Alpine tectonics in the Calabrian-Peloritan belt (southern Italy): New 40Ar/39Ar data in the Aspromonte Massif area

被引:40
作者
Heymes, Thomas [1 ]
Monie, Patrick [2 ]
Arnaud, Nicolas [2 ]
Pecher, Arnaud [1 ]
Bouillin, Jean-Pierre [1 ]
Compagnoni, Roberto [3 ]
机构
[1] Univ Grenoble 1, UMR 5025, LGCA, CNRS, F-38041 Grenoble, France
[2] Univ Montpellier 2, CNRS, UMR 5243, F-34095 Montpellier 5, France
[3] Univ Turin, DSMP, I-10125 Turin, Italy
关键词
Western Mediterranean; Calabrian-Peloritan belt; Alpine convergence/extension; Exhumation; 40Ar/39Ar dating; Mylonitic shear zones; METAMORPHIC CORE COMPLEX; CRUSTAL CROSS-SECTION; U-PB AGES; RB-SR; GEODYNAMIC EVOLUTION; OROGENIC EXTENSION; TYRRHENIAN SEA; SHEAR ZONES; K-FELDSPAR; SARDINIA CHANNEL;
D O I
10.1016/j.lithos.2009.10.011
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
This study provides new 40Ar/39Ar geochronological constraints on the age of the Alpine tectonics in the Aspromonte Massif (southern part of the Calabrian-Peloritan belt). This massif exposes the upper units of the Calabride Complex which originated from the European continental margin. The Calabride Complex was incorporated in the Alpine orogenic wedge and then integrated into the Apennines and Maghrebides fold- and-thrust belts. Throughout the Calabride Complex there is evidence for a two stage tectonic history, which remains however rather poorly dated: Alpine nappe stacking is followed by extensional reworking along the former thrust contacts or along new detachment surfaces. Our new ages suggest that exhumation of the uppermost units, which accompanied nappe stacking, probably started at 45 Ma and that the deepest units were almost completely exhumed at 33 Ma. This kinematics probably corresponds to syn-orogenic extension while the end of exhumation is clearly related to the extensional tectonics dated at 28.6 Ma along detachment structures. Our geochronological data reveal a very short lag time between accretional and extensional processes in this part of the Mediterranean Alpine orogenic belt. The direction of extension, when the units are restored to their initial position (i.e. before the opening of the Western Mediterranean basins and the bending of the arc) is NNE-SSW. Such a direction does not fit with the eastward slab-retreat model generally put forward to explain extension in the Western Mediterranean. In contrast, we provide evidence for roughly N-S middle Oligocene extension in the accretionary prism, not previously described in this part of the Mediterranean domain. (C) 2009 Elsevier B.V. All rights reserved. This study provides new 40Ar/39Ar geochronological constraints on the age of the Alpine tectonics in the Aspromonte Massif (southern part of the Calabrian-Peloritan belt). This massif exposes the upper units of the Calabride Complex which originated from the European continental margin. The Calabride Complex was incorporated in the Alpine orogenic wedge and then integrated into the Apennines and Maghrebides fold- and-thrust belts. Throughout the Calabride Complex there is evidence for a two stage tectonic history, which remains however rather poorly dated: Alpine nappe stacking is followed by extensional reworking along the former thrust contacts or along new detachment surfaces. Our new ages suggest that exhumation of the uppermost units, which accompanied nappe stacking, probably started at 45 Ma and that the deepest units were almost completely exhumed at 33 Ma. This kinematics probably corresponds to syn-orogenic extension while the end of exhumation is clearly related to the extensional tectonics dated at 28.6 Ma along detachment structures. Our geochronological data reveal a very short lag time between accretional and extensional processes in this part of the Mediterranean Alpine orogenic belt. The direction of extension, when the units are restored to their initial position (i.e. before the opening of the Western Mediterranean basins and the bending of the arc) is NNE-SSW. Such a direction does not fit with the eastward slab-retreat model generally put forward to explain extension in the Western Mediterranean. In contrast, we provide evidence for roughly N-S middle Oligocene extension in the accretionary prism, not previously described in this part of the Mediterranean domain. (C) 2009 Elsevier B.V. All rights reserved.
引用
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页码:451 / 472
页数:22
相关论文
共 124 条
[1]   Exhumation of the Schistes Lustres complex:: in situ laser probe 40Ar/39Ar constraints and implications for the Western Alps [J].
Agard, P ;
Monié, P ;
Jolivet, L ;
Goffé, B .
JOURNAL OF METAMORPHIC GEOLOGY, 2002, 20 (06) :599-618
[2]   Muscovite recrystallization and saddle-shaped 40Ar/39Ar age spectra: Example from the Blond granite (Massif Central, France) [J].
Alexandrov, P ;
Ruffet, G ;
Cheilletz, A .
GEOCHIMICA ET COSMOCHIMICA ACTA, 2002, 66 (10) :1793-1807
[3]  
ALVAREZ W, 1976, GEOL SOC AM BULL, V87, P891, DOI 10.1130/0016-7606(1976)87<891:AFCOTA>2.0.CO
[4]  
2
[5]  
[Anonymous], 1980, B SOC GEOL ITAL
[6]   HIGH COOLING AND DENUDATION RATES AT KONGUR-SHAN, EASTERN PAMIR (XINJIANG, CHINA) REVEALED BY 40AR/39AR ALKALI FELDSPAR THERMOCHRONOLOGY [J].
ARNAUD, NO ;
BRUNEL, M ;
CANTAGREL, JM ;
TAPPONNIER, P .
TECTONICS, 1993, 12 (06) :1335-1346
[7]  
ARNAUD NO, 1995, CONTRIB MINERAL PETR, V21, P249
[8]  
ATZORI P, 1990, EUR J MINERAL, V2, P363
[9]   Low-angle crustal ramp and basin geometry in the Gulf of Lion passive margin: Oligocene-Aquitanian Vistrenque graben, SE France [J].
Benedicto, A ;
Labaume, P ;
Seguret, M ;
Seranne, M .
TECTONICS, 1996, 15 (06) :1192-1212
[10]   INITIATION AND EVOLUTION OF THE OLIGOMIOCENE RIFT BASINS OF SOUTHWESTERN EUROPE - CONTRIBUTION OF DEEP SEISMIC-REFLECTION PROFILING [J].
BOIS, C .
TECTONOPHYSICS, 1993, 226 (1-4) :227-252