MICHAEL J. ORCHARD 1, EUGEN GR DINARU 2 AND ALDA NICORA 3

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Lucas, S.G. and Spielmann, J.A., eds., 2007, The Global Triassic. New Mexico Museum of Natural History and Science Bulletin 41.

1 Lucas, S.G. and Spielmann, J.A., eds., 2007, The Global Triassic. New Mexico Museum of Natural History and Science Bulletin A SUMMARY OF THE CONODONT SUCCESSION AROUND THE OLENEKIAN-ANISIAN BOUNDARY AT DE LI CAIRA, NORTH DOBROGEA, ROMANIA MICHAEL J. ORCHARD 1, EUGEN GR DINARU 2 AND ALDA NICORA 3 1 Geological Survey of Canada, 625 Robson Street, Vancouver, B.C., V68 5J3 Canada, morchard@nrcan.gc.ca; University of Bucharest, Faculty of Geology and Geophysics, Department of Geology and Palaeontology, Blvd. Nicolae Bãlcescu 1, RO Bucharest, Romania, egradin@geo.edu.ro; 3 Dipartimento di Scienze della Terra, Universita degli Studi di Milano, Via Mangiagalli 34, Milano, Italy, alda.nicora@unimi.it 2 Abstract The occurrence of conodonts in the Olenekian-Anisian boundary (OAB) beds at the De li Caira section in Romania is documented. Eight conodont first and last appearances occur at five different horizons spanning 4.25 m of strata. Of these, the fourth is the appearance of Chiosella timorensis, which coincides with the ammonoiddefined OAB. The other conodont events help to constrain the boundary. INTRODUCTION The De li Caira Hill lies in the province of Dobrogea in the southeasternmost part of Romania, between the lower course of the Danube and the Black Sea coast (Fig.1). Having an altitude of 175 m, the hill is located approximately 6 km east of Mihail Kog lniceanu village, and approximately 8 km west of Agighiol village. The coordinates are E and N. The name De li Caira is Turkish in origin, and the feature is actually known in Romanian toponymy under the name of Stânca Mare (Big Stone) or Muchea Ascu it (Sharp Summit). The area of the De li Caira Hill is included in the Agighiol Zone of the North Dobrogea (Fig.1), which is famous in classic literature for the spectacular development of Triassic ammonoid faunas (Kittl, 1908; Simionescu, 1913). The Agighiol Zone, which has an external position in the framework of the Triassic carbonate platform of the Tulcea Unit (Gr dinaru, 2000), is characterized by the development of thick sequences of Hallstatt-type massive limestones interbedded or grading laterally or vertically to Ammonitico Rosso-type nodular siliceous lime- FIGURE 1. Distribution map of the Triassic rocks in the North Dobrogean Orogene, showing the location of the De li Caira Hill (M.U., M cin Unit; N.U., Niculi el Unit; T.U., Tulcea Unit.

2 342 stones. The Tulcea Unit is the lowermost tectonic unit of the Early Alpine North Dobrogea fold and thrust belt (Gr dinaru, 2000), which in its turn represents the westernmost prolongation of the Cimmeride Orogenic System. During the Triassic, the North Dobrogea region was situated closer to the main Tethys region but post-triassic large-scale horizontal movement displaced the North Dobrogea terrane, which is an exotic terrane docked to Eurasia (Grãdinaru, 2000). De li Caira Hill is a candidate location for the Olenekian-Anisian boundary (OAB) Global Stratotype Section and Point (GSSP). The present contribution summarizes the conodont succession at the site and thereby contributes to our understanding of the correlation and definition of the OAB. BIOSTRATIGRAPHY The De li Caira section exposes a sequence of 60+ m thick, Hallstatt-type massive to well-bedded micritic limestones. These limestones are variously colored, mainly reddish, and are interbedded with subordinate Posidonia -bearing coquinoid limestones of possible tempestite origin, mainly in the lower half of the sequence. The Hallstatttype limestones are extensively bioturbated at some levels, whereas at other levels they show condensed sedimentation. The limestone sequence exposed at the De li Caira Hill was first studied by Kittl (1908) and Simionescu (1910), who described ammonoid faunas, including new taxa. During the last decades ammonoid faunas have been intensively collected from several stratigraphic levels by the second author (EG). This work has resulted in the recognition of at least eleven levels of distinct, stratigraphically successive ammonoid faunas in the upper half of the De li Caira section (Gr dinaru, 2000). The late Olenekian is demonstrated by the occurrence of very abundant and diversified ammonoid faunas including species of well-known late Spathian genera such as Procarnites, Albanites, Proptychitoides, Preflorianitoides, Ziyunites, Leiophyllites, etc., and several new ammonoid taxa. Of outstanding value is the occurrence in the latest Spathian of an olenikitid-like ammonoid species group informally assigned to the genus Deslicairites by Gr dinaru (2003). The basal Anisian is documented by the ParacrochordicerasJaponites Beds, in which the presence of a Karangatites-akin ammonoid and also of Romanites cf. simionescui Welter are recorded. The ammonoid and nautiloid faunas from around the OAB in the De li Caira section are of remarkable importance for the correlation of the Triassic in the Tethyan and Boreal realms (Gr dinaru & Sobolev, 2006). The next Anisian ammonoid assemblage in the section of the De li Caira section is diagnostic for the Aegeiceras ugra Beds, which are well known from other classic localities in the Tethyan Realm (Assereto et al., 1980; Gaetani et al., 1992; Balini & Krystyn, 1997; Waterhouse, 1999; Krystyn et al., 2004). Based on the ammonoid faunal succession, the OAB in the De li Caira section can be accurately placed between samples GR6 (=203/4) and GR7 (Figs. 3 and 4). A concurrent bioevent appears to be the first appearance datum (FAD) of Chiosella timorensis in a continuum that begins within the Triassopathodus ex gr. homeri and passes through the immediate predecessor Chiosella gondolelloides (Gr dinaru et al., 2002, 2006). CONODONT SUCCESSION Conodonts from De li Caira were collected over many years and by several workers. Some of these data have been presented in preliminary papers by Mir u (1974, 2000), Gr dinaru et al. (2002, 2006). The present contribution summarizes the conodont succession at De li Caira and thereby contributes to our understanding of the correlation and definition of the OAB. Figures 3 and 4 show several generations of sample numbers assigned to conodont collections as well as ammonoid collection levels (prefix GR). During a visit to Bucharest in 2000, two of us (MJO and AN) were shown the conodont collections made by the second author (EG) and these were divided into two subsets for further study in Vancouver and Milan. On the same occasion, the De li Caira section was visited and new continuous sampling took place on each side of the OAB defined by ammonoids. Results from this more detailed section spanning the immediate interval of the OAB is shown in Figure 4. Conodont samples reported here come from about 25 m of section, of which about three-quarters post-date the OAB. Several species present in the samples from the upper Olenekian Triassospathodus, Cratognathus spp. (Fig , 12, 18-22), Spathiscuspus, Gladigondoella carinata, and New genus A (Fig ) probably have a longer history FIGURE 2. Ammonoid sequence in the Olenekian-Anisian boundary in the De li Caira section, North Dobrogea, Romania.

3 FIGURE 3. Occurrence of conodont taxa from the section at De li Caira. 343

4 344 FIGURE 4. Occurrence of conodont taxa from the boundary beds at Desli Caira. prior to the latest Olenekian (as shown on Figs. 3 and 4), so their apparent FAD in this section is not regarded as significant. In contrast, nine conodont appearances (i.e., FAD) and disappearances (i.e., LAD) are identified as guides to identify the OAB in the De li Caira section. Several of these are coincident, and all occur within about 4.25 m of strata. For the remaining 20 m of section, the fauna maintains a relatively constant composition. Each of the OAB conodont taxa have been discussed elsewhere by Orchard et al. (2007). These conodont events are (with positions relative to the OAB): 1 FAD of Chiosella gondolelloides (-3 m) 2 LAD of Spathiscuspus (-1 m) 3 LAD of Neospathodus triangularis (0 m) 4 FAD of Chiosella timorensis (0 m) 5 LAD of Gladigondolella carinata (0 m) 6 FAD of Chiosella n. sp. A (0 m) 7 FAD of G. tethydis (+0.5 m) 8 LAD of Triassospathodus (+1.25 m) 9 FAD of Neogondolella (+1.25 m) These conodont events are grouped so as to define five datums at De li Caira: FIGURE 5. Illustrations of conodonts from Desli Caira. Scale bars = 200 microns (x80) for all figures except 1, 3 = 100 microns (x160). 1, 2, Neospathodus triangularis Bender, GSC , from sample G7. 3, 4, Spathicuspus spathi (Sweet), GSC , from sample 9036A. 5, 6, Triassospathodus ex gr. homeri (Bender), GSC , from sample 9036A. 7-9, Gladigondolella carinata Bender. 7, 9, GSC , from sample G7A, 8, GSC , from sample G7B. 10, Genus et sp. nov. A, GSC , from sample , 12, 22, Cratognathus sp. A. 11, 12, GSC , from sample 9036, 22, GSC , from sample , 23-25, Chiosella gondolelloides (Bender) , GSC , from sample 9047, 23-25, GSC , from sample ?, 17?, 31-34, Chiosella timorensis (Nogami). 16, 17, GSC , from sample 9044; element transitional to C. n. sp. A, 31, GSC , from sample G7D, 32-34, GSC , from sample , Cratognathus sp. B. 18, 19, GSC , from sample 204/5, 20, 21, GSC , from sample , Chiosella n. sp. A, GSC , from sample 821B. 29, 30, Gladigondolella tethydis (Huckriede), GSC , from sample , Neogondolella sp., GSC , from sample 9043.

5 345

6 346 Datum 1 The first significant datum is the FAD of Chiosella gondolelloides (Fig , 23-25) at about 3 m below the OAB. The appearance of C. gondolelloides is an easily recognized datum since the separation of the species from its apparent forebear and common associate, Triassospathodus ex gr. homeri (Fig. 5. 5, 6), is straightforward. Less so is the separation of small specimens of the former species from C. timorensis (Fig ), early growth stages of which may be indistinguishable. This poses problems in small, isolated collections of juveniles. Datum 2 The LAD of Spathiscuspus spathi (Fig. 5. 3, 4) at 1 m below the OAB is an earlier LAD than is seen elsewhere (e.g., at Guandao, China), where the species ranges into basal Anisian strata. The species is far less common in the Romanian faunas, and this datum is not a useful one for correlation. Datum 3 This is the major faunal change of the succession and involves two conodont FADs and two LADs, as well as change in the ammonoid fauna from characteristic Spathian to typical Anisian taxa. These all occur within the lowest part of bed 7 (Fig. 4). Most notable are the FADs of Chiosella timorensis and Chiosella n. sp. A (Fig ), the latter being distinguished by its distinctive terminal cusp. This datum also coincides with the LAD of both Gladigondolella carinata (Fig ) and Neospathodus triangularis (Fig. 5. 1, 2). These four conodont events are not entirely synchronous elsewhere, but they all cluster around the OAB. In Guandao, China, N. triangularis disappears earlier, and both the FAD of C. n. sp. A and LAD of G. carinata are later with respect to the FAD of C. timorensis. This may reflect relative condensation in the De li Caira succession. Datum 4 The FAD of Gladigondolella tethydis (Fig , 30) occurs 0.5 m above the OAB. This appearance in the early Anisian is consistent with records elsewhere (e.g., Orchard et al., 2007). Datum 5 At 1.25 m above the OAB, the LAD of Triassospathodus ex gr. homeri coincides with the FAD of Neogondolella sp. (Fig ). These two taxa are known to overlap elsewhere in Tethys and also in North America. In Tethyan successions, the overlap is within the basal Anisian, as it is in the De li Caira, but in North America it occurs first in the late Spathian. Although the overlap of taxa is not a reliable datum worldwide, the LAD of T. ex gr. homeri is nevertheless a reliable early Anisian event. ACKNOWLEDGMENTS In Vancouver, P. Krauss and H. Taylor provided essential technical support in preparing this work. The second author acknowledges the financial support received from the Romanian Academy by the Scientific Grants 84/1999 and 368/ This study is a contribution to IGCP 467 Triassic Time and trans-panthalassan Correlations. REFERENCES Assereto, R., Jacobshagen, V., Kauffmann, G. and Nicora, A., 1980, The Scythian/Anisian boundary in Chios, Greece: Rivista Italiana di Paleontologia e Stratigrafia, v. 85, n. 3-4, p Balini, M. and Krystyn, L., 1997, Middle Triassic ammonoids from Spiti Himalayas - a chance for major improvements in Tethyan Anisian subdivisions?: Albertiana, v. 19, p Gaetani, M., Jacobshagen, V., Nicora, A., Kauffmann, G., Tselepidis, V., Fantini Sestini, N., Mertmann, D. and Skourtsis-Coroneou, V., 1992, The Early-Middle Triassic boundary at Chios (Greece): Rivista Italiana di Paleontologia e Stratigrafia, v. 98, n. 2, p Gr dinaru, E., 2000, Introduction to the Triassic geology of North Dobrogea Orogene - an overview of the Triassic System in the Tulcea Unit and the ammonoid biostratigraphy; in Grãdinaru, E., ed., Bucharest: Workshop on the Lower-Middle Triassic (Olenekian-Anisian) boundary, 7-10 June 2000, Tulcea, Romania, Field Trip Section, p Gr dinaru, E., 2003, Ammonoid biostratigraphy around Olenekian/Anisian boundary in the De li Caira section (Romani) - a GSSP candidate: Triassic Geochronology and Cyclostratigraphy, a Field Symposium, St.Christina/Val Gardena, Dolomites, Italy, September 2003, Programme and Abstracts, p. 37. Gr dinaru E., Orchard, M., Nicora, A., Mir u, E. and Atudorei, V., 2002, Conodont succession across the Olenekian-Anisian boundary at De li Caira, Romania; in Piros, O., ed., I.U.G.S. Subcommission on Triassic Stratigraphy, STS/IGCP 467: Field Meeting, Veszprém, Budapest, Hungary, 5-8 September, 2002, p Gr dinaru, E. and Sobolev, E.S., 2006, Ammonoid and nautiloid biostratigraphy around the Olenekian-Anisian boundary in the Tethyan Triassic of North Dobrogea (Romania): correlation with the Boreal Triassic; in Nakrem, H.A.and Mørk, A., eds., Boreal Triassic 2006, Longyearbyen, Svalbard, August 2006: NGF Abstracts and Proceedings of the Geological Society of Norway, Trondheim, v. 3, p Gr dinaru, E., Kozur, H.W., Nicora, A. and Orchard, M.J., 2006, The Chiosella timorensis lineage and correlation of the ammonoids and conodonts around the base of the Anisian in the GSSP candidate at De li Caira (North Dobrogea, Romania): Albertiana, v. 34, p Kittl, E., 1908, Beiträge zur Kenntnis der Triasbildungen der nordöstlichen Dobrudscha. Denkschriften der mathematisch-naturwissenschaftlichen Klasse der kaiserlichen: Akademie der Wissenschaften, v. 81, p Krystyn, L., Balini, M. and Nicora, A., 2004, Lower and Middle Triassic stage and substage boundaries in Spiti: Albertiana, v. 30, p Mirãuþã, E., 1974, Über die conodontenfaunen des oberen Werfens und des tieferen Anis der nördlichen Dobrudscha/Rumänien: Geologica et Palaeontologica, v. 8, p Mirãuþã, E., 2000, Conodonts biostratigraphy; in Grãdinaru, E., ed., Bucharest: Workshop on the Lower-Middle Triassic (Olenekian-Anisian) boundary, 7-10 June 2000, Tulcea, Romania, Conference Section, Part 2 - Presentation of Deºli Caira attributes for a GSSP candidature, p Orchard, M.J., Lehrmann, D., Wei, J., Wang, H., and Taylor, H., 2007, Conodonts from the Olenekian-Anisian boundary beds, Guandao, Guizhou Province, China: New Mexico Museum of Natural History and Science, Bulletin. Simionescu, I., 1910, Studii geologice i paleontologice din Dobrogea. III. Fauna triasicã dela De li-caïra. La faune triasique de De li-caïra: Academia Românã, Publica iunile Fondului Vasile Adamachi, v. 26, p Simionescu, I., 1913, Studii geologice i paleontologice din Dobrogea. VI. Fauna amoni ilor triasici dela Hagighiol. Les ammonites triasiques de Hagighiol: Academia Românã, Publica iunile Fondului Vasile Adamachi, v. 34, p Waterhouse, J.B., 1999, The early and middle Triassic ammonoid succession of the Himalayas in western and central Nepal. Part 5. Systematic studies of the early Anisian: Palaeontographica, Abteilung A, v. 255, n.1-3, 84 p.

SUBCOMMISSION ON TRIASSIC STRATIGRAPHY ANNUAL REPORT 2003

SUBCOMMISSION ON TRIASSIC STRATIGRAPHY ANNUAL REPORT 2003 1. TITLE OF CONSTITUENT BODY and NAME OF REPORTER Subcommission on Triassic Stratigraphy (STS) SUBMITTED BY: Michael J. Orchard Chairman, STS Geological