Dating eclogite-facies metamorphism in the Eastern Alps -: approaches, results, interpretations:: a review

In the Eastern Alps, different tectonic units contain eclogites of Carboniferous, Cretaceous (eo-Alpine), and Cenozoic age: (i) In the structurally lower Penninic unit, which is exposed in the Tauern window, eclogites formed at peak P-T conditions of 2.4GPa and <= 630 degrees C as a result of subduction of the former European continental margin at the base of an imbricate stack of Mesozoic oceanic rocks below the Austroalpine domain. Amphibole and phengite 40Ar-39Ar and Rb-Sr multimineral isochron ages suggest an Eocene-Early Oligocene (< 45-31 Ma) age for the stage of deepest subduction and rapid exhumation/cooling. (ii) Variscan MORB-type eclogites are present in the central Otztal basement (2.7 GPa/730 degrees C; mean Sm-Nd age: 347 +/- 9 Ma), the eastern Silvretta (ca. 350 Ma), and the Ulten high-grade crystalline Q 36 4 Ma). These domains pertain to the N Apulian (Austroalpine) crust. (iii) In the southern Austroalpine units, eclogites and high-P metapelites are known from the Texel complex (1.3 GPa/520-600 degrees C), the Schober area (1.8 GPa/<= 690 degrees C), and the Saualpe-Koralpe-Pohorje domain (2.2-< 2.7 GPa/<= 750 degrees C). Their tectonic position and near-identical Cretaceous ages suggest a common subduction-exhumation history. This eo-Alpine high-pressure belt (EHB) resulted from burial of the strongly thinned, distal passive Neotethyan margin of the Meliata back-arc basin and, further west, pre-Alpine Austroalpine crust along an intracontinental subduction zone during the Late Mesozoic convergence of Apulia and Europe. Peak metamorphism and initial decompression/exhumation is dated by the Sm-Nd, Lu-Hf, U-Pb and Rb-Sr systems as close to 90 Ma, with mean exhumation rates in the range of 5-<= 10km/Ma for the time between 90 and 85 Ma B.P. In the Eastern Alps, different tectonic units contain eclogites of Carboniferous, Cretaceous (eo-Alpine), and Cenozoic age: (i) In the structurally lower Penninic unit, which is exposed in the Tauern window, eclogites formed at peak P-T conditions of 2.4GPa and <= 630 degrees C as a result of subduction of the former European continental margin at the base of an imbricate stack of Mesozoic oceanic rocks below the Austroalpine domain. Amphibole and phengite 40Ar-39Ar and Rb-Sr multimineral isochron ages suggest an Eocene-Early Oligocene (< 45-31 Ma) age for the stage of deepest subduction and rapid exhumation/cooling. (ii) Variscan MORB-type eclogites are present in the central Otztal basement (2.7 GPa/730 degrees C; mean Sm-Nd age: 347 +/- 9 Ma), the eastern Silvretta (ca. 350 Ma), and the Ulten high-grade crystalline Q 36 4 Ma). These domains pertain to the N Apulian (Austroalpine) crust. (iii) In the southern Austroalpine units, eclogites and high-P metapelites are known from the Texel complex (1.3 GPa/520-600 degrees C), the Schober area (1.8 GPa/<= 690 degrees C), and the Saualpe-Koralpe-Pohorje domain (2.2-< 2.7 GPa/<= 750 degrees C). Their tectonic position and near-identical Cretaceous ages suggest a common subduction-exhumation history. This eo-Alpine high-pressure belt (EHB) resulted from burial of the strongly thinned, distal passive Neotethyan margin of the Meliata back-arc basin and, further west, pre-Alpine Austroalpine crust along an intracontinental subduction zone during the Late Mesozoic convergence of Apulia and Europe. Peak metamorphism and initial decompression/exhumation is dated by the Sm-Nd, Lu-Hf, U-Pb and Rb-Sr systems as close to 90 Ma, with mean exhumation rates in the range of 5-<= 10km/Ma for the time between 90 and 85 Ma B.P. In the Eastern Alps, different tectonic units contain eclogites of Carboniferous, Cretaceous (eo-Alpine), and Cenozoic age: (i) In the structurally lower Penninic unit, which is exposed in the Tauern window, eclogites formed at peak P-T conditions of 2.4GPa and <= 630 degrees C as a result of subduction of the former European continental margin at the base of an imbricate stack of Mesozoic oceanic rocks below the Austroalpine domain. Amphibole and phengite 40Ar-39Ar and Rb-Sr multimineral isochron ages suggest an Eocene-Early Oligocene (< 45-31 Ma) age for the stage of deepest subduction and rapid exhumation/cooling. (ii) Variscan MORB-type eclogites are present in the central Otztal basement (2.7 GPa/730 degrees C; mean Sm-Nd age: 347 +/- 9 Ma), the eastern Silvretta (ca. 350 Ma), and the Ulten high-grade crystalline Q 36 4 Ma). These domains pertain to the N Apulian (Austroalpine) crust. (iii) In the southern Austroalpine units, eclogites and high-P metapelites are known from the Texel complex (1.3 GPa/520-600 degrees C), the Schober area (1.8 GPa/<= 690 degrees C), and the Saualpe-Koralpe-Pohorje domain (2.2-< 2.7 GPa/<= 750 degrees C). Their tectonic position and near-identical Cretaceous ages suggest a common subduction-exhumation history. This eo-Alpine high-pressure belt (EHB) resulted from burial of the strongly thinned, distal passive Neotethyan margin of the Meliata back-arc basin and, further west, pre-Alpine Austroalpine crust along an intracontinental subduction zone during the Late Mesozoic convergence of Apulia and Europe. Peak metamorphism and initial decompression/exhumation is dated by the Sm-Nd, Lu-Hf, U-Pb and Rb-Sr systems as close to 90 Ma, with mean exhumation rates in the range of 5-<= 10km/Ma for the time between 90 and 85 Ma B.P. In the Eastern Alps, different tectonic units contain eclogites of Carboniferous, Cretaceous (eo-Alpine), and Cenozoic age: (i) In the structurally lower Penninic unit, which is exposed in the Tauern window, eclogites formed at peak P-T conditions of 2.4GPa and <= 630 degrees C as a result of subduction of the former European continental margin at the base of an imbricate stack of Mesozoic oceanic rocks below the Austroalpine domain. Amphibole and phengite 40Ar-39Ar and Rb-Sr multimineral isochron ages suggest an Eocene-Early Oligocene (< 45-31 Ma) age for the stage of deepest subduction and rapid exhumation/cooling. (ii) Variscan MORB-type eclogites are present in the central Otztal basement (2.7 GPa/730 degrees C; mean Sm-Nd age: 347 +/- 9 Ma), the eastern Silvretta (ca. 350 Ma), and the Ulten high-grade crystalline Q 36 4 Ma). These domains pertain to the N Apulian (Austroalpine) crust. (iii) In the southern Austroalpine units, eclogites and high-P metapelites are known from the Texel complex (1.3 GPa/520-600 degrees C), the Schober area (1.8 GPa/<= 690 degrees C), and the Saualpe-Koralpe-Pohorje domain (2.2-< 2.7 GPa/<= 750 degrees C). Their tectonic position and near-identical Cretaceous ages suggest a common subduction-exhumation history. This eo-Alpine high-pressure belt (EHB) resulted from burial of the strongly thinned, distal passive Neotethyan margin of the Meliata back-arc basin and, further west, pre-Alpine Austroalpine crust along an intracontinental subduction zone during the Late Mesozoic convergence of Apulia and Europe. Peak metamorphism and initial decompression/exhumation is dated by the Sm-Nd, Lu-Hf, U-Pb and Rb-Sr systems as close to 90 Ma, with mean exhumation rates in the range of 5-<= 10km/Ma for the time between 90 and 85 Ma B.P.