The Elba Island: an Intriguing Geological Puzzle in the Northern Tyrrhenian Sea 85° Congresso Nazionale Della Società Geologica Italiana, Pisa 6-8 Settembre 2010

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Geological Field Trips

Società Geologica Italiana

2013 Vol. 5 (2.1) ISPRA Istituto Superiore per la Protezione e la Ricerca Ambientale

SERVIZIO GEOLOGICO D’ITALIA Organo Cartografico dello Stato (legge N°68 del 2-2-1960) Dipartimento Difesa del Suolo

ISSN: 2038-4947

The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea 85° Congresso Nazionale della Società Geologica Italiana, Pisa 6-8 settembre 2010

DOI: 10.3301/GFT.2013.03 The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - F. Menna - G. Nirta GFT - Geological Field Trips geological fieldtrips2013-5(2.1) Periodico semestrale del Servizio Geologico d'Italia - ISPRA e della Società Geologica Italiana Geol.F.Trips, Vol.5 No.2.1 (2013), 114 pp., 61 figs. (DOI 10.3301/GFT.2013.03)

The Elba Island: an intriguig geological puzzle in the Northern Tyrrhenian Sea 85° Congresso Nazionale della Società Geologica Italiana, Pisa 6-8 settembre 2010 Enrico Pandeli*,**, Gianfranco Principi*,**, Valerio Bortolotti*, Marco Benvenuti*, Milvio Fazzuoli*, Andrea Dini***, Franco Fanucci****, Francesco Menna*, Giuseppe Nirta* * Earth Sciences Department, University of Florence – Via G.La Pira, 4 – 50121 Florence (Italy) ** IGG-CNR, Section of Florence – Via G.La Pira, 4 – 50121 Florence (Italy) ***I GG-CNR, CNR Pisa Research Area - Via G. Moruzzi, 1 - 56124 Pisa (Italy) ***** Geosciences Department, University of Trieste - Via Weiss, 2 - 34127 Trieste (Italy)

Corresponding Author e-mail address: [email protected] Responsible Director Claudio Campobasso (ISPRA-Roma) Editorial Board Editor in Chief Gloria Ciarapica (SGI-Perugia) M. Balini, G. Barrocu, C. Bartolini, 2 Editorial Responsible D. Bernoulli, F. Calamita, B. Capaccioni, Maria Letizia Pampaloni (ISPRA-Roma) W. Cavazza, F.L. Chiocci, R. Compagnoni, D. Cosentino, Technical Editor S. Critelli, G.V. Dal Piaz, C. D'Ambrogi, Mauro Roma (ISPRA-Roma) P. Di Stefano, C. Doglioni, E. Erba, publishing group R. Fantoni, P. Gianolla, L. Guerrieri, Editorial Manager Maria Luisa Vatovec (ISPRA-Roma) M. Mellini, S. Milli, M. Pantaloni, V. Pascucci, L. Passeri, A. Peccerillo, Convention Responsible L. Pomar, P. Ronchi (Eni), Anna Rosa Scalise (ISPRA-Roma) B.C. Schreiber, L. Simone, I. Spalla, Alessandro Zuccari (SGI-Roma) L.H. Tanner, C. Venturini, G. Zuffa. ISSN: 2038-4947 [online]

http://www.isprambiente.gov.it/it/pubblicazioni/periodici-tecnici/geological-field-trips

The Geological Survey of Italy, the Società Geologica Italiana and the Editorial group are not responsible for the ideas, opinions and contents of the guides published; the Authors of each paper are responsible for the ideas, opinions and contents published. Il Servizio Geologico d’Italia, la Società Geologica Italiana e il Gruppo editoriale non sono responsabili delle opinioni espresse e delle affermazioni pubblicate nella guida; l’Autore/i è/sono il/i solo/i responsabile/i. DOI: 10.3301/GFT.2013.03 The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - F. Menna - G. Nirta

INDEX geological fieldtrips2013-5(2.1)

Information Tectonic evolution of Elba Island ...... 39 Accretionary stage ...... 39 Recommendations ...... 5 Pre-intrusion extensional stage ...... 39 Riassunto ...... 6 Syn- and post-intrusion stage ...... 41 Abstract ...... 11

Excursion notes Itinerary

Introduction ...... 15 Eastern Elba Island ...... 44 The tectonic unit of the Elba Island ...... 17 Stop 1. The tectonic units of the Spiagge Nere area ...... 45 The model of Trevisan ...... 17 Stop 2. Fe-ores of the Terranea area ...... 48 The new model ...... 20 Stop 3. The tectonic stack of the Ortano Valley (Ortano, Porto Azzurro unit “AU” (Complex I) ...... 20 Acquadolce, Monticiano-Roccastrada, Tuscan Nappe, Ortano unit “UO” (Complex II pp.) ...... 21 Gràssera units) ...... 49 Acquadolce unit “AU” (Complex II pp.) ...... 21 Stop 4. The calcshist bodies and the skarn of Torre di Rio ...... 54 Monticiano-Roccastrada unit “MU” (Complex III pp.) ...... 22 Stop 5. The Rio Marina mining area ...... 55 3 Tuscan Nappe “TN” (Complex III pp.) ...... 22 The Tuscan Nappe South of Cavo ...... 57 Gràssera unit “GU” (Complex III pp.) ...... 22 Stop 6. The Tuscan nappe succession ...... 58 Ophiolitic unit “OU” (Complex IV) ...... 23 The Tuscan epimetamorphic succession of Capo Eocene flysch unit “EU” (Complex V pp.) ...... 24 Castello ...... 61 Cretaceous flysch unit “CU” (Complex V pp.) ...... 24 Stop 7. The Tuscan epimetamorphic succession, Cala Mio-Pliocene magmatism in the Northern Apennines dell’Alga ...... 61 and in the tuscan Archipelago ...... 26 The Gràssera and ophiolitic units ...... 63 Tuscan Province Magmatic Rocks ...... 26 Stop 8. The Gràssera unit ...... 63 Elba Island ...... 27 Stop 9. The Gorgoli anticline ...... 64 Petrogenesis of the Elba Island granitoids ...... 30 Stop 10. The thrust contact Tuscan Nappe-Gràssera unit ....65

Ore deposits of Southern Tuscany and Elba Island: an Stop 11. The ophicalcites ...... 66 index overview ...... 32 Stop 12. The base of the Nisportino formation ...... 66 The Fe deposits of Elba Island ...... 34 Stop 13. The Nisportino formation ...... 67 The geological features of the marine area around the Stop 14. Pillow lavas ...... 69 Elba Island ...... 37 Stop 15. San Felo ophiolitic succession ...... 69

Stop 16. Fosso Acquaviva, serpentinites ...... 71 Stop 17. Monte Castello-Cima del Monte Pass. The folded structure of the Volterraio subunit and the shoshonitic dyke ..72 Western and Celtral Elba ...... 75 Stop 18. View on the Western Elba and the Cretaceous flysch unit of the Central Elba ...... 76 Stop 19. The rocks of the inner part of the M.Capanne contact metamorphic aureole ...... 77 Stop 20. The “eurite” quarry (S. Rocco or Cava di Caolino) ....80 Stop 21. The Monte Capanne monzogranite ...... 81 The ophiolitic units of western Elba ...... 89 Stop 22. The ophiolitic rocks of Punta Nera area ...... 90 4 The ophiolitic units of Pomonte-Fetovaia area ...... 93 Stop 23. The metamorphic metasediments of the Ogliera Bridge area ...... 93 Stop 24. The Tertiary flysch unit of the Fetovaia area ...... 95 Stop 25. The Tertiary flysch unit of the Central Elba ...... 96 Stop 26. The low-angle tectonic contact (Colle Reciso detachment fault) between the Ophiolitic unit and the underlying Tertiary flysch unit ...... 97 Stop 27. The sheeted dyke complex of the Ophiolitic unit at Colle Reciso ...... 98 The Monte Calamita promontory and its iron ores ....98 index Stop 28. The Calamita mine: Northern sector ...... 103 Stop 29. The Punta Calamita mine: Southern sector ...... 104

References ...... 106

DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1)

5 information ; [email protected] . Or: Via Carducci, . www.aptelba.it [email protected] E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . . Or: Calata Italia, 43 - 57037 - Portoferraio Elba Island (LI), Italy; Tel. . Or: Calata Italia, 43 - 57037 Portoferraio , Palazzo del Buro, via Magenta 26, 57038 Rio Marina del Buro, , Palazzo [email protected] , open from April to October, in , open from April to October, (LI), Italy. Tel. 0039 0565 962088; e-mail Tel. (LI), Italy. , [email protected] Parco Minerario dell’Isola d’Elba Elba Island Parco DOI: 10.3301/GFT.2013.03 150 - 57037 – Portoferraio – (LI), Tel. +39 0565 914671 - Fax +39 0565 914672 (Touristic Information) ; Tel. +39 0565 914672 (Touristic +39 0565 914671 - Fax – (LI), Tel. 150 - 57037 – Portoferraio Office: Bureau); Secretary’s +39 0565 916350 (Administrative +39 0565 930727 - Fax Recommendations Addresses for permissions and information - [email protected] 0039 0565 914671, Fax 0039 0565 914672, Internet Address: 0039 0565 914671, Fax - - APT - Agenzia Per il Turismo dell’Arcipelago Toscano (LI), viale Elba 4, 57037, Toscano dell’Arcipelago il Turismo - APT Agenzia Per 0039 0565; e-mail Tel Elba Island (LI), Italy. Portoferraio, Touristic Information: Touristic the Winter only with previous booking. - Nazionale Arcipelago Toscano Enfola (Portoferraio) Elba Island (LI), Italy Tel. 0039 0565 0039 919411; Fax 0565 919428; e-mail geological field trips 2013 - 5(2.1)

6 information E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 Periods These can be made excursions in all seasons. the climate and For the hours daylight summer the best season but would be it is not recommendedtourist pressure the climate is still good due to the excessive is much lower, influx of but Winter is tourists. In spring and autumn more rainy. usually lesssufficiently the and rainy mild but is definitely shorter. the daylight Equipment For these excursions good a big rig is not necessary, soled shoes collect samples it would beseason are sufficient. To and advisable grippy clothing and goggles. gloves appropriate to the Belowhelmet would be appropriate. In the escarpments the are absolutely necessary Capoliveri) mine galleries (e.g. il Ginevro, both sturdy shoes boots) (preferably and helmet. Riassunto (Appennino Settentrionale) la Toscana fra d’Elba è ubicata nel Mar Tirreno Settentrionale a metà strada L’Isola più l’affioramento e Corsica (Corsica Alpina). Il complesso edificio tettonico dell’Isola d’Elba, che è considerato a ferro e per gli evidenti è anche noto per i suoi giacimenti minerari occidentale della catena nord-appenninica, la messa in posto di corpi magmatici mio-pliocenici e le ultime fasi tettoniche tangenziali. tra rapporti alla scala 1:10.000 e 1:5.000 nell’Il rilevamento Nazionale CARG – ambito del Progetto di Cartografia Foglio 2001a) ha portato alla 2001 e da Bortolotti et al., Isola d’Elba (già parzialmente pubblicato da Babbini et al., dell’Isola d’Elba centro-orientale più articolato rispetto e strutturale stratigrafico ricostruzione di un panorama (1950) e Barberi et al. (1969). Sono stati infatti distinte al classico schema dei cinque “Complessi” di Trevisan Ligure e Piemontese. Prima della loro Toscano, unità tettoniche appartenenti ai domini paleogeografici nove del M. (monzogranito alcune di queste unità sono state intruse da plutoni granitoidi messa in posto, definitiva tipologia (aplitici, shoshonitici, calcalcalini e Azzurro) e da filoni di varia Capanne e di La Serra-Porto 8-2 Ma e 5.4 Ma. lamprofirici) tra geological field trips 2013 - 5(2.1)

7 information E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea (MU). E’ parte costituita dai metasedimenti silicoclastici in gran (PU). E’ costituita da filladi, quarziti, micascisti e anfiboliti (formazione di M. Calamita), (AU). E’ costituita da marmi passanti in alto a calcescisti e quindi filladi, metasiltiti (GU). E’ con scarse intercalazioni calcareo-silicee e composta da argilloscisti varicolori (FT). A Sud della Parata è rappresentata solo da brecce calcareo-dolomitiche spesso a è rappresentata (FT). A Sud della Parata (UO). Questa unità include formazioni metavulcaniche (porfiroidi) e metasedimentarie (UO). Questa unità include formazioni metavulcaniche Unità Monticiano-Roccastrada Unità Ortano Falda toscana Unità Gràssera Unità Acquadolce Unità Porto Azzurro DOI: 10.3301/GFT.2013.03 1- probabilmente di età paleozoica, che presentano una intensa ricristallizzazione a causa del metamorfismo termico probabilmente di età paleozoica, corteo filoniano aplitico (6.0-5.9 Ma). Localmente Azzurro e dal relativo indotto dall’intrusione di La Serra-Porto s.l.) e dolomie calcari dolomitici (Verrucano sono stati riconosciute anche metasedimenti silicoclastici quarzosi di tipo toscano della carbonatica mesozoica attribuibili alla originaria copertura cristallini, verosimilmente unità tettoniche. formazione del M. Calamita. I filoni aplitici si interrompono sul contatto con le soprastanti 2- quarzitico-filladiche (es. gli scisti di Capo d’Arco) correlabili con formazioni di età ordoviciana della Sardegna correlabili con formazioni di età ordoviciana quarzitico-filladiche (es. gli scisti di Capo d’Arco) anche in questa unità lungo la (Alpi Apuane). Alcuni filoni aplitici sono stati osservati e della Toscana centrale e Ortano. Capo D’Arco costa tra 3- metaarenarie con livelli di metacalcari e calcescisti con fossili del Cretacico inferiore. Al tetto è presente una metaarenarie con livelli lama tettonica di serpentiniti. Questa unità è stata attribuita al Dominio Piemontese e correlata con i calcescisti sono presenti alcune intrusioni filoniane con ofioliti dell’Isola di Gorgona. Nell’area del residence Capo d’Arco lamprofiriche (dicchi di Casa Carpini). E’ dei litotipi carbonatici in corpi di skarn tipica la locale trasformazione di Rio). metallici (es. skarn di Torre a silicati e minerali 4- carbonifero-triassici (formazione di Rio Marina del Permo-Carbonifero e gruppo del Verrucano triassico). Ad e gruppo del Verrucano carbonifero-triassici (formazione di Rio Marina del Permo-Carbonifero epimetamorfiche (da calcescisti e calcari essa appartengono anche le successioni giurassico-oligoceniche e presso Capo Pero) (Capo Castello, lungo la costa nell’area di Cavo diasprini allo Pseudomacigno) affioranti del Giove. di Valle l’area mineraria 5- a queste segue parte della tipica Successione Cavo, Auctt.), mentre verso «cellette» (calcare cavernoso superiore-Hettangiano e sedimenti calcareo- toscana comprendente carbonati di mare sottile del Triassico siliceo-marnosi pelagici del Sinemuriano-Dogger. 6- radiolaritiche (formazione di Cavo). Tra Cavo e la Parata, alla base di questa unità è presente un orizzonte e la Parata, Cavo Tra (formazione di Cavo). radiolaritiche forse di età cretacica, è stata attribuita Gràssera, decametrico di calcescisti (membro dei calcescisti). L’unità e per la sua tipica Toscana al Dominio Piemontese per le sue litologie poco confrontabili con quelle della Falda impronta metamorfica anchizonale. geological field trips 2013 - 5(2.1)

8 information E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea (EU). E’ costituita da argilliti con scarse intercalazioni calcareo-marnose, (CU). Questa unità ligure presenta alla base scarsi lembi di una successione (OU). Questa unità di provenienza ligure, è stata suddivisa in 7 subunità, (Acquaviva - ligure, è stata suddivisa in 7 subunità, (Acquaviva (OU). Questa unità di provenienza Unità del flysch paleogenico Unità Ofiolitica Unità del flysch cretacico DOI: 10.3301/GFT.2013.03 calcarenitiche, arenacee e localmente anche di brecce carbonatico-ofiolitiche (formazione di Colle Reciso). Il calcarenitiche, arenacee e localmente anche di brecce carbonatico-ofiolitiche (formazione Colle Reciso). una contenuto fossilifero dei litotipi carbonatici indica un’età medio eocenica. Questa unità rappresenterebbe meridionale. successione oceanica sintettonica (epiligure) sul tipo della formazione di Lanciaia Toscana sericitizzati (“Eurite” Auctt.), e porfidi (porfido di Filoni aplitici (apliti di Capo Bianco: 8-8.5 Ma) talora circa 8 e 7.4-7.2 Ma) intrudono i suddetti litotipi, ma Martino: rispettivamente e porfido di S. Portoferraio il basso non proseguono nell’unità ofiolitica. verso 9- analoga a quella dell’unità ofiolitica (ofioliti, vulcaniti e copertura sedimentaria) che passano a argilliti varicolori analoga a quella dell’unità ofiolitica (ofioliti, vulcaniti e copertura (arenarie di di età cretacica, ed infine ad una potente sequenza torbiditica da arenaceo-conglomeratica (formazione di Marina Campo) età Cretacico superiore. Anche Ghiaieto) a calcareo-marnoso-arenacea questa unità, come la precedente, presenta frequenti ed estese intrusioni di filoni e laccoliti, spesso porfirici, a composizione acida. specialmente nella parte orientale e centrale dell’edificio elbano è caratterizzato, Il presente assetto strutturale dell’isola, dalla presenza di numerose superfici tettoniche a basso angolo (thrusts e detachments), che Est. Alcuni di questi limiti sono chiaramente tettonico verso trasporto unità, con un generale delimitano le varie u. del flysch cretacico su paleogenico), altri (Falda Toscana; su Falda dei thrust (unità Gràssera Azzurro; u. u. del flysch cretacico su ofiolitica; Ortano Porto su u. Monticiano-Roccastrada; Toscana su u. del flysch paleogenico; ofiolitica Volterraio- u. Ofiolitica -sub. su u. Gràssera; ofiolitica -subunità Cavo- e infine le unità 2-9 sulla u. Porto e Volterraio-, Sassi Turchini M. Serra, Bagnaia- su u. ofiolitica -sub. -sub. cataclastico decametrico) sono faglie normali la faglia dello Zuccale sottolineata da un orizzonte tramite Azzurro, ASU, Mt. Serra - SSU, Capo Vita - CSU, Sassi Turchini - TSU, Volterraio- VSU, Magazzini - MSU and Bagnaia VSU, Volterraio- - TSU, Sassi Turchini Capo Vita - CSU, - SSU, Mt. Serra ASU, ma che inferiore sensibilmente diverse, da successioni di età giurassico-cretacica BSU) caratterizzate vulcano-sedimentaria serpentinizzate, oficalciti, Mg-gabbri ed una copertura comunque includono ultramafiti Un filone calcari a Calpionella e Argille Palombini). (basalti, diaspri M. Alpe, formazione di Nisportino, presso Porto shoshonitico (filone di M. Castello: 5,8 Ma) riempie faglie normali nella subunità Volterraio i basalti liguri dalla (filoni di M. Capo Stella) attraversano Alcuni filoni a composizione calc-alcalina Azzurro. parte occidentale del Golfo Stella. 8- 7- geological field trips 2013 - 5(2.1)

9 information nell’Acquadolce datate nell’Acquadolce 2 e S 1 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . La lunga storia geologica dell’Isola d’Elba inizia nel Paleozoico, quando le . La lunga storia geologica dell’Isola d’Elba inizia nel Paleozoico, DOI: 10.3301/GFT.2013.03 19 Ma), nonché, iii- l’impilamento delle unità liguri e piemontesi su quelle toscane (eventi collisionali e di 19 Ma), nonché, iii- l’impilamento delle unità liguri e piemontesi su quelle toscane (eventi i fenomeni di ripiegamento delle suddette unità inferiore); iv- dell’Eocene sup./Oligocene-Miocene serraggio successioni pre-carbonifere associate alle unità toscane inferiori furono oggetto delle deformazioni tettono- sudetico dell’Orogenesi (evento cui sono riconducibili i relitti di scistosità pre-alpina metamofiche varisiche, alle quali seguirono eventi Azzurro e Ortano, presenti nelle rocce metamorfiche delle unità Porto Varisica) medio- nel Trias sedimentari permo-carboniferi legati a bacini estensionali tardo-ercinici. Successivamente iniziò Giurassico superiore ebbe inizio il ciclo sedimentario alpino (Successione toscana). A fine Triassico-inizio tettonica iniziata nel Cretacico L’evoluzione giurassica. della Tetide la fase di rifting che portò all’apertura (Bacino Ligure-Piemontese), portò alla fine della inferiore con la consunzione della Tetide superiore-Terziario il blocco sardo-corso e l’Adria. collisione tra sedimentazione “oceanica” nell’Eocene superiore e alla successiva Da questo momento fino al Miocene inferiore si ha la deformazione polifasica dei margini europeo (Corsica) e In particolare le fasi magmatiche sono precedute da: i- la massima parte dei adriatico (Dominio Toscano). fenomeni plicativi e dei thrust riconosciuti nelle unità ofiolitica, del flysch paleogenico cretacico, deformativi intraoceanici assieme alla genesi di brecce ofiolitiche nell’unità del flysch paleogenico (eventi Azzurro, tettono-metamorfica principale delle unità toscane (Porto dell’Eocene); ii- la strutturazione S e Piemontesi (Acquadolce Gràssera; Toscana) e Falda Monticiano-Roccastrada a basso angolo prodotte dalla tettonica estensionale (attiva probabilmente in questo settore fin dal Burdigaliano- a basso angolo prodotte dalla tettonica estensionale (attiva ai fenomeni magmatici messiniano-pliocenici; altri ancora Langhiano), in tempi precedenti o penecontemporanei sono di su u. Acquadolce; Ofiolitica Gràssera) (u. Acquadolce su u. Ortano; Monticiano-Roccastrada Anche numerose faglie sotto regimi tettonici diversi. agito in tempi diversi complessa interpretazione, avendo (postdatato Un primo sciame, con andamento NE-SO la fase distensiva. normali ad alto angolo caratterizzano Magazzini e tra (unità ofiolitica) nella zona da un filone shoshonitico di 5.8 Ma) interessa la subunità Volterraio che la delaminazione NO-SE Questo sciame viene tagliato da un sistema di faglie trasferimento Azzurro. Porto che ha interessato l’intero edificio deformativo, interrompere. Un ultimo evento della faglia dello Zuccale sembra della faglia che tagliano la superficie suborizzontale NS, da faglie prevalentemente è rappresentato strutturale, dello Zuccale e che localmente ospitano i noti giacimenti ad ematite. magmatici messiniano-pliocenici hanno unità tettoniche e le loro relazioni con gli eventi le diverse tra I rapporti elbano: dell’edificio strutturale permesso di ricostruire la seguente evoluzione Eventi pre-magmatici (>8.5 Ma) geological field trips 2013 - 5(2.1) information 10 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . La risalita del plutone La Serra-Porto Azzurro dette luogo alla . La risalita del plutone Serra-Porto . In questo periodo si ha lo sviluppo e la risalita di magmi anatettici Appennino settentrionale, Arcipelago Toscano, Isola d’Elba, stratigrafia, assetto strutturale, DOI: 10.3301/GFT.2013.03 tettoniche e, infine, v- l’intercalazione dell’unità Acquadolce tra le unità Ortano e Monticiano-Roccastrada. Le le unità Ortano e Monticiano-Roccastrada. l’intercalazione dell’unità Acquadolce tra tettoniche e, infine, v- come la estensionali con faglie a basso angolo, fasi magmatiche sono precedute anche dai primi eventi (Miocene inferiore-medio). sull’unità Monticiano-Roccastrada Toscana della Falda sovrapposizione Eventi sin-magmatici (8.5-5.4 Ma) connessi alla risalita dell’astenosfera e all’assottigliamento crostale. Durante la risalita del plutone M. Capanne e all’assottigliamento crostale. Durante connessi alla risalita dell’astenosfera costituita dalle unità dei flysch, già intrusi da apliti e porfiriti, si scolla scorre (6.8 Ma) parte della sua copertura, questo - CEF). Durante oriente utilizzando una superficie a basso angolo (faglia dell’Elba centrale verso più ad est, a 5.8 Ma, si intrude un i processi di euritizzazione delle apliti (6.7 Ma). Poco avvengono movimento filone basico nell’unità ofiolitica e probabilmente anche quelli lamprofirici Acquadolce. Il prosieguo della est delle unità dei flysch sull’unità ofiolitica verso risalita del M. Capanne permise poi un ulteriore avanscorrimento NW-SE, e lo sviluppo delle faglie di trasferimento Azzurro, e di tutte le unità già impilate sulla Porto A 6.0-5.4 Ma la messa in posto del monzogranito delle unità in movimento. laterali probabilmente legate a rampe Azzurro e del suo complesso filoniano produsse l’estesa aureola termometamorfica attraverso di La Serra-Porto e, localmente, anche gli skarn. Acquadolce, Monticiano-Roccastrada Ortano, Azzurro, le unità Porto Eventi post-magmatici (< 5.4 Ma) e all’allontanamento dell’embrice tettonico dell’Elba orientale dalle corrispondenti unità separazione sfruttando una già esistente superficie tettonica a basso angolo (faglia dello Zuccale) al tetto centrale, Azzurro, del plutone di La Serra-Porto In questa fase, sempre legato al sollevamento Azzurro. dell’unità Porto si ebbe anche il retroscorrimento dell’unità ofiolitica sull’unità del flysch paleogenico nell’area di Colle Reciso. Come ultimo evento il suo completamento. La pila tettonica dell’Elba centro-orientale ha così raggiunto che hanno prodotto la tettonico si sviluppò un sistema di faglie normali ad alto angolo con orientazione N-S di costituire permettendo così ai fluidi mineralizzanti dell’edificio orogenico, a horst e graben frammentazione ad ematite (5.3 Ma). i corpi minerari del nel contesto dell’evoluzione all’Isola d’Elba è stata poi inquadrata relativa Questa ricostruzione degli eventi da una serie di schemi tettonici relativi all’intervallo Settentrionale, e illustrata sistema Corsica-Appennino Cretacico superiore - Attuale. chiave: Parole magmatismo, metamorfismo, giacimenti a ferro, geodinamica. geological field trips 2013 - 5(2.1) information 11 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea ). It is made up of phyllites, quartzites, micaschists and amphibolites (Mt. Calamita ). It is made up of phyllites, ). It is composed of marbles, grading upwards into calcschists and, finally, into into calcschists and, finally, upwards ). It is composed of marbles, grading PU ( AU ( ). It includes metavolcanites (porphyroids) and quartzitic-phyllitic metasediments (e.g. and quartzitic-phyllitic (porphyroids) ). It includes metavolcanites UO ( Acquadolce Unit Ortano Unit Porto Azzurro Unit DOI: 10.3301/GFT.2013.03 phyllites, metasiltstones and metasandstones with intercalations of calcschists which contain fossils Early phyllites, Capo d’Arco schists) which can be correlated to the Ordovician formations of Central Sardinia and Tuscany formations of Central schists) which can be correlated to the Ordovician Capo d’Arco were also recognised, and they occur along the coast between Capo d’Arco (Apuan Alps). A few aplitic dikes and Ortano. 3- Abstract The Elba (Northern Apennines between Tuscany Sea at midway Island is located in the Northern Tyrrhenian pile). The complex ElbaChain) and Corsica (Alpine structural I. stack of nappes, which is considered bodies and the the innermost outcrop of Northern Apennines Chain, is also well known for its Fe-ore relationships between the emplacement of Mio-Pliocene magmatic bodies and tectonics. of ElbaThe CARG geological survey I. performed at a scale of 1:10.000 and 1:5.000 , partially published by setting and structural Babbini et al. (2001) and Bortolotti (2001a) allowed a revision of the stratigraphic classical one, and eastern Elba I. This new scheme results more complex compared to Trevisan’s of the central 1969). Nine tectonic units 1950; Barberi et al., (Trevisan, tectonic “Complexes” based only on five which was and Ligurian (including the Ligurian-Piedmontese units) were defined, and they all pertain to the Tuscan tectonic pile, some of these units were domains. Before their final emplacement the Elba’s paleogeographic intruded by two acidic plutons (Mt. of and by dikes Azzurro monzogranites), Capanne and La Serra-Porto composition during the 8.5 to 5.4 Ma time interval. variable A total of nine units were recognised, from bottom to top: 1- fm.), probably of Paleozoic age. It shows a strong static recrystallisation due to the La Serra-Porto Azzurro age. It shows a strong static recrystallisation due to the La Serra-Porto fm.), probably of Paleozoic quartzitic network (6.0-5.4 Ma). On top of the Mt. Calamita fm., intrusion and the related aplitic dike s.l.) and crystalline dolostones dolomitic marbles were recognised metasiliciclastics (Verrucano are cut along the tectonic contact (Zuccale fault) with The aplitic dikes cover. attributed to its Mesozoic units described below. overlying 2- geological field trips 2013 - 5(2.1) information 12 ”), VSU ”, Mt. ”, BSU ASU ” and Bagnaia “ MSU ”, Magazzini “ ”, VSU ”, Volterraio “ Volterraio ”, E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. TSU The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea ). This Tuscan Unit largely consists of Upper Carboniferous-Triassic ). This Tuscan MU ( ). It is constituted by shales with calcareous-marly, calcarenitic and arenaceous ). It is constituted by shales with calcareous-marly, ”, Sassi Turchini “ Sassi Turchini ”, EU ( CSU ). This Ligurian Unit is composed of seven tectonic subunits (Acquaviva “ tectonic subunits (Acquaviva ). This Ligurian Unit is composed of seven ). South of the locality La Parata, this unit is composed only of calcareous-dolomitic, at ). South of the locality La Parata, ). It mostly consists of varicoloured slates with rare carbonate-siliceous and radiolarian slates with rare ). It mostly consists of varicoloured OU ( TN GU ( ( ”, Capo Vita “ ”, SSU Monticiano-Roccastrada Unit Ophiolitic Unit Gràssera Unit Tuscan Nappe Paleogene flysch unit DOI: 10.3301/GFT.2013.03 times vacuolar, breccias (“Calcare Cavernoso”), while northwards these rocks are overlain by Upper Triassic to by Upper Triassic these rocks are overlain while northwards breccias (“Calcare Cavernoso”), times vacuolar, Hettangian shallow marine carbonates, and Sinemurian to Dogger carbonatic, siliceous marly pelagic sediments. 6- Cretaceous age. This Unit has been attributed to the Ligurian Domain (Ligurian-Piedmontese units) and can be correlated with the “calcschists ophiolites” of Gorgona residence, some Island. Near Capo d’Arco into Fe- the carbonate lithotypes are transformed Locally, also occur. (Casa Carpini dikes) dikes lamprophyric skarn bodies. 4- metasiliciclastic rocks (the Permian-Carboniferous Rio Marina fm. and the triassic “Verrucano” group). It also Rio Marina fm. and the triassic “Verrucano” metasiliciclastic rocks (the Permian-Carboniferous to Oligocene epimetamorphic succession (from the calcschists and cherty limestones of includes a Jurassic and Capo Capo Castello calcschists, to the Pseudomacigno) which crops out along coast between Pero mining area. Giove and in the Valle Castello, 5- cherts intercalations (Cavo fm.). Between Cavo and La Parata, a basal decametric calcschist member also and La Parata, fm.). Between Cavo cherts intercalations (Cavo been originated in the Ligurian occurs. This anchimetamorphic unit, possibly of Cretaceous age, could have it is considered a Ligurian- Domain: because of its peculiar lithologic association and metamorphic overprint Piedmontese Unit. 7- Serra “ Serra which are characterised by serpentinites, ophicalcites, Mg-gabbros, and by their Jurassic to Lower Cretaceous by serpentinites, ophicalcites, Mg-gabbros, and their Jurassic which are characterised Calpionella limestones and Palombini (Basalts, Mt. Alpe cherts, Nisportino fm., cover volcanic-sedimentary normal faults cutting 5.8 Ma) fills two ENE-WSW-trending (Mt. Castello Dike: shales). A shoshonitic dike were also identified in the Ligurian (Mt. Capo Stella dikes) dikes Azzurro area. Some calc-alkaline in the Porto basalts along the western coast of Golfo Stella. 8- fm.). The fossiliferous content of the breccias (Colle Reciso by ophiolitic-carbonate intercalations and, locally, carbonate lithotypes points to a Middle Eocene age. This unit can be interpreted as syn-tectonic oceanic aplites origin of the Lanciaia fm. in Southern Tuscany. (Epiligurian Unit), which has the same paleogeographic geological field trips 2013 - 5(2.1) information 13 PU ) and Ligurian- MU , UO , PU , possibly related to Eocene intra- PU E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . They are recorded by: a- relics of the pre-Alpine schistosity within . They are recorded by: a- relics of the pre-Alpine (ophiolites, basalts and Jurassic-Cretaceous sedimentary cover slices), and sedimentary cover (ophiolites, basalts and Jurassic-Cretaceous ). It is a Ligurian, Helminthoid-type, oceanic succession. consists of basal OU CU ( , with production of ophiolitic-carbonate breccias within , with production of ophiolitic-carbonate CU and , which can be attributed to the Sudetic phase of the Variscan orogeny; b- folding and thrusting of the orogeny; , which can be attributed to the Sudetic phase of Variscan EU UO , Cretaceous flysch unit DOI: 10.3301/GFT.2013.03 OU of a sedimentary succession formed by Cretaceous Palombini shales and Varicoloured shales, which grade shales and Varicoloured of a sedimentary succession formed by Cretaceous Palombini (Ghiaieto sandstones) and then to a calcareous-marly-arenaceous into an arenaceous-conglomeratic upwards this unit is frequently intruded by (Marina di Campo fm.) flysch of Upper Cretaceous Age. Similar to the EU, and laccoliths. locally thick acidic dikes units (units 2- by a pile of eight structural and eastern Elba is characterised setting of central The structural onto the lowermost Porto by low angle tectonic surfaces (thrusts and detachments), which lays 9), separated (Zuccale by a decametric cataclastic horizon detachment fault marked Azzurro Unit (Unit 1) by a low-angle been tentatively fault and related cataclasite). The thrust surfaces (Upper Eocene-Early Miocene) have detachments, due to the extensional tectonics, which probably began during distinguished from the low-angle accompanied by magmatic Burdigalian-Langhian, and continued during Messinian-Pliocene times, was from the intrusions. Other low angle tectonic surfaces are of complex interpretation because they derived which occurred in different times and/or tectonic regimes. Among superposition of tectonic events preceded and followed fault system, which was trending transfer faults, we recognised a NW-SE the high-angle faults cut The N-S-trending trends, respectively. and N-S of normal faults, with WSW-NNE by two generations the whole tectonic pile, comprising all detachment faults. The study of the tectonic relationships between previous nine units and these suggests the following geological scenario for evolution units and the Messinian-Pliocene magmatic events, of the Elba Island: 1) Pre-magmatic stages (>8.5 Ma) and oceanic deformation events; c- main deformation and metamorphic events of Tuscan ( of Tuscan main deformation and metamorphic events c- oceanic deformation events; (Capo Bianco aplites: 8-8.5Ma), locally sericitised (the so-called “Eurite”), and porphyries (Portoferraio (Capo Bianco aplites: 8-8.5Ma), locally sericitised (the so-called “Eurite”), and porphyries intrude the sedimentary about 8 Ma and 7.4-7.2 Ma, respectivelly) and San Martino porphyries: porphyries succession, but do not crosscut the basal contact with underlying Ophiolitic Unit. 9- tectonised complex, similar to geological field trips 2013 - 5(2.1) information 14 , ) in in and CU UO onto , + CU OU + EU TN EU PU , EU onto GU , CU onto + OU , OU EU AU . The superposition of MU onto TN , and of MU and E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. ) and overthrusting of the oceanic units ( ) and overthrusting OU The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea AU in . This phase begins with the genesis and rise of anatectic melts due . High-angle, N-S trending normal faults dismembered the orogenic N-S . High-angle, 2 between AU relics and 19 Ma S 1 ”). During this event the acidic dykes of the basal part flysch were sericitised (“eurite”: the acidic dykes ”). During this event . The uplift of this granitoid caused, or completed, the separation of the eastern and central Elba of the eastern and central caused, or completed, the separation . The uplift of this granitoid CEF Northern Apennines, Tuscan Archipelago, Elba Island, stratigraphy, structural setting, magmatism, MU (already injected by acidic dikes), was detached and shifted eastwards along a low-angle fault (Central along a low-angle detached and shifted eastwards was (already injected by acidic dikes), and DOI: 10.3301/GFT.2013.03 onto the Tuscan ones, probably related to the Oligocene-Early Miocene collisional events; d- refolding of the ones, probably related to the Oligocene-Early Miocene collisional events; onto the Tuscan tectonic units and emplacement of MU can be considered the older extensional event by low-angle detachments (Middle Miocene). by low-angle MU can be considered the older extensional event 2) Syn-magmatic stages (8.5-5.4 Ma) to the uplift of asthenospheric mantle, within stretched inner part Apenninic orogenic belt. During the uprise of Mt. constituted by that was (6.8 Ma), the most of its cover, Capanne granitoid CU Elba fault, “ the Colle Reciso area, and the gliding north- or north-eastwards of CSU, completed the present tectonic frame of CSU, area, and the gliding north- or north-eastwards the Colle Reciso and eastern Elba. of central 3) Post-magmatic events (<5.4 Ma) fluids, with the formation of hematite-rich pile and allowed the final circulation of idrothermal-mineralising ores of eastern Elba, dated ~5.3 Ma. Thus, our reconstructions of Elba of the Island to geodynamic context I. relate the tectonic evolution starting the orogenic system Corsica-Northern Apennines. Furthermore, we offer a series of tectonic sketches from the Upper Cretaceous to Recent. words: Key metamorphism, Fe-ores, geodynamics. the central Elba, and the development of transfer faults (as lateral ramps of detachments) within the Ligurian ramps faults (as lateral of transfer Elba, and the development the central 6.0-5.4 Ma the emplacement of La Serra-Porto the onset of Zuccale fault. At units and, probably, produced a wide thermometamorphic aureola and local skarn bodies within the host Azzurro granitoid 6.7 Ma). Farther east, a shoshonitic dike intruded OU at 5.8 Ma and, possibly, lamprophyric dikes were dikes lamprophyric intruded OU at 5.8 Ma and, possibly, east, a shoshonitic dike 6.7 Ma). Farther A new uplift of the Mt.emplaced within AU. of Capanne caused a further glide eastwards Piedmontese units (S tectonic pile through the Zuccale detachment fault. During this stage, the back-gliding of tectonic pile through the Zuccale detachment fault. During this stage, back-gliding AU geological field trips 2013 - 5(2.1) excursion notes 15 Basin) and going up to the collision and successive polyphase collision and successive deformation of the European Western Tethys (Liguria-Piedmont Tethys Western (Corsica) and Adriatic (Tuscany consumption of the Mesozoic Domain) margins (Boccaletti et al., slightly modified (Barberi et al, Trevisan (1950), and successively Trevisan Miocene-Pliocene, starting with the 1967a; 1969), which divides the 1980; Abbate et al., 1980, 1980; Abbate et al., nappe pile into five complexes nappe pile into five Bortolotti et al., 1998a; 1998b, Bortolotti et al., geological frame proposed first by geological frame (Figs. 1a and 1b). Tertiary and goes up till the Late Tertiary 2001a). d’Elba) modify and complicate the New stratigraphical and structural data and structural New stratigraphical 2001a; CARG Project Sheet Isola begins in the Upper Cretaceous - Early (Babbini et al., 2001; Bortolotti et al., (Babbini et al., in the Palaeozoic; its tectonic evolution in the Palaeozoic; E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 1a - Geological sketch of the Elba Island (after Barberi et al.,1969). Fig. 1a - Geological sketch DOI: 10.3301/GFT.2013.03 INTRODUCTION The geology of the Elba for the relationships between complexity, interesting for the structural Island is very the Mio-Pliocenic magmatism and tectonics for being placed between Corsica Northern Apennine. In roots outcrop of the Northern Apennines. Its long-living geologic history takes fact, it is the south-westernmost geological field trips 2013 - 5(2.1) excursion notes 16 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 1b - Stratigraphic columns of the five complexes (after Barberi et al.,1969). (after Barberi et al.,1969). complexes columns of the five Fig. 1b - Stratigraphic DOI: 10.3301/GFT.2013.03 The new scheme we propose (Bortolotti et al., 2001a) The new scheme we propose (Bortolotti et al., (Figs. 2 and 3), comprises nine tectonic units, built (Adria continental margin), up of Tuscan Ligurian and Ligurian-Piedmont (Jurassic- Eocene oceanic domains) successions complexly piled up. The last domain is represented calcschists and by phyllites, meta-ophiolites which can be correlated with the “Schistes Lustrés” of the “Alpine” Corsica. is complicated by This frame extensional post-orogenic which produced the events, crust, thinning of the Tuscan the uplift of Moho and of the birth and evolution basin (Boccaletti et Tyrrhenian 1991; 1985; Bartole et al., al., Bartole, 1995; Carmignani et 1995). al., bodies (Marinelli, 1975; Serri et al., the emplacement of Late Miocene monzogranitic is linked these events To 1977; 2004) and the formation of ore deposits skarns (Tanelli, et al., 2002; Westerman 1993; Dini et al., of the Island. 2001) that constitute one of the best known geological characteristic et al., 1983; Tanelli geological field trips 2013 - 5(2.1) excursion notes 17 e. . transgressive b . quartzarenites, arenaceous schists, massive limestones (Hettangian); massive a d. . yellowish thermometamorphic vacuolar . yellowish b . Marbles, passing upward to calcschists and . Marbles, passing upward c (Norian-Rhaetian); E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea This Complex includes a sequence built up of muscovite-biotite schists This Complex includes a sequence built up of muscovite-biotite . vacuolar more or less dolomitic limestone, eteropic with black limestones . vacuolar Rhaetavicula c . “scisti macchiettati” (thermometamorphic schists with biotite and andalusite a . varicoloured marly shales and rare cherty calcareous levels (Dogger). cherty calcareous levels marly shales and rare . varicoloured f . Calcareous phyllites (Dogger). At the top of complex a sheet tectonitised (Dogger). At . Calcareous phyllites d This tuscan succession is made up of from the base: This complex comprises a metamorphic tuscan sequence similar to the Apuan Alps one. From (Calamita gneiss Auctt). DOI: 10.3301/GFT.2013.03 quartzitic sandstones, conglomerates and schists, which can be correlated with the Ladinian-Carnian quartzitic sandstones, conglomerates of the Monte Pisano; “Verrucano” cherty limestones (Lias); with intercalations of marls dolomitic and calcareous-dolomitic rocks of Norian-Rhaetian; spots), often graphitic, probably of Permo-Carboniferous age; probably of Permo-Carboniferous spots), often graphitic, with andalusite and plagioclase, and quartzitic and amphibolitic levels, which is attributed to the Paleozoic with andalusite and plagioclase, quartzitic amphibolitic levels, and crystalline dolomitic limestones The upper part is made of quartzites (Verrucano) (Permo-Carboniferous?). to linked thermally metamorphosed and intruded by aplitic dykes age. They are extensively of Triassic-Liassic Azzurro monzogranite. the La Serra-Porto Complex II. the base we can recognise: “cipollini” (Lias); serpentinite crops out. Complex III. and locally thermometamorphic schists (Late Carboniferous); quartzitic conglomerates THE TECTONIC UNITS OF ELBA ISLAND The model of Trevisan of the ElbaThe first organic geological map and related monograph performed by Lotti (1884, 1886). Island was the first to individuate allochthonous units in Elba (1910) was Termier Trevisan in the 50’s Island. Afterward, till which was, thrust complexes, (1950; 1951) and Barberi et al. (1967a; 1969) proposed their model of five a more complete statement of the evolution geological study on Elba Island. For the starting point for any now, of the geological interpretations see Bortolotti et al. (2001b). As already mentioned, according to Trevisan’s IV and V) (Fig. 1a). by Ligurian units (Complexes I, II and III) are overlain units (Complexes model, the Tuscany Complex I geological field trips 2013 - 5(2.1) excursion notes 18 Fig. 2 - Tectonic scheme of central and eastern scheme of central Fig. 2 - Tectonic Elba according to Bortolotti et al. (2001a). E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . c . Calpionella e . Gabbros; b This represents the . shales with siliceous f . . Radiolarites (Monte Alpe . Radiolarites d . Lherzolitic-harzburgitic a DOI: 10.3301/GFT.2013.03 limestones (Argille a Palombini, Cretaceous). Lower-Middle limestones (Late Tithonian?-Lower Cretaceous); Basalts; cherts) of the Malm; serpentinites; Complex IV lower Ligurian complex and consists of: geological field trips 2013 - 5(2.1) excursion notes 19 . Upper b . Paleocene-Eocene a E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea - Ortano UO It includes two flysch formations, tectonically superimposed. From the base: . - Acquadolce unit - Cretaceous - Porto Azzurro unit; - Porto CU AU PU - Monticiano-Roccastrada unit; - Monticiano-Roccastrada - Ophiolitic unit - Gràssera unit; - Gràssera - Tuscan Nappe; - Tuscan - Paleogene flysch - Paleogene - Capo Vita S.; - Capo Vita S.; - Acquaviva subunit; - Acquaviva . Porticciolo subunit, . Porticciolo - Monte Serra S.; S.; - Monte Serra - Santa Filomena S.); - Santa Filomena S.); - Volterraio S.; S.; - Volterraio 1 - Magazzini S.; - Magazzini S.; - Sassi Turchini S.; S.; - Sassi Turchini DOI: 10.3301/GFT.2013.03 a a - Bagnaia S.); - Bagnaia S.); b b ( TN GU OU b MU c d e f EU unit; unit; ( Complex V and eastern Elba tectonic Fig. 3 - The central pile. shales with intercalations of limestones and subordinately sandstones ophiolitic breccias; Cretaceous quartz-feldspatic sandstones and conglomerates, grading upward to a marly-calcareous upward grading sandstones and conglomerates, Cretaceous quartz-feldspatic succession. lie directly on the substantially their imbricated structure, in eastern Elba all the four upper complexes For autochthonous Complex I. in a tectonics which first piled up, as due to a polyphase E-verging The Authors consider this particular frame the tectonic pile on Complex was ones; afterwards, regime, the Ligurian units on Tuscan compressive tectonics due to the uplift of Mio-Pliocenic stocks Monte Capanne and La Serra- reorganised by gravity Azzurro. Porto flysch unit (after Bortolotti 2001a). et al., geological field trips 2013 - 5(2.1) excursion notes 20 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 The new model of the Elba has been significantly improved frame the tectono-stratigraphical During the last twenty years 1990; and Puxeddu, 1984; Pandeli et al., 1983; Puxeddu 1975; Bouillin, 1983; Deschamps et al., (Perrin, 1993; et al., 1992; Pertusati et al., 1995; Duranti 1992; Daniel & Jolivet, and Pialli, 1990; Deino et al., Keller 1995), as reported by Bortolotti et al. (2001b). et al., 1994; Pandeli Bortolotti et al., a more elaborated Elba we have On the base of their data and our mapping on western central-eastern been re- have of Trevisan, Complexes model (Figs. 2 and 3). The five complex tectono-stratigraphical interpreted and re-named. nine tectonic units: we recognised, from the base upward, In particular, Azzurro unit (“PU”) =1. Porto Complex I 2. Ortano unit (“UO”)= Complex II pp. Complex II pp. 3. Acquadolce unit (“AU”)= Unit (“MU”) = Complex III pp. 4. Monticiano-Roccastrada Nappe (“TN”) = Complex III pp. 5. Tuscan unit (“GU”) = Complex III pp. 6. Gràssera 7. Ophiolitic unit (“OU”) = Complex IV 8. Eocene flysch unit (“EU”) = Complex V pp. 9. Cretaceous flysch unit (“CU”) = Complex V pp. Porto Azzurro unit “AU” (Complex I) which ends with the thermometamorphic processes linked It shows a complex tectono-metamorphic history, intrusion (Messinian: ~~5.9 Ma in Saupé et al. 1982; Maineri al., Azzurro monzogranitic to the Serra-Porto Azzurro Unit mainly consists of the Monte Calamita the primary textures. The Porto 2003) which obliterated successions with local amphibolites intercalations) which phyllitic formation (micaschist and quartzose and Carboniferous-Permian basement, and probably includes Cambro-Ordovician represents the Tuscan 2005). The amphibolite intercalations result to be 1984; Garfagnoli et al., et al., formations (Puxeddu of the continental Tuscany metabasites similar to those found in the Late Cambrian-Early Ordovician intraplate Metamorphic Sequence is further on (e.g. in the Apuan Alps metamorphic core). The affinity to Tuscan geological field trips 2013 - 5(2.1) excursion notes 21 Probably, this unit is a Probably, ). East of Porto Azzurro the aplitic dykes, cutting the Azzurro the aplitic dykes, East of Porto ). E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 kilometric isoclinal fold with Ordovician metavolcanites at the core. metavolcanites kilometric isoclinal fold with Ordovician Acquadolce unit “AU” (Complex II pro parte) It corresponds to the Complex II successions from top of “calcare a cellette” (here considered marbles, partly dolomitic; they The complete succession begins with massive upwards. cataclasite horizon) a metapelitic siliciclastic succession with to (sometimes cherty) calcschists with, at their top, upwards grade et al. (1992) found a Lower Cretaceous microfauna; so they local calcschist intercalations. In the latter Duranti deformed and recrystallised by the Mio- consider all the succession as a metamorphosed Liguride, which was Pliocene intrusions. On the other hand Deino et al. (1992) obtained a 19-20 Ma for main schistosity which (1910) , Corti et al. (1996), Bortolotti intrusions. As suggested by Termier rules out its link with the granitoid strengthened by the presence of a transitional stratigraphical unit between the Verrucano and the overlying unit between the Verrucano stratigraphical strengthened by the presence of a transitional fm. (Carnian), which has the same stratigraphical similar to the Tocchi carbonate succession, very Mesozoic position in the successions of Southern Tuscany. (Zuccale fault) constitutes the fault associated with an about ten m thick cataclastic horizon A low-angle 2001a; 1993; Bortolotti et al., et al., e Pialli, 1990; Pertusati tectonic units (Keller contact with all the overlying 2005 2006a, 2006b; Garfagnoli et al., Collettini et al., Porto Azzurro Unit, do not cross this low angle tectonic surface and the fault breccias includes Porto it. Consequently, cataclastic matrix. Moreover thermometamorphic clast surrounded by a non-recrystallized area) affected this cataclasite is somewhere (e.g. Reale-Terranera the intrusions. Finally, the fault post-dates (hematite and limonite). mineralisations Fe post-intrusion by the later, Ortano unit “UO” (Complex II pro parte) limestone) of It corresponds to the successions of Complex II below “calcare a cellette” (= vacuolar (1951). Trevisan schists) locally crosscut quartzites (Capo d’Arco It comprises at the base thermally metamorphosed phyllites, their top porphyroids Azzurro Unit). At (similar to those intruded in the Porto and thin aplitic dykes by rare and quartzitic metasandstones to phyllites upward schists which grade and porphyritic basement of the This succession can be correlated with the Hercynian, Early Paleozoic metaconglomerates. 1994 et al., 1990; Pandeli and Puxeddu, Sardinia (Pandeli Apuan Alps and central geological field trips 2013 - 5(2.1) excursion notes 22 Limestone and Rhaetavicula E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea of Corsica (e.g. Inzecca units, Durand Delga, 1984) and the calcschists of units, Durand of Corsica (e.g. Inzecca Schistes Lustrés DOI: 10.3301/GFT.2013.03 et al. (2001a) and Pandeli et al. (2001a) these terrains probably correspond to a Liguria-Piedmont oceanic et al. (2001a) these terrains et al. (2001a) and Pandeli sequence as the the Gorgona island (cfr. Capponi et al., 1990; Orti et al., 2002). Also the presence of a serpentinite sheet at 1990; Orti et al., Capponi et al., the Gorgona island (cfr. its top agrees with this interpretation. Monticiano-Roccastrada unit “MU” (Complex III pro parte) (Rio metasediments of Late Carboniferous-Early Permian The base of this Unit is made fossiliferous graphitic 1983; successions are deposited (Deschamps et al., Marina fm. Auctt.), on which the detrital triassic Verrucano this Unit we ascribe also the epimetamorphic successions of Capo 2002). To 2001a; Pandeli, Bortolotti et al., which includes formations from respectively) (north and south of Cavo, and of Capo Pero dei Topi Castello-Isola 1995; Bortolotti et et al., (siliceous metalimestones) to the Oligocene (Pseudomacigno) (Pandeli Late Jurassic cover. 2001); they could represent part of the Verrucano al., Tuscan Nappe “FT” (Complex III pro parte) areas, it is represented only by calcareous-dolomitic Azzurro-Rio Marina, and Norsi-La Valdana In the Porto carbonatic ( also the overlying Auctt.); northwards, breccias (calcare cavernoso Calcare Massiccio - Late Triassic-Hettangian), carbonatic-cherty (Limano fm. and “Ammonitico Rosso” - Middle- Rosso” (Limano fm. and “Ammonitico carbonatic-cherty Calcare Massiccio - Late Triassic-Hettangian), marlstones - Dogger) crop out. formations (Posidonia Late Lias) and marly-carbonate Grassera unit “GU” (Complex III pro parte) marlstones, were considered as Posidonia position. Its terrains It represents a unit of doubtful paleogeographic 1969). It comprises at the base calcschists, sometimes with Nappe (Barberi et al., at the top of Tuscan manganiferous, slates and siltstones with rare cherts, but most of the unit is made up varicoloured 2001b). Its lithofacies are et al., 2001a; Pandeli siliceous and calcareous beds (Bortolotti et al., recrystallized they show a slight and Ligurian Domains. Moreover, different from those of all the formations both Tuscan Nappe and in Ligurian formations at its completely lacking in the Tuscan metamorphism (anchizone/epizone?), Nappe. These of the Tuscan It lies in tectonic unconformity on different terrains respectively. base and top, from a paleogeographic et al. (2001b) propose a provenance facts let Bortolotti et a. (2001a) and Pandeli one, possibly the Ligurian-Piedmont domain, as AU. domain west of the Tuscan geological field trips 2013 - 5(2.1) excursion notes 23 Sassi This is . (VSU) (ASU), constituted Monte Serra subunit Volterraio subunit Acquaviva subunit composed exclusively by serpentinised composed exclusively , (TSU) Fig. 4 - Columns of the ophiolitic subunits in eastern Elba (after Bortolotti et al., 2001a). Bortolotti et al., E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Ophiolitic unit “OU” (Complex IV) Supergroup (Abbate and Sagri, Its succession pertains to the Vara 1970). It is built up of some thrust sheets (subunits), characterised Tethys by ophiolites of the oceanic basement Western (serpentinites and gabbros -cropping out only in the lower ones) on (basalts) present a more or less complete volcanic which is generally Calpionella and sedimentary (Monte Alpe cherts, Nisportino fm., of Late Jurassic-Early shales) cover limestones and Palombini Cretaceous age. This unit can be interpreted as a relic of trapped oceanic crust originally near the Corsica European margin. Within this thick Unit we identified four main subunits (Fig. 4); from the bottom they are: (a) mainly by serpentinites (or ophicalcites), and Palombini shales with mainly by serpentinites (or ophicalcites), and Palombini at their base; b) the thin, cherty levels rare, in which the sequence begins with an ophicalcitised (SSU), is almost cover whose contact with the volcanic serpentinite level, tectonised, but in some outcrops the contact seems stratigraphical; includes, on the basalts, cherts (from few to some tens this cover m), the Nisportino fm. (some tens m) and Calpionella shales; c) the by Palombini north of Cavo, limestones covered, Turchini subunit the more complete and thick sequence. From bottom it basalts (3-400 m), Monte Alpe cherts (100-150 comprises gabbro, m), Nisportino fm. (100-120 m) and Calpionella limestones (at least 100 m). lherzolites and harzburgites;d)lherzolites the DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) excursion notes 24 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 Eocene flysch unit “EU” (Complex V pro parte) succession with turbiditic calcilutites, sandstones and ophiolitic breccias of It is represented by a shaly-marly Eocenic age. Cretaceous flysch unit “CU” (Complex V pro parte) shales, a lower shales and varicoloured In this second turbiditic unit we can distinguish, on top of the Palombini (Ghiaieto Sandstones) and an upper one with section, represented by siliciclastic sandstones and conglomerates marly limestones (Marina di Campo fm.). The age of the siliciclastic and calcareous-marly flysch is Campanian- shales Maastrictian. According our interpretation the minor ophiolitic slabs, Calpionella limestones and Palombini Azzurro could be the tectonised basal terms of subunit. cropping out north-east of Porto dykes, to Messinian aplitic and porphyritic particularly the second one- are cut by Tortonian These flysch units -and the 7.4 Ma S.Martino porphyry, sills and laccoliths (e.g the 8.4 Ma Capo Bianco aplite, 8 Portoferraio 2004, see later) that predate the about 6.9 Ma Monte Capanne et al., 2002; Westerman Dini et al., porphyry: 2002; Westerman 1984, U/Pb; Dini et al., 1993, Rb/Sr; Juteau et al., and Tonarini intrusion (Ferrara monzogranite 2004). All the pre-MonteCapanne magmatic bodies are cut along tectonic contact with underlying OU. et al., and its thermometamorphic aureole crop out (Fig. 5). In the western Elba, Monte Capanne monzo-granite Elba by the Eastern Border fault, is made up from the flysch units of central tectonically separated The latter, intruded by the pre- cover) of a recrystallised ophiolitic sequences (ophiolites and volcano-sedimentary This meta-ophiolitic porphyry). and laccoliths (e.g. Capo Bianco aplite Portoferraio MonteCapanne dykes related by Marinelli (1959), Barberi and Innocenti (1965; 1966), Bouillin (1983) to the succession was 1975; Spohn, 1981; other Authors (Perrin, On the contrary, Complex IV. Ophiolite Unit to the Trevisan’s referred them to Ligurian tectono-metamorphic rocks (similar and Spohn, 1982; Coli & Pandeli,2001) Reutter to the Schistes Lustrés) which were later thermally metamorphosed and deformed by Monte Capanne area, a weakly recrystallised or non metamorphic flysch unit (similar to those of the In the Fetovaia granitoid. 1969), tectonically lies on the thermally metamorphosed oceanic rocks Barberi et al., Complex V: Trevisan’s and Spohn , 1982). This flysch unit is made up of a basal serpentinite (Bouillin, 1983; Spohn, 1981; Reutter sequence with an olistostrome and ophiolitic breccias at the base. by a marly-calcareous body which is overlain sequence. In the serpentinite and gabbro olistoliths are locally present in the marly-calcareous Moreover, fossils were found (Bouillin, 1983; Spohn, 1981). Paleocene-Eocene ruditic levels, geological field trips 2013 - 5(2.1) excursion notes 25 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea CRF, Colle Reciso fault. Colle Reciso CRF, et al., 2002); EBF, Eastern Border fault; CEF, Central Elba fault; ZF, Zuccale fault; Elba fault; ZF, Central Eastern Border fault; CEF, 2002); EBF, et al., Complexes and the corresponding Units of Bortolotti et al., 2001 (modified from Dini and the corresponding Units of Bortolotti et al., Complexes Fig. 5 – Schematic structural and magmatic map of the Elba Island with Trevisan's Fig. 5 – Schematic structural DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) excursion notes 26 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 6 – Regional distribution Fig. 6 – Regional (after Dini et al., 2002). (after Dini et al., map of the magmatic bodies = TMP Magmatic Province Tuscan DOI: 10.3301/GFT.2013.03 MIO-PLIOCENE MAGMATISM IN THE NORTHERN APENNINES AND TUSCAN ARCHIPELAGO Tuscan Province Magmatic Rocks phase of the Apennine related to the post-collisional An intense magmatic activity, took place along the orogeny, border of the Italian Tyrrhenian during the Late Peninsula Miocene-Pleistocene (Peccerillo, 1985; 1990; 1993). This caused the emplacement of a wide variety of rocks at different crustal levels to intrusive), from volcanic (i.e., differences in with marked petrologic affinities, from strongly to calc- alkaline (ultrapotassic) 1987, et al., alkaline (Peccerillo 1989; Innocenti et al., 2001; Poli 1993; 1992; Serri et al., et al., 2004). Poli, igneous and mantle-derived Crust- rocks cropping out in the Tuscan Archipelago and Southern Tuscany (Fig. 6) were once grouped in a geological field trips 2013 - 5(2.1) excursion notes 27 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 single magmatic province (Tuscan Magmatic Province) owing to the consanguineity attributed them (Marinelli, Magmatic Province) (Tuscan single magmatic province were originated in the crust, whilst and rhyolites shown that only granites a number of authors have 1961). Recently magmas (similar to those of the Roman potassic and ultrapotassic calc-alkaline, Magmatic were Province) 1992, 1987; Conticelli and Peccerillo, et al., originated in a metasomatised lithospheric mantle source (Peccerillo 1993). Peccerillo, and Giglio islands, (ii) bodies of Elba, Montecristo, magmas form (i) the plutons and subvolcanic Crust-derived bodies of Sea), (iii) the intrusive Seamount, (Northern Tyrrhenian intrusion of the Vercelli the granite and flows of San Vincenzo and (iv) the lava in Southern Tuscany, Campiglia and Lago-Monteverdi, Gavorrano, 1989; Poli 1987; Pinarelli et al., et al., (Fig. 5; Peccerillo also in Southern Tuscany Roccastrada-Roccatederighi, magmas 2005). These crust-derived 2004; Dini et al., 1992; Poli, 1992; Innocenti et al., 1989b; Poli, et al., 1971; 1965, 1967; Borsi, Borsi and Ferrara, Borsi et al., were emplaced between 8 and 2 Ma (e.g., 1994; Dini et 1987; Barberi et al., 1985; Villa et al., and Tonarini, 1984; Ferrara Juteau, 1984; Juteau et al., et al., 1971; Civetta aging (Barberi et al., westward a general 2004), and have et al., 2002; Westerman al., et al., Peccerillo magmas (e.g., in time and space, with crust-derived magmas overlap, 1978). Mantle-derived 1993), although they were emplaced in a wider span of time, from 1992; Serri et al., 1987; Innocenti et al., 1985; 1985, 1993; Fornaseri, and Tonarini, Corsica) to 0.2 Ma (Monte Amiata) (Ferrara 14 Ma (Sisco, 1994). 1993; Barberi et al., 1992; Cioni et al., Turbeville, Elba Island plutonic masses crop out in the western (Monte Capanne, 6.9 Ma) and eastern (La Serra- monzogranitic Two aplite and pegmatite 5.9 Ma) sectors of the Elba Island (Fig. 5), along with their microgranite, Azzurro, Porto 1985, 1993; Boccaletti & Tonarini, 1984; Ferrara (Marinelli, 1959; Saupé et al. 1982; Jateau al., swarms dyke the 2003). The Monte Capanne intrusion post-dates et al., 1989; Maineri et al. 2003; Rocchi & Papini, “Christmas-tree” laccolithic complex (Fig. 7) including four intrusive multilayer emplacement of a subvolcanic units that were emplaced between ca. 8 and 7.4 Ma (Dini et al. 2002) into the ophiolitic successions around units are Elba. The oldest intrusive flysch units of central Monte Capanne and in the Cretaceous Paleogene and by two sills of the Capo Bianco aplite (ca. 8 Ma). represented by the small outcrop of Nasuto microgranite geological field trips 2013 - 5(2.1) excursion notes 28 The latter rocks, typically cropping out in a marine cliff is a very-fine west of Portoferraio, at Capo Bianco, phenocrysts of with tiny alkali-feldspar-granite grained locally showing quartz, feldspars and muscovite of tourmaline magmatic banding and concentrations monzogranitic- (orbicules). The slightly younger (ca. 8 Ma) consists porphyry Portoferraio syenogranitic small by many characterized of four main layers phenocrysts of quartz, feldspars and biotite. The (7.4 Ma), that is San Martino porphyry monzogranitic by prominent sanidine instead characterized megacrysts and by quartz, plagioclase, biotite emplaced into three main layers. phenocrysts, was Monte Capanne pluton (Dini et al., The monzogranitic 2004, 2005, 2008, 2010; 2002; Gagnevin et al., magma fed by several 2004) was et al., Westerman et pulses that coalesced into a single intrusion (Farina 2010). Three main facies can be detected in the al., pluton but the first two are more important: 1) by facies, characterized Sant’Andrea monzogranitic megacrysts and mafic numerous large K-feldspar San Piero 2) the granodioritic-monzogranitic enclaves; facies, typically quarried for its homogeneous texture of large megacrysts and mafic almost devoid facies show intermediate 3) San Francesco enclaves; E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 7 - Sketch of the geometrical relationships Fig. 7 - Sketch Elba Island at 6.8 Ma (after Dini et al., 2002). Elba Island at 6.8 Ma (after Dini et al., between the magmatic bodies of central and western between the magmatic bodies of central DOI: 10.3301/GFT.2013.03 features between the 1) and 2) facies (Dini et al., 2002; Westerman et al., 2004). The patchy distribution of 2004). The patchy et al., 2002; Westerman features between the 1) and 2) facies (Dini et al., then first and was facies, dominantly around the margin of pluton, suggests that it arrived the Sant’Andrea products and their geochemical/isotopic of the San Piero facies. Both facies are hybrid disturbed by arrival of the of a mafic component geochemically similar to K-andesites features can be modeled by the interaction geological field trips 2013 - 5(2.1) excursion notes 29 B) Contour map of Monte A) Fig. 8 – (after Farina et al., 2010). et al., (after Farina Capanne pluton showing the variability of Capanne pluton showing the variability megacrysts content (area %). geological cross- NW-SE Interpretative section of the Monte Capanne pluton. The S.Francesco facies (SA), Sant’Andrea facies (SP) are facies (SF) and S.Piero geometrically represented as three sheet extending across the whole pluton with shapes slightly upward-convex overall Island of Capraia and crustal melts Island of Capraia Cotoncello the leucogranitic like 2002). The at Elba (Dini et al., dyke (including swarm dyke leucogranite is associated the Cotoncello dyke) to the Monte Capanne magmatic these dykes In particular, event. compositions, syenogranitic have and they occur mainly close to the contact, within both the pluton’s pluton and its thermometamorphic a aureole. They commonly have thickness of up to tens metres. were emplaced late in These dykes the crystallization sequence of E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 Monte Capanne pluton, and are locally cut by dykes of the Orano porphyry (see below). Their isotopic age is porphyry of the Orano Monte Capanne pluton, and are locally cut by dykes are interpreted as a series of indistinguishable from that of the Monte Capanne pluton. The leucogranites similar to those of the San Piero facies characteristics products from a magma having fractionation geological field trips 2013 - 5(2.1) excursion notes 30 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 Monte Capanne pluton, a hypothesis further supported by the overlapping Sr and Nd isotopic compositions of further supported by the overlapping Monte Capanne pluton, a hypothesis Aplites and pegmatites occur commonly as thin (0.1 dykes. the Monte Capanne pluton and leucogranite cross-cutting the pluton, its thermometamorphic rocks and dykes, to 2 m) and short (up a few metres) veins to granodioritic of the monzodioritic swarm the dyke Finally, dykes. and, in some places, the leucogranite intruded the pre-Monte Capanne laccolithic complex, Monte pluton and its porphyry Orano 2002; Elba at 6.9-6.8 Ma (Dini et al., contact metamorphic aureole, and part of the flysch units central are typically dark and contain an olivine, clinopyroxene, porphyries 2003) (Fig. 7). Orano et al., Rocchi phlogopite assemblage that, coupled with geochemical and isotopic data, suggest a genesis from strongly lamproites. They are and Tuscan K-andesites modified mantle, as products intermediate between Capraia Monte Capanne). process (San Martino, in the earlier main hybridization distinctly different than those involved in eastern Elba is similar to the Monte Capanne pluton (Marinelli, 1959; Azzurro monzogranite La Serra-Porto Azzurro area and eastern Monte Calamita in the Porto 2003). Particularly, Saupé et al. 1982; Maineri al., crop out in the thermally and aplite dykes leucogranite its complex network of microgranite, promontory, are also felsic tourmaline-bearing dykes metamorphosed rocks of the Monte Calamita formation. Typical 2008). present (Dini et al., part of the Elba are also present in central-eastern Mafic dykes the occurrence of a 5.8 Ma Island. In particular, has been recorded by Conticelli et al. (2001) in the (Monte Castello dyke) shoshonitic dyke mantle-derived Messinian age of likely dykes quartz-dioritic Moreover, Azzurro. of Porto Ophiolitic Unit outcropping north-west in in the Acquadolce Unit (Case Carpini dyke Azzurro, are also present in the Capo Arco area, east of Porto between the Lacona and 2006) and in the Ophiolitic Unit of Monte Capo Stella promontory, et al., Pandeli and geochemical evidence of show petrographic both dykes in preparation); & Santo, Stella Gulfs (Pandeli and a crustal anatectic melt. magma similar to that of Capraia mixing between a calcalkaline mafic-intermediate Petrogenesis of the Elba Island granitoids Azzurro rocks point to an geochemical and petrological data of the Monte Capanne Porto Mineralogical, micaschists of Palaeozoic origin by partial melting (anatexis) of a crustal source, similar to the garnet-bearing 1989) that crops out in the southern part of Calamita et al., 1986; Poli et al., basement (Giraud Tuscan 2005). promontory (Garfagnoli et al., geological field trips 2013 - 5(2.1) excursion notes 31 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 The relatively high temperature (800-850°C), required to accomodate the degrees of melting experienced by high temperature The relatively 1989), is difficult to et al., element modelling, Poli this crustal source (35-45 wt.% on the basis of trace In this of the Apennine orogeny. following the collisional event reconcile only with isostatic re-adjustments acted as an additional supply to the heat magmas could have respect, underplating of mantle-dfigerived in conditions prevailing fluid-absent high degrees of melting under the general budget required to achieve 1987). (Clemens and Vielzeuf, levels middle- to lower-crust ElbaAt Island the rock composition closest to that of parental magma has been recognised be rocks 1992). On the 1989; Poli, et al., facies in Poli are absent (LF=leucocratic enclaves where mafic microgranular 1992) has been 1989; Poli, et al., other hand, the chemical composition of MF (MF=main facies in Poli magmas and the LF parental magma (CFC= with mantle-derived interaction modified by the physico-chemical 1991). The occurrence of such a and Tommasini, crystallization process, Poli contamination and fractional found in the MF of Monte Capanne enclaves) process is testified by the ubiquitous ME (=microgranular is difficult to quantify because directly dependent upon pluton. The extent of such modification, however, amount of basic and acid magma: the more magma higher equilibrium the relative for mixing with the surrounding acid magma and the more “residual” basic magma available temperature disruption and mingling of the basic magma, complicate things further, 1991). To and Tommasini, (stage 3, Poli as testified by the ME, during attainment of thermal equilibrium with acid magma (stage 2, Poli magma owing to the modified the composition of surrounding granite 1991) likely and Tommasini, texture exhibited by some ME). from the basic magma (schlieren-like of fragments incorporation geological field trips 2013 - 5(2.1) excursion notes 32 S. an Apenninic stage. ) (iii a Palaeozoic-Triassic(?), a Palaeozoic-Triassic(?), ) see above). see above). (ii ii, E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea a Middle-Late Palaeozoic, a Middle-Late Palaeozoic, ) (i Fig. 9 - Geological sketch map of Elba Island (modified from Maineri et al., 2003), with location of iron ores, industrial map of Elba Island (modified from Maineri et al., Fig. 9 - Geological sketch Piero, Seccheto, Cavoli. Tectonic lineaments: CEF = Central Elba fault; ZF = Zuccale EBF= Eastern Border fault. lineaments: CEF = Central Tectonic Cavoli. Seccheto, Piero, deposits and other mineral occurrences. Iron deposits: 1) Rio Albano; 2) Rio Marina; 3) Ortano; 4) Terranera; 5) Calamita; 6) occurrences. Iron deposits: 1) Rio Albano; 2) Marina; 3) Ortano; 4) Terranera; deposits and other mineral copper ± sulphides; 1): Cu = native deposits (see also Table Ginevro; 7) Sassi Neri. Abbreviations for the other mineral (a) = M.te Perone; Mg = silicates and/or magnesite; gr granite; turm = pegmatitic minerals; Sb = stibnite; Mn wad; Orello; (f) (d) = Santa Lucia; (e) Colle Reciso-Monte = Norsi; (g) Acquacalda; (h) (c) = Le Tombe; (b) = Pomonte; Ilario - Florio; (n) = Monte Fico; (o) S. – S. Ilario; (m) = S.Piero – S. (i) = Procchio; (l) S.Piero Magazzini-Volterraio; DOI: 10.3301/GFT.2013.03 To the second one would pertain the Fe (and Ba) metallogeny of Elba (and Ba) metallogeny the second one would pertain Fe To Island. been so far proposed and/or pyrite deposits of Elba Island two basic genetic models have oxide the Fe For Marinelli, 1983; Dechomets, 1985); b) and Lattanzi, 1986): a) “plutonistic epigenetic” (cf. (Tanelli Deschamps (cf. “syngenetic/hydrothermal-metamorphic” 1985). The first line et al., 1983; Lattanzi and Tanelli, for the ore event stocks as the key granitic reference to the intrusion of late-Apenninic of thought makes acknowledge the importance of Apenninic the second hypothesis genesis, whereas the authors favouring barite ores, which, at oxide in metamorphosing and partly remobilising the pyrite Fe tectonomagmatic event sedimentary formed in a sedimentary and/or hydrothermal would have least as pre-concentrations, age (stage and/or Palaeozoic of Triassic environments ORE DEPOSITS OF SOUTHERN TUSCANY AND ELBA ISLAND: AN OVERVIEW has been representing for about three millennia one of the most important mining regions Italy and Tuscany remains of metallogenic province region. Apart from economic aspects, the Tuscan the whole Mediterranean deposits associated with volcano- hydrothermal due to the occurrence of diverse primary scientific relevance 1994). They include, (Lattanzi et al., magmatic, metamorphic and geothermal environments sedimentary, deposits of Elba oxides among the others, Fe Island (Tanelli 1991, 2001). Fig. 9 and 10 provide et al., belts of Elba maps of the distribution major ore deposits and mineral sketch Island and of Southern Tuscany, respectivelly. can be found in TanelliA description and discussion of the metallogenic aspects Tuscany (1983) and Lattanzi et al. (1994), according to which well established in three main metallogenic epochs seem to be relatively (Figs. 10 and 11): Tuscany geological field trips 2013 - 5(2.1) excursion notes 33 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) excursion notes 34 (after Lattanzi et al., 1994). (after Lattanzi et al., Fig. 11 – Metallogenic evolution of Tuscany Fig. 11 – Metallogenic evolution The Fe deposits of Elba Island The iron deposits hosted in the eastern part of Elba Island feeded a longstanding mining and metallurgical activity, Iron” (beginning of dating back to the “first Mediterranean almost uninterruptedly and protracted the I millennium B.C.) In order to ago. since the Etruscans up to fifteen years and turn to better account such a long mining preserve heritage, a “Mining and mineralogical and invaluable tradition Mineralogical in eastern Elba has been recently Park“ 1997). and Benvenuti, Tanelli established (cf. E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 10 - Location of the most important ore Archipelago (modified after Tanelli & Lattanzi, 1983). Archipelago (modified after Tanelli deposits of southern Tuscany and of Tuscan deposits of southern Tuscany DOI: 10.3301/GFT.2013.03 The location of the main iron deposits eastern Elba are reported in Fig. 10. A broad and rough distinction can be made between iron ore deposits located to the north or south of Rio Marina. The iron deposits in the northern Rio Albano) Giove, portion (Rio Marina, Valle geological field trips 2013 - 5(2.1) excursion notes 35 Fig. 12 – Morpho-bathimetry of the shelf around Elba Island. Moving southward from Rio Marina southward Moving along the coast, a quite distinctive geological and mineralogical picture appears: in fact, rock outcrops up to Capo d’Arco predominantly belong to Trevisan Complex II, whereas the (1950)’s is magnetite rather main iron oxide than hematite. Pyroxene-epidote- skarn bodies, carrying ilvaite usually minor amounts of iron (magnetite, pyrite and minerals pyrrhotite) - which justified limited exploitation activity in the past - replace marbles and extensively at several calcareous phyllites Porticciolo, di Rio, places (Torre Ortano and Capo d’Arco). E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 and east of Porto Azzurro (Capo Bianco-Terranera) are constituted by stratiform, dyke-like or irregular bodies, hosted dyke-like are constituted by stratiform, Azzurro (Capo Bianco-Terranera) and east of Porto phyllites Complex III rocks, preferentially at the contact between Permo-Carboniferous (1950)’s by Trevisan calcareous and the overlying Middle Triassic) rocks (“Verrucano”, di Rio Marina”) or quartzitic/phyllitic (“Formazione is hematite, frequently associated with pyrite and/or its Auctt.). The main ore mineral (“Calcare Cavernoso” levels weathering products (“limonites”). geological field trips 2013 - 5(2.1) excursion notes 36 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 The famous iron deposits of Punta Calamita, Ginevro, and Sassi Neri are located at the southern margin of The famous iron deposits of Punta Calamita, Ginevro, Punta Calamita huge skarn bodies occur at the contact “Gneiss di M.te Calamita peninsula (Fig. 10). At hedenbergite, amorphous silica, goethite, epidote mainly includes ilvaite, Calamita”/marbles: their mineralogy pseudomorphs are mainly constituted by magnetite (and kenomagnetite) garnet. Ore minerals and andraditic peculiar feature with respect to common iron skarns, where magnetite is the after earlier hematite, a very Ginevro, associations. At peculiar mineral The Ginevro and Sassi Neri deposits show very primary iron oxide. amphibole, ferropargasite, associated is dominated by the presence of a rare for instance, skarn mineralisation and epidote. The main ore garnet and only minor amounts of hedenbergite, ilvaite with grossularite-almandine is magnetite. mineral and Lattanzi, 1986; Lattanzi Tanelli discussed elsewhere (cf. As more extensively 1994; et al., Benvenuti, for iron 2001), no completely satisfactory genetic model has been so far developed et al., 1996; Tanelli deposits of eastern Elba iron ores, as lack of detailed and updated studies on the various Island. The general do not allow relationships of their host-rock well as the complex and still partially obscure tectono-stratigraphic seems to model (b) above if the “syngenetic/hydrothermal-metamorphic” definite conclusions, even to draw and compositional features of some textural better explain the geological setting and mineralogical, (cf. Polveraio Calamita - Poggio (Deschamps et al., 1983), P.ta Giove Rio Marina - Valle deposits, like Torrini, 1990) and Sassi Neri (Del 1990). Tredici, geological field trips 2013 - 5(2.1) excursion notes 37 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 THE GEOLOGICAL FEATURES OF MARINE AREA AROUND ELBA ISLAND stable tectonic area, surrounded by important Archipelago is a relatively The continental margin of the Tuscan by the Viareggio the N it is separated subsiding basins. To Line, while to the south a Basin through the Livorno the west this margin is bounded by deep Corsican to the most depressed areas exists. To transition gradual between the Elba the E Piombino Channel is way it from the Corsica Isle. To Basin which separates Island phases of the sea level. and the continent, working as a real connection bridge during Pleistocene low-standing The main morpho-geological features of the area are represented by small islands, Elba Island (fig. 12) and axis, bordering the Corsicanby the Pianosa Ridge, an antiformal structure, with N-S Basin. Minor but considerable for the extension and thick of sediments are Punta the inner margin. Most considerable basins characterize Ala Basin, Pianosa and Giglio Basin. Basin and, on the N side, The Capraia extensional. Minor compressive Sea was The tectonics responsible for the origin and present setting of Tyrrhenian The recent geodynamic deformations are signaled by some Authors in the Plio-Pleistocene levels,, or transpressive stability by limited subsidence of basin and relative (Upper Pleistocene-Holocene) has been characterized evolution tectonic feature in the whole area. of islands. The Pianosa Ridge shows evidences rising; it is the most active Around the Elba by outcrops of a pre-Tortonian -50 m is most characterized area over Island the bathymetric limited sedimentary accumulations of the Stella, Lacona, Campo and Procchiosubstratum; Gulfs, represent as in Portoferraio beachs or, the submarine extension of pocket the result of deposition silty-clayey Bay, sediments carried by coastal currents. The outer shelf shows three different situations: in the Capraia- the Plio-Quaternary levels eustatic sequences, reaches the thickness as several Basin, organized of about 500 m. The Basin is a tectonic depression surimposed on Apennines structures, subsiding and actually it from the northern part of Pianosa Ridge; called “Canale dell’Elba” which separates limited by a canyon - the Punta Ala In the northern part of NS trending, up to 2 seconds deep. Basin is an important half graben, lowstandings of of these are related to the sea level five this Basin six sedimentary sequence are recognized, the Upper Pleistocene, while six one includes Holocene sediments; by some by an Holocene sequence characterized - to the south of Elba an erosion surface is covered rise. sea level sedimentary bodies defining a paleo-lagoon, formed during the post-glacial geological field trips 2013 - 5(2.1) excursion notes 38 Fig. 13 - Structural around the Elba Island. sketch of the marine area sketch and folds) deforms also the Upper Pleistocene showing that this Ridge is a very or compressive active structure. transpressive E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 The “Canale dell’Elba” is a main morphological feature of the shelf. It coincides with tectonic limit between The “Canale dell’Elba” is a main morphological feature of the shelf. Caparia Basin and northern part of Pianosa Ridge is partially interested by submarine erosion. The tectonic setting of whole area (Fig. 13) is mainly determined by normal fault which cuts the Miocene and structures (faults a lower part of Plio-Pleistocene sequences. Only near the Pianosa Ridge some compressive geological field trips 2013 - 5(2.1) excursion notes 39 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea affinity thrust on Tuscan units, till east of Elba, in the southern Tuscany affinity thrust on Tuscan “Schistes Lustrés” DOI: 10.3301/GFT.2013.03 (Roselle, Monte Argentario areas). (Roselle, Pre-intrusion extensional stage to the uplift and emersion of Apenninic orogen, caused by both an The extensional phenomena are linked at the end of piling up nappes, and an uplift asthenosphere in isostatic re-equilibration 1985, 1972; Boccaletti et al., sea will come into being (Boccaletti e Guazzone, area where the Tyrrhenian e Mascle, 1990; Serri 1991; Kastens et al., 1986; Channel e Mareshal, 1989; Jolivet e Ryan, 1990; Malinverno 2001a). The beginning of these processes in the 1995; Bortolotti et al., 1991; Carmignani et al., et al., area corresponds to the opening of CorsicaTyrrhenian Basin during the late Burdigalian-Langhian (Bartole in the latest Middle Miocene-earliest Late Miocene also 1991; Bartole, 1995) (Fig. 17). Likely, et al., TECTONIC EVOLUTION OF ELBA ISLAND Ligurian and Ligurian-Piedmont of the Island, which includes units Tuscan, The complex tectonic frame case three main Alpine stages can In any it difficult to reconstruct its geodynamic evolution. Domains, makes be pointed out. Accretionary stage units that piled up the Ligurian and Ligurian-Piedmont units on Tuscan This stage includes all the events of deformation and and culminated with the deformation of paleomargin Adria block. These events displacements began in the oceanic domain Late Cretaceous-Eocene (Figs. 14 and 15) went horizontal Miocene with the collisional and ensialic phases (Fig. on during the Late Eocene, Oligocene and Early-?Middle 1984; Carmignani and Kligfield, 1990). During these last 1980; Principi and Treves, 16) (Boccaletti et al., Nappe units -but also the Acquadolce Tuscan Monticiano-Roccastrada, Capo d’Arco, Azzurro, the Porto events 1992)- dated to 19-20 Ma, Deino et al., unit, which has a Ligurian-Piedmont affinity (its metamorphism was also the time in which Miocene was acquired their main tectonic regional imprint. The Early-?Middle sequences with geological field trips 2013 - 5(2.1) excursion notes 40 Upwards flow Upwards c- Upper portion of Lower portion of a- b- Tenda Massif; Tenda T- Fig. 14 - Schematic cross-section of the tectonic units is exaggerated. orogenic system Corsica-Northern Apennines during Late Cretaceous-Early Paleocene times. formed by the accretionary wedge (AW) crust material; trapper AW formed by ocean crust; AW For of the deepest portions AW. explanation, see text. The legend for the geological units is shown in Fig. 17. Note that in this and the following figures, Italic types are used for the formations during their deposition, normal types for the accreted units; the thickness of sediments and E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea zigzag Serra di Pigno slice; Serra S- Path of the hydrating fluids rising from of the hydrating Path Tenda Massif; Tenda Fig. 15 - Schematic cross-section of the Figs. 14 and 17. For explanation, see text. Figs. 14 and 17. For arrows- the other symbols see For the subducting slab. orogenic system Corsica-Northern Apennines Eocene times. during Late Paleocene-Early T- DOI: 10.3301/GFT.2013.03 beginning of exhumation the Elba tectonic building took place, through low angle faults, which dismembered and juxtaposed units coming from different (e.g. the tectonic levels structural intercalation of the Acquadolce unit units. between two Tuscan geological field trips 2013 - 5(2.1) excursion notes 41 - a Corsica External c- b- metamorphic feeders of the d- Vertical arrows- Monteverdi Marittimo unit (internal Monteverdi - b “Schistes Lustrés” and calcschists with Fig. 16 - Schematic section of the see text. orogenic system Corsica-Northern Apennines during Oligocene-Early Miocene times. a- ophiolites (ductile metamorphic rocks of the and AU and GU in Central deep portion of AW: Eastern Elba) and their exhumation (upwards trajectories; and eastwards) Ligurides and Internal Ligurides; offshore magmatism of Sardinia calc-alkaline hatched arrows- Corsica. Vertical and Western to feeders of the tholeiitic magmatism linked the opening of Ligurian-Balearic basin. thrusts: Probable out-of-sequence portion) onto the Lanciaia fm. The area explanation, outlined is shown in Fig. 17. For Cretaceous Elba flysch onto Paleogene Elba Cretaceous Elba flysch onto Paleogene flysch; Ligurides and epi-Ligurides; unit. Tuscan E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea (Figs. 18 a, b, c) (Figs. 18 a, b, DOI: 10.3301/GFT.2013.03 Syn- and post-intrusion stage The emplacement and uplift of the Messinian main intrusive bodies (i.e. the Monte Capanne and La Serra-Porto The emplacement and uplift of the Messinian main intrusive of the Elba units movements caused the thermometamorphism and last horizontal Azzurro monzogranites) 2004) and the younger et al., 2003; Westerman Maineri et al., Elba fault (CEF; Central through the low-angle 1995; 1993; Daniel & Jolivet, et al., 1993; Pertusati fault (Bouillin et al., Zuccale fault and Colle Reciso example, the main thrust 2006a, 2006b). For 2003; Collettini et al., 2001a; Maineri et al., Bortolotti et al., tectonic pile (Zuccale fault), is clearly post- Azzurro unit from the overlying the Porto surface which separates Azzurro unit Azzurro pluton and crossing the Porto belonging to the La Serra-Porto intrusion: all the dykes, authors, to are related, according many movements host rocks, end at the fault surface. These last horizontal geological field trips 2013 - 5(2.1) excursion notes 42 - n- 2a Elba g- Corsica anatectic of the La and b- - Corte slices; o- b 1 Tenda Massif. Tenda c- T- Ligurids; Elba Cretaceous f- h- “Schistes Lustrés” and Adriatic metamorphic e- j- internal Tuscan metamorphic internal Tuscan k- non metamorphic Cervarola and non metamorphic Cervarola external Tuscan metamorphic external Tuscan - successive boundaries between - successive Neogene lacustrine deposits; C i- , - east-vergent master detachment - east-vergent l- B m- 2b , A of the Monte Capanne and Tuscan metamorphic units; Tuscan Tuscan Nappe; Tuscan Serra di Pigno slice. For explanation, see di Pigno slice. For Serra - Fig 17 - Schematic section of the orogenic a text. The area outlined is shown in Fig 18. basement s.l.; basement (Ortano unit –UO- in the Elba Island); Azzurro unit –PU- in the Elba basement (Porto Island); underplating magmatic bodies; beneath Elba Island. zone fault. progressive west-vergent master detachment west-vergent progressive faults; S- the subducting slab and lithospheric asthenospheric mantle, due to the eastwards Hatched lines- shifting of the subduction zone. magmatism feeders of the supra-subduction ( Azzurro plutons). Serra-Porto flysch unit; Umbria units; system Corsica-Elba-Northern Apennines during Langhian-earliest Messinian times. a- calcschists with ophiolites; flysch unit; Paleogene Middle Eocene neoautochthon; d- E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 the gravity sliding (detachments) of the tectonic units, due to uplifting magmatic domes (Pertusati the gravity 2001a) since 6.7 Ma (Maineri et 1995; Bortolotti et al., 1994; Daniel and Jolivet, 1993; Boullin et al., et al., body Azzurro monzogranitic 2003). The final stages of the uplift partially cooled La Serra-Porto al., caused also the deformation of Zuccale fault. In the Early Pliocene, main part of high angle, generally geological field trips 2013 - 5(2.1) excursion notes 43 Monte CEF 2), l- “Schistes - Paleogene b k- i- Tuscan Nappe; Tuscan Acquadolce unit; f- d- CEF 1 and - Paleozoic successions of the Paleozoic Mesozoic cover of the Porto cover Mesozoic a Ophiolitic unit; La Serra-Porto Azzurro pluton; La Serra-Porto a- b- shoshonitic dykes; q-aplitic and q-aplitic shoshonitic dykes; h- Ortano unit; m- p- Cretaceous flysch unit; c- j- acidic and basic dykes and enclaves in the and enclaves acidic and basic dykes Early Messinian (6.7-6.2 Ma). Late Messinian high angle normal faulting and Grassera unit; Grassera Monticiano Roccastrada unit; Monticiano Roccastrada Messinian (6-5.5 Ma). Final uplift of the La Serra aplitic and porphyritic dykes within the Ligurids; dykes aplitic and porphyritic Fig. 18 - Schematic sections of the Elba Island microgranitic dykes in the Porto Azzurro unit. in the Porto dykes microgranitic e- Azzurro unit; Porto Azzurro unit; Porto flysch unit; g- from 6.7 to 0 Ma (uppermost Messinian Present). A- final uplift of the Monte Capanne pluton and of development quasi-contemporaneous detachment faults ( producing westwards and eastwards delamination and eastwards producing westwards of the tectonic pile; B- of ZDF- Azzurro pluton and development - Porto (1) divergent Zuccale (2) and RDF- Colle Reciso delaminations; C- formation of the ore the contemporaneous line represents the The sketched mineralisations. Monte Capanne-Monte Arco present W-E section. topographic n- o- plutonic bodies; Lustrés” and calcschists with ophiolites; Capanne pluton; N-S-trending normal faults of eastern Elba N-S-trending were originated and sealed by the hematite-rich ores (5.3 Ma in Lippolt et al., 2001a). 1995; Bortolotti et al., E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 44 Fig. 19 - General map of the Fig. 19 - General itineraries and Stops in the Elba Island. itineraries In the Eastern Elba Island the tectonic pile is well exposed (Barberi et al., 2001a; 1967a; 1969; Bortolotti et al., 2001). In this part of Babbini et al., the field trip (Fig. 16) we will visit best outcrops of the lowermost tectonic units (from the bottom: Porto Acquadolce and Ortano, Azzurro, units), to Monticiano-Roccastrada recognise their tectonic relationships (Fig. 2) and the setting of hosted bodies.Fe-ore to From Portoferraio A few kilometres Azzurro. Porto along the road Azzurro, Porto beyond to Rio Marina, we turn right the (Fig. 20). Spiaggia di Reale E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Field Trip Itinerary and Stops DOI: 10.3301/GFT.2013.03 The general map of the itineraries and Stops is shown in Fig. 19. The itineraries are three: Eastern Elba, and Stops is shown in Fig. 19. The itineraries map of the itineraries The general Elba and Calamita promontory. and Central Western EASTERN ELBA ISLAND Azzurro and Rio Marina (Eastern Elba). between Porto The metamorphic tectonic units and the Fe-ores geological field trips 2013 - 5(2.1) itinerary 45 pro area Spiagge Nere (Calamita gneiss Auctt. is made up of grey to grey-greenish polydeformed is made up of grey to grey-greenish E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. parte), Stop 1. The tectonic units of the In this area (Fig. 21), the contact (Zuccale fault) of Porto imbricated units (Acquadolce Azzurro unit with the overlying unit) crops out. unit and Monticiano-Roccastrada a- Monte Calamita formation The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 21 - Geological sketch map of the Fig. 21 - Geological sketch fault. Fig. 20 - and Itinerary Stops in eastern Elba. Spiaggia di Reale-Spiagge Nere-Terranera mining Nere-Terranera Spiaggia di Reale-Spiagge normal fault, 2) Low-angle area. 1) High-angle DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 46 2 ). 3 folds 2 folds are 3 , while fracture 2 isoclinal folds are rarely preserved because of the D preserved isoclinal folds are rarely 1 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Alpine structures completely transpose the Hercynian structures Alpine structures completely transpose structures. A centimetric to decimetric-spaced, high angle fracture structures. A centimetric to decimetric-spaced, 2 2 and D and D 1 1 folding. Relic centimetric D folding. Relic 3 (Zuccale fault). It is an about 10 m-thick horizon consisting of an ochre-yellowish, often consisting of an ochre-yellowish, (Zuccale fault). It is an about 10 m-thick horizon DOI: 10.3301/GFT.2013.03 These dykes are also locally dissected by N250-trending low-angle shear bands. The top contact with the are also locally dissected by N250-trending low-angle These dykes end abruptly against this surface (Fig. 22). is sharp and the dykes cataclastic horizon mineralised overlying Looking to the North, we can see a fine view of Terranera The contact is gently dipping to the W/WNW. which is cut in the go 5-6 m up the cliff to beginning of a canyon and of the mining area. We Lake cataclastic rocks. b- Zuccale cataclasite mostly from the underlying Monte foliated polymictic breccia. Its clasts (millimetric up to 10-15 cm) derive more or less kaolitised) and from the overlying cut by aplitic dykes Calamita fm. (micaschists and phyllites of the Rio Marina fm.). The angular/subangular phyllites unit (e.g.: the black graphite Monticiano-Roccastrada cleavage (generally with a N20° to N50° dip direction in the Terranera area), which displaces the Monte with a N20° to N50° dip direction in the Terranera (generally cleavage and is consistent with the axial direction of latest folds (A Calamita fm. and the included aplite dykes, characterised by a wide spread of the axial strike (mainly in the SW and NW quadrants) and a sub-vertical (mainly in the SW and NW quadrants) by a wide spread of the axial strike characterised is associated to F to discrete crenulation cleavage zonal a pervasive axial surface. Moreover, quartzitic phyllites and micaschists whose protolith is probably Paleozoic in age (Puxeddu et al., 1984; Pandeli et al., in age (Puxeddu and micaschists whose protolith is probably Paleozoic quartzitic phyllites 1994). The Alpine main schistosity has an attitude of N120/45 or N310/25 and is strongly overprinted et al., Azzurro (e.g. static biotite and andalusite) due to the La Serra-Porto by static thermometamorphic minerals intrusion (5.9monzogranitic & Tonarini, 1982; Ferrara 1971; Saupé et al., age: Borsi & Ferrara, Ma radiometric 2003), which crops out west of this area (Barbarossa beach). The metasedimentary 1985; 1993; Maineri et al., and are cross-cut by centimetric/decimetric white tourmaline-bearing rocks do not show Fe-mineralisations of the Monte framework The structural network of the Messinian granitoid. aplites, which belong to the dyke by centimetric/decimetric, tight to isoclinal folding (F2) of the Calamita fm. at the mesoscale is characterized S1) which were deformed main continuous schistosity (related to the first Alpine tectono-metamorphic event the D and following faults. In particular, open to close folds, metric decametric in size by younger The D Moreover, transposition. cleavage is connected to D cleavage eventually present in these rocks (e.g. the pre-Alpine intrafolial schistosity relics in some of the typical intrafolial present in these rocks (e.g. the pre-Alpine eventually which outcrops of the Monte Calamita fm. in promontory). F3 deformed aplitic dykes clearly cut through the ductile D show a N-S to NE-SW orientation of the axis and a west-low dipping axial surface; the D orientation of the axis and a west-low to NE-SW show a N-S geological field trips 2013 - 5(2.1) itinerary 47 Fig. 22 - Contact of the Monte Calamita fm. (MCF) abruptly end against the cataclasite. with the overlying Zuccale cataclasite (ZC) at Terranera. Zuccale cataclasite (ZC) with the overlying intruded in the Monte Calamita fm., The aplitic dykes, clasts are generally aligned along the foliation and clasts are generally Fe-oxides the whole rock is affected by pervasive and by mineralisations /hydroxides W- decimetric/metric asymmetric to overturned clasts and metric, more or facing folds. Moreover, tectonic slices of the Acquadolce less mineralised, are included in the unit (green quartzitic phyllites) breccia; one of these slices, tectonically capped by crops out along the Rio Marina fm., the graphitic road to the cottage. E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Here the foliated breccia (plunging to the N or W) includes also many carbonatic and Here the foliated breccia (plunging to N or W) includes also many DOI: 10.3301/GFT.2013.03 The Carboniferous-Permian Rio Marina fm. (Monticiano-Roccastrada unit) tectonically rests on the cataclastic Rio Marina fm. (Monticiano-Roccastrada The Carboniferous-Permian with grey quartzitic metasiltstones and phyllites This formation includes black graphitic horizon. metasandstones locally imprinted by thermometamorphic biotite or andalusite spots. continue down to We Spiagge Nere where the tectonic breccia is well exposed. c- Zuccale cataclasite. matrix. Metric foliated, more or less chloritised serpentinite clasts in a dominant phyllitic-carbonate rare calcschists are locally present within bedded marbles and grey-whitish tectonic slices of whitish to yellowish These carbonate rocks probably belong to the Acquadolce unit (Ortano Marbles, the cataclastic horizon. Azzurro unit. The marbles show pervasive of the Porto cover calcschists) or correspond to the Mesozoic at a sub-centimetric are also boudinaged even levels cataclastic textures, while the calcschist and phyllite foliation of the cataclastic the absence of blastesis along pervasive reveal scale. Microscopic observations These data point to a “cold” indicating that the thermometamorphism predate cataclastic event. horizon, Azzurro formed after the intrusion of La Serra-Porto which was nature of this cataclastic horizon, geological field trips 2013 - 5(2.1) itinerary 48 century and ended about th E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Mining works at Terranera started in the 18 Mining works at Terranera DOI: 10.3301/GFT.2013.03 30 years ago. They were partially carried out by open pit excavations, now occupied by the Terranera They were partially carried out by open pit excavations, ago. 30 years Lake, (hematite with minor oxides The exploited ores consisted of lenses Fe fed by both fresh and marine waters. Trevisan’s basement (Rio Marina fm., magnetite) and pyrite at the tectonic contact between Paleozoic predominantly succession. The upper portion of the deposit was “Verrucano” Complex III) and the overlying of pyrite. According to Lotti (1886), alteration from the exogenous constituted by limonitic masses, derived the Rio normal fault (Zuccale fault) which separates below the low-angle the iron orebody extended even Complex I). The genetic processes leading to the Marina fm. from the underlying Calamita (Trevisan’s several to be better defined. Ongoing research should try solve of this deposit still await development magnetite (which is otherwise the dominant Fe problems, among which the predominance of hematite over cropping out at the nearby south of Rio Marina) and the relationships with skarn bodies (extensively oxide Punta delle Cannelle). monzogranite. Therefore, the foliation of breccia seems to be due mechanical iso-orientation its clastic monzogranite. kinematic 2006a, 2006b). Several (see also Collettini et al., elements, possibly in a fluid-rich environment a “top to NE” or “mantled” or faulted clasts, etc.) reveal indicators (asymmetry of folds, intrafolial The opposite sense of shear could suggest a repeated utilisation this cataclastic horizon SW” sense of shear. in this outcrop the foliation appears gently during the last emplacements of eastern Elba units. Finally, folded, possibly by a later deformation event. which closes to the north Spiagge Nere, is made up of Monte Calamita fm. (see before. The promontory, has an antiformal shape. The cataclastic horizon cataclasite horizon a-). The contact with the overlying of the triassic below the quartzite and green to whitish-pearly phyllites disappears northwards, unit. trending syncline of the Monticiano-Roccastrada This latter represents the core of a NW-SE “Verrucano”. reach the eastern part of beach in front acidic TerraneraWe Lake. Stop 2. Fe-ores of the Terranera area Here (Fig. 21) and quartzites of the Rio Marina fm. crop out, cross-cut by N320-360 phyllites the graphitic a main beyond Easthwards, and faults filled by hematite±quartz±adularia mineralisations. trending fractures of the Acquadolce unit (serpentinite altered in talcschist fault, the uppermost levels mineralised high-angle and metasandstones) underlie the Rio Marina fm. chloritic phyllites tectonically covering The Fe-ores of the Terranera mine. geological field trips 2013 - 5(2.1) itinerary 49 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea (Fig. 24). The Ortano succession recalls the Fig. 23 - Geological sketch map of the Ortano Valley. Fig. 23 - Geological sketch DOI: 10.3301/GFT.2013.03 We come back to Spiaggia di Reale and continue the road come back to Spiaggia di Reale We outcrops of to Rio Marina. Along the road we cross many (Ophiolitic unit; see Stop 15). ophiolites and of their cover the serpentinite sheet at top Pass, After the San Felo of the Acquadolce unit is visible on right, at the Monte of Rio Elba, the round-about 3-i). At Fico quarry (see Stop. we turn to the right and reach Ortano residence. Stop 3. The tectonic stack of the Ortano Valley (Ortano, Acquadolce, Monticiano-Roccastrada, Tuscan Nappe, Gràssera units) along the southern part of residence (Fig. 23) walk We as far the wharf ruins; then we continue southwards along the quartzitic cliff (path) until a landslide. Near the rocks crop out which represent the sea, phyllitic-quartzitic geometrical base of the non-fossiliferous, W-plunging Ortano unit Ordovician lower-middle part of the well-known Tuscan lower-middle Ordovician 1994) et al., basement of the Apuan Alps (Pandeli Paleozoic Auctt., Sardinia (Nappe Zone (Fig. 25), and of the central 1992). In et al., 1990; Duranti & Puxeddu, Pandeli this unit corresponds to the “Acidic particular, and and metasediments” (porphyroids metavolcanites metasiliciclastic schists) and “Transgressive porphyritic and quartzites, Capo d’Arco phyllites (Silver-grey cover” similarities of the schists). The lithological-petrographical geological field trips 2013 - 5(2.1) itinerary 50 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea of the 1996). “type”- Fig. 25 - Restored Northern Paleozoic basement & Pandeli, Apennines succession (after Elter Fig. 24 - Tectonic-stratigraphic sketch of sketch Fig. 24 - Tectonic-stratigraphic of the formations, approximate). of the formations, approximate). the Ortano and Acquadolce units (thicknesses DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 51 which was deformed and metamorphosed which was ) plunging westwards. The Acquadolce unit (Fig. 4) was plunging westwards. (Late Ordovician?). They are shining silver-grey phyllites They are shining silver-grey (Late Ordovician?). s E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea (Middle Ordovician?). This is a metric horizon of alternating dark- This is a metric horizon (Middle Ordovician?). Acquadolce unit, . (Ortano schists Auctt.) (Ordovician?). They consist of grey-greenish to brown phyllites, They consist of grey-greenish . (Ortano schists Auctt.) (Ordovician?). (Middle Ordovician?). They are massive to poorly stratified, grey to brownish acidic to poorly stratified, They are massive (Middle Ordovician?). DOI: 10.3301/GFT.2013.03 traditionally interpreted as a Mesozoic-Cainozoic Tuscan-type metamorphic sequence (Trevisan, 1951; Barberi metamorphic sequence (Trevisan, Tuscan-type interpreted as a Mesozoic-Cainozoic traditionally of the & Pialli, 1990) which represented the “cover” 1977; Keller 1975; Boccaletti et al., 1969; Perrin, et al., et al. (1993) et al. (1992) and Pertusati Duranti rocks (Ortano unit). On the contrary, underlying Paleozoic Complex IV considered it as a part of the Ophiolitic unit (Trevisan’s with pale grey/whitish, decimetric to metric, locally coarse-grained quartzitic metasandstones and with pale grey/whitish, decimetric to metric, locally coarse-grained These lithotypes are locally crosscut by quartz±chlorite veins. metaconglomerates. the lower where we can observe along the road of residence, we reach southern quarry, Walking formations of the metamorphic Capo d’Arco schists and the Silver-grey phyllites and quartzites ( below and above the porphyroids, respectively) the porphyroids, and quartzites ( below above phyllites schists and the Silver-grey Capo d’Arco Therefore, the unit at the top of porphyroids. could suggest that they represent the same stratigraphical at the core. megafold with the porphyroids represent an east-vergent Ortano unit as a whole may a- Capo d’Arco schists quartzitic phyllites, micaschists and minor quartzites which include typical syn- and post-tectonic quartz veins and quartz veins micaschists and minor quartzites which include typical syn- post-tectonic quartzitic phyllites, are present. In the levels phyllite graphitic local thermometamorphic “spots” (andalusite, cordierite) . Locally, of coarse pale- metric to decametric horizons schists include lenticular, surrounding areas, the Capo d’Arco grey/whitish quartzites and quartzitic metarudites. Looking to the SE, morphological discontinuity in Isolotto schists. d’Ortano corresponds to the contact between a quartzitic body and metapelites of Capo d’Arco porphyroids. we can see well exposed outcrops of the overlying Coming back along the path up to wharf, b- Porphyroids by a millimetric (3-4 mm) augen texture due to quartz and feldspar which are characterised metavolcanites of augen quartzites and In the middle and upper parts of this unit, levels (sanidine) porphyroclasts. metasediments. Post-tectonic schists”) probably correspond to volcanic-rich (“Porphyritic quartzitic phyllites continue along the white road until a We of chlorite+quartz+epidote±tremolite/actinolite locally occur. veins black rocks are exposed. the top of porphyroids, little square in front of the theatre residence. At c- Blackish quartzites and phyllites to: These rocks pass upwards quartzitic levels. and 10-20 cm-thick fine-grained grey/black quartzitic phyllites d- Silver-grey phyllites and metasandstone geological field trips 2013 - 5(2.1) itinerary 52 with calcschist intercalations (Early Cretaceous). They are , E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea (“Calcare Cavernoso” or “Vacuolar dolomitic limestone” Auctt.). It is a 10-15 m thick, pale or “Vacuolar (“Calcare Cavernoso” . (“Ortano Marble” Auctt., Cretaceous?). This unit is about 15 m thick and includes massive (“Ortano Marble” Auctt., . This more than 50 m thick unit is made up of 10-40 cm thick, grey and grey-greenish DOI: 10.3301/GFT.2013.03 represented by a more than 250 m-thick succession of grey, grey-greenish and black quartzitic phyllites and and black quartzitic phyllites grey-greenish represented by a more than 250 m-thick succession of grey, calcschists beds with millimetric grey green to black phyllite layers. Siliceous white quartzitic bands and nodules layers. calcschists beds with millimetric grey green to black phyllite (metacherts) are present, particularly in the middle-upper part of succession along road (about 100 m of caIcite±pyrite±quartz and adularia are ubiquitous. The contact with the shop). Veins after the souvenir with calcschists intercalations is gradual. phyllites overlying continue along the road for about 200 m. We h- Grey and greenish phyllites metasiltstones grey to yellowish carbonate rock, roughly stratified and affected by variable recrystallisation which often obliterates and affected by variable carbonate rock, roughly stratified grey to yellowish well-cemented calcareous breccia with marble and subordinate phyllite the previous textures. Locally it is a vacuolar, are locally present. In spite of the recrystallisation, clasts (more frequent in the lower part). Dolomitic horizons and pyrite, especially in the cataclastic textures are frequent at the microscopic scale as scattered Fe-oxides carbonate-micaceous-quartzitic matrix. This unit is considered a tectonic breccia formed during the emplacement of the Acquadolce onto Ortano unit. Thick skarn a thermometamorphic imprint is present (clinopyroxene±garnet±amphibole). Locally, are associated to the cataclasite north of Ortano horizons (hedenbergite±ilvaite) (Ortano pyrite±pyrrhotite Valley (e.g. the for the metasomatic fluids and Fe-ores represented an important pathway mine). Therefore, this horizon alignment). skarns and ores, north of the Ortano area, along same structural Tignatoio and Porticciolo f- Valdana Marble of bands and horizons saccharoidal marbles with local yellowish medium to coarse grained, grey-whitish, also occur. levels and discontinuous millimetric phyllitic dolomitic marble. Rare with the overlying The transition Along this contact decimetric by an about 1 m thick alternating marble-calcschist horizon. calcschists is marked folds are locally present. shop. and reach the same contact behind souvenir cross the valley We g- calcschists by the intrusions of the Messinian-Pliocene granitoids. On the other hand, Corti et al. (1996), Bortolotti by the intrusions of Messinian-Pliocene granitoids. et al. (2001a) correlate this succession to the “Schistes Lustrés” of Gorgona(2001a) and Pandeli Island; (1910). the analogies of this sequence with “Schistes Lustrés” were also pointed out by Termier e- Valdana cataclasite geological field trips 2013 - 5(2.1) itinerary 53 Monticiano Roccastrada unit . (Cavo fm., see Stops 8 and 10). fm., (Cavo Tuscan Nappe E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Gràssera unit Its thickness is about 150 m. A massive grey, cataclastic, calcareous-dolomitic grey, Its thickness is about 150 m. A massive . (Late Carboniferous-Early Permian). In this section the maximum thickness of (Late Carboniferous-Early Permian). . It consists of grey-greenish and vine-reddish slates siltstones with syn-/post-tectonic . It consists of grey-greenish It is massive dark green serpentinite (lherzolite) about 100 m thick. Local shear bands and dark green serpentinite (lherzolite) It is massive . DOI: 10.3301/GFT.2013.03 n- Cavo formation siliceous limestone beds are present. and rare Local blackish manganiferous levels quartz veins. The Gràssera shales of the Ophiolitic unit. unit tectonically underlies the Palombini square of Rio Marina (in front of Rio Elba and reaches the central The trip continues coming to the round-about di Rio o Torre along the dock as far old tower with clock (Torre walk dock). We of the panoramic degli Appiani) and then we took the road on right, along cliff. metasiltstones with local decimetric/metric levels of calcschists and rare grey-greenish metagraywackes. Post tectonic Post metagraywackes. grey-greenish of calcschists and rare metasiltstones with local decimetric/metric levels et al. area), Duranti of adularia±tremolite/actinolite±albite are locally present. North Ortano (Porticciolo veins calpionellids and globigerinids of Early Cretaceous in the carbonate intercalations.(1992) found radiolarians, 200 m ahead along the road, to right (near a house) serpentinite sheet at top of Acquadolce unit crops out. i- Serpentinite foliation are present. of the road close to a small house (to left), where Monticiano reach the curve We unit is thrust onto the serpentinite of Acquadolce unit.Roccastrada The m- “Calcare Cavernoso” breccia, locally characterised by vacuolar structures, is the dominant lithotype. At times, grey-pearly and times, grey-pearly structures, is the dominant lithotype. At by vacuolar breccia, locally characterised or Horizons also occur. are present. Calcite±Fe-oxides/hydroxides clast and quartz grains greenish phyllitic triassic dolostones and dolomitic limestones are sometimes recognisable as metric boulders of poorly stratified carbonate sand). and sedimentary fillings (yellowish well as karst alterations About 300 m ahead, we find the tectonic contact (by a system of high angle normal faults) (St. Caterina fault) and the between the “Calcare Cavernoso” includes here only the Rio Marina fm. l- Rio Marina formation formation is about 50 and metasiltstones with grey quartzitic phyllites m. Its lithologies are black graphitic of quartz±pyrite are locally observed. tectonic veins metasandstone intercalations. Post of the After the curve fault) puts in contact the Rio Marina fm. with normal fault (Terranera west-plunging road, a high-angle, of the basal carbonate breccia (“Calcare Cavernoso”) geological field trips 2013 - 5(2.1) itinerary 54 ” Ilva Ar radiometric age of 19-20 Ma Ar radiometric 39 Ar/ 40 prismatic crystals with submetallic luster were here described for the first time in 1802. They were subsequently attributed to a new mineral species, called “ilvaite” after the Latin name “ of Elba degli come back to the Torre Island. We Appiani clock tower and continue along the dock to the small tower. This tower is built on a decametric metacarbonate marble to grey-greenish (grey-whitish horizon of the and calcschist) within the phyllites tight to Acquadolce unit. Syn-metamorphic axial plane isoclinal folds with a pervasive schistosity are well exposed. Deino et al. (1992) obtained a for the main schistosity. for the main schistosity. 1886). E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . This skarn is exceptionally well developed (Fig. 26). It preferentially replaces the well developed . This skarn is exceptionally bodies at Torre di Rio (after Lotti, bodies at Torre . Here the upper portion of lower subunit (Porticciolo subunit) of the Acquadolce unit . Here the upper portion of lower subunit (Porticciolo Fig. 26 - View from the sea of skarn DOI: 10.3301/GFT.2013.03 Stop 4. The calcschist bodies and the skarn of Torre di Rio The calcschist bodies crops out. It is represented by a NW-plunging succession of centimetric to decametric marbles and calcschists crops out. It is represented by a NW-plunging (a metric grey/whitish calcschist bed is well exposed along the road) with minor grey/greenish quartzitic intercalations. Going on the road, all rocks show more and evidence of hydrothermalism phyllite of fan-shaped the tectono-metamorphic texture. The appearance epidote) which obliterates (yellow-green di Rio skarn. hedenbergite crystals marks the contact with Torre The skarn of Torre di Rio masses of of the Acquadolce unit, forming large, almost monomineralic calcareous interbeds in the phyllites (locally in centimetric to decimetric mega-rossette and fan-shaped epidote, hedenbergitic pyroxene (after hedembergite), with associated quartz, chlorite and minor amounts of iron aggregates) and ilvaite (magnetite, pyrite and pyrrhotite), which justified a limited exploitation activity in the past. Mesoscale minerals occurring preferentially along the textures clearly indicate that the calcschist are replaced by skarn minerals striated 205-206). Black, vertically schistosity planes of the rock, as already pointed out by Lotti (1886, pp. geological field trips 2013 - 5(2.1) itinerary 55 Fig. 28 - Tectonic and stratigraphic Fig. 28 - Tectonic unit in the Rio Marina area sketch of the Monticiano-Roccastrada sketch th E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 27 - Panoramic view of the Rio Marina mines. Ser- serpentinites; RM- Rio view of the Rio Marina mines. Ser- Fig. 27 - Panoramic green quartzites member; V3- white-pink member). Marina fm. V- “Verrucano” group (V1- Verruca fm.; V- Monte Serra quartzites (V2- Monte Serra fm.; V- group (V1- Verruca “Verrucano” Marina fm. V- DOI: 10.3301/GFT.2013.03 Stop 5. The Rio Marina mining area Looking to NW (Fig. 27), the landscape is dominated by Rio Marina and Vigneria mines) Giove Valle Zuccoletto, mines (from the left: Bacino, with the ruins of a castle 16 del Giove, and by the Monte Torre century). The Rio Marina ores are hosted in the Permo-Carboniferous group metasiliciclastics (Rio Marina fm.) and in the triassic “Verrucano” the north of last unit (Fig. 28). To of the Monticiano-Roccastrada house of Rio Marina (Fig. 27), the tectonised serpentinite lying at top by the of the Acquadolce unit crops out and is tectonically covered metasediments of the Rio Marina fm. (graphitic Permo-Carboniferous geological field trips 2013 - 5(2.1) itinerary 56 Green quartzites . Prevailing quartzose pale grey/pink quartzose . Prevailing E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . The iron deposits occurring at Rio Marina and northwards of it, almost . The iron deposits occurring at Rio Marina and northwards . The “Verrucano” group metasediments represent the basal transgression . The “Verrucano” Parallel- to cross-stratified (e.g. herring-bone cross-bedding) and rippled, pale to cross-stratified Parallel- . They are exposed in the upper part of the Valle Giove mine and on the eastern flank Giove . They are exposed in the upper part of Valle . It widely crops out in the mining areas behind and to north of Rio Marina (e.g. DOI: 10.3301/GFT.2013.03 phyllites and metasiltstones with quartzitic metasandstones and minor metaconglomerates. Paleoenvironment: and metasiltstones with quartzitic metasandstones minor metaconglomerates. phyllites area) (Fig. 27), the whole del Giove Giove-Torre Behind Rio Marina and Vigneria (i.e. Valle deltaic-coastal). group succession crops out at the top of Rio Marina fm. (Fig. 28). “Verrucano” Geology of the Rio Marina mines of the Alpine sedimentary cycle. The “Verrucano” succession of Elba The “Verrucano” of the Alpine sedimentary cycle. Island (Deschamps, 1980; Deschamps et 2002), probably late Ladinian-Carnian in age and more than 350 m thick, is made up of al. 1983; Pandeli, & Tongiorgi, group succession of the Pisani Mts. (Rau three lithological units correlatable with the “Verrucano” 1974). From the base to top they are: Verruca formation and and Vigneria). This formation is made up of violet minor greenish phyllites Giove Valle Bacino, metasiltstones, laminated quartzites and lenticular (up to 4-5 m thick) quartzitic metaconglomerates. continental with medium to high sinuosity rivers. Paleoenvironment: Monte Serra quartzites del Giove.of the Monte Torre members were distinguished; from the base they are: 1- Two member (= “Quarziti verdi”) 2- littoral. Paleoenvironment: metaconglomerates. interbeds and rare quartzites with phyllitic grey-greenish White-pink quartzites member (= “Quarziti bianco-rosa”) deltaic? Paleoenvironment: levels. and quartzites with minor phyllitic metaconglomerates marbles, calcschist mine, slices of non-fossiliferous, varicoloured Giove In the westernmost part of Valle succession or limestones) are tectonically intercalated in “Verrucano” Giove (Valle and calcareous phyllites Fig. 28). Similar lithotypes are also present in the Vigneria sub-surface underlie the “Calcare Cavernoso”(see (Vigneria limestones) tectonically interposed between the serpentinite and Rio Marina fm. These succession of Mesozoic- lithotypes probably represent tectonic slices of an epimetamorphic Tuscan varicoloured age (e.g. the Capo Castello succession of Stop 7). Cainozoic The Fe-ores of the Rio Marina mines bodies, hosted by or vein massive etc.) are constituted by stratiform, Rialbano, Giove, (Valle up to Cavo (1950)Trevisan’s (Rio phyllites Complex III rocks, preferentially at the contact between Permo-Carboniferous calcareous levels and the overlying Middle Triassic) rocks (“Verrucano”, Marina fm.) or quartzitic/phyllitic Gillieron, 1959) in the northern sector (Cala Seregola, According to some authors (cf. (“Calcare Cavernoso”). geological field trips 2013 - 5(2.1) itinerary 57 ., et al ., 1982; Ciarapica 1982; Ciarapica ., et al ., 1988) (fig. 22). ., et al ., 1985;., Fazzuoli et al E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea ., 1969; Perrin, 1975; Boccaletti et al., 1977) and therefore the formational names are 1975; Boccaletti et al., 1969; Perrin, ., et al DOI: 10.3301/GFT.2013.03 1987; Fazzuoli & Maestrelli-Manetti, 1973; Fazzuoli & Maestrelli-Manetti, 1973; Fazzuoli 1987; Fazzuoli Rialbano) the setting of orebodies is markedly controlled by tectonic lineaments, produced during the Rialbano) the setting of orebodies is markedly area), Deschamps et al. (1983) recognised Giove at least Rio Marina (Valle Nevertheless, Apenninic event. which could of the “Verrucano”, within a particular horizon pyrite mineralisation the occurrence of stratiform represent the relic of a syngenetic iron protore. All these deposits include hematite as main ore mineral habitus or flattened, rhombohedral show either a typical lamellar-micaceous “oligisto”), which may (variety Pyrite is also common, predominantly as by iridescent films of iron hydroxides. crystals, often covered or limonites, massive as well. Exogenous been observed or cubes have although octahedra pyritohedra, especially at Rialbano and locally constitute the main ore minerals, concretionary (sometimes stalactitic) may underground mine workings partly be noticed that in the 50’s-60’s showings. To other northern mineral as “Rio Marina exploited a hematite pyrite orebody associated with skarn silicates, known in the literature The scarcity of geologic documentation and the unaccessibility to underground workings do not profondo”. features of the deposit. allow to study in more detail the otherwise peculiar setting and mineralogic The trip continues along the road to Cavo. Rio Marina fm. crops out as far After the Vigneria mine graphitic group and quartzites of the “Verrucano” as to the Ripabianca area where contact with basal phyllites a wire-net protection).succession is exposed (beyond cross the Rialbano Creek (view on Monte Sassera We and pink violet phyllites quartzites) and go up the winding road (outcrops of Triassic made up of Monte Serra cliff, fm.) and reach the Rialbano mining area (hematite+limonite±pyrite). Here quartzites of the Verruca unit is due to an and the slates of Gràssera contact between the basal “Verrucano” high-angle mineralised dolomite Triassic the top of Monte Calendozio, normal fault (Punta del Fiammingo fault). At east-plunging group). quartzites (“Verrucano” limestones tectonically rest onto the Monte Serra About 1 km ahead, along the continue unit is in tectonic contact (Punta del Fiammingo fault) with the Rio Marina fm. We road, the Gràssera Creek (close to the Cala del Telegrafo). as far Fornacelle THE TUSCAN NAPPE SOUTH OF CAVO In the Eastern Elba Nappe, crops a sedimentary succession,pertaining to the Tuscan Island, South of Cavo, Authors for a long time (e.g. Cocchi,1871; Lotti,1886; Trevisan, out. This link has been recognised by many 1950; Barberi same than those of the Tuscan Nappe in central and southern Tuscany Nappe in central same than those of the Tuscan (Ciarapica geological field trips 2013 - 5(2.1) itinerary 58 Fig. 29 - Tectonic-stratigraphic sketch of the Tuscan Nappe succession. of the Tuscan sketch Posidonia E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea (upper portion). The formation . From Fornacelle Creek up to the fault in . From Fornacelle DOI: 10.3301/GFT.2013.03 From the bottom upwards, the sedimentary succession consists of From the bottom upwards, di Corfino Pania following formations (Fig. 29): “Calcare Cavernoso”, Grotta Giusti cherty Calcare Massiccio, Monte Cetona fm., fm., Limano cherty limestones, Ammonitico”, limestones, “Rosso Stop 6. The Tuscan Nappe succession block faulting of the area, it is not possible to observe Owing the severe succession, but four partial, stratigraphic a continuous stratigraphic all along the main road (see Fig. 30). intervals, Monte Cetona formation Marlstones (Bortolotti et al., 2001). From le Fornacelle Creek 2001). From le Fornacelle Marlstones (Bortolotti et al., along thenorthwards, most of these Rio Marina - Cavo, Road formations crop out. Cala del Telegrafo. correspondence of the road bend overlooking The main lithotypes are dark grey calcilutites, up to 1 m thick, abundant marlstones cm- to dm- thick, and dolomitised calcilutites or coarsely crystalline dolomites, 1 to 2.5 m thick. In the upper portion of 20-50 cm thick, bioclastic and oolitic grainstone formation, dark grey, and packstone beds crop out. Dm-thick coquina beds, corresponding to also occur. storm-layers, Grotta Giusti cherty limestones consists of grey calcilutites and subordinately fine calcarenites, 5-100 laminations and cm thick (mainly 10-20 cm) with abundant horizontal chert nodules and silicified areas. Cm-thick shaly beds are rare frequent, as well dm-thick beds of more or less shaly marlstones. with the overlying The transition The beds plunge 30-50° northwards. formation is stratigraphic. geological field trips 2013 - 5(2.1) itinerary 59 . . The section consists mainly of pink or pale grey calcilutite beds, up to 70 cm thickness is 20 thick (prevailing cm), with cm-thick, grey or pink shaly beds. Grey chert nodules are present. Calcilutite beds, are sometimes nodular, intersected by abundant stylolites In to bedding or wavy. parallel the upper half of section, 45 cm thick calcirudite bed occurs. Beds plunge 30-40° to the north. Limano cherty limestones Grey or pale brown pinkish grey calcilutite beds with rare chert nodules constitute the main Rosso Ammonitico Fig. 30 - Schematic columnar sections of the Tuscan Nappe succession at the Stop 6. E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . The lower half of the section mostly consists grey or pinkish, slightly marly, DOI: 10.3301/GFT.2013.03 lithotype. In the lower portion of section beds, up to 140 cm thick, are intersected by abundant The bedding joints consist to the bedding. In upper portion, 5-30 cm thick beds prevail. stylolites, parallel of stylolites and mm-thick shaly marly beds. Grey calcarenite beds up to 180 cm thick are present, as calcareous and cherty clasts, slump well as two 50 cm thick calcirudite beds with cm- to dm-sized debris flow structures. Most beds plunge 30-40° northeastwards. Posidonia marlstones to the bedding and inclined by abundant stylolites parallel calcilutite beds, up to 360 cm-thick, characterised joints. Grey calcarenite and calcirudite beds up to 25 cm thick are also present. The calcarenites show cleavage bedding and laminations, indicating turbiditic laminations; calcirudites slump structures, graded horizontal mass-flow processes. geological field trips 2013 - 5(2.1) itinerary 60 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea (lower portion). The outcrop consists of 5-15 cm-thick beds dark grey marlstones to the East and Grotta Giusti cherty limestones (lower portion) Posidonia . The Calcare Massiccio crops out in a big quarry on the left side of road (western slope Marlstones continues along the E-W oriented stretch of the road. Marlstones continues along the E-W Posidonia DOI: 10.3301/GFT.2013.03 fine calcarenites and calcilutites, horizontally laminated, with abundant beds and nodules of grey cherts. The fine calcarenites and calcilutites, horizontally trending fold system deforms the earlier north-south here an east-west beds plunge 30° to 50° northwards: system. Calcare Massiccio pale grey or whitish calcarenites and calcilutites, The formation consists of massive, of Monte le Paffe). systems, fracture sometimes intensely recrystallised and dolomitised. The quarry is intersected by pervasive the Calcare On both sides of the quarry, and plunges 70° northwards. the main of which trends east-west by the Grotta Giusti limestone. Massiccio is tectonically overlain as far reaching the parking area of Capo Castello (Fig. 31). and continue northward cross Cavo We The upper half of the section mostly consists of pale grey, more or less marly and silty calcilutite beds, up to The upper half of the section mostly consists pale grey, laminations. Grey shales and marlstones, cm- to dm-thick, often with 160 cm-thick, sometimes with parallel are abundant. Dm-thick beds of dark grey calcarenites with filaments present and, in the slaty cleavage, beds of calcirudites, 50 to 160 cm thick, with cm- dm-sized uppermost portion of the section, also five The outcrop (that is seawards). calcareous and subordinate cherty clasts. Beds plunge 30°- 50° northwards of Going on towards Cavo, two normal fault, oriented SE-NW and N-S, individuate minor horst of “Calcare two normal fault, oriented SE-NW and N-S, Cavo, Going on towards with the Massiccio”, the West. Grotta Giusti cherty limestones geological field trips 2013 - 5(2.1) itinerary 61 = 2 /S 2 - varicoloured c event into centimetric to decametric close event 2 ), the first two syn-metamorphic in greenschist 3 and D hectometric isoclinal, recumbent fold defined along the Cala 2 1 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea , D 1 - metagraywackes (Pseudomacigno, Oligocene). From the structural point of view, Oligocene). From the structural (Pseudomacigno, - metagraywackes - “Maiolica”-type, grey cherty limestones (?Early Cretaceous); d b - Varicoloured cherty calcschists and crystalline limestones (Capo Castello calcschists, - Varicoloured a ) and is associated to a main D = calcite + sericite ± quartz hematite to the lithological chlorite), which is parallel 0 1 structures were deformed and transposed by the D structures were deformed and transposed 1 DOI: 10.3301/GFT.2013.03 phyllites and calcschists with metalimestones and metacalcarenites (varicoloured sericitic schists, Late and calcschists with metalimestones metacalcarenites (varicoloured phyllites Cretaceous/Eocene) and, (D at least three ductile deformation events subdivisions (S Late Dogger?-Malm?); THE TUSCAN EPIMETAMORPHIC SUCCESSION OF CAPO CASTELLO Stop 7. The Tuscan epimetamorphic succession, Cala dell’Alga shales of the Ophiolitic unit crop out, which In the parking area and along beach to north, Palombini fault separates normal Cala dell’Alga a high-angle a thick ophiolitic breccia (on the beach). Eastwards, overlie the Ligurid formations from Capo Castello epimetamorphic rocks. The Capo Castello fossiliferous metamorphic succession (cropping out also at the Scandelli and Isola see Fig. 31a) belongs to the Tuscan respectively, to the north and south of Capo Castello, dei Topi, 1995) and includes et al., unit (Pandeli metamorphic succession of the Monticiano-Roccastrada low-grade (from the bottom): dell’Alga-Capo Castello-Isola dei Topi alignment (see Fig. 31a and b). dei Topi Castello-Isola dell’Alga-Capo The D hematite±sericite) (Fig. 32). Gentle to open folding, generally with sub-horizontal axial plane with sub-horizontal hematite±sericite) (Fig. 32). Gentle to open folding, generally facies, are distinguished. After about 100 m, we turn to the right and go the road to Capo Castello. From the parking area, we take turn left and reach the first two little rocky promontories We down a little road with stairs till the Cala dell’Alga. sericitic schists are well exposed and clearly show Here the varicoloured along the northern side of gulf. their tectono-metamorphic imprint. and metric and calcschists with levels phyllites sericitic schists” are made up of varicoloured The “varicoloured grey limestones. These rocks show a main continuous penetrative bodies of recrystallised, at times cherty, schistosity (S isoclinal synforms and antiforms (e.g. the NE-vergent synformal anticline of the eastern part Capo Castello) isoclinal synforms and antiforms (e.g. the NE-vergent to discrete crenulations (C axial planes and spaced, zonal NNW/SSE-trending with sub-vertical, geological field trips 2013 - 5(2.1) itinerary 62 of (b) and cross-sections (a) event and a possible anti- event 3 , Fig. 32) and fracture cleavage, , Fig. 32) and fracture 3 event. 4 Fig. 31 - Geological sketch map Fig. 31 - Geological sketch the Capo Castello area (after Pandeli et al., 1995). et al., the Capo Castello area (after Pandeli The low-grade metamorphic succession of Capo Castello The low-grade formations probably represents part of the pristine cover metasediments belonging to the of the triassic “Verrucano” unit and reconstructs in the Elba Monticiano-Roccastrada typical succession of the Tuscan Island the stratigraphical metamorphic ridge (from the Apuan Alps-Mts. Pisani to area).Monticiano-Roccastrada Coming back to the parking to (from Cavo area, the trip continues along la Parata road. Rio Elba) panoramic apenninic-trending D apenninic-trending represent the coaxial D crenulations/kinking (C E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 63 (see Ophiolitic unit THE GRÀSSERA AND OPHIOLITIC UNITS road exposes the two lowest subunits of The la Parata subunits) and and Acquaviva Ophiolitic unit (Monte Serra to Case Braschi unit. From Cavo the underlying Gràssera unit. we cross only the Gràssera Stop 8. The Gràssera unit of the road to left, some stop at a big curve We Here the upper portion of hundred metres from Cavo. formation, see Bortolotti et al, 2000) unit (Cavo Gràssera crops out. It consists of greenish and wine-red slates manganiferous siliceous limestones siltstones with rare slaty cleavage, and cherts. These rocks show a pervasive deformed by open to close folds with a spaced fracture are also syn-tectonic quartz veins Typical cleavage. present. we enter the Near Case Braschi Bortolotti et al., 2000; Fig.Bortolotti et al., 33), but the contact is covered by a slide. The first outcrops pertain to the Acquaviva shales are subunit. Here ophicalcites and Palombini before the watershed tectonically repeated as lenses. At the Gorgoli Creek we cross thrust contact between subunit, Monte Serra and the overlying Acquaviva represented here by Calpionella limestones. This formation crops out for some hundred metres and no evident structures are visible along the road. E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 32 - The Varicoloured Sericitic schists in the Fig. 32 - The Varicoloured Cala dell’Alga area. For details see text, Stop 7. area. For Cala dell’Alga DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 64 Stop 9. The Gorgoli anticline stop at the bridge along Gorgoli Creek ad go We upstream some tens metres crossing the whitish and a fault thick beds of the Calpionella limestones; beyond the core of a big cutting the creek, we can observe On the with a NE vergence. anticline trending NNW-SSE, right side a succession dipping to the NE crops out, here ii- a cliff some made up of: i- a few metres of pillow lavas, metres high of thin-bedded red cherts and siliceous shales (Monte Alpe cherts) and, iii- the Nisportino fm., here formed, just from the base, by pale grey marly On the left side of member. calcilutites of the Rivercina the structure same succession dips to NW. Coming back to the road, we cross twice same anticline, faulted on its eastern side. After 1 km of very folded Calpionella limestones we cross again the subunit. The contact along the road is Acquaviva faulted. In this area we can reconstruct the disrupted and condensed succession of this subunit: at the top of the ophicalcites little quarry on right, some chert beds (Monte Alpe cherts) crop out in the E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 33 - Schematic columnar sections of the main subunits of the Ophiolitic unit (after Bortolotti et 1994). al., DOI: 10.3301/GFT.2013.03 Mediterranean scrub; along the road the cherts grade upwards to Palombini shales. to Palombini upwards scrub; along the road cherts grade Mediterranean with minor internal subunit terrains for about 2 km, the road cuts Acquaviva Pass, From here, to near the La Parata ophicalcites are well exposed. shales and the overlying thrusts: on the road two contacts between Palombini 250 m unit. we cut the hidden thrust contact between Ophiolitic and underlying Gràssera Pass before the La Parata closely spaced. The road runs four units of the eastern Elba tectonic pile crop out very zone In the La Parata Ophiolitic unit. On the road lies thrust contact with overlying unit. Immediately above on the Gràssera Nappe and, a the faulted contact with Tuscan scrub covers the other side of road, Mediterranean unit. little to the east, faulted contact between this latter and Monticiano-Roccastrada geological field trips 2013 - 5(2.1) itinerary 65 Fig. 34 - The thrust contact (La Parata thrust fault, Bortolotti et al., Fig. 34 - The thrust contact (La Parata belonging to the Gràssera unit), 200 m south of Parata Pass, Stop 10. Pass, unit), 200 m south of Parata belonging to the Gràssera 2001a) between the triassic calcare cavernoso (CV) of the Tuscan 2001a) between the triassic calcare cavernoso fm. calcschist member (CM) of the Cavo Nappe and the overlying in the Ortano (Stop 3 m, n). This structure is part of the Valley normal faults which dissects the system of westward-high-angle the North, it lowers Monte tectonic pile of eastern Elba. To subunit and the subunit, with respect to Acquaviva Serra unit; to the South, same structure underlying Gràssera Nappe. unit with respect to the Tuscan lowers the Gràssera and crosses some tens the road turns south-west Afterwards, of metres ophicalcites. E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea century flourished the charming Gràssera village, destroyed by the terrible pirate Khair by the terrible pirate village, destroyed century flourished the charming Gràssera th DOI: 10.3301/GFT.2013.03 Eddin (Red Beard).The only remains are the ruins of San Martino church, immediately on left road, Eddin (Red this name to the unit in its memory. gave the underground aqueduct and name of creek. We Mine) Giove of Rio Marina (foreground, the Valle on the Fe-mines a spectacular panorama From here we can enjoy quartzites) of the triassic Verrucano where the upper formation (Monte Serra del Giove and on the Monte Torre (the western side of Monte del Giove), unit (see Stop 5) crop out. Westward group of the Monticiano-Roccastrada fault), with the “Calcare Cavernoso” normal fault (Terranera is in contact, through a high-angle the “Verrucano” Nappe. of the Tuscan road up to the crossroad with little (to left) for 200-300 m along the Parata continue southwards We cemetery of Rio Marina. Here the road intersects St. Caterina Normal fault high angle normal fault, just observed Stop 10. The thrust contact Tuscan Nappe-Gràssera unit of the Tuscan limestones (“Calcare Cavernoso”) a little outcrop of Triassic Along the road, 200 m south of Pass, unit (Fig. 34). The latter is here represented by its basal Gràssera Nappe shows the thrust contact with overlying fm.). In the calcschists last folding portion: brown-grey polydeformed calcschists (calcschist member of the Cavo schistosity relics). (see the intrafolial on a previous tectono-metamorphic layering pervasive is very event until the 16 Nearby, geological field trips 2013 - 5(2.1) itinerary 66 . A basal a E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . This formation is composed of three distinct members, from the bottom: . A level, formally distinguished as Rivercina member (11-30 m), consisting of marly formally distinguished as Rivercina . A level, b . An upper section (50-70 beds of by red siltstones and/or shales with rare m) characterised c DOI: 10.3301/GFT.2013.03 level (15-30 m thick), made up of siliceous calcilutites, red siliceous siltstones and, locally, marlstones (15-30 m thick), made up of siliceous calcilutites, red siltstones and, locally, level and/or shales; Stop 11. The ophicalcites cases their upper subunit, although in many These ophicalcites probably constitute the base of Monte Serra prefer to call these rocks ophicalcitised serpentinites contact with the basalts is more or less tectonised. We because they do not show all the structures of typical ophicalcites eastern Liguria. They are pervasively become more and preferential trend. The veins without any serpentinites with scattered calcite veins fractured more frequent near the upper contact. A little more than 100 metres passed the ophicalcites we enter a subunit (from Monte Alpe cherts of the Monte Serra made up of the sedimentary cover strongly folded zone, to Calpionella limestones). Stop 12. The base of the Nisportino formation the contact between Monte Alpe cherts and Nisportino fm. Near the first creek (Fig. 35) we can observe Nisportino formation calcilutites; on the siltstones. The upper section ends with by calcilutites prevailing siliceous calcilutites, followed upwards a few meters of siltstones and marly shales. According to calcareous nannofossils the age is Berriasian. and siltstone of the Monte Alpe cherts crop out. Here red siliceous claystone Along the road upper levels metres above cherts. All the sequence is thin-bedded. Five and laminated clay-rich on radiolarites beds prevail On the right, to its base and at top, little quarry. the road, on right side of creek, we find a very two cherty calcilutite beds, and in between a thin-bedded sequence of siliceous siltstones we can observe cherts. The contact between Monte Alpe cherts and Nisportino fm. has been placed at the with rare claystones more metres of the same type succession and we find five base of the first calcareous bed. Going upwards of the formation that we called Rivercina level then 15-20 metres of light grey marly calcilutites, a key of the formation will be seen with a thick bed of siliceous calcilutite. The upper levels It ends upwards member. in the next Stop. geological field trips 2013 - 5(2.1) itinerary 67 c- ni- of- pb- Monte di- Gabbros; - g Calpionella limestones; Rivercina member; Rivercina Basalts; ri- cc- Serpentinites. Gràssera unit: Serpentinites. Gràssera - normal faults. b - f- s low angle tectonic surfaces: thrusts and l- Quaternary deposits. Ophiolitic unit: Fig. 35 - Geological map of the area south-east detachments; Palombini shales; Palombini of Nisportino, with the location of Stops 12 and 13. of Nisportino, q- Nisportino fm., with Nisportino fm., Alpe cherts; Ophicalcites; fm. Cavo We stop at the last bend of road (Fig. 35). We marly calcilutites are tectonically The Rivercina but we can see the siliceous cut away, The upper portion limestone beds at their top. of the formation consists alternating marly and siliceous siltstones, cherty cherts. Upwards, clay-rich calcilutites and rare the calcilutites, scarce at base, become more and abundant. The top of the of light by a thick level formation is marked the well-bedded, grey marly siltstones. Above, silty or shaly whitish calcilutites, without any E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 We come back to the road (Fig. 35), to San Pietro and turn right towards Nisporto. Along this road we see Nisporto. come back to the road (Fig. 35), San Pietro and turn right towards We to the left with a big oak we cut again contact a curve cherts and serpentinites in tectonic contact. At the first bend between Monte Alpe cherts and Nisportino fm. Here the limestones are completely decalcified. At exposing the top and with clear NE vergence, anticline trending N-S of the road we cross core a reverse of the Monte Alpe cherts and basal portion Nisportino fm. Stop 13. The Nisportino formation geological field trips 2013 - 5(2.1) itinerary 68 e is E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 36 - Panorama from Mt Strega-Monte Serra pass towards Nisportino-Pietre Rosse. The succession of the Monte Serra Nisportino-Pietre Rosse. pass towards from Mt Strega-Monte Serra Fig. 36 - Panorama surface between Monte Serra and Volterraio subunits. and Volterraio surface between Monte Serra the type locality of Nisportino fm. a- Basalts; b- Monte Alpe cherts; c- Nisportino fm.; d- Calpionella limestones; t- Thrust Nisportino fm.; d- Calpionella limestones; t- the type locality of Nisportino fm. a- Basalts; b- Monte Alpe cherts; c- subunit (to the right) is overlain by the Volterraio subunit (central-left part of the figure). The Nisportino-Pietre Rosse zon part of the figure). The Nisportino-Pietre Rosse subunit (central-left by the Volterraio subunit (to the right) is overlain DOI: 10.3301/GFT.2013.03 intercalations, constitute the Calpionella limestones fm. The transition can be observed in the quarry near can be observed intercalations, constitute the Calpionella limestones fm. The transition pass, on the right of road, where it is dissected by some minor faults. of the serpentinite slices which run along thrust contact between The road exposes some fragments subunit (Fig. 2), which constitutes the hills to South. Volterraio and the overlying Monte Serra In front of by the subunit, overthrust the succession of Monte Serra (Fig. 36), we can observe us, looking westwards Hill). The well exposed succession of the latter subunit includes subunit, to the left (Pietre Rosse Volterraio by Monte Alpe cherts and, then the Nisportino fm. (type-section). basalts at the base, overlain in which the then to Rio nell’Elba, where we cross a complicate, thin “Schuppenzone”, go back to San Pietro, We subunits are implicated. An outcrop of serpentinite the Sassi Turchini and Volterraio Sassi Turchini Monte Serra, geological field trips 2013 - 5(2.1) itinerary 69 (pillow basalts). pass on the Portoferraio Bay (the built on the Monte Alpe cherts that Monte Capanne in the background). stratigraphycally lie onto the Basalts The Pisan Medieval Volterraio Castle is Fig. 37 – Panorama from the Volterraio E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 subunit is immediately below the village. continue up to the We Volterraio crossing a thick basalt Pass, a succession. From the pass we enjoy wonderful view to the east, toward visited in the morning, and the zone the Portoferraio to the west, toward the MedievalBay, Volterraio Castle to the (Fig. 37) and, on the horizon, which we will Monte Capanne Massif, proceed, and We tour the next day. stop some hundred metres further on, where the road skirts long high of pillow basalts. walls Stop 14. Pillow lavas the basalts Here, along the walls, are represented by large sized and by the crystallisation of chlorite, albite, actinolite by a strong oceanic alteration characterised pillow-lavas, come We structures and some pillow-shelves. and pumpellyite. In some of these pillows we can see variolitic runs near and crosses, before, la Ginestra, The road, beyond Azzurro. Porto back to Rio nell’Elba and go toward basalts and, further on, the serpentinite and the Monte Serra the thrust contact between Sassi Turchini delle Shortly after the Fosso gabbro. serpentinite and the Volterraio thrust contact between the Sassi Turchini subunit we enter the Acquaviva Maceratoie Stop 15. San Felo ophiolitic succession subunit, which shows an ophiolitic klippe, pertaining to the Monte Serra we can observe Shortly past San Felo, reduced succession, well exposed in a little quarry on the right of road. This klippe constitutes an a very geological field trips 2013 - 5(2.1) itinerary 70 . a E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Close to the quarry, and on its left side, they show a detrital facies, with small fragments of and on its left side, they show a detrital facies, with small fragments Close to the quarry, . DOI: 10.3301/GFT.2013.03 ophicalcites, cropping out on the road, which show two different facies. Far from the quarry they are ophicalcites, cropping out on the road, which show two different facies. Far type, see Cortesogno close one another (“Breccia di Levanto” very serpentinites with calcite veins fragmented 1987) et al., east-vergent, reverse, almost isoclinal syncline (Fig. 38). The succession comprehends, from the bottom: reverse, east-vergent, Fig. 38 - The little quarry near San Felo. pillow Oph- ophicalcites; Ba- basalts; Ya- breccia; Ch- Monte Alpe cherts; CC- Calpionella limestones. geological field trips 2013 - 5(2.1) itinerary 71 . A few b . The Monte c E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . Calpionella limestones, with the typical well-bedded, whitish calcilutites. The d DOI: 10.3301/GFT.2013.03 Alpe cherts, in their typical facies. At the base some dm of red shales including a big pillow lava; upwards the base some dm of red shales including a big pillow lava; Alpe cherts, in their typical facies. At alternating with siliceous siltstones and shales, more about ten metres of thin bedded radiolarites abundant going upward; of the Nisportino fm.contact is sharp and probably tectonised: no traces Some hundred metres further on, we Creek. reach the Acquaviva meters of a basalt breccia on the right side of the quarry while, on its left side few pillow lavas; meters of a basalt breccia on the right side quarry while, its left few pillow lavas; serpentinite dispersed in a calcitic cement (“Framura Breccia” type see Cortesogno et al., 1987); Breccia” type see Cortesogno et al., serpentinite dispersed in a calcitic cement (“Framura Stop 16. Fosso Acquaviva, serpentinites go up a big boulder, and stop at the end of small road. We Just crossed the bridge, we turn right along river to spinel- from spinel-bearing lherzolites a composition ranging made up of serpentinised tectonites. They have and plagioclase. The plagioclase bearing harzburgites. The rock of the boulder contains interstitial clinopyroxene crosscutting the peridotite with can see also some dykelets occurrence is usually concurrent with stable spinel. We (2 some distance from the dykelets At different trends. They are made up of altered plagioclase and clinopyroxene. These data can suggest that poichiloblasts enclosing serpentinised olivine grains forms mm-sized cm) clinopyroxene impregnated by mafic melts producing plagioclase and been extensively peridotites have the Sassi Turchini The presence of impregnated mantle peridotites is reminiscent the upper- patches and veins. clinopyroxene 1994a; 1994b). & Vaggelli, 1994; Tartarotti (Bortolotti et al., zone mantle-lower oceanic crust transition Azzurro (Fig. 20) and, just before the cross- come back to the road and, turning right, we go through Porto We Mar di Carpisi Crocetta mining area (in the Fosso il Buraccio-La we turn right towards road to Spiaggia del Lido, high. a country road on the right which climb up La Serra A few tens of meters ahead, we take Valley). contact between the Monte Calamita fm. and underlying La Serra- Along the road, we cross intrusive to a little plateau with threes. Here the tectonic superposition of and arrive Azzurro monzogranite Porto the landscape is NW, Azzurro unit crop out. Looking towards the Porto Cretaceous flysch unit above Crocetta mining area. This mine is still an important producer of raw by the Buraccio-La characterized Capo Bianco metasomatized Exploitation focoused on pervasively industry. materials for the ceramic aplite (the so-called “eurite”), located in the basal part of Cretaceous flysch unit, which porphyritic 2003). This at 6.7 Ma (Maineri et al., underwent significant potassium enrichment during the sericitic alteration Elba detachment fault of metasomatic fluids along the Central process has been referred to the infiltration geological field trips 2013 - 5(2.1) itinerary 72 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 (CEF) during the uplift of Monte Capanne plutonic body which altered magmatic bodies present at to the north and cross Cretaceous flysch unit, a track take base of the Cretaceous flysch unit. We higher unit of the Ligurian Domain in Elba Island, which include the body of Capo Bianco aplite. We reach a country road (see below) at the divide. from area (Fig. 20 and 39). In particular, road by cars (jeep) is that runs from the Valdana A more practicable just after 700 m the as far C. Marchetti Locality (Valdana, Azzurro we continue to Portoferraio Porto on and La Crocetta (panorama the road on right to Buraccio-C.Traditi cross road to Lacona). Here we take the La Crocetta Mine) and reach divide. Near divide we cross repeatedly contact with a very locally associated with aplites. Just before the pass, we turn left, porphyry) (Portoferraio dyke large porphyritic bad and narrow road (only for little cars). Here we cross a thin outcrop (10-20 m) of Paleogene very on a very Going flysch unit and we enter immediately the Ophiolitic (all these tectonic contact are not observable). complicated folded structure in the Calpionella limestones and underlying we can see on the left a very up, Nisportino fm. Stop 17. Monte Castello-Cima del Pass. The folded structure of the Volterraio subunit and the shoshonitic dyke just We stop on a small rock spike. (Fig. 39) and go down by foot some tens metres. We stop on the Pass We crossed an which uplifts the Monte Alpe cherts, on we are, respect important normal fault, dipping NW, can note the difference of tectonic style on two sides: cherts are strongly to the Nisportino fm. We isoclinal folds, the Nisportino fm. shows a large anticline, with some minor folds deformed, with tight, vertical to note that in spite of the have at the core (Fig. 40), which is on our right (E) in Monte Alpe cherts. We softly folded. complicated folds present in the cherts, contact line with underlying basalts is very very where the rugged the little church (Madonna di Monserrato), can see this contact immediately beyond We landscape of the cherts is substituted by smooth and woody hills. In the hills close sea underlying units of basement (Ortano unit) that constitutes the coastal relieves crop out, included the metamorphic Paleozoic Azzurro. Porto along the fault plane a cataclastic breccia, some end we can observe, go down some metres westward We metres thick, made up only of cherts; the marly limestones on other side are undisturbed. Along fault geological field trips 2013 - 5(2.1) itinerary 73 - s- g Colle Neogene pf- Rivercina Calpionella basalts; ri- d- - b cc- Quaternary deposits; q- Marina di Campo fm.; Palombini shales; Palombini Nisportino fm., with Nisportino fm., Monte Alpe cherts; serpentinites. cf- ni- - pb- s di- Fig. 39 - Geological map of the area. North gabbros; member; Reciso fm.; Reciso limestones; Monte Castello. Monte Castello. shoshonitic Monte Castello dyke; acidic dykes; plane we can observe a some dm thick plane we can observe in Conticelli (Monte Castello dyke mafic dyke more west turns 2001). This dyke et al., and crosscuts the Monte Alpe right (N-S) cherts, the Nisportino fm. and Calpionella limestones, finally it enters a fault (Fig. 39). It has a E-W successive texture with phenocrysts of porphyritic with olivine, plagioclase and clinopyroxene, The xenocrysts. seldom large K-feldspar is strongly altered and original mineralogy E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Ar dating performed on the k-feldspar-rich groundmass give a cooling age of groundmass give Ar dating performed on the k-feldspar-rich 40 Ar/ 39 DOI: 10.3301/GFT.2013.03 5.83±0.14 Ma. The whole rock chemistry indicates that the parental magma has a shoshonitic composition, chemistry element data and mineral These data together with trace with a clear alkaline-potassic affinity. suggest that the magma belong to italian Plio-Pleistocene potassic suite, and closely resemble rocks cropping out at the Capraia The presence of olivine ghosts with euhedral Island and in the Southern Tuscany. replaced by secondary minerals. Clinopyroxene and plagioclase in some cases are still preserved, whereas and plagioclase in some cases are still preserved, Clinopyroxene replaced by secondary minerals. Mg-chromite inclusions also occur in the olivine olivine is entirely replaced by smectite aggregates. Euhedral plagioclase, k-feldspar, ghosts. In the most fresh samples groundmass is made by clinopyroxene, magnetite and apatite. geological field trips 2013 - 5(2.1) itinerary 74 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea upper portion of the Nisportino fm. (NF) and, finally, in the external limbs, by Calpionella limestones (CC). upper portion of the Nisportino fm. (NF) and, finally, Fig. 40 - Panorama on the complex anticline north of Monte Castello. The core is made of Rivercina fm. (RM) overlain by the fm. (RM) overlain The core is made of Rivercina on the complex anticline north of Monte Castello. Fig. 40 - Panorama DOI: 10.3301/GFT.2013.03 Mg-chromite inclusions suggest that the magma has a strong primitive composition. The presence of Mg-chromite inclusions suggest that the magma has a strong primitive clearly indicates that the mafic magma and the lack of reaction paragenesis from a monzogranite, xenocrysts to its cooling. successively intruded the monzogranite fault system is important for dating the brittle tectonics of eastern Elba. In fact SW-NE is very This dyke older that 5.8 the thrust of (Fig. 39). This latter moves system, which is younger Ma, and is cut by the NW-SE fault system to the east. This faults?) and does not interrupt the N-S (transfer subunit on the Acquaviva Volterraio latter fault system can be considered the last tectonic structure of Elba come back to the main road, Island. We and then to Portoferraio. geological field trips 2013 - 5(2.1) itinerary 75 Fig. 41 – Itinerary central Elba. central and Stops in western the Biodola Gulf to Enfola Cape), we continue for some kilometers as far the landscape opens on the Procchio Gulf and on the Monte Capanne massif in the background. We stop at a panoramic point. E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 WESTERN AND CENTRAL ELBA the main geological feature of western Elba: i) to observe This part of the field trip (Fig. 41) is devoted and ii). its thermometamorphic aureole consisting in different swarm Monte Capanne pluton with associated dyke types of hornfels after a ophiolitic succession. During the trip we will also visit some outcrops flysch units in the road to Procchio. we take Portoferraio, Elba. Leaving (Lacona-Colle Reciso) and Central (Fetovaia) the Western outcrops of the Cretaceous From the Campitelle locality (cross-road to Napoleonic San Martino Villa), several are present. After the pass (on right, beautiful view on dykes flysch unit cut by locally decametric S.Martino geological field trips 2013 - 5(2.1) itinerary 76 sketch map of Fig. 42 - Geological western Elba Island. -wide and 1016 m (a.s.l.) high. Along its slopes, -wide 2 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 Stop 18. View on the Western Elba and Cretaceous flysch unit of Central The Stop allows us to introduce the geology of western Elba (Fig. 42), dominated by Monte Capanne magmatic body (6.9 Ma) which is about 10 Km monzogranitic part of the contact metamorphic aureole, made up of a ophiolitic succession, is preserved (e.g. Procchio- part of the contact metamorphic aureole, made up a ophiolitic succession, is preserved geological field trips 2013 - 5(2.1) itinerary 77 - grey fine-grained a -calcarenitic to marly very thick beds (up to 6 m); -calcarenitic to marly very c -dark grey very fissile shales which occur in beds showing -dark grey very d E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. -thick-bedded (1-4 m), grey, medium/coarse-grained quartz- medium/coarse-grained (1-4 m), grey, -thick-bedded The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea b DOI: 10.3301/GFT.2013.03 frequently, their base is made of an arenaceous level, with carbonate cement, grading upward to the upward with carbonate cement, grading their base is made of an arenaceous level, frequently, to marlstone, calcarenite which in its turn grades very variable thickness; their mineralogical association is similar to that of the arkosic turbidites of the Ghiaieto association is similar to that of the arkosic thickness; their mineralogical variable very The lithotypes a- and b- closely alternate at the base of formation, b-, but also includes vermiculite. ss., and d- upwards.c- road to continue the trip crossing Procchio and continuing along panoramic We the road to Spartaia on right. Marciana Marina. A few kilometrs ahead, we take quartz-feldspathic thin-bedded sandstones, quartz-feldspathic feldspathic sandstones with a carbonatic cement, Spartaia-Paolina Isle and Marciana Marina-Marciana areas). These contact metamorphic rocks are also Spartaia-Paolina the At porphyries). intruded by the pre-Capanne laccolithic complex (e.g. Capo Bianco aplites, Portoferraio fault) the about NS-trending Eastern border fault (Colle Palombaia-S.Piero-S.Ilario-Procchio back of Procchio, Elba respect to the ophiolitic downthrown to the east non-metamorphic Cretaceous flysch unit of Central thermally metamorphosed succession. Along the slope of road, marly limestones with marl, siltstone and shale interbeds Cretaceous (7.4 porphyry of the S.Martino flysch unit (Marina di Campo fm.) crop out. These rocks are intruded by dykes by alternation of four main lithotypes: Ma). The Marina di Campo fm. is characterised Stop 19. The rocks of the inner part M.Capanne contact metamorphic aureole reach the parking area of Spartaia beach. Along road, in front Désirée Hotel, intrusive We and the thermally dykes, intruded by leucogranitic contact between the Monte Capanne monzogranite, a take Ophiolitic succession) is exposed. We metamorphosed host rocks (Monte Alpe cherts of the recrystallized where metacarbonates with metapelite intercalations path along the cliff of western part Spartaia bay reach crosscut the foliated thermally metamorphosed rocks. We dykes crop out. Some undeformed leucogranitic by polydeformed calcschist and marble (Fig. 43) that we correlate to in a few minutes quarry cut characterised porphyry. of the Portoferraio the Calpionella limestones. These rocks are crosscut by a foliated dyke feature of this outcrop (see also Metric to decametric, tight isoclinal folds represent the main structural the mesoscale, a interprete these folds as F2. At 1995). We Spohn, 1981; Bouillin, 1983; Daniel & Jolivet, S2) is associated ti discrete crenulation cleavage, axial plane foliation (zonal millimetric to centimetric-spaced plunge. Thir axial planes have with a SW or northward and NNW-SSE NE-SW mainly strike to F2, whose axes geological field trips 2013 - 5(2.1) itinerary 78 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 43 – Outcrop of polydeformed calcschist and marble west of the Spartaia Bay. These rocks are crosscut by a foliated Fig. 43 – Outcrop of polydeformed calcschist and marble west the Spartaia Bay. Portoferraio porphyry dyke. porphyry Portoferraio DOI: 10.3301/GFT.2013.03 a NW dip. F2 deformed a previous metamorphic layering which correspond to the lithologic partitions F2 deformed a previous metamorphic layering a NW dip. replaced by the contact alignements, are generally (S1//?S0). S2 and S1, outlined by opaque minerals are locally present. A unrooted F1 isoclinal folds of decimetric size (e.g. biotite). Rare metamorphic minerals that cut the S1 foliation of metacarbonates, is present at porphyry, of foliated Portoferraio metric dyke In fact, S2 is related to D2 deformation event. dyke The foliation of the porphyritic top of the outcrop. crossing the folded contact (Fig. 44). continues from the metacarbonates to dyke geological field trips 2013 - 5(2.1) itinerary 79 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 44 - Folded contact between the foliated porphyritic dyke and the deformed metacarbonates. dyke contact between the foliated porphyritic Fig. 44 - Folded DOI: 10.3301/GFT.2013.03 The association contact metamorphic minerals (metacarbonates: wollastonite, calcic plagioclase, diopsidic The association contact metamorphic minerals metapelites: biotite, intermediate-calcic scapolite K-feldspar; grossularitic garnet, vesuvianite clinopyroxene, facies that is consistent with the is typical of the pyroxene plagioclase, cordierite, andalusite and k-feldspar) of 600°-700°C at P 2kbar (Barberi & nearness of the Monte Capanne plutonic body with peak temperatures grow statically and mimetically 2007). The HT minerals et al., 2002; Rossetti Innocenti, 1965; Dini et al., veins. the D2 structures in plague and foliation-parallel above are crosscut by a decimetric to centimetric spaced fracture The folded metacarbonates and the foliated dyke geological field trips 2013 - 5(2.1) itinerary 80 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 cleavage filled by high temperature (vesuvianite, grossularite wollastonite) and hydrothermal (e.g. epidote, grossularite wollastonite) and hydrothermal (vesuvianite, filled by high temperature cleavage quartz) mineralizations. occurred after the intrusion of Portoferraio The data suggest that the D2 ductile folding and shearing event connected to the hot emplacement of Monte Capanne pluton which here produced and it is likely porphyry rocks. During or immediately after these processes, HT fluid infiltration discarge of the cover a northward and contact metamorphism of the deformed metasedimentary rocks. produced hydrofracturing road and continue to Marciana Marina. Just before the village, at Punta della come back to the panoramic We in amphibole hornfels facies) are well exposed and include an metabasalts (transformed Crocetta, pillow-lavas cross Marina di Campo and continue about 8 Ma). We porphyry, (Portoferraio dyke about 2 m-thick porphyritic road. After about a kilometer from Marciana, we stop in along the panoramic to Marciana and then Zanca di Caolino locality in Fig. 5). front of a quarry (Cava Stop 20. The “eurite” quarry (S. Rocco or Cava di Caolino) industry. material for ceramic Capo Bianco aplite body (8.4Ma) as raw The quarry exploited a metasomatized stages of the Monte Capanne pluton, produced a to the final exhalative The metasomatic fluid, linked potassium enrichment (sericitization) of the aplitic body which is included in a laccolithic rocks (thermally metamorphosed The latter is intruded in mainly metapelitic-metasiltitic porphyry. Portoferraio said geological units. The S. finally cut the above dyke and a mafic Orano dyke shales). A S.Martino Palombini restoration. quarry is now in environmental Rocco we turn on the right, going down slope as far road and reach Zanca; continue along the panoramic We a path along the western cliff and reach Capo Sant’Andrea. take We the parking area of Capo Sant’Andrea. geological field trips 2013 - 5(2.1) itinerary 81 (=main facies) MF locally exhibits a marked inequigranular texture due to inequigranular locally exhibits a marked K-feldspar the occurrence of large Karlsbad-twinned megacrysts (up to 10 cm along the c axis; Fig. 46). In Monte Capanne pluton the monzogranitic particular, The Monte Capanne pluton (about 6.8 Ma) and the are among the and aplitic dykes related leucogranitic oldest magmatic rocks outcropping in the Elba island 1971; 1962; Borsi & Ferrara, (Eberhardt & Ferrara, 1984; Coli et al., 1982; Juteau et al., Saupe et al., 2004, 2005, 2002; Gagnevin et al., 2001; Dini et al., et al., 2004; Farina et al., 2008, 2010; Westerman 2010). The main body intrudes a ophiolite succession oceanic basement and volcanics, including the Jurassic to Cretaceous pelagic and their Upper Jurassic rocks which Barberi et al. (1969) sedimentary cover attributed to their Complex IV widely outcropping in Eastern Elba. These rocks which form a well developed thermometamorphic aureole all around the Mt. Capanne pluton. The main magmatic body of the Mt 2002; 1992; Dini et al., Capanne intrusion (Poli, 2004 ) is represented by a light-grey, et al., Westerman hypidiomorphic medium-to coarse-grained (MF in Fig. 45). The monzogranite E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 45 - Classification normative diagram (after diagram Fig. 45 - Classification normative rocks names with quartz- as prefix (after Coli e al., 2001). as prefix (after Coli e al., rocks names with quartz- Streckeisen & Le Maitre, 1979) for the Monte Capanne Streckeisen Azzurro magmatic bodies. Data from Juteau, and Porto et 1987; Poli et al., 1984; Peccerillo 1984; Juteau et al., 1992. Numbers with asterisks refer to 1989b; Poli, al., DOI: 10.3301/GFT.2013.03 was fed by several magma pulses that coalesced into a single intrusion. Three main facies can be detected in fed by several was by facies, characterized Sant’Andrea the pluton but first two are more important: 1) monzogranitic Stop 21. The Monte Capanne monzogranite Capo Sant’Andrea - Punta del Cotoncello area. geological field trips 2013 - 5(2.1) itinerary 82 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 46 - Mesoscopic textural feature of the external Fig. 46 - Mesoscopic textural (see text for explanation) (after Coli e al., 2001). (see text for explanation) (after Coli e al., portions of the Monte Capanne pluton, where MF is typically megacrysts. These megacrysts K-feldspar enriched in euhedral in conditions of the acid end member, respond to a high-volatile 1986). This is the early phases of crystallisation (Vernon, testified by their accidental inclusion in the large mafic enclaves which represent a at Capo Sant’Andrea, that can be observed sub-crustal end- remnant of a partially mingled and mixed megacrysts Note the iso-orientation of K-feldspar member. DOI: 10.3301/GFT.2013.03 numerous large K-feldspar megacrysts and mafic numerous large K-feldspar San Piero 2) the granodioritic-monzogranitic enclaves; facies, typically quarried for its homogeneous texture of large megacrysts and mafic enclaves; almost devoid facies show intermediate features 3) S.Francesco 2002; between the 1) and 2) facies (Dini et al., 2010). The et al., 2004; Farina et al., Westerman facies in Westerman megacrysts-rich facies (Sant’Andrea 2004) is well exposed in some outcrops along the et al., outer portions of the pluton and especially at Capo and is also typical of the external parts Sant’Andrea, Giglio and Archipelago (e.g., other plutons of the Tuscan Montecristo). Beside the megacrysts, MF is composed of perthitic orthoclase, quartz, plagioclase, and biotite, whilst apatite, zircon, tourmaline, sphene, and monazite occur as accessory phases. Furthermore, facies) the in some place (expecially the Sant’Andrea is dotted by abundant mafic microgranular monzogranite with ellipsoidal shapes, centimetric to enclaves up 1-2% of the They commonly make decimetric in size. geological field trips 2013 - 5(2.1) itinerary 83 LF and MF or San Piero facies (LF) Microgranites and aplites have a fine-grained and aplites have Microgranites Fig. 47 - Orano mafic dyke at Capo Sant’Andrea. Note the at Capo Sant’Andrea. mafic dyke Fig. 47 - Orano the Monte Capanne monzogranite (after Coli e al., 2001). (after Coli e al., the Monte Capanne monzogranite sinuous trending, and the iso-orientation of c-axis of K-feldspar sinuous trending, and the iso-orientation of c-axis were generated megacrysts in the host. These characteristics by injection of mafic magma in a crystal-mush represented of the Mt. Capanne and Porto Azzurro plutons as well of the Mt. Capanne and Porto part of the island. bodies in the central the subvolcanic aplites and pegmatites They consist of rnicrogranites, (M4P). texture and are composed of quartz, K-feldspar, with minor tourmaline and plagioclase and muscovite a coarse- on the other hand, have biotite. Pegmatites, texture and are composed of quartz, K-feldspar grained of accessory and tourmaline associated to a large variety phases. The Elba pegmatite are world-famous for their of polychrome museum quality minerals superb, which can reach dimensions tourmaline and K-feldspar, outcrop surface, and locally, like in the Capo like outcrop surface, and locally, tend to enclaves mafic microgranular Sant’Andrea, reaching metric increase in abundance and size, facies diameters. The leucocratic rock, equigranular consists of a fine-to medium-grained in to syenogranite from monzogranite ranging is similar to the composition (Fig. 45). The paragenesis although with less biotite and plagioclase. Small MF, can also of primary muscovite amounts (<2 vol.%) are absent. enclaves but mafic microgranular occur, from a few millimetres up and dykes, veins Leucocratic to 2 m in width, commonly crosscut both the E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 84 some MAP rocks from (Table 1; Fig. (Table LF MF and (iv) the less evolved MF and MF; AMP dyke cropping out at Capo dyke OD (from 0.71464 to 0.71528) and low Nd (from 0.51209 to 0.51212) i O & Taylor, 11.40-11.43; Turi (i.e., Sr 144 18 because of: (i) the dark-grey to greenish because of: (i) the dark-grey 86 Nd/ Sr/ (Juteau, 1984). These values, coupled with (Juteau, 1984). These values, high peculiar mafic dykes (Orano dyke = OD) also dyke (Orano peculiar mafic dykes crosscut the Monte Capanne pluton near NW of Monte Capanne, and at Capo Orano, These dykesSant’Andrea. are different from MAP colour; (ii) the sinuous trending indicating they were injected into the still molten (iii) the presence of mafic monzogranite; and K-feldspar enclaves microgranular the macrocrysts like composition than Sant’Andrea. high rocks have The Elba island intrusive 45). In Fig. 47 is shown a 20 cm wide, WNW to ESE-trending up to several decimetres. Beside up to several 87 143 1976) and trace element data (Poli, 1992) are element data (Poli, 1976) and trace for the crustal origin of strongly suggestive parental magmas. The Elba island rocks, however, are the least Elba island rocks, however, Archipelago Tuscan of the overall peraluminous rocks (ASI = 1.01- and mainland crust-derived E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 48 - Photograph of mesoscopic texture the external Fig. 48 - Photograph Bacon, 1986; Poli & Tommasini, 1991) (after Coli e al., 2001). 1991) (after Coli e al., & Tommasini, Bacon, 1986; Poli portions of the Monte Capanne pluton at Capo Sant’Andrea. Large portions of the Monte Capanne pluton at Capo Sant’Andrea. are mafic enclaves ellipsoidal to irregular shaped light gray crystals shown. It is also evident the presence of large K-feldspar crystals In the latter case K-feldspar in both MF and enclaves. withnesses of the mixing process. Note also represent xenocrysts the irregular rounded to cuspate contact between enclaves and host and the host rocks, which suggest that both enclaves 1984; Vernon, were molten at the moment of inclusion (e.g., DOI: 10.3301/GFT.2013.03 1.16), and together with petrological and geochemical data establish that the monzogranite magmas of the Elba 1.16), and together with petrological geochemical data establish that the monzogranite Island are not pure crustal melts, but somehow contaminated via mixing and/or mingling with sub-crustal 1992). 1992; Poli, 1987; Innocenti et al., et al., 1987; Poli et al., Peccerillo magmas (e.g., geological field trips 2013 - 5(2.1) itinerary 85 and the ME of the Monte Capanne pluton and in MF Fig. 49 - Cartoon showing the main textural explanation see the text (after Coli e al., 2001). explanation see the text (after Coli e al., characteristics of the enclave-host contact. For of the enclave-host characteristics E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea can be readily a pseudoporphyritic texture, and is suggestive of a plastic behaviour texture, and is suggestive a pseudoporphyritic ME ME forming 1-2 vol.% of the outcrop surface. They consist of dark-grey, fine-grained rocks ranging from rocks ranging fine-grained of the outcrop surface. They consist dark-grey, forming 1-2 vol.% are fragments of mafic magmas injected and are fragments DOI: 10.3301/GFT.2013.03 host rock. Three main structures are generally encountered: a) K-feldspar megacrysts crosscutting the contact encountered: a) K-feldspar host rock. Three main structures are generally leaving megacrysts, completely surrounded by the enclave, and the host; b) K-feldspar between the enclave inside of movements are suggestive trail exhibiting a schlieren-like with complex textures; c) enclaves a trail together with the ellipsoidal to rounded shapes, cuspidate the partially molten host. These characteristics, margins, and the magmatic texture indicate that ME distinguished from the angular and metamorphic occurring along the contacts between enclaves Monte Capanne pluton and the country rock. mechanically disrupted (mingling) into the host- Bacon, 1986; Campbell and magma (e.g., granitoid 1991). & Tommasini, 1985, 1986; Poli Tumer, of the ME Is similar to that The paragenesis higher (MP), although they have host-granitoid biotite and plagioclase contents. The chemical composition of the large plagioclase and K-feldspar in crystals IS identical to the corresponding mineral origin for pointing to a xenocrystic the host-granite, into the ME which were incorporated these minerals between the interaction during the physico-chemical 1984; Frost & Vernon, basic and acid magmas (e.g., 1989a). et al., Mahood, 1987; Poli during the incorporation into the host-granitoid magma. Fig. 49 shows the relations between into the host-granitoid during the incorporation OD, from centimetres to ellipsoidal shapes and range in composition (Fig. 45). They have tonalite to monzogranite megacrysts and plagioclase crystals (Fig. 48). The accidental embodiment of K-feldspar some meters in size the gives from the host-granitoid Mafic microgranular enclaves (ME) are commonly present in the enclaves Mafic microgranular geological field trips 2013 - 5(2.1) itinerary 86 and by the c-axis of K-feldspars (Fig. 46), and of K-feldspars and by the c-axis MF E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea . The structural study was performed by Boccaletti & Papini (1989) at the meso- and performed by Boccaletti & Papini study was . The structural DOI: 10.3301/GFT.2013.03 Structural analysis microscopic scale, in order to obtain the orientations of internal structures different magmatic bodies part of Elbathe Western which affect the whole Monte and fractures Island to be compared with the trend of dykes Capanne pluton itself. The internal structures consist of planes and lineations, defined in the field by average occurring in the and xenoliths orientation of the enclaves 1979; Marre, 1982). The fabric of the internal (Pitcher, plagioclase, and the (001) plane of biotites muscovites & body shape and on its emplacement conditions (Fernandez information both on the intrusive structures gives 1983). The internal structures, therefore, are the witnesses of stresses et al., 1977; Femandez Tempier, magmatic mass underwent during the uplift and solidification phases in high crustal levels. The internal structures formed during the emplacement of magma, from a heterogeneous distribution flowing in suspension the melted mass, through higher viscosity states (crystal mush) crystals and enclaves 1972). Since the magmatic phase solidifies with continuity, to the complete solidification (Pitcher & Berger, solid submagmatic flow, result from different mechanisms, such as magmatic flow, may foliations in granitoids et al. as explained by Paterson and low temperature, moderate state deformations at high temperature, example, a pronounced (1989), which also suggest some criteria to recognise the foliation origin. For of internal structures near the intrusion margins is a good indicator magmatic foliation that can parallelism isoorientation usually increases at as the degree of mineral body, be used to infer the shape of intrusive 1977). & Templer, Balk, 1937; Femandez the intrusion margins (e.g., In the study of Monte Capanne pluton, linear and planar structures were determined by iso-orientation bodies. and in the porphyric and biotite crystals both at micro- mesoscale in the monzogranitic K-feldspar been studied at the microscope only as regards aplitic bodies, crystals have Plagioclase and muscovite in the phenocrysts are good markers biotite crystals and K-feldspar because of their fine texture. In particular, field of the internal structure fabrics because their crystalline habitus, as first tend to orient themselves to the (010) planes, giving also rise, parallel themselves according to the (001) planes and second arrange in the field, to spectacular alignments (Fig. 46). Linear structures were also measured field through (ME), which tend to assume ellipsoidal shapes during the enclaves iso-orientation of mafic microgranular (Marre, 1982; to the direction of maximum strain emplacement phases, rotating the major axis subparallel 1989). Ramsay, geological field trips 2013 - 5(2.1) itinerary 87 Fig. 50 - Accumulations and fluidal structures determined Cotoncello (after Coli et al., 2001). Cotoncello (after Coli et al., by K-feldspar phenocrysts in the granodiorite at Punta del phenocrysts in the granodiorite by K-feldspar The structural study was completed with the study was The structural measurement of the orientations brittle tensional which develop and fractures, structures, such as dykes in the Monte Capanne during the cooling phases. Dykes or aplitic material body usually contain microgranitic and are persistently iso-oriented in the external part of the intrusion. and concentric attitude, radial They have showing regular angular relationships with respect to been classified the internal structures, so that they have as longitudinal and cross joints (Balk, 1937). been sampled, have When metric to decametric dykes the iso-orientation of crystals both in and near to its maximum elongation (Fig. 47). parallelises dyke megacrysts may Both biotite crystals and K-feldspar flow structures and accumulations in the display that indicate a faster degree of cooling monzogranite common and they are usually Their presence is not very margins, as can be near the monzogranite developed seen at Punta del Cotoncello (Figs. 50 and 51). the internal structures of monzogranite Altogether, an arcuate attitude near the margins, that have indicates how the outcropping mass corresponds to entire pluton. This is also confirmed by the presence of margins (e.g., flow structures near the monzogranite E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 88 Fig. 51 - Fluidal whirling structures (schlieren) evidenced by maintain this fluidal structure (after Coli e al., 2001) . maintain this fluidal structure (after Coli e al., biotite crystals at Punta del Cotoncello. It is a particular feature biotite crystals at Punta del Cotoncello. cooling, which allowed to indicating a rapid of this zone, Capo Sant’Andrea-Punta del Cotoncello area) and by the Capo Sant’Andrea-Punta Only in the eastern part of attitude of the dykes. the internal structures do not rotate, monzogranite direction, instead, they show a constant WNW-ESE mass 15 not which allows to infer that the granitic completely outcropping, but probably continues under the country rocks and alluvial deposits to east. the magmatic In the internal part of monzogranite foliation evidences two magmatic domes, corresponding and Capanne peaks. to the Giove back and reach Punta del Cotoncello along the walk We village. Here the iso- coast east of Capo Sant’Andrea megacrysts and of K-feldspar orientation of the c-axis fluidal whirling structures evidenced by both biotites phenocrysts are visible (Figs. 50 and and K-feldspar 51). The presence of these features indicates a rapid cooling of the margins pluton. the car take We continue along the panoramic We and return to Zanca. After Elba to Colle d’Orano-Mortigliano. road of Western these villages, we enter from the Monte Capanne to the metasedimentary rocks of contact granitoid metamorphic aureole and then (Sedia di Napoleone stop at the cross- area) in the meta-serpentinites. We locality. road to Casa Peria E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 89 of the Alpine (NE) Corsica. Schistes Lustrés E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 THE OPHIOLITIC UNITS OF WESTERN ELBA area in Fig. della Fornace Elba (e.g. those of Chiessi-Punta Nera-Punta The Ophiolitic successions of Western area in Fig. 52b) are mostly constituted by metaophiolites (serpentinites, 52a and of Fetovaia-Pomonte (cherts, Calpionella limestones and Palombini and a metasedimentary cover gabbros with basaltic dykes) data: intrusion (~6.9 Ma radiometric shales). This unit directly lies on the Monte Capanne monzogranitic 2002) which produced an evident thermometamorphic 1985; Dini et al., & Tonarini, 1984; Ferrara Jateau et al., studied by Marinelli imprint on the oceanic rocks. The thermally metamorphosed rocks were extensively (1959), Barberi & Innocenti (1965; 1966), and Bouillin (1983) which related the Ophiolite unit to Complex (1951) thermometamorphosed and deformed by the intrusion of Monte Capanne IV of Trevisan (2001) recognised a & Spohn (1982) and Coli Pandeli (1975), Spohn (1981), Reutter Perrin monzogranite. of these rocks which the former Author referred to tectono-metamorphic framework pre-granitoid (2001) of the Alpine chain, while others ascribed it to Apenninic tectogenesis. Coli & Pandeli evolution suggested a possible correlation of this ophiolitic unit with the According to Spohn (1981) and Reutter & Spohn (1982), the structural setting of Fetovala-Pomonte and Punta setting of Fetovala-Pomonte & Spohn (1982), the structural According to Spohn (1981) and Reutter folds, later flattened and west- Ophiolite unit is constituted by a series of synmetamorphic east-vergent Nera 2001) by the uplifting of Monte Capanne intrusion. 1995; Coli & Pandeli, discharged (Daniel & Jolivet, ward up to the medium-high grade The latter produced also the recrystallisation of oceanic wall-rocks facies: Barberi and Innocenti, 1965; 1966; Spohn, 1981). (hornblende- to pyroxene-hornfels by a substancially un- area (Fig. 52b) the thermometamorphosed Ophiolite unit is overthrust In the Fetovaia & Spohn, 1982). This latter is 1975; Bouillin, 1983; Spohn, 1981; Reutter metamorphic flysch unit (Perrin, the lower part of a basal serpentinite. Moreover, by a calcareous-marly flysch which overlays characterised by ophiolitic sandstones and breccias an olistostrome horizon calcareous-marly flysch is characterized including calcareous, cherty and ophiolitic clasts in a dominant foliated shaly matrix. In the ruditic horizons 1975; fossils were also found (Lotti, 1886; Bouillin, 1983; Perrin, breccia Auctt.), Paleocene-Eocene (Fetovaia correlated by Barberi et al. Spohn, 1981). This flysch unit, which show only a local weak recrystallisation, was Elba. widely outcropping in the Central Complex V, sequences of the Trevisan’s (1969) to the similar Tertiary geological field trips 2013 - 5(2.1) itinerary 90 - The microscopic features of the Calpionella E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. discrete (Fig. 54a) and spaced axial plane crenulation cleavage The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea 2 intrafoliar isoclinal rootless hinges (Fig. 54b). intrafoliar Under the microscope limestone are represented by foliated rocks imprinted HT-LP The structural and petrographic studies, performed by the and petrographic The structural Authors during the CARG Project, substancially confirmed data of Spohn (1981) and Coli & Pandeli maps and structural (2001) about the Ophiolite unit in westernmost Elba, but suggest a more important role in the ductile main folding and body. of the Monte Capanne intrusive shearing event Stop 22. The ophiolitic rocks of Punta Nera area the road crosscuts two F2 synclines made up southwards, Moving (at of metaophiolites (limbs) and the metasedimentary cover the cores) (Stop 22a in Figs. 52a and 53a, Stop 22b facing and 53b). The F2 synclines are tight to isoclinal, eastward the core, west. At with axial plane dipping of about 60° towards shales (Stop 22a) are Calpionella limestones and also Palombini present. Both the synclines are flattened and refolded by F3 open axial plane fracture west with sub-horizontal, folds, facing towards resulted from the discharge of Monte Capanne uplift. cleavage, Ophiolites appear to be strongly foliated in continuous type 1 Thermometamorphic garnet is present in the cleavage. metacherts, whereas wollastonite (locally rosette-like)+pyroxene can be locally recognised in the recrystallised Calpionella of strongly foliated metaophiolites marks limestones. A thin levels the anticline hinge between two synclines. The outcrops of metacherts and Calpionella cherty limestone are locally of the by tight to isoclinal mesofolds with refractions characterised S Fig. 52a - Geological sketch maps of Fig. 52a - Geological sketch (modified from Coli & Pandeli, 2001). (modified from Coli & Pandeli, Punta Nera-Punta della Fornace area della Fornace Punta Nera-Punta DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 91 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 52b - Geological sketch maps of Fig. 52b - Geological sketch Pandeli, 2001). Pandeli, Fetovaia-Pomonte area (modified from Coli & Fetovaia-Pomonte DOI: 10.3301/GFT.2013.03 minerals (monocline pyroxene+wollastonite); the thin pyroxene+wollastonite+k-feldspar+biotite skarn levels the thin pyroxene+wollastonite+k-feldspar+biotite (monocline pyroxene+wollastonite); minerals or calcschist intercalations within the marbles. These with probably correspond to previous lepidoblastic phyllitic in these samples are spherical to are sometimes mimetic on the foliation (S1?//S0). Peculiar minerals HT-LP aggregates of wollastonite. Frequent are the millimetric to centimetric tight/isoclinal fold ellipsoidic radial structures of the F2 mesofolds) that deformed previous foliated structure (S1) and has a (parassitic by which is often obliterated axial plane cleavage millimetric-spaced penetrative variously isoclinal rootless hinges and boudinated layers thermometamorphism at the microscopic scale. Local intrafoliar The deformed or to syn-tectonic veins. quartz are probably referred to primary cherty layer of polycrystalline is dissected (also millimetric faults are present) by a later foliation, imprinted by thermometamorphic minerals, which Is likely cleavage spaced fracture to the discharge open D3 folds; referable are filled by calcite; veins these fractures of calcite+quartz±adularia are also present. continue the trip to Chiessi. Along We Stop road, the spectacular panoramic by is characterised place of Punta Nera outcrops of medium-high grade thermometamorphosed dark green serpentinites with the blastesis of neo- and ortho- olivine+talc+clino-amphibole After this, we amphibole (anthophyllite). cross the a tectonic contact (syn-intrusion geological field trips 2013 - 5(2.1) itinerary 92 . =Palombini P E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea (Stop 22a) The road cross-cuts a) =Calpionella limestone, C) metamorphic blastesis (brown C 0 =cherts, D =ophiolites, (Stop 22b) Nucleation of a D2 syncline, gently refolded by D3 d b) Fig. 53 – Stops north of Punta Nera: Fig. 53 – Stops north of Punta Nera: (after Coli & Pandeli, 2001). (after Coli & Pandeli, shales; west fold related to the Monte Capanne uplift and discharging towards two D2 synclines pre-dating the Monte Capanne intrusion, both west; in synclines are flattened and refolded by an D3 fold, facing towards of the road there is a good outcrop cut into that the cliff on right-side late fold. DOI: 10.3301/GFT.2013.03 hornblende, pyroxene and plagioclase) overprinted by retrograde and plagioclase) overprinted hornblende, pyroxene phases (tremolite/ actinolite, chlorite, etc.). This HT- mineralogical nearby the LP metamorphism is referred to ductile shear zones oceanic ridge. and continue along the cross Pomonte We Isle, the contact between road. In front of the Ogliera panoramic metachert is well exposed. the metabasalt and overlying and these rocks are crosscut by whitish aplitic dykes Moreover creek (Fig. 52b) the Ogliera reach the bridge above sills. We detachment fault?) which separates the metaserpentinites from underlying thermally metamorphosed detachment fault?) which separates to the Monte linked of leocogranites porphyry, of Portoferraio dykes shales intruded by several Palombini contact with the Monte Punta del Timone, close to the intrusive At porphyry. Capanne stock and of Orano are foliated as thermometamorphosed host rocks dykes porphyry Capanne pluton, some of the Portoferraio the at Punta della Testa, Just before Pomonte, cross Chiessi and continue to Pomonte. shales). We (Palombini The gabbros are locally flaser some outcrops of its ophiolitic contact aureole made up gabbro. pluton preserve The flaser and are cross-cut by undeformed basaltic dykes. structures of the gabbro are due to oceanic metamorphism. These structures are well-studied in the Northern Apennines and (up to 700 with a HT-LP linked geological field trips 2013 - 5(2.1) itinerary 93 The F2 folds deformed at . & Pandeli, 2001). & Pandeli, tectono-metamorphic limestone (Calpionella Fig. 54b - Structural occurrence of a previous rootless hinges record the features of the meta-cherty E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. deformation event (after Coli deformation event The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea limestone): intrafolial isoclinal limestone): intrafolial Fig. 54a - Structural features of the meta- cherty limestone (Calpionella limestone): of refractions cleavage the axial plane spaced S2 crenulations cleavage (looking down the plunge of the folds axis) which is gently folded by the discharge D3 event (after Coli (S3 cleavage) 2001). & Pandeli, DOI: 10.3301/GFT.2013.03 THE OPHIOLITIC UNITS OF POMONTE-FETOVAIA AREA Stop 23. The metamorphic metasediments of the Ogliera Bridge area F2 syncline (Figs. 52b and 55). The along the road it is possible to cross a well exposed east-facing Walking west of about 50° syncline is tight to isoclinal with the axial plane plunging towards geological field trips 2013 - 5(2.1) itinerary 94 thermometamorphic imprint: whitish strings and irregular areas/spots of monocline pyroxene+feldspar±biotite assemblage ±quartz; the same mineral (at a cleavage fills also a later fracture medium angle respect to the main foliation). These rocks are finally cross- or oxides/hydroxides cut by Fe The Calpionella adularia±epidote veins. limestone (as the calcareous shales) are intercalations of the Palombini to whitish dark grey or grey-greenish by striped meta-limestone characterised foliation (alternating a granolepidoblastic crystalline limestone and fine-grained or calcschist levels) probably phyllitic which predates the thermometamorphic The latter are well represented minerals. interbeds that are in the ex-phyllitic E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. ), relics of intrafolial isoclinal rootless hinges are present and ), relics of intrafolial The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea 2 All the sampled rocks are characterised by a medium-grade thermometamorphism. In by a medium-grade All the sampled rocks are characterised the Fig. 55 -55 Fig. bridge area: view of the Ogliera Stop 23, general the road cross a tight syncline S2 cut by S3 crenulation cleavage. shales, C= Calpionella limestone, D = cherts (after P= Palombini 2001). Coli & Pandeli, DOI: 10.3301/GFT.2013.03 the mesoscale the main S1 foliation (//S0?) which is parallel to the lithologic partitions.the mesoscale main S1 foliation (//S0?) which is parallel The core of the shales, the limbs are drown syncline is constituted by Calpionella limestones, including boudins of Palombini by cherts. Within the axial plane foliation (S probably testify a tectonometamorphic event (D1) which pre-dates that of the F2 meso-folds. The whole probably testify a tectonometamorphic event C3 allowing a kinematic cleavage outcrop is cross-cut by a large spaced (1÷2 cm) crenulation to fracture of a cottage there is good related to the uplift of Monte Capanne. In gate-yard discharge westwards, are often injected along the main foliation of rocks. metacherts. Thin aplitic dykes outcrop of poly-folded Under the microscope - shales a mimetic or static blastesis of brown less recrystallised dark grey/black slaty lithotypes of the Palombini is present. Other samples show a strong biotite on the white micas+chlorite±quartz slaty cleavage geological field trips 2013 - 5(2.1) itinerary 95 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea towards west. No penetrative tectonic-fabric or evidence of tectonic-fabric west. No penetrative towards ° - The marly and marly-limestones lithotypes show a local weak recrystallisation. The - The marly and marly-limestones DOI: 10.3301/GFT.2013.03 transformed into a whitish monocline diopsidic pyroxene+feldspar+garnet±quartz skarn; scattered monocline into a whitish monocline diopsidic pyroxene+feldspar+garnet±quartz transformed which locally contain marble levels and garnet are also present in the alternating fine to medium-grained pyroxene weak in the skarn levels, of quartz and small cubic pyrite crystals. Particularly or granoblasts porphyroblasts the foliation) are present. crenulations (about perpendicular to the foliation) and static garnets (which overprinted by “ghosts” of a weak axial plane Locally millimetric/centimetric tight folds deform the foliation and are characterised of calcite+adularia±chiorite±epidote?. The samples These rocks are cut by later veins crenulation cleavage. (sometimes without tourmaline and including poikiloblastic diopsidic pyroxene) collected close to the aplitic dykes + garnet scapolite (after feldspar) ± vesuvianite wollastonite + clinopyroxene are massive ±plagioclase/K-feldspar or the skarn are affected by calcite ± amphibole? skarn without evidence of foliated structures. Either the dykes and locally with biotite quartzites with later secondary quartz veins cherts are granoblastic The grey-greenish veins. The static blastesis + tourmaline with blue-green pleochroism muscovite) (quartz + K-feldspar pegmatitic dykelets at the microscopic scale, previous fold structures and foliations of quartz+green-brown biotite often obliterates, quartzites) Locally the biotite is instead mimetic on previous sheet-silicates (alternating of quartzites and phyllitic and/or chlorite?) of the foliation. In some less recrystallised samples, tight to isoclinal folds with (muscovite crenulations clearly deformed the foliation. A lot of small magnetite or pyrite crystals are spaced zonal pervasive, frequently scattered in these rocks. Stop in front of the Fetovaia continue the trip and reach a panoramic We promontory and Punta Le Tombe. Stop 24. The Tertiary flysch unit of the Fetovaia area The outcropping lithologies at the Stop 24a (Fig. 52b) are represented by alternating centimetric to decimetric- and marls minor grey-black by weathering) marly-limestones thick beds of dark grey (pale grey-yellowish shales and grey calcareous sandstones siltstones. A gabbro olistolith is also present. The bedding dipping of about 30°÷40 generally thermometamorphic imprinting are present. A large spaced (1÷2 cm) crenulation cleavage locally affected the thermometamorphic imprinting are present. A large spaced (1÷2 cm) crenulation cleavage west and allows a discharge kinematic related to the uplift gently dips towards rocks; the crenulation cleavage the rocks and crystal growth) cross-cut vertically (with euhedral of the Monte Capanne intrusion. Calcite veins carbonate fluid-rich environment. testify a flattened episode of deformation in overpressured At the microscope (ex. bedding and laminations). These rocks contain variable primary sedimentary structures are well preserved geological field trips 2013 - 5(2.1) itinerary 96 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 amounts of quartz grains, white micas and scattered oxides and carbonised plant debris. The shaly lithotypes white micas and scattered oxides amounts of quartz grains, in are made up sheet silicates (including abundant white micas)±quartz and organic pigment. Particularly are present. by alignments of opaque minerals) crenulations (locally marked these latter lithotypes weak zonal postdate the crenulations. of calcite are common and generally Secondary veins go down to the sea (Stop 24b in Fig. 52b) where ophiolitic sandstone and breccias lenticular beds are We The latter is made up of millimetric to metric a decametric olistostrome horizon. present and overlie limestone), cherty (Monte Alpe cherts) and ophiolitic clasts in a calcareous, (Calpionella limestone, Palombini through matrix. These ruditic deposits, dated Paleocene-Eocene dominant black, foliated silty-shaly (e.g. Nummulites), also include olistolites that are mainly represented by serpentinites. A peculiar foraminifers cherts, is present along the slope between olistolith, preserving the contact between basalts and overlying road and Punta Le Tombe. road crossing the tectonic contact between serpentinite (at base of continue along the panoramic We with local outcrops of flysch unit) and the underlying Monte Capanne monzogranite Tertiary the Fetovaia as far the Colle di Palombaia. and Seccheto-Cavoli go on to Fetovaia thermally metamorphosed rocks. We east the Cretaceous flysch of Central normal Eastern Border fault downthrown towards Here the high-angle reach respect to the thermally metamorphosed ophiolite rocks. We Elba (intruded by pre-Capanne dykes) intruding the porphyry the road to Lacona. A wide laccolitic body of S.Martino Marina di Campo and take the pass, beautiful views of eastern side Cretaceous flysch unit is well exposed along the road. At (Lacona)-Eastern Elba (Porto M.Capanne massif (including the Eastern Border fault) and of central promontory). Azzurro-Capoliveri-Calamita at a camping and continue arrive Before reach Lacona, we turn on the right to Punta della Contessa. We along the path to seaside (Stop 25 in Fig. 41). Stop 25. The Tertiary flysch unit of the Central Elba fm.). It is flysch unit crops out (Colle Reciso Along the path typical lithologic association of Tertiary made up of highly fissile grey shale, which occurs in thick beds, and that shows minor intercalations sandstones. The limestone beds turbiditic calcarenites and fine-grained limestones and marlstones, of rare The similar to the “palombini” beds described above. siliceous calcilutites, some dm thick, very are dark grey, geological field trips 2013 - 5(2.1) itinerary 97 ; Collet, 1934, Nummulites, Globorotalia E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 in Raggi et al., 1965; Raggi et al., 1965) point to a Middle(?) Eocene age. et al., 1965; Raggi et al., in Raggi continue crops out. We reach the Punta della Contessa where a serpentinite, interpreted as olistolite body, We the cape. Here polymictic breccias are well exposed and include clasts of North beyond along the sea towards ophiolite (serpentinite, gabbro), basalt and minor marly limestones in a carbonate matrix containing (Nummulites). Serpentinite olistolith and the ophiolitic breccias are related to an olistostrome macroforaminifera (see Stop 24). flysch unit of Fetovaia flysch unit similar to that seen in the Tertiary within the Teriary horizon (ColleThe trip continue crossing Lacona and taking the road to Portoferraio Reciso During the climb to Pass). flysch unit is exposed on the eastern slope of roadthe pass, Tertiary (Stop 26 in Fig. 41). bedding surfaces are generally covered by a dark green smear. The marlstone beds are some dm thick and by a dark green smear. covered bedding surfaces are generally and do strongly fragmented Due to the intense tectonisation, all these intercalations are generally dark grey. faunas ( Macro and microforaminiferal not constitute continuous levels. Stop 26. The low-angle tectonic contact (Colle Reciso detachment fault) between the Ophiolitic unit and the underlying Tertiary flysch unit a track fm., the typical lithofacies of Colle Reciso Upslope (western slope of Monte Orello), just above tectonic contact, outlined an old Calpionella limestone quarry) crosses the low-angle (running to SW towards cataclasite), between the Ophiolitic unit and underlying (Colle Reciso by a polymictic cataclasite horizon flysch unit are flysch unit. Here the tectonic relationships between Ophiolitic unit and Tertiary Tertiary that suggest a backthrust of the former with respect to the eastern Elba as well movement inverted cataclasite) that consists by a tectonic breccia (Colle Reciso the latter unit. The fault surface is marked above Capo Bianco aplites and San fm., of clasts up to pluridecametric blocks basalts, serpentinites, Colle Reciso fm. from the Colle Reciso in a shaly matrix which probably derives Martino porphyrites, detachment fault occurred during or slightly before the Zuccale think that the Colle Reciso We Azzurro pluton triggered (as seen for Zuccale fault) by the uplift of La Serra-Porto activity and might have (see Fig. 18B). continue trough the pass (on right, a road leads to present quarry of Calpionella We fm. crops out) and about 300 limestone, whereas to the left, limestone-dominated facies of Colle Reciso complex associated to gabbro on the left. Here a peculiar of sheeted dyke we reach a bend curve m beyond is exposed (Stop 27 in Fig. 41). geological field trips 2013 - 5(2.1) itinerary 98 Ar) were found for the ferrodiorites of Southern Tuscany 39 Ar/ E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea 40 DOI: 10.3301/GFT.2013.03 and plagiogranites of central Tuscany, linked to the basalts. linked Tuscany, of central and plagiogranites return to Portoferraio. We THE MONTE CALAMITA PROMONTORY AND ITS IRON ORES bodies of ElbaSome of the most important Fe-ore Island occur in the southern part of Calamita peninsula 1997). The 1977; Benvenuti, 1967b; Tanelli, Azzurro unit (Barberi et al., (South-Eastern Elba) within the Porto us to visit the Calamita mine (Northern and Southern sectors). field trip will take present-day Introduction Azzurro unit which is the deepest tectonic The Monte Calamita promontory is mainly made up the Porto Ligurian and Ligurian-Piemontese pile (Figs. 1, 2, 3 and 56) of Tuscan, Elba structural of the central-eastern intruded by Late Miocene-Lowermost 2005). This unit was 2001a; Garfagnoli et al., Nappes (Bortolotti et al., in this part Moreover, and mainly acidic dykes. Azzurro monzogranite) (e.g La Serra-Porto Pliocene granitoids of the island, relationships between emplacement plutonic bodies and final deformations Zuccale fault that directly superimposes the the tectonic stack are easily detectable: e.g low-angle Stop 27. The sheeted dyke complex of the ophiolitic unit at Colle Reciso This sheeted dyke The intruding gabbro. dykes complex consists of diorites, micro-gabbros and plagiogranite quartz and magmatic, rarely pl crystals, minor subhedral diorites show holocrystalline structure, with euhedral metamorphic, amphiboles (hornblende). They also show fluidal structures with aligned pl and amphibole are titanite and zircon. The micro-gabbros show holocrystalline structure with crystals. The accessory minerals and crystals of pl, partially amphibolised pyroxenes small crystals. The main component are euhedral holocrystalline structure granular have is zircon. The plagiogranites The accessory mineral subordinate oxides. qz and subordinate magmatic amphiboles (hornblende). The pl crystals, a few subhedral with euhedral and titanite. The maximum thickness of the complex is about 50m. are epidote, oxides accessory minerals Very 1973) (Callovian). indicates 161.23 Ma (Bigazzi et al., age obtained with fission tracks A radiometric 1995, similar ages (157 Ma, Bortolotti et al., geological field trips 2013 - 5(2.1) itinerary 99 Fig. 56 – Geological sketch map and geological cross- Fig. 56 – Geological sketch Garfagnoli et al., 2005). Garfagnoli et al., sections of the Monte Calamita promontory (after Cretaceous flysch unit above the Porto Azzurro unit the Porto Cretaceous flysch unit above Azzurro unit (Figs. 56 and 57) (Fig. 56). The Porto probably pre-Carboniferous consists of a Paleozoic, basement (Monte Calamita metamorphic complex), by the ?triassic which is unconformably overlain quartzites) metasiliciclastics (Barabarca Verrucano metacarbonates and ?Upper Triassic-?Hettangian Calanchiole marble fm. and the overlying (Tocchi and crystalline dolostone). In the Monte Calamita main lithofacies were metamorphic complex, five albite and mapped. Garnet-bearing-, recognized mica-schists (lithofacies a) geometrically underlie a unit (lithofacies b); porphyroids phyllitic-quartzitic (lithofacies e), metabasite bodies d) and siliciclastics (lithofacies c) are also graphite-rich present. The rocks of lithofacies a are similar to micaschist those of the ?pre-Paleozoic-?Paleozoic complex of the Larderello geothermal field, whereas the other lithofacies can probably be correlated with formations of the Tuscan the ?Ordovician metamorphic succession (e.g. Apuan Alps). The of the complex deformation-metamorphic evolution Azzurro unit consists of the following events Porto E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 100 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. Fig. 57 – Stratigraphic and structural sketch of the units cropping out in sketch and structural Fig. 57 – Stratigraphic The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea the Monte Calamita promontory (after Garfagnoli et al., 2005). the Monte Calamita promontory (after Garfagnoli et al., ) which 3 ), recognized in ), recognized ) of the whole x 4 ) in the greenschist 2 and D 1 DOI: 10.3301/GFT.2013.03 probably occurred during or immediately after the thermometamorphic imprint (including the magnetite-rich skarn bodies), caused by Neogene magmatic the uplift of intrusions; d) subsequently, the magmatic bodies caused low-angle Azzurro detachments within the Porto unit (between the Monte Calamita metamorphic complex and the Mesozoic and between the latter cover) tectonic units (e.g. Zuccale overlying Azzurro unit and fault between the Porto the Cretaceous flysch). A final weak antiformal folding (D promontory took place before the trending and N-S of NW-SE development The mineralizations. sometimes Fe-rich normal fault systems, locally sealed by hydrothermal, high-angle Azzurro unit is similar to that of the Porto tectonic, metamorphic and magmatic evolution lithostratigraphical, detected for the Larderello geothermal region. Thus, Monte Calamita area can be considered as an older, but similar geological model for the deep structure of southern Tuscany. (Fig. 58): a) a Variscan tectono- (Fig. 58): a) a Variscan (D metamorphic event the Monte Calamita metamorphic complex, which is defined by a pre-Alpine relicts (garnet); b) foliation and mineral two Alpine tectono-metamorphic folding (D events facies, which also deformed the Mesozoic (D c) a later folding event cover; geological field trips 2013 - 5(2.1) itinerary 101 Fig. 58 – Sketch of the deformation- Fig. 58 – Sketch al., 1992) (after Garfagnoli et al., 2005). 1992) (after Garfagnoli et al., al., metamorphic evolution of the Porto Azzurro unit of the Porto metamorphic evolution 1986; (chronological data after Klingfield et al., 2000; Deino et 1982; Brunet et al., Saupe et al., From Portoferraio we take the road to Porto we take From Portoferraio In the Mola plain (west of Porto Azzurro. the road to Capoliveri Azzurro), then we take with outcrops of Cretaceous flysch. Just at the tectonic superposition of Capoliveri, Azzurro unit (made flysch unit onto the Porto up Monte Calamita fm. and Barabarca quartzites: Figs. 56 and 57) is recognizable. within the Monte Calamita on moving keep We grey to brown micaschists, fm. (Paleozoic and quartzites locally intruded by phyllites Stop in see also the Terranera aplitic dykes: the village of Pareti eastern Elba). Just above (visible looking down the slope) we can some lenticular dark green bodies of observe amphibolites (tremolite+andesinic plagioclase et al. +chloritespheneapatite) which Puxeddu (1984) referred to WPB metabasites intercalated within the metasediments of finally reach the Monte Calamita fm.. We former seat of Calamita mine headquarter (Figs. 59 and 60). (“Palazzo”) E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 102 1976). Fig. 60 – Location of the principal mine workings at Calamita Mine (after Calanchi et al., E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Fig. 59 – Itinerary and Stops in the Calamita promontory (SE Elba). DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) itinerary 103 mine (after Gillieron, 1959). Fig. 61 – Schematic N-S cross Fig. 61 – Schematic N-S section through the Monte Calamita E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea DOI: 10.3301/GFT.2013.03 Stop 28. The Calamita mine: Northern sector mines in Figs. 60 and 61) (Polveraio-Macei carbonate rocks are present. In particular they mainly represented In this area thermometamorphic Mesozoic intercalations with local phyllitic in colour, crystalline dolostone and dolomitic limestone, grey-whitish by stratified whitish saccaroidal marbles or poorly stratified the east, along road, massive To ?Upper Triassic). fm., (Tocchi represent a portion are also present. These carbonate rocks may (?Hettangian) with local grey dolomitic levels to the west, a quartzitic sequence (“Barabarca of the Monte Calamita fm.. Farther cover of the pristine Mesozoic is interposed between the Monte Calamita fm. and carbonate Verrucano) quartzite”=Middle-Upper Triassic of metasomatism, which led to the development hydrothermal been affected by extensive rocks. The latter have the most abundant, and an ilvaite- skarn, quantitatively two main types of skarn: a garnet (andradite)-rich 1990). As shown in Fig. 61, the skarn bodies mainly occur at tectonic contact hedenbergite skarn (Torrini, between metacarbonates and the underlying Monte Calamita fm.. times, but only in the middle of past century (around Iron exploitation at Calamita probably started in pre-Roman performed at an industrial scale. Stella (1921, 1933) estimates that least 2 million tonnes of iron 1860) it was geological field trips 2013 - 5(2.1) itinerary 104 O) have been reported by Cocco & Garavelli (1954). From been reported by Cocco & Garavelli O) have 2 · 2 H 4 E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. O 2 The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea O) and oxalite (FeC O) and oxalite 2 ·3 H 3 ) 4 O 2 Fe(C 3 CKNOWLEDGEMENTS DOI: 10.3301/GFT.2013.03 a textural point of view, at Calamita mine magnetite commonly occurs as pseudomorph point of view, a textural earlier hematite. This after and may peculiar feature with respect to common iron skarns, where magnetite is the primary oxide, is a very 1977). Tanelli, preceeded the skarn formation (cf. indicate that the deposition of iron concentrations A ore had been exploited since 1860 up to his times, and that the reserves were apprioximately of the same order were apprioximately ore had been exploited since 1860 up to his times, and that the reserves mine working areas (Fig. 60): magnitude. The northern sector of the Calamita mine is subdivided into several Coti Nere. The exploited ores were strictly associated with both types of skarns Albaroccia, Macei, Polveraio, Civetta, bodies of magnetite described, and consisted of lenses massive above hematite). Additional (±kenomagnetite, amounts of sphalerite, chalcocite, arsenopyrite, bornite and pyrite. Moreover, phases include goethite and trace sulfides (pyrrhotite, pyrite, chalcopyrite ± malachite, azurrite, chalcantite, etc.) were locally masses of Fe-Cu 1990). exploited at the contact between garnet skarn and magnetite lenses. (Torrini, Stop 29. The Punta Calamita mine: Southern sector (Alto and Basso) mine workings (Fig. 60). In this southern sector along the road to Vallone southward move We magnetite lenses associated with hedenbergite- of the Calamita mine exploitation activity focussed on several cliffs (Punta della Calamita). just on the seaward skarn bodies, beautiful examples of which can be observed ilvaite to the contact between metacarbonates and M.te The skarn and ore bodies are mostly elongated parallel in the metacarbonates and easily Calamita fm. (Fig. 61). A U-shaped trench (altitude: 112 m. a.s.l.) excavated the beginning Alto). At Basso and Vallone the two main mine working areas (Vallone visible from the road separates the limonitic gossan of iron ores, which were subsequently of the past century production mainly involved (=Copper the so-called “Grotta Rame” for magnetite. At exploited almost exclusively site, just below the U- Cave) been reported have been described from which a wealth of fine copper minerals have shaped trench, Cu-rich veinlets like “organic” minerals rare moreover, Alto, Vallona etc.). At (including malachite, azurrite, atacamite, paratacamite, minguzzite (K of Florence), Simone Tommasini of Florence), Sandro Conticelli (University thank Massimo Coli (University We of (IGG-CNR Florence) who partecipate to perform the first version Moratti of Florence), Giovanna (University 2001), that represent the Elba Island, during the Meeting EL.I.C.A 97 (Coli et al., the field trip of Western starting point for the correspondent part of present field trip guide. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - F. Menna - G. Nirta g e o l o g i c a l

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DOI: 10.3301/GFT.2013.03 geological field trips 2013 - 5(2.1) references 106 n r- o- epo- centra- 1994) - e: stato , 169-210. n L. (1969) n L. (1967a) E. Pandeli - G. Principi - V. Bortolotti - M. Benvenuti - M. Fazzuoli - A. Dini - F. Fanucci - A. Dini F. - M. Fazzuoli Bortolotti - M. Benvenuti Menna - G. Nirta - G. Principi V. E. Pandeli - F. The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea Riunione Estiva S.G.I., settembre 1992, 333-385. S.G.I., Riunione Estiva a dell’arte. Studi Geol. Camerti, Vol Spec., 1991/1, 115-140. Spec., dell’arte. Studi Geol. Camerti, Vol sioni. 76 Nova 7, 7-30. Nova - Note illustrative della Carta Geologica d’- Note illustrative 32 pp. Geol. d’It., 126 (Isola d’Elba). Serv. Italia alla scala 1:100.000, Foglio A, 74, 579-617. Mem, Ser. le e orientale. Scala 1:13.500. DB MAP, Firenze. le e orientale. Scala 1:13.500. DB MAP, A, 72, 306-398. Ser. Mem., Sci. Nat., Soc. Tosc. d’Elba). Atti 25, 735-768. 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Palaeoecology, Palaeoclimatology, system in the Northern Apennines and Southern Alps. Palaeogeography, 21, 359-373. Mem. Soc. Geol. It., modello strutturale, nuovo 117, 7-38. on the seismo-tectonics of Northern Apennines. Tectonophysics, Considerations 108, 699-710. Capanne (Isola d’Elba). Boll. Soc. Geol. It., 42, 300-301. Petrol., Memorie, 71, 232-243. Sci. Nat., Soc. Tosc. Atti Toscano). DOI: 10.3301/GFT.2013.03 Bouillin J.P., Poupeau G. & Sabil N. (1994) - Etude thermo-chronologique de la dénudation du pluton Monte Capanne (Ile Poupeau Bouillin J.P., A. (1976) - Dal Rio G. & Prati Calanchi N., dell’Elba orientale. Ed. Cacciari, Bologna, 102 pp. Miniere e minerali Bortolotti E. & Principi G. (2001b) - The geology of Elba Island: an historical introduction. Ofioliti, 26 (2a), 79- Pandeli V., Borsi S., Ferrara G. & Tongiorgi E. (1967) - Determinazione con il metodo K/Ar delle età rocce magmatiche della Toscana. G. & Tongiorgi Ferrara Borsi S., Principi rocks from the eastern Elba is Martin S., G. (1994) - Ultramafic & Vaggelli Cellai D., P. Bortolotti V., Tartarotti G., PrincipiBortolotti E., Pandeli M., Fazzuoli and eastern Elba Isla (2001a) - Geology of the central Babbini A. & Corti S. G., V., Marcucci M. & Principi Gardin S., Bortolotti V., unit between the Monte Alp a transitional G. (1994) - The Nisportino Formation: Bortolotti Tartarotti ofiolitiche dell’Elba orientale: aspetti G. (1991) - Le sequenze Principi G., & Vaggelli Martin S., P. V., Boccaletti M., Calamita F., Deiana G., Gelati R., Massari F., Moratti G. & Ricci Lucchi F. (1990) - Migrating foredeep-thrust b (1990) - Migrating G. & Ricci Lucchi F. Moratti Massari F., Gelati R., Deiana G., Calamita F., Boccaletti M., pr G. & Mazzuoli R. (1965) - Studio petrologico e datazione con i metodi K/Ar Rb/Sr di una roccia granitica Ferrara Borsi S., Blak R. (1937) - Structural behavior of igneous rocks. Mem. Soc. Geol. 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