I I Rivista Italiana di Paleon roìor,iaeSrrltrqrriia I rolur ;;- -, | f;-' "oo, l UPPER OLENEKIAN (SPATHIAN) AMMONOIDS FROM CHIOS (LO\T/ER TRIASSIC, GREECE): TAXONOMY AND STRATIGRAPHIC POSITION. DOROTHEE MERTMANN' & VOLKER TACOBSHAGEN' Receh:ed July 1st,2002; accepted June 25,20A3 Key-raords: Ammonoidea, Triassic, Olenekian, Chios, Greece. There, the fossils are included in red limestones of rhe Hallstatt facies (Marmarorrapeza. Formation). Renz & Abstact. On the Greek island of Chios, Lower Triassic sections Renz (1948) have delivered rich ammonoid faunas from red limestones of the Hall- published a palaeontological description of statt facies. Here, we present a palaeontological description of Spatl-rian its ammonoids in a monograph. Bender (1970) was the ammonoids, which have been collected during two field campaigns by first to collect fossils from measured sections (CM i, kalian-German teams (Assereto et al. 1980; Gaetani et al. 1992). The II, III) in order to establish coordinared ammonoid and ammonoid assocìations are composed of Ceratitida and Phyllocerati- conodont stratigraphies. This author recognized, more- da, each order containing species of the Noritaceae, Hedenstroemia- ceae, Xenodiscaceae, Dinaritaceae, Pinacocerataceae, Phyllocerataceae, over, that the Spathian beds are overlain by lowermost Ptychitaceae, lJssuritaceae and Megaphyllitaceae. Long ranging gen- Anisian ones s/ith ammonoids comparable with faunas era, e.g. Procarnites and Leioplrylliter, are present as well as endemic of the so-called Hydaspian substage from the Himalayas ones, e.g. Cbiotites, which occurs exclusively in the Lower Trìassic of and Timor. Furthermore, Jacobshagen & Tietze (1974) Chios. The ammonoìd association is indicative of the Probungarites- described an associarion of both Spathian and Lower Subcolwmbites zone sensu Kumn.rel (1973a,). The baugi zone, installed as uppermosr Olenekian in North America, is not represented by am- Anisian ammonoids from a nearby secrion of Parthenis monoids on Chios. Hill. Based on those findings and new specimens from Bender's section CM II, Assereto (1974) proposed rhe Riassunto. Le successioni di calcari rossi in facies di Hallstatt Aegean as lowermost substage of the Middle Triassic nel Triassico inferiore dell'isola di Chios (Grecia) hanno fornito una and Marathovouno as ricca fauna ad ammonoidi. In questo arricolo sono descritte le faune hill its type locality. In 1.975, a ad ammonoidi di etàL Spathiana, raccolte durante due campagne di ter- team of Italian and German geologisrs conducted by R. reno effettuate da un gruppo di rìcercatori Italiani e Tedeschi (Asse- Assereto and V Jacobshagen worked on Mararhovouno reto et al. 1980; Gaetani et il.1992). Le associazioni ad ammonoidi si Flill, measuring 6 sections (A-G, Fig. 2) and collecting compongono di Ceratitida and Phylloceratida, di cui sono rappresen- fossils bed by bed with the aim to define the tate specie di Noritaceae, Fledenstroemiaceae, Xenodiscaceae, Dinari- Olenekian/ taceae, Pinacocerataceae, Phyllocerataceae, Ptychitaceae, {.Jssuritaceae Anisian boundary on the base of ammonoids and cono- e Megaphyllitaceae. Sono presenri generi ad ampia distribuzione verri- donts. Their biostratigraphical resuks were presented cale come Procarnites e Leioplryllites, così come generi endemici quale by Assereto et al. (1980). Nicora (1977) published pal- Chiotites, che si rinviene solo nel Triassico inferiore di Chios. Lasso- aeontological descriptions of the conodonts found in ciazione ad anrmonoidi è indicativa della zona a Prohungarites-Subco lumbites sensu Kummel (1973a). La zona rd haugi, considerata come these sections, and the Aegean ammonoids were de- Olenekiano terminale nel Nord America, non è rappresentata tra gli scribed by Fantini Sestini (1981). To complete these ammonoidi di Chios. investigations, a second field campaign was performed in 1989 by M. Gaetani and A. Nicora (Milano), V Tse- lepidis (Athens) and V Jacobshagen (Berlin) rogether Introduction with Milano students. Re-measuring and fossil collec- tions were confined on crucial parts of the sections A, Lower Triassic ammonoid faunas are very rare C, D, and G. Data concerning the Anisian part of the in the Mediterranean regions. The Chios occurrence secrions were published by Gaetani et al. (1992).Fur- was detected by Ktenas & Renz (1928,193 1) on Mara- thermore, research was extended to a section of the thovouno Hill, west of the town of Chios (Figs. 1, 2). Parthenis area. FR Geologie, Institut fùr Geologische \lissenschaften, Malteserstr. 74-1OO,D-12249 Berlin, Germany. Email: [email protected] 418 D. Mertmann &. V Jacobshagen Chios km-i-J:-, + |]:re_:_ + 10 km 1-25 'It-v 1km :F Upper Unit Fig. 2 - Geological map of the area west of Chios town (A), .rnd the location of the sections measured by different authors. Lower Unit 1-Palaeozoic, 2-Basal Formation including Lor-er Carbon- I lcenozoic ate Formation, 3-Variegated Formation, 4-Upper Carbonate Formation, 5-Cenozoic. P Location of Parthenis scction. I Mesozoic ;| eataeozoic Fig. 1 - Chios Island (B) in the Egean Sea r.est of mainland Greece (A). bedded limestones, with late Olenekian (Spathian) bi- valves and conodonts in their upper parrs (Kauffmann 1978). To their top, but also laterally, the bedded iime- stones pass over to thick, unbedded limestones and dolo- The presenr plper is focussed on rhe taxonomy and mites of the Lower Carbonate Formation (Lower Car- the stratigraphic position of the Lower Triassic ammo- bonate Series; Tieftriadische Massenkalke und -dolomite, noids collected during the two field campaigns of 1925 Besenecker et al. 1968), which have yielded some Spathi- and 1989. Appendix 1 indicates the correlation berween an conodonts as we1l. It is composed of wackestones to the section, the sample and numbering of the ammonoids. packstones interfingering with bedded dolomites, show- Appendix 2 quotes the ammonoids mentioned in Assereto ing ooids in places. In the surroundings of Chios town et al. (1980) and Gaetani et aI. (1992). However, due to the above-mentioned Marmarotrapeza Formation (Kalk the re-evaluation of the collection changes have been made von Marmarotrapeza, Ktenas & Renz 1928) follows with concerning the determination of species and genera. a sharp contact. Red nodular limestones of the Hallstatt facies are typical, with ammonoids, filamenrs, rare fo- raminifers, and conodonts. The thickness usually does not Geological framework exceed 15 m. To the west and north of Chios town it is absent or reduced in thickness. The formation straddles According to Besenecker et a1. (1968, 1971) the the Olenekian/Anisian boundary. At the Marathovouno island of Chios is composed of two main tecronic unirs hillock the Anisian part is confined to 2.0-3.50 m, but in (Fig. 1), which probably belong to the Pelagonian nap- other places it is even missing (e. g. in the Parthenis sec- pes (Jacobshagen 1986). The lower unit, once considered tion of Gaetani et a|. 1992). The Marmarotrapeza Fm. is as autochthonous, shows at its base epizonal schists fol- overlain by the Variegated Formation (Variegated Se- lowed by a thick grayu'acke-slate sequence of Silurian - ries; Bunte Serie, Besenecker et al. t968;, a succession of Carboniferous age (Besenecker et al. 1968; Zanchi et aI. red to purple slates and sandy marls with intercalations of 2003). The latter is unconformably overlain by a Triassic limestones, radiolarites, conglomerates and tuffitic hori- succession, vrith a few occurrences ofJurassic limestones zons, dated to an Anisian-Ladinian age by few conodont and, locally, Early Tertiary conglomerates on the top. The findings (Tietze 1969).k conrains m-thick olistoliths of upper unit is preserved in some outliers, only. Its sequence red limestones with Spathian and even Middle Anisian starts with fossiliferous Upper Palaeozoic deposits that ammonoids and conodonts (Gaetani et aL 1992, see Fig. are covered by red clastics of Liassic age. Triassic rocks 2). \flest of Chios town, rhe Variegated Formarion con- are missing in berween, but a few small relics. tinues to an alternation of limestones and cherts, which Our studies refer to the Triassic of the lower unit yielded Middle Triassic and Carnian fossils (Tietz e 1969). exposed in the vicinity of Chios town. Tietze (1969) The Mesozoic sequence of the lower unit ends with the mapped that area. Its sequence starts with a Basal For- Upper Carbonate Formation with shallow-warer lime- mation (Basale Serie, Besenecker et al. tles; containing stones of Upper Triassic and Jurassic age, nor ro be con- red conglomerates and sandstones that grade upward to sidered here. Lower Triassic ammonoids from Chios 419 Marathovouno W Marathovouno E Parthenis Fig.3 - Sketch of the tectono-sedì- mentary evolution during the Variegated Formation Triassic (modified after Gaeta- ni et al. 1992). Not to scale. The Lower and Middle Triassic sequence reflects to peritidal carbonate platform (Lorver Carbonate For- a Tethyan evolution which took place in an extensional mation). The Hallstatt facies of the Marmarotrapeza Fm. regime (Fig. 3, Gaetani er al. 1992; Stampfli et aI.1,991; points to downwarping of the platforn-r and strong subsid- Stampfli er. a|. 20a2).It started with a transgressive er-enr ence. The equivalent sedimentation ended diachronously. at its beginning and the following forrnation of a subtidal The V.rriesared Formarion on top, deposited in a marine Marathovouno tn .Y9d\ -Y .: *,G .e Section A, v) v) CandD oÈàìÈ{ p È=òCv.^È Y \rr *a :!* )l= PP.\9+F è- O+: cH 149 .ò - cH 148 àuoolE oo "# -cH 147 a .Ems$ cH 146 c .v) - cH 145 .s c È PTffi] .9 .o É"'Éffi .@ cH 144 c ++ ,T331 i{ Parthenis T330 T329 -N89/'166 à= := c -,N89/1 58 185 îT : CH 33N .o_ f .l- CH 32 YC Mr- 184, 184a -cH 31 o9.\- -cH 30 c F'*l rR? 1R?'"-- -cH 29 c w ìàir -ct 28 o ct 27 -Y -cH 26 a) _CH c 25 a) -ct 24 -ct 23 CH 22 CH 21 cH 20 _CH 19 -cH l8 -cH17 /cH 16 covered t,óÀ 1í - medium-beddedlimestone :cN12 _ -cH 11 -cH 10 :.'a:):r::l -cH 9 cH8 .l' CH7 f petitic nodular limestone CH 6a-c ]u l = illlnil -cH 5 llllll l1l 'ff -CH4a-cH4b |-F cH3 ffi massive limeslone t, ; ; dolomite I-ig.