150 100 4 1 (1) Q Q 265.96 200 RML OMPF 30 AS 0 15 0 RML FMC 65 0 60 LL Czc 30 MUZ 40 Cz 300.78 15 50 Cz 311.53 50 310.43 50 15 RML 311.69 MSV 75 GI ER 25 RML ACN RML 30 RML 0 15 250 FUST 250 USS 235.03 Q 312.84 200 C 0 20 0 20 0 35 RML OMPF OMPF RML 362.79 310.93 354.56 350 GG IAN 300 0 30 300 0 RA A 311.84 332.04 RGI OLA 15.2 % 12.7 % 25.0 % 17.4 % 14.5 % 29.5 % 19.6 % 16.4 % Transtensive fault Shear zone eastern boundary Fault 2nd mylonite zone (5.5 < g < 11.5) Radiometric ages (Ma) * Ar/Ar, **Rb/Sr, *** K/Ar n=80 S1 foliation 200 IS FR 20 0 GST 2.6 % 3.6 % 5.3 % 7.1 % 10.5 % 10.7 % 21.1 % 17.9 % 26.3 % 21.4 % 1.4 % NE SHEAR ZONE GERREI UNIT 800 2.9 % MONTE GRIGHINI UNIT 600 600 TC FMC 10.0 % MGt 328.84 200 18.6 % RML ACN RML USS F1-F2 fold axis n=80 MGl TC MUZ MGm 0 MGl Cz Cza Czc MGm TZa -200 Cza UMz MGm A’ NE MONTE GRIGHINI UNIT 800 RML USS RML MGm 600 MGt TC TZb Ghenniespos TC 400 TC RML PRF Czc MUZ Czb MUZ PGm Cza TC MGm TZa Cza MGl Cza Cz Cz 13 000 m N GERREI UNIT 800 TC 299.03 Serra Canna SA 150 200 30 0 250 1489 0 TZb -200 B’ NE CASTELLO MEDUSA UNIT MONTE GRIGHINI UNIT 800 0 CSA MGM TZb TZa PRF MSV 1490 Perda Arrubia TC MGm Cz TC CSA USS USS MGt C C’ 400 500 750 1km M.E.Spano gratefully acknowledges the Sardinia Regional Government for the financial support to her PhD scholarship (P. O. R. Sardegna F. S. E. Operational Programme of the Autonomous Region of Sardinia, European Social Fund 2007–2013 - Axis IV Human Resources, Objective l.3, Line of Activity l.3.1.). 0 Financial support from Università degli Studi di Cagliari and Università degli Studi di Pisa is aknowledged. -200 The authors wish to thank the Ente Foreste della Regione Autonoma della Sardegna for hospitality during the field work. MGm TZa TZa Topographic map from the 1.10.000 C.T.R. (Carte Tecniche Regionali) maps Regione Autonoma della Sardegna. 200 TC MGl -200 UMz 250 600 TC TC ACN USS 0 1488 TZa MGt UMz MGd TC RML MUZ 304.53 283.54 USS TZb Br.cu Fogaies 400 200 MGm SHEAR ZONE Su Cruccuri RML 1487 TZb PGm TCa Czb PGl 600 310.40 RML 1486 USS TC Cz Acn 200 TC TZb Czb MSV SHEAR ZONE 340.76 250 8°50’00’’ 400 USS 12.9 % SW 44 Mogorella 1485 Toccori TCa 400 TC 251.83 0 # 1484 800 Cuccuru Mannu 8.6 % n=80 B 2 0 2km 1 (g > 11.5) n=110 14.3 % PRF 322.59 00 0 Truzzulla 0 S 298.21 200 250 35 TER 0 216.59 1483 20.5 % GERREI UNIT 200 354.41 266.90 20 211.25 15 1482 (1.15 < g < 5.5) Thrust g <1.15) 300 8°50’00’’ East from Greenwich UTM (Universal Transverse Mercator) Grid, Zone 32S (ED50) 209.14 Roma 1940 - Gauss Boaga Ovest 1481 000 m E 10.9 % n=75 4414 2km 1750 13.0 % MSV 300 1500 15.2 % Cuccuru e Uas 0 25 13 000mN 1250 1Km 1st mylonite zone -200 Scale 1:25.000 750 9.1 % A 350 307.83 500 7.3 % 10.9 % 600 388.74 0 44 250 8.7 % 10.6 % 400 346.30 20 0 7.6 % AS 332.80 213.54 245.95 (0.35 < DU 334.86 333.10 A 30 142.87 313.16 5.5 % SW ACN RML 6.5 % F2 fold axis 800 234.10 232.90 5.3 % 4415 RML BA RML RML N protomylonite zone 0 mineral lineation OMPF 250 BGR RML 3.6 % 16 OMPF PRA MAIORI 2km 1 OMPF 315.22 OMPF 200.28 200 1.8 % 4.3 % mineral lineation Ms** 295 ± 9 Bt*** 302 ± 6 ACN 350 0 MINDAPIRA Diorite Monte Grighini Unit 2.2 % 3.8 % -200 OMPF RML PRF DDI Tonalite-monzogranite Castello Medusa Unit 0 PRF 383.70 ZIO d 2000 Gerrei Unit 1.5 % 15.8 % OMPF 375.24 60 1500 n=70 25 226.60 176.80 F3 fold axis 0 ACNb ACNb 10 44 0 388.97 281.34 180.44 1000 500 0 n=150 M. Filighi Leucogranite 18.8 % 15.7 % 344.14 25 RML Q 12.0 % M. Fogaies Ms* 296 ± 1.5 Ms** 305 ± 6 0 # 384.62 300 RML 170.59 10.7 % 30.3 % Cuccuru e’Uas Ultramylonite 15.9 % ACN 312.74 14 25.0 % n=132 Q 80 MGM 45 Cataclasite 10 5.7 % 10 35 321.17 128.81 C-plane 44 RML MGM SGAa SGA ACNa 300 218.38 13.0 % Ms** 299 ± 5 Neogene ultramylonite zone OMPF 321.83 ACNa 312.57 10 PRA MESA 130.41 35 ACNa USS RML 15 30 314.44 BUS 240.17 150.69 17 OMPF SGA Bt*** 304 ± 6 SW 25 40 343.51 20 338.88 IS AR 10.1 % 8.0 % 9.3 % S2 foliation 80 RML 20 RML 6.7 % 417.80 35 20 30 5.3 % 7.2 % OMPF 250 RML 401.43 30 250 Q 44 RML OMPF MGl 35 15 4.3 % 5 300 ACN 251.17 10 3 25 50 358.56 40 ACN 44 344.70 PRF 353.13 BA 75 ACNa 35 OMPF AR Q ACN M.Grighini Bt** 294 ± 9 Bt*** 302 ± 6 20 4.0 % n=132 OMPF OMPF 50 3MGL 0 ACN S-plane 401.57 RGHENTU 425.94 40 15 272.54 MGl 80 ACNb a) acidic metavolcanics, b) metarkoses and metasandstones (Upper Ordovician - 440 Ma) graph of shear strain (g) vs. width (d) of shear zone 400 25 0 25 15 Villaurbana 334.95 30 RD 70 440.25 15 0 45 453.45 355.35 350.13 50 257.99 270.39 Su Pinnoi UMz 343.00 270.45 PE 80 50 35 RML PRA PINNA 10 ZI IZ MODD PRF 268.51 MGl 75 a Allai Ms* 300 ±1.2 Ms** 297 ± 5 Gerrei Unit 300 44 65 332.69 44 D MGm 75 80 2.7 % 18 A AN D SE MASONI A 350 GA Q 16 Cz 1.3 % 3.0 % 0 40 403.19 OMPF 85 TZ - Truzzulla Formation N 15.2 % 244.59 0 10 ACN USS ON MGd 40 MGl 40 ACN AL 30 0.8 % 10.6 % USS Qd TCb MGl 350 270.9950 139.23 PRF 467.60 80 Qd MGL UMz MGm 129.17 45 b TC 425.01 70 0 25 Qd SU CRUCCURI 60 MGd 10 PIR 45 55 10 Q TC 0 400 MGl CUSSORGIU MANNU USS 45 35 Qd MGm RML Schists, micaschists with minor paragneisses (TC) and hornfelsed schists (TCh), a) white quartzites, b) marbles (Upper Ordovivcian - Silurian) g 0 39°54’00’’ 356.76 30 0 PA L USS MONTI PALLA 84.94 0 35 351.66 25 10 MGl 460.42 Qd a Monte Grighini Unit 6.8 % 50 M.PAGLIARTANA TC - Toccori Formation 1.4 % 280.24 Qd b Ms* 302 ± 0.24 Ms** 298 ± 5 shear strain (g =2cotan2q’) inferred on the basis of angle (q’) between shear planes (C-plane) and foliation (S-plane) in the synkinematic intrusions Shear zone 275.11 280.19 15 Main road (lower-hemisphere equal-area; n = number of data) OMPF 400 12 85 350 SU 121.69 10 45 ACN 118.55 0 30km Tectonic sketch map of the Monte Grighini Complex Trace of geological section Map distribution of deformation zones 25 44 17 MGt Czb ACN Q RML 45 MGd 0 Stereographic projections of structural elements USS M.FILIGHI 60 Ad 401.49 60 50 45 PRF 4419 240.81 35 US RAB SAR Bt** 293 ± 4 20.5 % as US 30 35 PAL Posada-Asinara line 404.93 RML LA Ben 20 A 0 10 B MGl Cz GU E IGH FIL OMPF MGm 55 MUZ 112.25 114.07 30 M.IRONI 50 TC 75 25 92.95 SU Qd 30 100 22 Cagliari 273.32 CO RI TZb 10 496.84 55 PGm ACN Uss Q Qd 512.40 513.06 40 MGl 30 USS Br.cu Fogaies 15 MGm 40 0 RML Qd 50 25 18 C’ Serra Capo d' Acqua 45 20 A’ MONTE GRIGHINI UNIT a) intensely fractured medium-grained mylonitic monzogranites (PGm) and b) mylonitic leucogranites (PGl) 271.85 30 50 80 RML Czb TZb 60 UMz PGm 338.27 MGM TC MGl RML 35 Csa 20 533.18 IGLESIENTE Capo Spartivento A Ultramylonitic and minor mylonitic leucogranites and monzogranites 39°54’00’’ 40 336.92 15 Qd Main thrusts Fossiliferous locality PG - Perdoseddu granites OMPF 300 25 233.50 Qpd 70 00 4417.74 IS 45 MSV 70 75 80 IL 25 60 MGm 450 ARBURESE Strike-slip fault b 350 CUCCURU E’UAS 250.58 75 400 MSV Cz PGl 185.21 184.88 283.12 0 25 343.36 PE 60 TCh RC 25 MGt PO PRF PRF MGd CZa USS PGm RD C 35 40 80 O SULC Metarkoses, quartzites and metaconglomerates (Upper Ordovician) 35 0 45 Qd 500 371.17 40 MGm 80 R AA Transtensive fault Normal fault a UMz - Ultramylonite zone 148.40 RU C ON 577.44 Qd 40 A 50 TCb 400 External zone with thrusts and folds AN EI MGM - Metarcose di Genna Mesa a MGM BIA CID GERR Cz - Cataclasite zone Csa 270.42 TZb SAR External zone 350 USS 20 Q TCa 80 399.05 12 Mt.Grighini Ms** 307 ± 5 4420 400 45 USS 60 I S BA MGl MGm 80 40 MUZ 170.62 A MGl Main thrust Cataclastic rocks with small bodies of a) shale, b) silicized metalimestones and c) hornfels c b 10 D E GH DE S USS 225.54 600 617.12 LATE VARISCAN SHEAR ZONE A A PIR 296.25 206.61 Csa DU Quartzites, metasandstones and metaconglomerates (Middle - ?Upper Ordovician) Grey-greenish phyllites, a) marbles and calc-schists (?Silurian - ?Lower Carboniferous) 0 C’’ 55 70 614.26 80 SGA 40 ACN 45 15 MGd 600 75 10 USS MSV 19 ZU 400 RML 80 27 415.11 A S’EN 30 20 M. CRISTU 25 PRF MUZ 0 80 25 0 265.52 Ad 50 60 264.32 300 MUZ - Metarenarie di Su Muzzioni CSA - Complesso di Sa Lilla 15 OMPF USS Funt.na s'Eremita 662.72 669.74 UZ 75 35 65 80 50 35 TR 430.51 70 433.36 20 Ad 44 MGm 20 RML 44 Qd 432.07 0 BARBAGIA Riu Gruppa-Castello Medusa Unit Monte Grighini Unit Axial plane trace of F3 antiform and synform CASTELLO MEDUSA UNIT a 65 TZb 15 Gerrei Unit Axial plane trace of F2 antiform and synform Basic to intermediate metavolcanites (Middle - ?Upper Ordovician) Q OMPF 40 Nuoro MSV - Monte Santa Vittoria Formation 0 Qd Cz 10 Z TZb TCa 663.02 647.95 I UZZ MAT 370.96 TC 35 65 USS 35 PGm 60 Calc-alkaline metapyroclastites with rhyolitic-dacitic composition (?Middle - Upper Ordovician) 4421 USS 250 Q Ad MGm Sandstones and quartzite sandstones. Fluvial-deltaic deposits (Lower Eocene) Meana Sardo Unit IS OMPF 297.27 50 70 PRF - ‘Porfiroidi’ Ad - Aplite and pegmatite dykes TC 293.66 MGl Qd FMC - Monte Cardiga Formation Posada Arburese Unit Axial plane trace of F1 antiform and synform 55 TCh N.ghe MAIORI Metarkoses, quartzites and metaconglomerates (Upper Ordovician) Qd - Quartz dykes, Qpd - Quartz-plagioclase porphyry dykes 30 50 303.12 65 Qd s'Ispelunca Minore TZa MGd 550 75 44 100 TZb 25 Csaa 18 Mylonitic stretching lineation Continental heterometric deposits (Upper Oligocene Lower Aquitanian) LATE VARISCAN DYKE SYSTEM RML Csa A MGd Qd Q ED Cz USS 350366.84 80 649.28 Qd 85 244.95 55 MGl 70 OMPF OMPF 50 20 Sassari Sarrabus Unit MGM - Metarcose di Genna Mesa 0 70 Nuraxeddu POS 15 235.14 RML GHENNIES 380.59 Qd 55 Cz 40 Q N External nappes USS - Ussana Formation VARISCAN BASEMENT RML TZb 80 MGd A MGM 45 0 65 650 MGm 290.27 70 GALLURA Barbagia Unit Mylonitic/ultramylonitic foliation 30 0 382.52 LA 552.97 386.90 OMPF 50 NT 75 M.GRIGHINI 670.22 TCh 50 350 OMPF 195.76 Qd PAL Internal nappes Stretching/mineral lineation 300 44 25 DD 350 USS 25 150 UMz US XE I CH MGt 50 270.90 250 80 ACN 403.01 TCa Qd TZa TIN MGd MGd 21 50 70 80 RML Ad 370.99 0 M.za s' Iscibi RML 40 55 25 MGl 15 4422 OMPF 266.95 25 85 65 TZb 60 70 RML 40 100 400.63 539.69 TCh 20 OMPF Funt.na Cruccuris za 100 CUCCURU MANNU 80 45 USS 45 350 22 RML 40 45 Mit ACN PRF 40 12 409.21 60 60 TCh IS ACN MGd 2 400 PRF 350 MGt 75 ACN I. Asinara 0 00 TR 10 0 USS USS 10 Sd 500 km Variscan massifs 15 TC 15 60 310.27 Co 0 75 Py Nappe zone Metapelites, a) fossiliferous metasiltites, b) fossiliferous metalimestones (encrinite) (Upper Ordovician) a OM Amphibolite-facies metamorphic complex ACN - Argilloscisti di Riu Canoni b Dacitic to rhyodacitic pyroclastic flows (Oligo-miocene) DU 35 40 Pe/Br Migmatite complex Cataclastic foliation Bau Accas 55 23 Q PO RA DA TCh TZb 44 RML AA Alps Hv Axial zone Black shales; a) nodular metalimestones (Silurian Lower Devonian) OMPF - Calc-alkaline volcanics B’ 65 TOCCORI 70 TCa 400 39°57’00’’ 20 PE Cz Variscan granitoids F3 fold axis SGA - ‘Scisti Neri’ Formation a Heterometric and heterogenic conglomerates with cineritic matrix (Upper Aquitanian - Lower Burdigalian) BM z MD MC F2 fold axis GERREI UNIT RML - Marmilla Formation OMPF RDU Q 140.69 15 TZb 80 40 45 373.99 65 25 20 USS Qd USS PERDA R CO 65 250 44 350 Cz 35 75 TC S A ON 55 Qd 60 75 ACN Qd Cz 60 TCa TU SAN 40 350 80 0 15 70 MGl 284.29 30 300 80 Q 15 Allai Ib Sp Equigranular fine-grained diorites Alternation of arenaceous and clay marls (Upper Burdigalian Middle Langhian) 250 OMPF 200 306.00 S3 axial plane foliation Post-Variscan covers MGd - Monte Grighini diorites 200 OMPF 197.38 294.92 57 20 40 A’ 50 MGt - Monte Grighini tonalites STz Am F1 fold axis GST - Marne di Gesturi Formation 65236.57 15 ACN 191.16 40 TCa OMPF LE UMz272.88 MGm Cz PRF PRF 23 MGm 20 350 ACN 25 44 TZb 200 45 278.00 60 S2 axial plane foliation Foliated fine-grained tonalites Q M S Rhz Protomylonitic-mylonitic medium-grained biotite-bearing monzogranites Subalkaline and alkaline basaltic to dacitic lavas (Pliocene) 150 60 MGl 75 M.PODDIGAS 171.65 18 OMPF PU TC BGR - Basalti delle Giare 39°57’00’’ 200 Qd 44 C PI 144.20 A ANN ALA AP USS 40 200 TCh 15 2 MGm MGm 80 200.72 242.10 50 252.23 Lz 20 162.10 45 80 UMz PRF R 24 50 150 MGl 295.10 Alluvial terraced and in evolution deposit (Holocene - Pleistocene) 0 25 O CI 550 0 RML 350 20 Cz ACN Q - Quaternary deposits Q 20 15 OMPF RE MGl 80 Q GI OS 70 356.95 MGm N MGm - Monte Grighini monzogranites 154.66 15 0 BGR Geological map of the Variscan chain of Sardinia S1 axial plane foliation 0 100 350 251.11 24 30 RI BGR 376.99 Protomylonitic-mylonitic fine-grained muscovite-bearing leucogranites POST-PALEOZOIC SEDIMENTARY AND VOLCANIC SUCCESSION OMPF 150 0 SPAS PERDAS AUSS STRUCTURAL SYMBOLS: MGl - Monte Grighini leucogranites 317.84 15 TC MONTE GRIGHINI INTRUSIVE COMPLEX (305-290 Ma) GEOLOGICAL LEGEND: 327.40 91.29 IO MA Q 25 Q 150.48 166.23 M.OLLASTRA 44 OMPF 25 0 35 160.20 MGm BGR 44 300 OMPF RA 194.05 284.98 CO 312.46 SER MGm TC 355.51 Q FUS 0 (3) ARPAS, Dipartimento provinciale di Sassari LA OMPF 15 (1) Dipartimento Scienze della Terra, Università di Pisa (2) Dipartimento Scienze Chimiche e Geologiche, Università di Cagliari CSA U MP N DI BIANC A 250 USS USS DE OMPF 137.46 OMPF Q 44 132.42 200 200 105.48 10 0 315.08 MGM CSA 100 (2) (1) (2) (3) (2) G. Musumeci, M.E. Spano, G.P. Cherchi, M. Franceschelli, P.C. Pertusati, G. Cruciani MGm MGM 150 Q BGR 25 Geological map of Monte Grighini Variscan Complex (Sardinia, Italy) 251.19 209.07 Q Q 90 250 0 15 RML 00 OMPF OMPF OMPF GST 89 0 50 150 0 OMPF Q 4 8°50’00’’ 84.82 150 10 88 20 26 4 A 0 # 81.56 44 487 486 85 RR 4 NU 84 300 4 20 0 83 10 4 350 82 AG 4 SA 81 000 m E 200 4 C’’ © Journal of Maps, 2014