THE METAMORPHISM AND THE RELATIONSHIP BETWEEN INFRA AND SUPRASTRUCTURES OF THE BİTLİS MASSIF - TURKEY

Yıl 1993, Cilt: 115 Sayı: 115, 1 - 13, 01.08.1993

Metin Şengün

Öz

The infrastructure of the massife consists essentially of amphibolites, gneisses and micaschists intruded by a
biotite granite and the successive hololeucocratic phase. The mantling rocks of the suprastructure comprise metapelitic rocks
unconformably underlying metacarbonates dated as Middle Devonian- Mesozoic. The infra-suprastructure boundary is
interpreted as a surface of transgressive overlap. The rocks of infra and suprastructure are involved in isoclinal folds with ductile
deformation along most of the boundary conclusively suggesting in situ position of the suprastructure during the Alpine
deformation. The shear planes are discontinous, en echelon and run independent of the infra-suprastructure boundary. A
uniform sequence of Palaezoic rocks, which is not intruded by the granites of the infra-structure, together with the
infra-suprastructure boundary being a sedimentary contact, are conclusive evidence for the existence of a Precambrian event.
Eradication of Precambrian paragenesis occurs in the flanks of major folds where a complete Alpine zoning exists from very low
grade to anatectic conditions as exemplified by the Kesandere section in contrast to the preservation of Precambrian
parageneses in the unsheared competent rocks of the infrastructure of the hinge areas. There is no gap in physical conditions
with regard to a single episode of deformation. The gap occurring between the infra and the suprastructure is due to different
physical conditions of Precambrian and Alpine deformations. Retrograde effects are presumably due to an Alpine imprint on the
Precambrian parageneses, whereas they are attributed to a continous process of deformation with conternparaneous uplift and
progressive dimunition of physical conditions in the case of imprint on early Alpine parageneses. The interpretation herein
presented in relation to nature of infra and suprastructure boundary and metamorphism of Bitlis massive is consistent, for all
aspects, with the regional geologic data showing that it is the deformed Alpine passive margin of the Arabian plate. 

Anahtar Kelimeler

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Kaynakça

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