Orogenic to Non-Orogenic Magmatic Events: Overview of the Late Variscan Magmatic Evolution of the Alpine Belt

Bernard BONIN

Makale detayları

Orogenic to Non-Orogenic Magmatic Events: Overview of the Late Variscan Magmatic Evolution of the Alpine Belt

Yazarlar:

Bernard BONIN

Yayıncı:

TUBITAK

Dergi:

Turkish Journal of Earth Sciences 1998 Vol.7 Issue 3, pp.133-144

Belge Tipi:

Makale

Yayın Tarihi:

2/1998

Belge Dili:

Türkçe

Document ID (Org No.):

2000733014

Sıklık:

İki Aylık

eISSN:

1303-619X

pISSN:

1300-0985

Özet:

 

The Alpine belt comprises several pieces of Pre-Mesozoic basement, which have received various imprints of the successive  Paleozoic orogenic episodes. If Pre-Mesozoic palinspatic reconstructions are taken into account, the Alpine basement can be  considered as one single area before Mesozoic continental breakup. Contrasting magma associations were emplaced according to  space and time.  There exists a controversy about the existence of the Caledonian orogenic episode. The Lower Paleozoic orogenesis was advocated  through different lines of evidences in the southern Alpine basement, such as emplacement of Ordovician and Silurian protoliths of  calc-alkaline and alkaline orthogneisses.  The Variscan orogenic episode ended with the Late-Devonian collisional stage. Then, the Alpine basement was subjected to large-scale  shearing effects accompanying lithosphere distensional thinning, high geothermal regimes and low-pressure regional  metamorphism. The middle crust ultimately underwent "wet" and/or H 2 O-deficient partial melting processes, which may or may  not have been induced by the intrusion of mantle-derived melts. Peraluminous crustal melts were associated and/or mixed with high-K  basic magmas.  Lower to Middle Carboniferous high-K calc alkaline suites characterize the culmination of the post-collisional stage, that was related  to uplift and erosion in short-lived transpressional and/or transtensional environments. At the Permian-Carboniferous boundary, near  alkaline suites, yielding both alkaline and calc-alkaline features, were emplaced as volcanic-plutonic massifs in a major distensional  regime and mark the end of the Variscan orogenesis sensu stricto.  Upper Carboniferous to Early Permian calc-alkaline granitoids were emplaced only at the southern flank of the Variscan belt. They  yield features characteristic of subduction-related suites and resemble closely the circum-Pacific Cordilleran batholiths. They indicate  a renewed ocean-continent plate margin convergence, which could be related to the alleghanian orogenesis. This episode, well  developed in the southern Appalachians, can be evidenced in North Africa, the Alpine belt and further east to Asia.  Mid-Permian post-orogenic and Late Permian to Triassic early anorogenic alkaline complexes constitute a part of the Western  Mediterranean alkaline province. Associated thermal imprints were recorded in the basement mineral isotopic clocks. The anorogenic  magmatic activity can be related both to continental consolidation of the European plate and precursory stage in the formation of  the Meso-Tethys oceanic basin.

 

The Alpine belt comprises several pieces of Pre-Mesozoic basement, which have received various imprints of the successive  Paleozoic orogenic episodes. If Pre-Mesozoic palinspatic reconstructions are taken into account, the Alpine basement can be  considered as one single area before Mesozoic continental breakup. Contrasting magma associations were emplaced according to  space and time.  There exists a controversy about the existence of the Caledonian orogenic episode. The Lower Paleozoic orogenesis was advocated  through different lines of evidences in the southern Alpine basement, such as emplacement of Ordovician and Silurian protoliths of  calc-alkaline and alkaline orthogneisses.  The Variscan orogenic episode ended with the Late-Devonian collisional stage. Then, the Alpine basement was subjected to large-scale  shearing effects accompanying lithosphere distensional thinning, high geothermal regimes and low-pressure regional  metamorphism. The middle crust ultimately underwent "wet" and/or H 2 O-deficient partial melting processes, which may or may  not have been induced by the intrusion of mantle-derived melts. Peraluminous crustal melts were associated and/or mixed with high-K  basic magmas.  Lower to Middle Carboniferous high-K calc alkaline suites characterize the culmination of the post-collisional stage, that was related  to uplift and erosion in short-lived transpressional and/or transtensional environments. At the Permian-Carboniferous boundary, near  alkaline suites, yielding both alkaline and calc-alkaline features, were emplaced as volcanic-plutonic massifs in a major distensional  regime and mark the end of the Variscan orogenesis sensu stricto.  Upper Carboniferous to Early Permian calc-alkaline granitoids were emplaced only at the southern flank of the Variscan belt. They  yield features characteristic of subduction-related suites and resemble closely the circum-Pacific Cordilleran batholiths. They indicate  a renewed ocean-continent plate margin convergence, which could be related to the alleghanian orogenesis. This episode, well  developed in the southern Appalachians, can be evidenced in North Africa, the Alpine belt and further east to Asia.  Mid-Permian post-orogenic and Late Permian to Triassic early anorogenic alkaline complexes constitute a part of the Western  Mediterranean alkaline province. Associated thermal imprints were recorded in the basement mineral isotopic clocks. The anorogenic  magmatic activity can be related both to continental consolidation of the European plate and precursory stage in the formation of  the Meso-Tethys oceanic basin.

Makale detayları

Orogenic to Non-Orogenic Magmatic Events: Overview of the Late Variscan Magmatic Evolution of the Alpine Belt

Yazarlar: Bernard BONIN

Yayıncı: TUBITAK

Dergi: Turkish Journal of Earth Sciences 1998 Vol.7 Issue 3, pp.133-144

Belge Tipi: Makale

Yayın Tarihi: 2/1998

Belge Dili: Türkçe

Document ID (Org No.): 2000733014

Sıklık: İki Aylık

eISSN: 1303-619X

pISSN: 1300-0985

Sayı

Yazarlar:

Bernard BONIN

Yayıncı:

TUBITAK

Dergi:

Turkish Journal of Earth Sciences 1998 Vol.7 Issue 3, pp.133-144

Belge Tipi:

Makale

Yayın Tarihi:

2/1998

Belge Dili:

Türkçe

Document ID (Org No.):

2000733014

Sıklık:

İki Aylık

eISSN:

1303-619X

pISSN:

1300-0985