Volume n° 5 - from P37 to P54 32nd INTERNATIONAL GEOLOGICAL CONGRESS TRIASSIC CARBONATE PLATFORMS OF THE DOLOMITES: CARBONATE PRODUCTION, RELATIVE SEA-LEVEL FLUCTUATIONS AND THE SHAPING OF THE DEPOSITIONAL ARCHITECTURE Leader: M. Stefani Associate Leaders: P. Brack, P. Gianolla, L. Keim, F. Mauer, C. Neri, N. Preto, A. Riva, G. Roghi, F. Russo Field Trip Guide Book - P44 Field Trip Florence - Italy August 20-28, 2004 Post-Congress P44 P44_copertina_R_OK C 18-06-2004, 14:40:21 The scientific content of this guide is under the total responsibility of the Authors Published by: APAT – Italian Agency for the Environmental Protection and Technical Services - Via Vitaliano Brancati, 48 - 00144 Roma - Italy Series Editors: Luca Guerrieri, Irene Rischia and Leonello Serva (APAT, Roma) English Desk-copy Editors: Paul Mazza (Università di Firenze), Jessica Ann Thonn (Università di Firenze), Nathalie Marléne Adams (Università di Firenze), Miriam Friedman (Università di Firenze), Kate Eadie (Freelance indipendent professional) Field Trip Committee: Leonello Serva (APAT, Roma), Alessandro Michetti (Università dell’Insubria, Como), Giulio Pavia (Università di Torino), Raffaele Pignone (Servizio Geologico Regione Emilia-Romagna, Bologna) and Riccardo Polino (CNR, Torino) Acknowledgments: The 32nd IGC Organizing Committee is grateful to Roberto Pompili and Elisa Brustia (APAT, Roma) for their collaboration in editing. Graphic project: Full snc - Firenze Layout and press: Lito Terrazzi srl - Firenze P44_copertina_R_OK D 26-05-2004, 15:11:36 Volume n° 5 - from P37 to P54 32nd INTERNATIONAL GEOLOGICAL CONGRESS TRIASSIC CARBONATE PLATFORMS OF THE DOLOMITES CARBONATE PRODUCTION, RELATIVE SEA-LEVEL FLUCTUATIONS AND THE SHAPING OF THE DEPOSITIONAL ARCHITECTURE AUTHORS: M. Stefani1, P. Brack2, P. Gianolla1, L. Keim3, A. Mastandrea4, F. Mauer5, C. Neri1, N. Preto6, E. Ragazzi6, A. Riva1, G. Roghi7, F. Russo4 1 Università di Ferrara - Italy 2 ETH, Zürich - Switzerland 3 Boze Autonome Provinz - Italy 4 Università di Calabria - Italy 5 Petroleum Institute - Abu Dhabi 6Università di Padova - Italy 7CNR Padova - Italy Florence - Italy August 20-28, 2004 Post-Congress P44 P44_R_OK A 4-06-2004, 11:29:14 Front Cover: Middle Triassic, clinostratifi ed slope breccias forming the southern portion of the Catinaccio-Rosengarten Massif, here visible in a spectacular summer sunset light. P44_R_OK B 4-06-2004, 11:29:17 TRIASSIC CARBONATE PLATFORMS OF THE DOLOMITES CARBONATE PRODUCTION, RELATIVE SEA LEVEL FLUCTUATIONS AND THE SHAPING OF THE DEPOSITIONAL ARCHITECTURE P44 Leader: M. Stefani Associate Leaders: P. Brack, P. Gianolla, L. Keim, F. Mauer, C. Neri, N. Preto, A. Riva, G. Roghi, F. Russo Introduction (Gaetani et al. 1981, Senowbari-Daryan et al., 1993; Gianolla P. and Stefani M. Russo et al., 1998b, 2000), the biostratigraphic The spectacular Triassic outcrops of the Dolomites and chronological framework was substantially have been playing a major role in the understanding refi ned (Brack & Rieber, 1993; Mietto and Manfrin, of the carbonate platforms since the XIX Century, 1995a), the sequence stratigraphic understanding as witnessed by a the huge number of publications, was enhanced through basin-platform correlation mainly written by German, English, French and and refi ned dating (Gianolla et al., 1998a and Italian speaking geologists. The seminal studies references herein). During the last 20 yr, the origin by Richthofen (1860) and Mojsisovics (1879) of the platform-top sedimentary cyclicity (Figure already recognized the “reef” nature of the 1.2) has triggered a hot debate, particularly on the Dolomite platforms, described their steep slope interpretation of the Latemar Platform (Goldhammer clinostratifi cations (Ueberguss-Schichtung), and et al., 1990; Brack et al., 1996; Egenhoff et al., provided a fi rst bio-chrono-stratigraphic framework 1999; Preto et al., 2001), without, for the time being, (Figure 1.1). After a somewhat extenuate research reaching any eventual conclusion. period during the fi rst half of the XX century, great The Dolomites Region is placed at the junction attention was refocused on the Dolomites successions between German, Italian and Ladin speaking areas through the last 40 years. During this time interval, and each individual place is therefore often described a fi rst geometric and sequence stratigraphic synthesis by three quite different names (e.g. Rosengarten = was achieved (Bosellini, 1984), the major role of the Catinaccio = Cadenàc, second c pronounced as in non coralline bioconstructors and the importance of child), the use of which is still triggering sensitive the synsedimentary cementation were recognized socio-political emotions. The intrinsic stratigraphic Figure 1.1 - The Mojsisovics’ (1879) “prophetic” geological profi le of the visited Cernera – Crepa de Formìn carbonate platforms. The geometric relationships between the depositional bodies are essentially depicted as in the modern P37 to P54 n° 5 - from Volume interpretation, even if some minor brittle tectonic structures are missing and the chonological interpretation provided by the original German text is somewhat different form the modern one. Moving from SW to NE, observe the fault, presently considered as an overthrusting of Permian evaporites (a Bellerophon Schichten) onto Middle Triassic volcanogenic units (g Augitporphyrtuffe), the Anisian Upper Serla Plafrorm (Unterer Mushelkalk), the low relief Contrìn Platform (d Oberer Mushelkalk) interfi ngering with Dont Fm basinal beds (e Buchensteiner Schichten), the aggradational-retrogradational uppermost Anisian Cernera Platform (g Wengener Dolomit), which was terminated by an early drowning and onlapped by terrigenous and volcanoclastic beds (f Augitporphyrtuffe and g Wengener Schichten), followed by basinal argillaceous-calcareous beds (Cassianer Schichten), shallowing up into a Cassian platform (h Cassianer Dolomit). For further explanation see introduction and Day 4 texts. 3 - P44 P44_R_OK 3 26-05-2004, 15:21:31 Leader: M. Stefani P44 Figure 1.2 - A spectacular view of the cyclic Latemar platform-top succession, punctuated by high frequency emersion surfaces, the interpretation of which has triggered a hod debate, through the last 20 years. Coeval platform and basinal units will be visited during the trip. variety, the long lasting geological research history structural framework and were severely affected by and the glottological complexity of the area a Middle Triassic magmatic event. The trip will move combine to make the stratigraphic terminology of from west to east, starting with Anisian-Ladinian the Dolomites quite a complex one indeed. We have pre-volcanic platform and basin carbonates (Schlern made some effort to simplify the intricate litho-bio- Day 1; Seceda, Odle, Day 2), to move then on other chrono-sequence stratigraphic terminology, but we pre- (Cernera, Day 4; Marmolada, Day 6) and post- nevertheless felt compelled to still give an articulate volcanic (Sella, Day 3) isolated high relief platforms. stratigraphic picture of the Dolomites. The guide The younger visited units consist of Carnian low authors themselves enjoy different linguistic and relief, terrigenous-carbonate units (Falzarego area, scientifi c backgrounds and have sometime expressed Day 5). diverging geological views; the guide editor (M. Stefani), while thoroughly reviewing the paper, Regional tectonic setting has chosen not to impose his personal opinions, The Dolomite Mountains form the central-northern preserving this signifi cant diversity as a scientifi c portion of the Southern Alps (Figure1.3, Doglioni, Volume n° 5 - from P37 to P54 n° 5 - from Volume richness and as a way to illustrate the geological 1987; Castellarin et al., 1998; Castellarin & Cantelli, research in its making, at the risk to expose the reader 2000), a non metamorphic south-vergent thrust belt to some degree of complexity; we hope that the actual belonging to the much larger Alpine Chain and view of the spectacular outcrops of the region will deriving form the comparatively gently deformation clarify any discussion. of a passive continental margin of the Mesozoic The excursion will be aimed at illustrating both basin, Tethys Ocean. The region records several tectonic slope and platform facies, always framed within and magmatic events including: (i) Permian rifting their large depositional geometry. The carbonate and massive magmatism, inducing a lithospheric platforms of the Dolomites grew in quite an active anisotropy that was to signifi cantly infl uence the P44 - P44_R_OK 4 26-05-2004, 15:21:35 TRIASSIC CARBONATE PLATFORMS OF THE DOLOMITES CARBONATE PRODUCTION, RELATIVE SEA LEVEL FLUCTUATIONS AND THE SHAPING OF THE DEPOSITIONAL ARCHITECTURE P44 Figure 1.3 - Structural scheme of the Dolomites and of the surrounding Southernalpine region. (After Castellarin et al. (1981) – modifi ed ). Triassic and Alpine evolution. (ii) Middle Triassic distribution of the stratigraphic units. Only minor (trans-) tensional tectonics, associated with Tertiary basaltic diking is known from the Dolomites differential subsidence and uplifting and climaxing region. A large portion of the present elevation was into a magmatic event. The short-lived Ladinian event generated during the last 5 million years, even during induced epicrustal intrusions (Monzoni, Predazzo, the Quaternary times, which saw the development of Cima Pape) and a signifi cant shoshonitic volcanism several massive glacial episodes, the imprinting of (Sloman, 1989). A late Ladinian slowing down of which is visible