Exhumation of the Schistes Lustrés complex: in situ laser probe 40Ar/39Ar constraints and implications for the Western Alps

Journal of Metamorphic Geology - Tập 20 Số 6 - Trang 599-618 - 2002
Philippe Agard1, Patrick Monié1, Laurent Jolivet1, Bruno Goffé1
1École Normale Supérieure - PSL, Paris, France

Tóm tắt

AbstractThe Schistes Lustrés (SL) suture zone occupies a key position in the Alpine chain between the high‐pressure (HP) Brianconnais domain and the ultrahigh‐pressure (UHP) Dora Maira massif, and reached subduction depths ranging from c. 40–65 km (Cottian Alps). In order to constrain the timing of HP metamorphism and subsequent exhumation, several phengite generations were differentiated, on the basis of habit, texture, paragenesis and chemistry, as belonging to the first or second exhumation episode, respectively, D2 or D3, or to earlier stages of the tectono‐metamorphic evolution. Ten carefully selected samples showing D2, D3 (D2 + D3), or earlier (mostly peak temperature) phengite population(s) were subjected to laser probe 40Ar/39Ar analysis. The data support the results of the petrostructural study with two distinct age groups (crystallization ages) for D2 and D3 phengite, at 51–45 and 38–35 Ma, respectively. The data also reveal a coherent age cluster, at 62–55 Ma, for peak temperature phengite associated with chloritoid which were preserved in low strain domains. The age of the D3 event in the SL complex appears very similar to ages recently obtained for greenschist facies deformation on the border of most internal crystalline massifs. Exhumation rates of the order of 1–2 mm yr−1 are obtained for the SL complex, which are compatible with velocities documented for accretionary wedge settings. Similarly, cooling velocities are only moderate (c.5 °C Myr−1), which is at variance with recent estimates in the nearby UHP massifs.

Từ khóa


Tài liệu tham khảo

10.1007/s004100000190

10.2113/172.5.617

10.1046/j.0263-4929.2001.00322.x

10.1002/9781444313574

10.1016/S0012-821X(99)00161-2

10.1007/s004100050086

Ballèvre M., 1990, Deep Structure of the Alps, 227

Ballèvre M., 1993, The Combin fault: compressional reactivation of a late Cretaceous‐early Tertiary detachment fault in the Western Alps, Schweizrische Mineralogische Petrografische Mitteilung, 73, 205

10.1029/1999JB900136

Bonhomme M. G., 1980, Interpretation of potassium‐argon isotopic data related to metamorphic events in south‐western Alps, Schweizrische Mineralogische Petrografische Mitteilung, 60, 81

Bosse V. Féraud G.&Ballèvre M. 2000.Géochronologie des roches éclogitiques du complexe de Champtoceaux (massif Armoricain France): cohérence des méthodes U‐Pb Sm‐Nd Rb‐Sr et40Ar/39Ar.18e Réunion Des Sciences de la Terre Société Geologique de France Paris.

10.1130/0016-7606(1998)110<0985:LCEOTC>2.3.CO;2

10.1016/0012-821X(70)90146-9

10.1038/379505a0

Burg J. P., 1997, Orogeny Through Time, Special Publication 121, 1

10.1016/S0040-1951(01)00158-5

Caby R.&Bonhomme G. 1982.Whole‐rock and fine fraction K‐Ar isotopic study of radiolarites affected by the alpine metamorphism.5th International Conference on Geochemistry and Isotope Geology International Geological Congress Tokyo.

10.1127/ejm/3/2/0263

10.1007/BF01131997

10.1007/BF00381295

10.1111/j.1525-1314.1998.00147.x

Coward M., 1989, Alpine Tectonics, Special Publication, 45, 1

10.1007/s004100050141

10.1016/0016-7037(96)00170-6

De Wever P., 1981, Datation de la base des schistes lustrés postophiolitiques par des radiolaires (Oxfordien‐Kimmeridgien moyen) dans les Alpes Cottiennes (Saint Véran, France), Comptes Rendus de l'Academie Des Sciences, 292, 467

Delaloye M., 1976, K‐Ar radiometric age determinations of white micas from the Piemonte zone, french‐italian western Alps, Contributions to Mineralogy and Petrology, 57, 297, 10.1007/BF03542939

Deville E., 1986, La klippe de la pointe du Grand Vallon (Vanoise‐Alpes occidentales): un lambeau de métasédiments à foraminifères du Maastrichitien supérieur couronnant les nappes de ‘Schistes Lustrés’, Comptes Rendus de l'Academie Des Sciences, 303, 1211

10.1111/j.1440-1738.1995.tb00149.x

10.1007/BF00373790

10.2475/ajs.298.1.30

10.1038/42446

10.1016/S0040-1951(97)00143-1

Ernst W. G., 2000, Ultrahigh‐Pressure Metamorphism and Geodynamics in Collision‐Type Orogenic Belts, International book series, 3

10.1029/96TC02477

10.1007/BF00373092

Gebauer D., 1999, Alpine geochronology of the Central and Western Alps: new constraints for a complex geodynamic evolution, Schweizrische Mineralogische Petrografische Mitteilung, 79, 191

Gebauer D., 1997, 35 Ma old ultrahigh‐pressure and evidence for very rapid exhumation in the Dora Maira Massif, Western Alps, Lithos, 41, 5, 10.1016/S0024-4937(97)82002-6

10.1016/S0012-821X(00)00221-1

10.1046/j.1365-2117.2000.00114.x

10.1029/2000JB900039

10.1016/S0012-821X(98)00152-6

10.1016/0012-821X(94)00079-4

10.1016/0016-7037(85)90246-7

10.1016/0009-2541(95)00106-9

10.1016/0191-8141(93)90170-F

Hess J. C., 1994, Phanerozoic Time Scale, 19

Hunziker J. C. Desmons J.&Hurford A. J. 1992. Thirty‐two years of geochronological work in the Central and Western Alps: a review on seven maps pp.1–59 Lausanne.

Hurford A. J., 1990, Standardization of fission track dating calibration: recommandation by the Fission Track Working Group of the IUGS Subcommission on Geochronology, Chemical Geology, 80, 171

Jäger E., 1973, Die Alpine orogenese im lichte der radiometrischen Alterbestimmung, Eclogae Geologicae Helvetiae, 66, 11

10.1016/S0009-2541(01)00264-9

10.1029/2000TC900018

10.1130/0091-7613(1996)024<0747:SAASOF>2.3.CO;2

10.1016/S1251-8050(97)82369-5

Le Pichon X., 1988, Plate kinematics and tectonics leading to the Alpine belt formation; A new analysis, Geological Society of America (special paper, 218, 11

Lemoine M., 2000, De L'océan Á la Chaîne de Montagnes. Tectonique Des Plaques Dans les Alpes

Lemoine M., 1984, Découverte de foraminifères planctoniques du Crétacé supérieur dans les schistes lustrés du Queyras (Alpes occidentales). Conséquences paléogéographiques et tectoniques, Comptes Rendus de l'Academie Des Sciences, 229, 727

10.1016/0009-2541(94)90033-7

10.1016/0040-1951(81)90017-2

Maluski H., 1988, 40Ar/39Ar laser‐probe multi‐dating inside single biotites of a Variscan orthogneiss (Pinet Massif Central, France), Chemical Geology, 73, 245

McDougall I., 1988, Geochronology and Thermochronology by the 40Ar/39Ar Method

10.1046/j.1525-1314.1999.00198.x

Michard A., 1996, Did the Western Alps develop through an Oman‐type stage? The geotectonic setting of high‐pressure metamorphism in two contrasting Tethyan transects, Eclogae Geologicae Helvetiae, 89, 43

Monié P., 1985, La méthode 40Ar/39Ar appliquée au métmorphisme alpin dans le massif du Mont‐Rose (Alpes occidentales). Chronologie détaillée depuis 110 Ma, Eclogae Geologicae Helvetiae, 78, 487

10.1127/ejm/2/3/0343

Monié P., 1989, Mise en évidence de l'âge éocène moyen du métamorphisme de haute‐pression dans la nappe eclogitique du Monviso (Alpes occidentales) par la methode 39Ar‐40Ar, Comptes Rendus de l'Academie Des Sciences, 309, 245

10.1007/BF00375313

10.1111/j.1525-1314.1997.00022.x

10.1080/00206810009465078

10.1029/TC009i005p01143

10.1080/00206810009465085

10.1111/j.1365-3121.1993.tb00237.x

10.1046/j.1525-1314.1996.00338.x

10.1046/j.1525-1314.1999.00220.x

10.1127/ejm/3/1/0007

10.1016/S0024-4937(97)00041-8

Ring U., 1999, Exhumation Processes: Normal Faulting, Ductile Flow and Erosion, Special Publication 154, 55

Ring U., 1999, Exhumation Processes: Normal Faulting, Ductile Flow and Erosion, Special Publication 154, 1

Rubatto D., 1999, Eo/Oligocene (35 Ma) high‐pressure metamorphism in the Gornergrat zone (Monte Rosa, Western Alps): implications for paleogeography, Schweizrische Mineralogische Petrografische Mitteilung, 79, 353

10.1016/0009-2541(94)00132-R

10.1016/0168-9622(87)90025-X

10.1016/0016-7037(95)00440-8

10.1007/978-94-015-9050-1_7

10.1016/0016-7037(92)90364-O

Schärer U., 1999, EUG Meeting No. 10. J. Conf. abstr.

Schwartz S. 2001.La zone piémontaise des Alpes occidentales: un paléo‐complexe de subduction. Arguments métamorphiques géochronologiques et structuraux.Documents Du B.R.G.M. no. 302. Bureau des Recherches Géologiques et Minierés Orléans.

10.1016/S0985-3111(00)00112-1

De Sigoyer J. Villa I.&Cosca M. 2000.Informations39Ar/40Ar sur des roches métamorphisées à HP‐BT à prendre ou à laisser?18e Réunion Des Sciences de la Terre J. Conf. abstr. Paris.

10.1111/j.1365-2117.1992.tb00046.x

Stampfli G. M.&Marchant R. H. 1997.Geodynamics evolution of the Tethyan margins of the Western Alps. In:Deep Structure of Switzerland. Results from NFP 20(edsLehner P. H. Frei W. Horstmeyer H. Mueller S. Pfiffner A.&Steck A.) BinkhaüserVerlag Basel.

10.1029/95JB02885

10.1111/j.1440-1738.1994.tb00104.x

10.1111/j.1525-1314.1997.00038.x

10.1046/j.1365-3121.1998.00156.x

10.1029/94TC02051

10.1130/0091-7613(1997)025<0927:NEFCIE>2.3.CO;2

10.1016/0012-821X(93)90097-S

10.1144/jgs.158.3.439

10.1007/BF00371320

Thông tin
Thông tin xuất bản

Journal of Metamorphic Geology

Tập 20 Số 6

599-618

Thông tin tác giả