffs, acted as an olistolith that was translocated is the most significant outcrop of the Hallstatt facies in the in-between the radiolarites. Argolis Peninsula, not only referring to its dimensions, Krystyn and Mariolakos (1975), based on conodont but also because of its richness in macro- and microfauna, Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 255 which covers the entire stratigraphic evolution of the Tri- Concerning the relationship of the Hallstatt facies with assic. Additionally, in Theokafta, the relationship of the the stratigraphically overlying radiolarites, it has not yet Hallstatt facies with the underlying (keratophyric tuffs) been clarified as to whether the radiolarites were deposited and the overlying formations (radiolarites) is very clear before or after the deposition of the Hallstatt Limestones (Fig. 4). (Fig. 6). As it was previously noted, the radiolarites are,

Fig. 1 Sketch map of the study area showing the relationship of the Hallstatt Formation with the surrounding formations. 256 JOURNAL OF PALAEOGEOGRAPHY July 2013

Fig. 2. Limestones of the Hallstatt facies around the Ancient Theater of Epidaurus in the Argolis, Peninsula.

Fig. 3 Red, micritic, ammonoid-bearing limestones of the Hallstatt facies from the locality Theokafta of Epidaurus (Argolis Penin- sula). Age: Upper Anisian (Illyrian, biozone Nevadites). Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 257

Fig. 4 The Theokafta outcrop is composed of the following lithologic formations, from base to top: keratophyric tuffs, limestones of the Hallstatt facies, radiolarites and limestones with cherts. The contact of the Hallstatt Limestones with the underlying keratophyric tuffs and the overlying radiolarites is stratigraphic.

Fig. 5 An overview of the studied geological section.

in places, in direct contact with the keratophyric tuffs, Hallstatt Limestones started to be deposited in the Lower as well (Fig. 7). In the studied sequence, radiolarites are Anisian, whereas deposition of the limestones with cherts tectonically overlain by the limestones with cherts (Fig. should have started later, possibly in the Lower Ladinian. 6) and have been dated as Lower Ladinian-Middle Lias- In the area of Theokafta, both the “packet” radiolarites/ sic, on the basis of conodonts (Krystyn and Mariolakos, limestones with cherts, as well as, the “packet” kerato- 1975). The limestones with cherts are considered to have phyric tuffs/radiolarites, are inversely stratified (Figs. 6, been deposited in a neighboring area, to that of the Hall- 7). Inverse stratification is the result of post Upper Jurassic statt Limestones, directly upon the keratophyric tuffs. The compressional tectonism, resulting in folding and over- 258 JOURNAL OF PALAEOGEOGRAPHY July 2013

Fig. 6 The stratigraphic contact of the Hallstatt facies with the overlying radiolarites and the tectonic contact of the radiolarites with the “limestones with cherts”.

Fig. 7 The tectonic contact of the keratophyric tuffs (Skythian) with the Middle-Upper Jurassic radiolarites.

thrusting (Fig. 8). horizontal translocation of the resulted blocks is observed. Starting from the lower part of the section, along the 3 Lithostratigraphy contact with the keratophyric tuffs, towards the top, a formation of brownish-reddish limestones is observed, aver- The studied section is situated in a very short distance aging 8 m in thickness (lithologic units A0 to A8). It is north of the “Asklipieion” of Ancient Epidaurus, at the characterized by layers enriched in ammonoids and nau- eastern slopes of Theokafta. Due to a system of faults, tiloids, orientated parallel to the stratification, as well as normal to the stratification, fragmentation and significant by concentrations of Fe- and Mn-oxides, along specific Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 259

Fig. 8 Radiolarites overthrusted on the keratophyric tuffs and limestones with cherts overthrusted on radiolarites, due to inverse stratification.

surfaces (Figs. 9, 10). Hallstatt Limestones and the underlying keratophyric tuffs Lithofacies and biostratigraphic research has been fo- e.g., this layer marks the beginning of carbonate sedimen- cused on the lowermost horizons of the Hallstatt Lime- tation. In fact, the uppermost portion of layer A1 is a thin stones of Anisian age (average thickness about 1.30 m), layer, averaging 3-4 cm in thickness, consisting of frag- where a dense sampling has been performed, followed by ments of macrofauna and reworking, fine-grained, volcanic detailed facies analysis (lithologic units A0 to A3). That keratophyric material. Layer A2 represents the initial layer part consists of two characteristic lithological units (Fig. of the Hallstatt facies (with the subdivisions A2/1a, A2/1b, 11): A2/2, A2/3 and A2/4). Layer A2/1a, averaging 8-10 cm in The first lithological unit, comprises the layers A1 and thickness, is characterized by a brecciated appearance, due A2. Layer A1, a thin layer averaging 4-5 cm in thickness, to the presence of abundant, mainly angular lithoclasts and is friable mylonitic volcanic material, located between the crystal clasts of variable size. The lithoclasts are volcanic 260 JOURNAL OF PALAEOGEOGRAPHY July 2013

Fig. 9 The studied section in the locality Theokafta. On the right edge of the photo, at the base of the section, the contact with the keratophyric tuffs is shown. The lowest layers of the section are rich in ammonoids and nautiloids.

Fig. 10 The stratigraphic contact of the grayish keratophyric tuffs with the reddish Hallstatt Limestones.

in origin and are derived from the underlying keratophyric facies (Fig. 12), with the unique occurrence of macro- tuffs. In most cases they have suffered calcitization. Layer fauna. These layers are rich in Fe- and Mn-oxides that A2/1b, averaging 5 cm in thickness, is a brownish-reddish mark hardground horizons and reach several centimeters limestone that developed on an irregular, eroded surface. in thickness. Layer 2/2 consists of a lower brecciated facies averaging The studied lowest part of the section is characterized ~7 cm in thickness, whereas the upper part consists of a by condensed sedimentation. Synsedimentary and early biomicrite rich in ammonoids. burrowing differentiate the primary texture characteris- The second lithological unit, 1 m thick, comprises tics of the deposited sediments. Omission surfaces and layer A3 (A3/1, A3/2) and corresponds to the characteris- hardgrounds sensu Bathurst (1975) and Bromley (1978), tic reddish-brownish, nodular limestones of the Hallstatt are very common along certain horizons. The hardgrounds Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 261

Fig. 11 The studied lowest members of the Hallstatt Limestones, averaging in thickness ~1.30 m, that comprise the first (A1, A2) and the second (A3, A4).

are characterized by intense relief and concentrations of Fe-Mn-oxides. Along such surfaces, ammonoids are ori- 4 Facies analysis of the lowermost ho- entated parallel to the stratification. Ammonoids have suf- rizons of the Hallstatt Limestones fered dissolution, mainly affecting the upper part of the shell and seldom both the lower and the upper part. Ses- The lowermost horizons of the Hallstatt Limestones of sile foraminifera of the genus Tolypammina commonly are Theokafta represent typical hiatus beds/concretions sensu observed on hardgrounds and/or lithoclasts. Hardground Wetzel and Allia (2000), characterized by discontinuous surfaces are commonly overlain by thin layers composed sedimentation and erosion (Fig. 11). They consist of red of clastic material, averaging 1 mm-4 cm in thickness. ammonoid-bearing hemipelagic limestones with calcium Along discontinuities, stromatactis-like cavities have been carbonate nodules floating in an Fe-oxides enriched matrix developed, revealing rapid synsedimentary lithification. It with dispersed lensoid/prismatic calcium carbonate crys- should also be noted that no mixing of the fauna has been tals. detected. Starting from the contact with the underlying kera- 262 JOURNAL OF PALAEOGEOGRAPHY July 2013 tophyric tuffs and towards the top, the following nine to subrounded lithoclasts of variable size, gradually de- lithostratigraphic horizons appear (A/A, A1, A2/1a, A2/1b, creasing upward. Plagioclase crystals are medium basic A2/2, A2/3, A2/4, A3/1, A3/2), and include radiolarian (andesine) and quartz crystals show magmatic erosion. packstones, volcaniclastic facies, packstones/floatstones All components have been derived from the underlying with ammonoids and lag deposits: volcanic rock (keratophyric tuff) and are cemented by and Strat. Unit A/A: The lowermost carbonate horizon intensively impregnated by Fe- and Mn-oxides as well as which overlies the basal volcanic rock (keratophyric tuffs). matrix that gradually assimilates them. Facies: Radiolarian packstones (Fig. 12A). Upper part: Start of Hallstatt sedimentation. Red col- Microcomponents: Radiolarians (micritized and calci- oured limestones. fied), benthic foraminifera, ostracods and molluscs. Facies: Packstones/floatstones with ammonoids (Fig. Texture: Nodular. Nodules are surrounded by a black- 13D). ened rim enriched in Fe-oxides. Dissolution surfaces, Microcomponents: Radiolarians, benthic foraminifera along the contacts of coalescing nodules, are marked by (Arenovidalina chialingchiangensis HO and Nodosarii- Fe-oxide microstylolites. (Fig. 12B). dae), molluscs, brachiopods, ostracods, echinoderms and Interpretation: Limestones with autochthonous hemi- gastropods. pelagic faunal elements (radiolarians) and allochthonous Texture: Nodular in places. Lime nodules are sur- reefal detritus (foraminifera, ostracods). rounded by a matrix enriched in Fe- and Mn-oxides. Bio- Lithologic Unit A: It comprises the layers A1 and A2 clasts show evidence of boring and are coated by Fe-oxide and averages 3-4 cm in thickness. rims. Biomolds are filled with geopetal fill (pelmicrite/ A1 sparitic cement). Strat. Unit: Volcaniclastic horizon (averaging 4-5 cm Interpretation: Strongly condensed sediments due to in thickness), consisting of fragments of macrofauna and low rate of sedimentation. Limestones with autochtho- reworked, fine-grained, volcanic keratophyric material. It nous hemipelagic bioclasts (ammonoids, radiolarians, is characterized as “mylonite” due to its friable character, filaments) and allochthonous reefal detritus (benthic fo- which lies between the keratophyric tuffs and the overly- raminifera, ostracods, gastropods). Oxygen-rich bottom ing Hallstatt Limestones and marks the start of carbonate water. sedimentation. It consists of relic crystals of feldspars (pla- Age: Ammonoids of the species Megaphyllites chiosen- gioclase), quartz and mafic minerals, as well as lithoclasts sis FASTINI-SESTINI are recorded for the first time in the (lag deposit). All components are derived from the under- study area. Fastini-Sestini (1981) recorded the above spe- lying keratophyric tuffs and are gradually assimilated by cies in Chios and defined it as Aegeian in age (lower Ani- a ferruginous micritic and/or crystalline matrix consisting sian). Assereto (1974) referred to beds with Megaphyllites of dispersed lensoid/prismatic calcite crystals (Figs. 12C, evolutus WELTER of lower Aegeian age, whereas Bender 13A). Calcium carbonate nodules occur in places, and are (1970) considers them as Lower Anisian. In the study area assimilated as well by the same matrix (Figs. 12D, 13A, these beds are considered to be lower Anisian, and possi- 13B). bly upper Skythian (Tselepidis et al., 1989). A2 A2/1b Layer A2 represents the basal layers of the Hallstatt fa- Strat. Unit: Hallstatt horizon averaging 5 cm in thick- cies (subdivisions from base to top: A2/1a, A2/1b, A2/2, ness. It consists of a brownish-reddish limestone that has A2/3 and A2/4). developed on an irregular, eroded surface. A2/1a Facies: Red packstones/floatstones with ammonoids Strat. Unit: Contact between the volcaniclastic facies (Fig. 14A). and the overlying Hallstatt facies, averaging 8-10 cm in Microcomponents: Gastropods, molluscs, echino- thickness. The contact is marked by circumgranular crack- derms, ostracods, radiolarians and benthic foraminifera. ing and Fe-oxides rims (Fig. 13C). Texture: Bioclasts are dissolved, and biomolds are Lower part: Volcaniclastic facies characterized by red- filled geopetally. Abundant relic crystals of quartz, plagio- dish colour and brecciated appearance due to the presence clase and mafic minerals (kerostilb) and a few lithoclasts; of abundant, mainly angular clasts of variable size of frag- all components are derived from the underlying kerato- ments of crystals (Fig. 13D), including plagioclase, quartz, phyric tuff. Discontinuities are marked by Fe-oxides and mafic minerals (kerostilb and rarely biotite) and angular have a tendency to form immature hardgrounds. Nodules Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 263 are rare in this facies. Facies: Packstones/floatstones with ammonoids (Figs. Interpretation: Strongly condensed sediments due to 14C, 14D) low rate of sedimentation. Limestones with autochtho- Microcomponents: Abundant benthic foraminifera nous hemipelagic bioclasts (ammonoids, radiolarians, (Dustomminidae and Nodosariidae), echinoderms, gastro- filaments) and allochthonous reefal detritus (benthic fo- pods, molluscs and ostracods. raminifera, ostracods, gastropods). Oxygen-rich bottom Texture: Bioclasts have been bored, forming a rim rich water. in Fe-oxides, and ammonoid biomolds have been filled by Age: Fauna includes the species Leiophyllites confucii cloudy fibrous cement overlain by blocky cement and/or (DIENER) and Leiophyllites suessi (MOJSISOVICS), in by chalcedony (Fig. 15A). association with Procladiscites cf. brancoi MOJSISO- Interpretation: Limestones with autochthonous hemi- VICS, Procladiscites sp., Beyrichites, Ptychites and Dis- pelagic faunal elements (ammonoids) and allochthonous coptychites. The association of L. confucii and the genus reefal detritus (foraminifera, ostracods, gastropods). Procladiscites, according to Assereto et al. (1980), sug- Age: Macrofauna are not well preserved and are repre- gests a lower Anisian age (Aegeian). This age has been sented mainly by debris of ammonoids, e.g., Balatonites attributed to similar layers of Chios. balatonicus MOJSISOVICS, Flexoptychites acutus (MO- The age of lower Anisian is supported by the presence JSISOVICS) and genera Bulogites, Discoptychites, Mono- of the foraminifera Tolypammina gregaria and Duostom- phyllites, Megaphyllites, which characterize the Biozone minidae, which appear for the first time in this layer at Ar- balatonicus. In addition, the unit also contains Arenovi- golis, in the study section of Theocafta. dalina chialingchiangensis HO, Ataxophragmidae, as well An analogous age (Aegeian-Bithinian) is attributed as dispersed bioclasts. The presence of Meadrospira insol- by Krystyn (1975) to layers with L. confucii and Procli- ita, which does not occur later than the Pelsonian, further discites, which are referred as the lowest horizon of the suggests a Pelsonian age for that horizon. “Hallstatt” facies. Later on, Krystyn (1983) confines the According to Assereto (1974), Krystyn (1983) and Vi- age of this horizon to the Bithynian, in the Biozone ismidi- erlyng (1987) the Biozone balatonicus comprises the en- cus (upper Bithynian), which is considered as the oldest tire Pelsonian, substituting the Biozone binodosus, which biozone of the Hallstatt facies. in Europe refers to the upper Pelsonian of Germany. However, from the lowest layers of the Hallstatt facies A2/3 in Theocafta, among others, the species M. chiosensis have Strat. Unit: Hallstatt horizon. been determined, suggesting that the base of this horizon Facies: Packstones/floatstones, rich in ammonoids should have an older age and it be included in the Biozone (lower 5 cm, in thickness). Towards the top they are in osmani (lower Bithynian), and may be even older. In con- contact with wackestones-packstones with calcified ra- clusion, in the lowest 15 cm of the section, the Biozones diolarians occur (Figs. 15B, 15C). osmani (A1) and ismidicus (A2) appear, followed by the Microcomponents: Molluscs, echinoderms, gastro- development of a hardground surface. pods, ostracods, filaments, and foraminifera. A2/2 A2/4 Strat. Unit: Hallstatt horizon Strat. Unit: Hallstatt horizon Lower part: Lower part: Facies: Packstones/floatstones with ostracods, radiolar- Facies: Packstones/floatstones with ammonoids. ians and echinoderm debris. Crystals, in places intensively Texture: Condensed sedimentation. Along hardgrounds impregnated by Fe- and Mn-oxides (Fig. 14B). surfaces, Bioclasts have been dissolved. Fauna: Macrofauna lacking. Age: According to Pelosio (1973), identified species are Texture: Dispersed relic crystals of feldspars and predominantly those of the family Ptychitidae (more than quartz assigned to a microbrecciated texture. All compo- 70%): Ptychites stolicskai MOJSISOVICS, P. canavarii nents float in micritic matrix and in some places they are MARTELLI, P. oppeli MOJSISOVICS, Flexoptychites cemented by sparite. flexuosus (MOJSISOVICS), F. cf. studeri (HAUER), F. cf. Interpretation: Lag deposit due to interruption of sedi- gibbus (BENECKE), Discoptychites sp. “Paraceratites” mentation, during which components from a semilithified trinodusus (MOJSISOVICS), “P. elegans” (MOJSISO- hardground surface were reworked. VICS), “Paraceratites” sp. Semiornites sp., Monophyllites Upper part: sphaerophyllus (HAUER), Megaphyllites sandalinus MO- 264 JOURNAL OF PALAEOGEOGRAPHY July 2013

JSISOVICS, Gymnites obliquus MOJSISOVICS, G. in- whereas within the upper part a characteristic fauna has cultus (BEYRICH), Proarcetes escheri (MOJSISOVICS). been detected including Parakellnerites sp., Ptychites cf. According to Mojsisovics (1882), Arthaber (1914), oppeli MOJSISOVICS, Proarcestes sp. and Procladis- Jacobshagen (1967), Pelosio (1973) and Assereto (1974), cites sp., which taking into consideration the conodonts the species Paraceratites is confined to this horizon and in microfauna included, as well, corresponds to the Biozone association with species from the family Ptychitidae and Parakellnerites (Krystyn and Mariolakos, 1975; Krystyn, the species Semiornites coincide with the Biozone trino- 1983). The Biozone Parakellnerites follows the Biozone dosus (Illyrian). trinodosus, both corresponding to Illyrian, however, due to Microfauna are similar to that of the previous horizon, the lack of characteristic fauna, in-between these horizons, except for the observed decrease of A. chialingchiangensis the boundary was not determined. HO and extinction of M. insolita (HO), which favours an A3/2 Illyrian age. Strat. Unit: Hallstatt horizon, averaging 25 cm in A zone of condensed fauna, referred to as the balatoni- thickness. cus-trinodosus zone, developed in Epidavros above the Facies: Packstones/floatstones rich in ammonoids with ismidicus zone, and is considered to be Pelsonian-Illyrian a parallel orientation, enriched in Fe-oxides, and contain- in age (Krystyn, 1983). ing dissolution seams. Ammonoids molds are filled with The above data show that although sedimentation was geopetal fill. very condensed, condensation did not reach the level of Microcomponents: Echinoderms, molluscs, gastro- mixed fauna, and for that reason it is possible to differenti- pods and foraminifera (Tolypammina gregaria WENDT, ate several biozones. Arenovidalina chialingchiangensis HO, Duostomiidae, Upper part: Thickness about 3 cm. Ataxophragmiidae and Nodosariidae). Facies: Comprised of small clasts of volcanic origin Texture: Ammonoids with a parallel orientation. (plagioclase, titanomagnetite, lithoclasts) and a few bio- Interpretation: Limestones with autochthonous hemi- clasts. Clasts of volcanic origin are arranged parallel to pelagic faunal elements (ammonoids) and allochthonous each other. reefal detritus (foraminifera, gastropods). Lithologic unit B: Includes layers A3 and A4, which Age: Ammonoids include Nevadites humboldtensis correspond to the characteristic reddish-brownish, nodular SMITH, Proarcestes bramandei (MOJSISOVICS), P. es- limestones of the Hallstatt facies, with the unique occur- inensis (MOJSISOVICS), P. subtridenticus (MOJSISO- rence of macrofauna and averages 1 m in thickness (Fig. VICS), Sturia semiarata MOJSISOVICS and the genera 11). These layers are rich in Fe- and Mn-oxides that mark Anolcites, Protrachyceras, which characterize the Biozone hardground horizons. reitzi (Nevadites). Concerning the stratigraphic position of A3 the zone reitzi (Nevadites), Krystyn and Mariolakos (1975) A3/1 and Brack and Rieber (1986) considered it to coincide with Strat. unit: Hallstatt horizon. Homogeneous, massive the Illyrian (Anisian), whereas Rieber (1973) and Krystyn limestone characterized by brownish-reddish colour, aver- (1983), considered it to be Fassanian (Ladinian). aging 1 m in thickness. In Theokafta, the Biozone Nevadites is situated on the Facies: Packstones/floatstones with ammonoids (Fig. Biozone Parakellnerites and coincides with the extinction 15). of Ptychites and Paraceratites and the first appearance of Microcomponents: Molluscs, gastropods, echino- Trachyceratidae and the genus Anolcites, as well as the derms, ostracods, radiolarians, filaments and foraminifera. genus and species Sturia semiarata and Monophyllites Texture: Condensed sediments. Discontinuities are wengensis. According to these data, a Fassanian (Lower marked by Fe-oxides and correspond to immature hard- Ladinian) age is attributed to this horizon. grounds (firmgrounds). Glauconite has been observed to fill cavities along hardgrounds. Several microstylolites 5 Biostratigraphy transect the matrix, resulting in a nodular texture. Interpretation: Limestones with autochthonous hemi- Detailed study of the ammonoid fauna from the lowest pelagic faunal elements (ammonoids) and allochthonous horizons of the studied sequence in Theokafta (Epidaurus) reefal detritus (foraminifera, ostracods, gastropods). revealed 35 genera, including five that are reported for the Age: The lower part of this layer is poor in macrofauna, first time and 94 species, of which 23 are referred to as Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 265

Fig. 12 A-Radiolarian packstone consisting of calcitized radiolarians. Bioclasts include foraminiferas, ostracod and mollusc debris (arrow, Layer A/A), 2.5X; B-Radiolarian packstone commonly exhibit a nodular structure. Dissolution surfaces, along the contacts of coalescing nodules, are marked by Fe-oxide-rich microstylolites (Layer A/A), 2.5X; C-Volcaniclastic facies, consisted of relic crystals of plagioclase, quartz and mafic minerals, as well as lithoclasts of variable sizes. All components have been assimilating by the surrounding micritic matrix, enriched in Fe-oxides. Note a relic crystal of andesine (arrow). Pyrite is disseminated in the surrounding matrix (Layer A1), 2.5X (plane polarized light); D-Calcium carbonate nodules (arrow a), assimilated by matrix enriched in Fe-oxides that includes dispersed lensoid/prismatic calcite crystals (arrow b, Layer A1), 5X.

new species. The following stratigraphic units have been island, that was previously determined in Theokafta. The distinguished (Fig. 16). uppermost biozone includes the new species Proarcestes jacobshageni, representing its appearance in Aegaeian. 5.1 Anisian The identification of this stratigraphic subdivision demon- The lowest members of the study section are attributed strates an age of the keratophyric tuffs as Lower Anisian to the Anisian (average thickness about 1.45 m). In this (Scythian or even older). interval the following stratigraphic subdivisions are distin- Bithynian guished, from the oldest to youngest (Fig. 16): The Bithynian includes the Biozones Hollandites and Aegaeian Procladiscites/Leiophyllites, which are very rich in fauna The Aegaeian is determined by the species Japonites content (70% of the total fauna). sp., Megaphyllites sp., Proarcestes n. sp. and Ptychites op- Biozone Hollandites: The Biozone Hollandites is de- peli, which characterizes the Biozone Japonites/Paracro- termined by the presence of the genus Hollandites, which chordiceras or the Biozone “Aegeiceras” ugra of Chios is accompanied by the new genera Reflingtites, Proarces- 266 JOURNAL OF PALAEOGEOGRAPHY July 2013

Fig. 13 A-Carbonate nodules (arrow a) and relic crystals of plagioclase (arrow b), floating in a ferruginous matrix with dispersed pyrite (Layer A1), 1.6X; B-Carbonate nodule (arrow a), partially assimilated by a “mylonitic-like matrix” enriched in Fe-oxides, consisting of relic crystals of quartz and feldspa (Layer A1), 1.6X; C-Contact of the volcaniclastic facies (arrow), with the overlying Hallstatt facies, deliniated by circumgranular cracking and Fe-oxides rims (Layer A2/1a, lower part), 1.6X; D-Packstones/floatstones with radiolarians, molluscs (arrow a), brachiopods (arrow b), ostracods, echinoderms, gastropods (arrow c), as well as benthic foraminifera represented by Arenovidalina chialingchiangensis HO and Nodosariidae. Meniscus cements commonly developed under bioclasts (Layer A2/1a, upper part), 1.6X.

tes, Judicarites, Danubites and Megaphyllites, as well as zoldianus. Sturia cf. mohamedi and Ptychites oppeli. This biozone Biozone Balatonites: The biozone Balatonites is char- occupies the lower part of layer A2/1b and corresponds to acterized by the presence of the genus Balatonites and the lower part of the osmani biozone of the Bithynia area the accompanying fauna Ptychites oppeli, P. opulentus, in Asia Minor. Instead, the Biozone Procladiscites/Leio- Flexoptychites acutus, Schreyerites ragazzonii and Rein- phyllites is more appropriate the upper part of this layer, flingites sp., which most probably corresponds to the sub- which is rich in fauna including the species Leiophyllites zone balatonicus. suessi and Leiophyllites confucii, along with the accompa- Biozone zoldianus: The biozone zoldianus is character- nied fauna Proarcestes cf. svbtridentinus, being equivalent ized by the species Bulogites zoldianus and the same ac- to the remained upper part of the subzone osmani and the companying fauna as in the biozone Balatonites, as well subzone ismidicus of Bithynia. as Paraceratites aff. trinodosus, Megaphyllites sandali- Pelsonian nus, Ptychites seebachi, P. progressus, Flexoptychites flex- The Pelsonian comprises the biozones Balatonites and uosus, F. gibbus, Psilosturia sp., Epigymnites incultus and Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 267

Fig. 14 A-Packstone/floatstone with ammonoids, associated with gastropods (arrow a), molluscs, echinoderms, ostracods, radiolarians (arrow b) and benthic foraminifera debris (Layer A2/1b), 1.6X; B-Packstones/floatstones characterized by a microbrecciated texture and composed of bioclasts (gastropod, arrow), feldspars and quartz crystals, in places intensively impregnated with Fe- and Mn-oxides. All components float in micritic matrix (Layer A2/2, lower part), 1.6X; C-Packstone/Floatstone with ammonoids, associated with echinoderms (arrow a), gastropods (arrow c), molluscs (arrow b) and ostracods and benthic foraminifera. Note the mollusc at- tacked by microborers (upper right) (Layer A2/2, upper part), 1.6X; D-Packstone/Floatstone with ammonoids, associated with benthic foraminifera (arrow a), echinoderms, gastropods, molluscs (arrow b) and ostracods (Layer A2/2, upper part), 1.6X.

Danubites sp. The biozone zoldianus that has been recog- ary has been officially set higher (Bracket al., 2005). nized for first time at Theokafta, and is considered to be Biozone trinodosus: The Biozone trinodosus is rich equivalent to the homonymous subzone of Vörös (1987, in fauna, mainly characteristic genera and species of the 1993) in the Balaton area of Hungary. Ptychitidae family (80%), represented by the genera Pty- Illyrian chites, Discoptychites, Flexoptychites and for first time in In the Illyrian, three biozones have been distinguished, Argolis the genus Aristoptychites. Additionally, new gen- namely the Biozone trinodosus, the Biozone Parakellne- era and species appear in this biozone which is character- rites/Reitziites and the Biozone Nevadites. Krystyn (1983) ized as a stable biozone in the alpine system, including: suggested that the Biozone Nevadites, recorded in the Sageceras walteri, Norites gondola, Bulogites cf. gosavi- Hallstatt facies, should be included in the Fassanian (La- ensis, Philippites erasmi, Lardaroceras krystyni, Lardaro- dinian), instead of the Illyrian (Anisian), as previously was ceras sp. cf. Lardaroceras sp. ind. BALINI, Lardaroceras mentioned. However, the Nevadites biozone is recently sp., Judicarites euryomphalus, J. arietiformis, Proarcestes considered Anisian because the Anisian/Ladinian bound- bramantei, Proarcestes aff. obonii, Flexoptychites angus- 268 JOURNAL OF PALAEOGEOGRAPHY July 2013

Fig. 15 A-Ammonoid biomold filled geopetally with internal sediment (arrow) and cloudy fibrous cement overlaid by blocky cement and/or chalcedony (Layer A2/2), 1.6X (Normal Nicols); B-Packstone/Floatstone rich in ammonoids, overlain by a radiolarian packstone consisting of calcified radiolarians. Note the irregular relief of the discontinuity surface. The lower part is intensively impregnated by Fe-oxides (Layer A2/3), 1.6X; C-Discontinuity corresponding to the contact of packstone/floatstone that is rich in ammonoids and radiolarian packstone with calcified radiolarians (upper part). The contact is marked by pyrite rims and irregular relief. The ammonoid shell in the centre has been intensively bored (Layer A2/3), 1.6X; D-Packstone/Floatstone with ammonoids, associated with molluscs, gastropods, echinoderms, ostracods, radiolarians, filaments and foraminifera. Discontinuities are marked by Fe-oxides and correspond to immature hardgrounds (Layer A3/1), 1.6X.

to-umbilicatus, Flexoptychites studeri, Ptychites uhligi, P. Biozone Parakellnerites/Reitziites: The Biozone Para- breunigi, P. stoliczkai, Discoptychites suttneri, D. pauli, kellnerites/Reitziites is unified, due to the short extent of D. domatus, D. megalodiscus, Aristoptychites sp., Parac- appearance of the characteristic taxa from both biozones. eratites cf. elegans, Epigymnites obliquus,? Anagymnites In the layer that is situated in an height of 1.25 m within sp. In addition the following taxa have been recognized: this biozone, the characteristic genus Parakellnerites oc- Danubites sp., Judicarites meneghinii, Ptychites oppeli, P. curs, represented by different species but mainly by Para- opulentus, P. progressus, P. seebachi, Flexoptychites flex- kellnerites cf. zoniaensis; the accompanying fauna is rep- uosus, F. acutus, Sturia sansovinii, Psilosturia sp., Epigy- resented by the new species Paraceratites cf. subnodosus, mnites incultus, Proarcestes esinensis, P. jacobshageni, Nevadites sp. 1, Proarcestes extralabiatus, Sturia semi- Megaphyllites sandalinus, Monophyllites sphaerophyllus arata, while the occurrence of Flexoptychites flexuosus and Leiophyllites confucii. continues. At 1.35 m above the base, the genus Reitziites Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 269

Fig. 16 The principal stratigraphic subdivisions and the respective biozones of Anisian and Ladinian (Tselepidis, 2007). appears for first time (Brack and Rieber, 1993). Addition- their stratigraphic subdivision in the section at Theokafta. ally, the new species Reitziites n. sp. is detected in the up- Biozone Nevadites: The Biozone Nevadites is attributed permost layers of this biozone, just above the appearance to the Anisian and specifically constitutes the uppermost of the genus Parakellnerites and the accompanying fauna biozone of the Anisian before the Ladinian. It consists Joannites joannis-austriae, Sturia forojulensis, Epigym- of three subzones (crassus, serpianensis, chiesense), but nites incultus, Procladiscites crassus and Monophyllites in the same study is unified and is referred as Nevadites wengensis. The genus Reitziites is assumed to have devel- (sensu lato). In the study section, the Biozone Nevadites oped after the genus Parakellnerites. The short distance is recognized in layer A5/1, which is extremely rich in fos- between the two stratigraphic layers (1.25 m to 1.35 m), sils, represented by the species Nevadites cf. crassiorna- where representatives of the two genera occur, complicates tus, Nevadites sp., Sageceras haidingeri, Halilucites sp., 270 JOURNAL OF PALAEOGEOGRAPHY July 2013

Chieseiceras chiesense, Anolcites julium, Proarcestes esi- and erosion. Synsedimentary and early burrowing pro- nensis, P. escheri, P. extralabiatus, Joannites klipsteini, cesses differentiated the primary textural characteristics of J. kossmati, J. joannis-austriae, Procladiscites crassus, the deposited sediments. Multiphase diagenesis occurred Flexoptychites angusto-umbilicatus, Sturia semiarata, S. not very deep below the sediment surface and includes, forojulensis, Epigymnites icultus, E. obliquus, E. ecki, E. boring, encrustation, burial and cementation. Similar mul- bosnensis, Japonites raphaelis-zojae, Monophyllites argo- tiphase diagenetic events have been described by Savrda licus, M. wengensis, and Mojsvarites agenor. and Bottjer (1988). Detailed sedimentological study enabled reconstruc- 5.2 The Anisian/Ladinian boundary tion of diagenetic events. Some layers or nodules under- The subdivision of the Hallstatt-type limestones and the went early lithification, preventing rearrangement during determination of the Anisian/Ladinian boundary is deter- burial. In the uncemented beds, the effects of subsequent mined from data based on the fauna that is present at the mechanical and chemical compaction are clearly recogniz- Theokafta section/Epidavros and after considering all the able. Grain-supported sediments developed fitted fabrics, scientific data from respective areas of the Tethys. whereas in mud-supported sediments dissolution seams Since the genus Nevadites is attributed to the Anisian were generated. and belongs to Ceratitidae or the Aplococeratidae, we Cement types, all of which are now calcite, include suggest that the Anisian/Ladinian boundary should be micrite, fibrous and blocky cement. Micrite cement is ho- delineated by the presence of fauna of the family Par- mogeneous and/or peloidal and occurs between the com- aceratidae. According to our observations, the Anisian/ ponents of the volcaniclastic substrata (quartz, plagioclase Ladinian boundary coincides with the first appearance and mafic minerals crystals; Fig. 12C). Fibrous cement of representatives of Trachyceratidae, especially of the fills voids resulting from dissolution of carbonate hells genus Eoprotrachyceras (Subcomission on Triassic Stra- when exposed to pore fluids. The length of the crystals in- tigraphy, IUGS) crease towards the center. The fibrous cement is cloudy and includes fluid inclusions and pyrite grains. Micrite and 5.3 Ladinian fibrous cement are usually associated with pyrite. Clear In the study section, the Ladinian starts at a height of crystals of blocky cement fill the remaining pore space and 1.45 m above the base of the Hallstatt Limestones. A dis- voids (Fig. 15A). The fact that all cement types contain py- tinctive feature of the Anisian/Ladinian boundary is the rite, except for the late blocky cement, indicates carbonate formation of layers rich in Fe- and Mn-oxides that com- precipitation within the sulphate reduction zone. monly infill joints vertical to the stratification. The boundary coincides with the base of the layer rich in ammonoids, 7 Palaeoenvironment of deposition layer A5/1, which is principally characterized by the genus Eoprotrachyceras. The deposition of the red nodular ammonoid-bearing pelagic Hallstatt Limestones of the Argolis Peninsula, 5.4 Fassanian upon the carbonate-free volcaniclastic substrata, as hia- The Fassanian comprises the lowermost Ladinian. In tus beds/concretions, is considered to be due to anaerobic terms of the study section, only the Biozone curionii, at oxidation of organic matter by microbes, which provided the lower part of Ladinian, is considered. excess alkalinity and induced carbonate precipitation. For Biozone curionii: The Biozone curionii is character- the development of such a rich fauna of cephalopods in the ized by representatives of the family Trachyceratidae, Hallstatt Limestones, sunlight is necessary and likely hap- mainly of the genus Eoprotrachyceras and the species pened on differentially-subsided and intermittently elevat- Chieseiceras chiesense, Eoprotrachyceras cf. margarito- ed “deep swells” (Hornung and Brandner, 2005; Hornung sum, Protrachyceras sp., P. gredleri, Anolcites aff. julium, et al., 2007). After drowning, the sea mounts were covered Megaphyllites jarbas, etc. by pelagic carbonate deposits. Further slight rotation of the blocks along listric faults may have led to additional dif- 6 Diagenesis ferential subsidence of the blocks. In terms of sequence stratigraphy, the studied Hallstatt The studied Hallstatt facies corresponds to hiatus beds/ hiatus concretions and beds are considered genetically concretions characterized by discontinuous sedimentation linked to rising or high sea-level (e.g., Van Wagoner et Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 271 al., 1988), formed at the initiation of transgressions (e.g., ites, is stratigraphic. Voigt, 1968; Fürsich et al., 1991), as well as during the 3) Nine lithostratigraphic horizons have been distin- time of maximum rate of transgression, in areas where the guished, including radiolarian packstones, volcaniclastic sediment input is strongly reduced (“condensed section”). facies, packstones/floatstones with ammonoids and lag During the Lower Triassic, which corresponded to a deposits. nonglacial time interval, the shelf occupied a large area 4) Nine distinct ammonoid biozones from the Anisian of shallow-water deposition, which could often have been to Ladinian have been defined by Tselepidis (2007), doc- affected by storms, resulting in winnowing of the concre- umenting deposition on Hallstatt deep swells with a low tions and the formation of hiatus beds. On the other hand, depositional rate for nearly 5 million years (using the time- third-order sea-level changes may have played a signifi- scale of Gradstein et al., 2004). The biozones: Japonites/ cant role in the formation of the hiatus beds. Paracrochordiceras, Hollandites, Procladiscites/Leio- According to the available data from the present re- phyllites, Balatonites, zoldianus, trinidosus, Reitziites/ search, concerning the deposition, the development and Parakellnerites and Nevadites are included in the Anisian the location of the Hallstatt-type limestones in the Helle- and the curionii in the Fassanian (lower Ladinian). Al- nides and generally in the Alpine orogenetic system, it is though sedimentation was very condensed, it did not reach considered that the depositional area was either united or the level of mixing fauna. that there was a direct and broad communication between 5) Sedimentation rate was very low and facies show different palaeogeographic areas, which is confirmed by evidence of early lithification near the sediment/water in- the distribution of ammonoids and lithology. Taking into terface. Omission surfaces, firmgrounds and mineralized consideration the present location of the Hallstatt Forma- hardgrounds were widespread. tion, in the context of the Hellenides, such an area should 6) Synsedimentary and early burrowing processes dif- be located between the sub-Pelagonian (western part of ferentiate the primary texture characteristics of the depos- the Pelagonian zone) and Pindos geotectonic zones, which ited sediments. Multiphase diagenesis occurred not very during the Triassic corresponded to a platform slope and a deep below the sediment surface and includes boring and/ deep ocean, respectively. According to Brack et al. (2007), or encrustation, burial and cementation. in Triassic successions of the Eastern Alps (Dinarides, 7) Cement types include micrite, botryoidal, fibrous and Hellenides), the widespread Middle Triassic Han Bulog blocky calcium carbonate cement. The fact that all cement Limestones (ammonoid-bearing pelagic limestones) may types contain pyrite, except for the late blocky cement, in- have formed partly in similar slope environments. dicates carbonate precipitation within the sulphate reduc- Apart from the Hallstatt-type limestones, the limestones tion zone. with cherts are considered to be deposited in the same en- 8) The deposition of the Hallstatt Limestones, upon the vironment, corresponding to the sub-Pelagonian zone, due carbonate-free volcaniclastic substrata, is considered to be to their direct relationship with the Hallstatt-type lime- due to anaerobic oxidation of organic matter by microbes, stones and their development over the same underlying which provided excess alkalinity, inducing carbonate pre- formation (e.g., the keratophyric tuffs) and also because cipitation. of their content in cephalopod fauna (siliceous phase) dur- 9) In terms of sequence stratigraphy, the Hallstatt Lime- ing the Triassic (especially during the Carnian). The fact stones, as hiatus beds and concretions, are genetically that during this interval, the formation of limestones with linked to a rising or high sea-level. They are considered cherts was extended over an area that occupied the exter- to be formed at the initiation, as well as during the time of nal margins of the sub-Pelagonian zone towards the Pindos maximum rate of transgression, in areas where the sedi- zone, confirms the aforementioned statements. ment input is strongly reduced (“condensed section”). 10) Hallstatt facies were deposited on differentially 8 Conclusions subsided and intermittently elevated “deep swells”. Fur- ther slight rotation of blocks, along listric faults, may led 1) The Middle Triassic Hallstatt facies of the Argolis to additional differential subsidence of the blocks. Peninsula consist of hiatus beds/concretions characterized 11) Shelf bathymetry and third-order sea-level changes by discontinuous sedimentation and erosion. may have played a significant role in the formation of the 2) The contact of the Hallstatt facies with the underly- Hallstatt beds. ing volcanic rock, as well as with the overlying radiolar- 12) The depositional area of the Hallstatt-type lime- ‘‘‘;

272 JOURNAL OF PALAEOGEOGRAPHY July 2013 stones in the Hellenides and generally in the Alpine oro- Greece). Inang. Diss. Univ. Basel, 137. genetic system, was either united or there was a direct and Bender, H., 1962. Tieftriadische Hallstätter Kalke und Tuffe in Nor- broad communication between different palaeogeographic dattika. Marburg: Sitz. Ber. Ges. Zur Beförderung ges. Natur- areas, and is confirmed by the distribution of ammonoids wiss, 83-84: 65-79. and lithology. Bender, H., 1970. Der Nachweis von Unter-Trias (“Hydasp”) auf der Insel Chios. Annales Géologiques de Pays Helléniques, 19: 12- 13) Hallstatt Formation deposition occurred between 464. the sub-Pelagonian (western part of the Pelagonian zone) Bender, H., Hirschebrg, K., Leuteritz, K., Manz, H., 1960. Zur Ge- and Pindos geotectonic zones, which during the Triassic ologie der Parnass-Kiona zone under Olonos-Pindos zone im Tal corresponded to a platform slope and deep ocean, respec- des Asklepieion (Argolis). Annales Géologiques de Pays Hellé- tively. niques, 11: 201-213. 14) The Hallstatt facies of the Argolis Peninsula is con- Bender, H., Kockel, F., 1963. Die Conodonten der griechischen Tri- sidered part of the widespread Middle Triassic Han Bulog as. Ann. Geol. Pays Hellen., 14: 436-445. Limestones (ammonoid-bearing pelagic limestones) of Bornovas, J., 1962. Die Cephalopodenkalke von Pyramis bei Argos the Eastern Alps (Dinarides, Hellenides), which may have (Peloponnes). Mit Beiträgen von H. Bender und V. Jacobshagen. been formed partly in platform slope environments, simi- Praktika Akadimias Athenon, 37: 378-386. lar to those of the Southern Alps. Brack, P., Rieber, H., 1986. Stratigraphy and ammonoids of the Low- er Buchenstein of the brescian prealps and giudicarie and their significance for the Anisian-Ladinian boundary. Eclogae Geo- Acknowledgements logicae Helvetiae, 79(1): 181-225. Brack, P., Rieber, H., 1993. Towards a better definition of the An- The authors are highly indebted to Professor Feng Ze- isian-Ladinian boundary: New biostratigraphic data and cor- nzhao (the Editor-in-Chief of JOP) and an anonymous re- relations of boundary sections from the Southern Alps. Eclogae viewer for their constructive suggestions and proposals. Geologicae Helvetiae, 86(2): 415-527. Brack, P., Rieber, H., Mundil, R., Blendinger, W., Maurer, F., 2007. References Geometry and chronology of growth and drowning of Middle Triassic carbonate platforms (Cernera and Bivera/Clapsavon) in Angiolini, L., Dragonetti, L., Muttoni, G., Nicora, A., 1992. Triassic the Southern Alps (northern Italy). Swiss Journal of Geosciences, stratigraphy in the island of Hydra. Rivista Italiana di Paleonto- 100: 327-347. logia e Stratigrafia, 98(2): 137-180. Brack, P., Rieber, H., Nicora, A., Mundil, R., 2005. The global bound- Arthaber, G. V., 1914. Die Trias von Bithynien (Anatolien). Wien: ary stratotype section and point (GSSP) of the Ladinian Stage Beitr. Paläont. Geol. Österr. Ung., 27(2-3): 85-206. (Middle Triassic) at Bagolino (Southern alps, Northern Italy) and Assereto, R., 1971. Die Binodosus-Zone: Ein Jahrhundert wissen- its implications for the Triassic. Episodes, 28(4): 233-245. schaftlicher Gegensätze. Sitzber. österr. Akad. Wiss. (math. na- Brandner, R., 1984. Meeresspiegelschwankungen und Tektonik in turw. Kl. Abt. I), 179(1-4): 25-53. der Trias der NW-Tethys. Jahrbuch fur Geologischen Bundesan- Assereto, R., 1974. Aegean and Bithynian: Proposal for two new stalt Wien, 126: 435-475. Anisian substages. Österr. Akad. Wiss. Schriftenr. Erdewiss. Bromley, R. G., 1978. Hardground diagenesis. In: Fairbridge, R. W., Komm., 2: 23-39. Bourgeois, J., (eds). The Encyclopedia of Sedimentology. Assereto, R., Jacobshagen, V., Kauffmann, G., Nicora, A., 1980. The Coleman, M. L., Raiswell, R., 1993. Microbial mineralization of or- Scythian/Anisian boundary in Chios, Greece. Rivista Italiana di ganic matter: Mechanisms of self-organization and inferred rates Paleontologia e Stratigrafia, 85(3): 715-736. of precipitation of diagenetic minerals. Royal Society of London, Bachmann, G. H., Jacobshagen, V., 1974. Zur Fazies und Entstehung Philosophical Transactions, Series A, 344: 69-87. der Hallstätter Kalke von Epidauros (Anis bis Karn) Argolis, Creutzburg, N., Klocker, P., Küss, S. E., 1966. Die erste triadische Griechenland. Zeitschr. Deutsch. Geol. Ges. Bd., 125: 195-223. Ammonoideen-Fauna der Insel Kreta. Ber. Naturf. Ges. Freiburg, Baird, G. C., 1976. Coral encrusted concretions: A key to recognition 56: 183-207. of a “shale-on-shale” erosion surface. Lethaia, 14: 105-122. Dercourt, J., 1964. Contribution à l’étude géologique de un secteur Bannert, D., Bender, H., 1968. Zur Geologie der Argolis-Halbinsel. du Péloponnèse septentrional. Annales Géologiques de Pays Geol. et Paleont., 2: 151-162. Helléniques, 15(1): 1-418. Bathurst, R. G., 1975. Carbonate sediments and their diagenesis. Douvillé, H., 1900. Sur la distribution géographique des Rudistes, Development in Sedimentology. Amsterdam: Elsevier Publ. Co., des Orbitolines et des Orbitoides. Bull. Soc. Géol. France, 3(28): 12: 658. 222-235. Baumgartner, P. O., 1985. Jurassic sedimentary evolution and Meso- Dürkoop, A., Riechter, D. K., Stritzke, R., 1986. Fazies, Alter und zoic nappe emplacement1 in the Argolis Peninsula (Peloponnes, Korrelation der triadischen Rotkalke von Epidauros, Adhami und Fotini A. Pomoni and Lithofacies palaeogeography and biostratigraphy of the lowermost Vassilis Tselepidis: horizons of the Middle Triassic Hallstatt Limestones (Argolis Penin- Vol. 2 No. 3 sula, Greece) 273

Hydra (Griechenland). Fazies, 14: 105-150. Hallstätter-Scholle von Epidauros (Griechenland). Sitzber. Ös- Dürr, St., 1975. Über Alter und geotectonische Stellung des Men- terr. Akad. Wiss. (math. nat. Kl. Abt. I), 184(8-10): 181-195. deres-Kristallins/SW. Marburg: Anatolien und seine äquivalente Mertmann, D., Jacobshagen, V., 2003. Upper Olenekian (Spathian) in der mittleren Ägäis. H. Schr. Univ. Marburg, 106. ammonoids from Chios (Lower Triassic, Greece): taxonomy and Epting, M., Unland, W., Schmidtka, K., Christodoulides, A., 1976. stratigraphic position. Rivista Italiana di Paleontologia e Strati- Middle Triassic sediments of selected regions in the Southern grafia, 109(3): 417-447. Alps (Italy) and their significance for paleogeography and paleo- Mitzopoulos, M. C., Renz, C., 1938. Fossilführende Trias im structural evolution. Neues Jahrbuch für Geologie und Paleon- griechischen Othrysgebirge. Eclogae Geologicae Helvetiae, tologie Abh, 151: 1-30. 31(1): 71-73. Fantini-Sestini, N. F., 1981. Lower Anisian (Aegean) Ammonites Mojsisovics, E. V., 1882. Die Cephalopoden der mediterranen Trias from Chios Island (Greece). Rivista Italiana di Paleontologiae provinz. Abh. K. K. geol. Reichsanst., 10: P.322, T.94. Stratigrafia, 87(1): 41-66. Monnet, C., Brack, P., Bucher, H., Rieber, H., 2008. Ammonoids of Fürsich, F. T., Oschmann, W., Jaitly, A. K., Singh, I. B., 1991. Faunal the Middle-Late Anisian boundary (Middle Triassic) and the response to transgressive-regressive cycles: Example from the transgression of the Prezzo Limestone in eastern Lombardy-Giu- Jurassic of western India. Palaeogeography, Palaeoclimatology, dicarie (Italy). Swiss Journal of Geosciences, 101: 61-84. Palaeoecology, 85: 149-159. Pelosio, G., 1973. Le ammoniti del Trias medio di’ Asklepieion (Ar- Fürsich, F., Baird, G. C., 1975. Taphonomy and biologic progression golis, Grecia). I. Fauna del “Calcare a Ptychites” (Anisico sup.). associated with submarine erosion surfaces from the German Mem. Soc. Ital. Sci. Natur. E Mus. Civ. Di Storia Nat., 19: P.139- Lias. Neues Jahrbuch für Geologie und Palaontologie, Monat- 168, T.15-21. shefte, 321-338. Raiswell, R., 1987. Non-steady state microbiological diagenesis and Gaetani, M., Jacobshagen, V., Nicora, A., Kaufmann, G., Tselepides, the origin of concretions and nodular limestones. In: Marshall, J. V., Fantini-Sestini, N., Mertmann, D., Skourtsis-Coroneu, V., D., (ed). Diagenesis of Sedimentary Sequences. Geological Soci- 1992. The Early-Middle Triassic Boundary at Chios (Greece). ety of London, Special Publication, 36: 41-54. Rivista Italiana di Paleontologia e Stratigrafia, 98: 181-204. Raiswell, R., 1988. Chemical model for the origin of minor lime- Gradstein, F., Ogg, J., Smith, A., 2004. A geologic time scale. Cam- stone-shale cycles by anaerobic methane oxidation. Geology, bridge: University Press, 589. 16: 641-644. Hesselbo, S. P., Palmer, T. J., 1992. Reworked early diagenetic con- Renz, C., 1906a. Trias und Jura in der Argolis. Zeitshr. Deutsch. cretions and the bioerosional origin of a regional discontinuity Geol. Ges., 58: 379-395. within the British Jurassic marine mudstones. Sedimentology, Renz, C., 1906b. Über neue Trias Vorkommen in Argolis. Stuttgart: 39: 1045-1065. Zentralbl. Min. Geol. Pal., 1606. Hornnung, T., Brandner, R., 2005. Biochronostratigraphy of the Renz, C., 1910a. Die mesozoischen Faunen Griechenlands. 1-Teil: Reingraben Turnover (Hallstatt Facies Belt): Local black shale Die triadischen Faunen der Argolis. Palaeontogr, 58: P.1-104, events controlled by regional tectonics, climatic change and plate T.1 -7, Fig. 15. tectonics. Facies, 51: 460-479. Renz, C., 1910b. Stratigraphische Untersuchungen im griechischen Hornung, T., Spatzenegger, A., Joachimski, M. M., 2007. Multi- Mesozoikum und Paläozoikum. Wien: Jb. k. k. geol. Reichsanst., stratigraphy of condensed Ammonoid beds of the Rappoltstein 60: 421-636, Abb.38, T.5. (Berchtesgaden, southern Germany): unravelling palaeoenviron- Renz, C., 1939. Nachträge zu den triadischen Cephalopodenfauna mental conditions on “Hallstatt deep swells” during the Reingra- der Argolis. Praktika Akadimias Athenon, 14: 235-255. ben Event (Late Lower Carnian). Facies, 53(2): 267-292. Renz, C., 1955. Die vorneogene Stratigraphie der normalsedi- Jacobshagen, V., 1967. Cephalopoden-Stratigraphie der Hallstätter mentären Formationen Griechenlands. Institute of Geology and Kalke am Asklepieion von Epidauros (Argolis, Griechenland). Subsurface Research, 3-16: 1-637, Abb.3, T.11, 6 geol. Karten. Geol. et Pal., 1: 13-33. Rieber, H., 1973. Die Triasfauna der Tessiner Kalkalpen. XXII. Jacobshagen, V., Tieze, K. W., 1974. Biostratigraphische Probleme Cephalopoden aus der Grenzbitumenzone (Mittlere Trias) des im Skyth/Anis-Grenzbereich auf der Insel Chios (Ägäis). Schrif- Monte San Georgio (Kanton Tessin, Schweiz). Schweiz. Paläont. tenr. Erdwiss. Komm. Österr. Akad. Wiss., 2: 115-123. Abh., 93. Kendall, C. G. St. C., Schlager, W., 1981. Carbonates and relative Römermann, H., 1968. Geologie von Hydra (Griechenland). Geol. changes in sea level. Marine Geology, 44: 181-212. and Paleont., 2: 163-171. Krystyn, L., 1983. Das Epidauros-Profil (Griechenland)- ein Beitrag Sakellariou, M. B., 1938. Faune triassique près d’ Aghia Moni (Nau- zur Conodonten-Standardzonierung des tethyalen Ladin und Un- plie) en Argolide. Prakt. Akad. Athènes, 13: 723. terkarn. In: Zapf, H., (ed). Neue Beiträge zur Biostratigraphie der Savrda, C. E., Bottjer, D. J., 1988. Limestone concretion growth doc- Tethys-Trias. Schriftenr. Erdwiss. Komm. Österr. Akad. Wiss., 5: umented by trace fossil relation. Geology, 16: 908-911. 231-258. Schlager, W., Schollnberger, W., 1974. Das Prinzip stratigraphischer Krystyn, L., Mariolakos, I., 1975. Stratigraphie und Tektonik der Wenden in der Schichtfolge der Nördlichen Kalkalpen. Mit- 274 JOURNAL OF PALAEOGEOGRAPHY July 2013

teilungen der Geologischen Gesellschaft Wien, 66(67): 165-193. mentier, H. W., Ross, C. A., Van Wagoner, J. C., (eds). Sea-Level Spears, D. A., 1989. Aspects of iron incorporation into sediments Changes: An Integrated Approach. SEPM, Special Publications, with special reference to the Yorkshire Ironstones. In: Young, T. 42: 39-45. P., Taylor, W. E. G., (eds). Phanerozoic Ironstones. Geological Voigt, E., 1968. Über Hiatus-Konkretionen (dargestellt an Beispielen Society of London, Special Publication, 46: 19-30. aus dem Lias). Geologische Rundschau, 58: 281-296. Τselepidis, V., 2007. Paleontological and stratigraphical study of Vörös, A., 1987. Preliminary results from the Aszòfö section (Middle the ammonoidea from Epidaurus, Greece. Contribution of the Triassic, Balaton area, Hungary): A proposal for a new Anisian knowledge of the palaeogeographic distribution of the “Hallstatt ammonoid subzonal scheme. Fragm. Mineral. Paleont., 13: 53- facies” in the Hellenides. Ph.D. Dissertation, Thessaloniki. 64. Τselepidis, V., Varti-Μataranga, Μ., Μatarangas, D., Skourtsi-Coro- Vörös, A., 1993. Redefinition of the Reitziites Zone at its type region neou, V., 1989. Contribution to the knowledge of lithology and (Balaton area, Hungary) as the basal zone of the Ladinian. Acta biostratigraphy of the lower parts of the “Hallstatt” facies red Geol. Hungarica, 36(1): 15-38. limestones, in Theokafta area (Epidauros). Bulletin of the Geo- Wetzel, A., Allia, V., 2000. The significance of hiatus beds in shal- logical Society of Greece, 23(2): 33-48. low-water mudstones: An example from the middle Jurassic of Τsoflias, P., 1969. Geological construction of the Northernmost part Switzerland. Journal of Sedimentary Research, 70(1): 170-180. of Peloponnesus, Achaia District. Annales Geologiques de Pays Wilson, M. A., 1985. Disturbance and Ecologic Succession in an Up- Helleniques, 21: 554-651. per Ordovician Cobble-Dwelling Hardground Fauna. Science, Van Wagoner, J. C., Posamentier, H. W., Mitchum, R. M., Vail, P. 228(4699): 575-577. R., Sarg, J. F., Loutit, T. S., Hardenbol, J., 1988. An overview of the fundamentals of sequence stratigraphy and key definitions. (Edited by Wang Yuan, Liu Min) In: Wilgus, C. K., Hastings, B. S., Kendall, C. G. St. C., Posa-