Volume n° 1 - from PR01 to B15 32nd INTERNATIONAL GEOLOGICAL CONGRESS THE PALEOZOIC BASEMENT THROUGH THE 500 MA HISTORY OF THE NORTHERN APENNINES Leader: E. Pandeli Associate Leaders: F.A. Decandia, M. Tongiorgi Field Trip Guide Book - B05 Field Trip Florence - Italy August 20-28, 2004 Pre-Congress B05 B05_copertina_R_ok C 28-05-2004, 18:57:04 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 B05_copertina_R_ok D 20-05-2004, 10:39:31 Volume n° 1 - from PR01 to B15 32nd INTERNATIONAL GEOLOGICAL CONGRESS THE PALEOZOIC BASEMENT THROUGH THE 500 MA HISTORY OF THE NORTHERN APENNINES AUTHORS: E. Pandeli (Department of Earth Sciences, University of Florence and CNR-Institute of Earth Sciences and Earth Resources, Florence Section - Italy) F.A. Decandia (Department of Earth Sciences, University of Siena - Italy) M. Tongiorgi (Department of Earth Sciences, University of Pisa - Italy) Florence - Italy August 20-28, 2004 Pre-Congress B05 B05_R_ok A 20-05-2004, 10:48:11 B05_R_ok B 20-05-2004, 10:48:13 THE PALEOZOIC BASEMENT THROUGH THE 500 MA HISTORYOF THE NORTHERN APENNINES B05 Leader: E. Pandeli Associate Leaders: F.A. Decandia, M. Tongiorgi Introduction Dinner and overnight stay in Siena (a visit to Campo Tuscany represents a unique area as the Paleozoic Square and the Cathedral is also included). basement and the overlying, mostly siliciclastic, The third day will be spent visiting the Variscan pre- syn-rift sediments (“Verrucano”) are exposed along fl ysch and fl ysch deposits and the overlying marine the whole Apennine Chain (Vai and Martini, 2001). fossiliferous Permian rocks in the Farma Valley As a whole, these continental-to-marine sedimentary (Monticiano area, South of Siena). Dinner and overnight successions and volcanic rocks record a lengthy stay in Grosseto (visit to the Cathedral Square). geological time interval which includes the Eo- On the fourth day, our last day, we will visit the Caledonian (Middle Ordovician) and the Variscan Upper Permian-Lower Triassic marine siliciclastics orogenic events (Early-Middle Carboniferous), the (Mt. Argentario Sandstones) and their Verrucano post-Variscan extension (Late Carboniferous-Early cover in the Mt. Argentario Promontory. Return to Permian) and the Alpine rifting (Late Permian- Florence in the afternoon. Triassic). In the Oligocene-Middle Miocene times, Useful additional maps and guidebooks: these rocks also experienced the polyphased Alpine - Apuan Alps: Sheets 96 (Massa) and 104 (Pisa) tectono-metamorphism. of the Geological Map of Italy at 1:100.000 During the fi eld trip we will visit the Paleozoic- scale, Geological Survey of Italy; Carmignani L. Carnian type-successions of the Apuan Alps, the (1984)-Carta geologico-strutturale del Complesso Pisani Mountains, Iano, the Monticiano-Roccastrada Metamorfi co delle Alpi Apuane (1:25.000 scale, Foglio Ridge and the Mt. Argentario Promontory. The fi eld nord), Litografi a Artistica Cartografi ca, Firenze; trip stops will allow us to reconstruct the tectono- Carmignani L. et alii (1993) – Tettonica distensiva del sedimentary evolution of the southern part of the Complesso Metamorfi co delle Alpi Apuane, Guida all’ Variscan chain, as well as that of the Triassic rifting in escursione, Università di Siena; Carmignani L. et alii this Adriatic sector of Gondwanaland. The itinerary is (2000)–Carta Geologica del Parco delle Alpi Apuane interesting also from a touristic point of view because (1:50.000 scale), S.E.L.C.A., Firenze. it crosses typical Tuscan landscapes (the Versilia - Pisani Mountains: Sheets 104 (Pisa) and 105 coast, the lower Arno Valley, the Chianti and Siena (Lucca) of the Geological Map of Italy at 1:100.000 hills, and Maremma) as well as artistic towns (Pisa, scale, Geological Survey of Italy; Rau A. & Tongiorgi S.Gimignano, and Siena). A logistical summary of the M. (1974)–Carta Geologica dei Monti Pisani a fi eld trip follows (starting from Florence): sud-est della Valle del Guappero (1:25.000 scale), The subject of the fi rst day will be the Paleozoic- Litografi a Artistica Cartografi ca, Firenze. Triassic successions of the Apuan Alps in the - Iano: Sheet 112 (Volterra) of the Geological Map Levigliani-Mt. Corchia area (SE of Massa), where a of Italy at 1:100.000 scale, Geological Survey of typical Upper Cambrian-Silurian/Devonian section Italy; Costantini et alii (1991)–Carta Geologica di of the Tuscan basement is well exposed and is Iano (Prov. di Firenze) (1:5.000 scale), S.E.L.C.A., unconformably overlain by the basal siliciclastics Firenze; (Verrucano) and carbonates of the Alpine sedimentary - Farma Valley (Monticiano-Roccastrada Ridge): cycle. Impressive “natural” geological cross-sections Sheet 120 (Siena) of the Geological Map of Italy at 1: of the Apuan metamorphic core and views onto the 100.000 scale, Geological Survey of Italy; famous marble quarries represent points of additional - Mt. Argentario Promontory: Sheet 135 (Orbetello) interest for this fi eld trip. Dinner and overnight stay of the Geological Map of Italy at 1:100.000 scale, will be in Pisa (with a visit to “the Square of Miracles” Geological Survey of Italy; Gianniello et alii where the Leaning Tower is). (1964)–Carta Geologica del Monte Argentario e del PRO1 to B15 n° 1 - from Volume The second day will focus on the Paleozoic-Carnian Promontorio del Franco (Isola del Giglio), Litografi a successions of the Pisani Mountains (Northwest of Artistica Cartografi ca, Firenze. Pisa) and Iano (North of Volterra) where peculiar sections of late-/post-Variscan (Upper Carboniferous- Regional geological setting Permian) continental-to- marine sedimentary cycles F.A. Decandia & E. Pandeli and the overlying “classic” Verrucano type-successions The Northern Apennine chain (Figure 1) developed are exposed. View of S.Gimignano, a medieval town. after the closure of the Ligurian Ocean (a narrow arm 3 - B05 B05_R_ok 3 20-05-2004, 10:49:27 Leaders: E. Pandeli B05 Figure 1 - Geological sketch map(A) and section (B) of the Northern Apennines (after Elter & Pandeli, 1996). of the Jurassic Tethys) and the subsequent collision of orogenies and magmatism (Pandeli et alii, 1994, the European (i.e. Corsica-Sardinia block) and African and references therein), and with the subsequent fi rst (i.e. Adria microplate) continental margins during the marine transgression, which marked the beginning Oligocene-Aquitanian interval (Vai and Martini, of the Alpine sedimentary cycle. The transgression 2001, and references therein). The geological history over the Variscan mainlands gave rise to a SW- of the Northern Apennines can be divided into three NE trending epicontinental basin which occupied main stages: 1) a pre-collisional stage in which the a tectonic depression(s) bounded by extensional depositional processes were dominant; 2) a collisional faults. The Anisian-Ladinian transgressive deposits stage in which compressional and metamorphic are represented by: a) the lower siliciclastic and processes developed; and 3) a post-collisional stage carbonatic sedimentary cycle of Punta Bianca-Massa in which extensional and shortening processes (NW of Apuan Alps) which includes alkaline basalts Volume n° 1 - from PRO1 to B15 n° 1 - from Volume developed in the inner (i.e. western) and in the outer (Passeri, 1985; Martini et alii, 1986 and references (i.e. eastern) zones, respectively. The extensional therein); b) part of the Cala Piatti carbonatic process was accompanied by magmatism. succession outcropping at Mt. Argentario (Decandia and Lazzarotto, 1980); and c) the pink limestone Pre-collisional stage clasts, derived from a carbonate platform, which This began during the Anisian with the extension occur within the Triassic Verrucano of the Farma of the continental crust, which had previously area, south of Siena (Cocozza et alii, 1975). At experienced the Eo-Caledonian and Variscan the end of the Ladinian, the eastern margin of the B05 - B05_R_ok 4 20-05-2004, 10:49:30 THE PALEOZOIC BASEMENT THROUGH THE 500 MA HISTORYOF THE NORTHERN APENNINES B05 carbonate platform emerged and regional extensional - The Sub-Ligurian Domain. This occupies the processes produced new, wide, sedimentary basins transitional area between the Ligurian Domain and in which the siliciclastic fl uvial and coastal deposits the Tuscan Domain, and is characterized by pelagic of the Verrucano Group accumulated (Tongiorgi et ?Upper Cretaceous/Paleocene-Oligocene, shaly- alii, 1977; Costantini et alii, 1987/88; Pandeli, 2002). calcareous-arenaceous successions. Locally-reworked mafi c volcanics were also found - The Tuscan Domain. This consists of continental (Costantini