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Balkanska, E.*; Georgiev, S.*; Kounov, A.*; Anti
, M.*; 田上 高広*; 末岡 茂; Wijbrans, J.*; Peytcheva, I.*
Geologica Carpathica, 73(1), p.3 - 23, 2022/02
被引用回数：1 パーセンタイル：17.24(Geosciences, Multidisciplinary)The central parts of the Sredna Gora Zone in Bulgaria have experienced a complex Alpine tectonic evolution. The main tectonic and thermal events since the end of the Triassic are the Late Jurassic-Early Cretaceous (Early Alpine) and Late Cretaceous-Paleogene (Late Alpine) compression/transpression separated by Late Cretaceous island-arc magmatism and intra/back-arc extension and basin formation. During the Cenozoic, the area was mainly under post-orogenic extension. Here, we present the first apatite and zircon fission-track results and new muscovite and biotite 
Ar/
Ar age analysis on late Carboniferous-Permian granitoids together with Late Cretaceous volcanic and subvolcanic rocks and Late Maastrichtian-Danian conglomerates from the Panagyurishte basin, which allowed us to reveal the Alpine thermal and tectonic evolution of the Central Sredna Gora Zone. Our new results disclosed the existence of several thermal and cooling episodes related to different tectonic and magmatic events in the studied area. The 40Ar/39Ar dating of samples from the metamorphic basement constrain the thermal peak of an Early Alpine thermal event at about 139-137 Ma at temperatures between 
300 and 400
C. Through the apatite FT dating and thermal modelling, the time of a Late Alpine (post-Danian) event was constrained at 65-55 Ma, during which the tectonically buried sediments of the Panagyurishte basin attained temperature of 
120C. The Cenozoic cooling and exhumation of the Central Sredna Gora Zone metamorphic basement was related to post-orogenic extension and denudation which took place probably at two stages during middle Eocene to Oligocene.
Balkanska, E.*; Georgiev, S.*; Kounov, A.*; Peytcheva, I.*; 田上 高広*; 末岡 茂
no journal, ,
ブルガリア・Sredna Gora帯のVariscan期の基盤における冷却・削剥史の推定を目的として、アパタイトFT解析を実施した。標高の異なる4試料からは年代と標高に正の相関がみられ、見掛けの削剥速度は0.45mm/yrと推定された。FTデータに基づいた熱履歴逆解析の結果では、45-35Ma頃に中程度の冷却が認められた。この冷却は、造山運動後の削剥と、始新世のThrace盆地形成に伴う引張に関連している可能性がある。
Balkanska, E.*; Georgiev, S.*; Kounov, A.*; Anti, M.*; 田上 高広*; 末岡 茂; Wijbrans, J.*; Peytcheva, I.*
no journal, ,
We present the first apatite and zircon fission-track results coupled with new muscovite and biotite Ar/Ar analysis on samples from the pre-Mesozoic granitic basement and the Upper Cretaceous to Danian volcano-sedimentary cover, which allowed us to reveal the Alpine thermal and tectonic evolution of the central parts of Sredna Gora Zone. Our new results disclosed the existence of several heating and cooling episodes related to different tectonic and magmatic events in the studied area.
Balkanska, E.*; Georgiev, S.*; Marton, I.*; Kounov, A.*; Peytcheva, I.*; Anti, M.*; 田上 高広*; 末岡 茂; Wijbrans, J.*
no journal, ,
The Chelopech high-sulphidation epithermal Au-Cu deposit in Bulgaria is part of the Panagyurishte Ore District situated within the Late Cretaceous Apuseni-Banat-Timok-Sredna Gora metallogenic belt. The time of the magmatic and ore-forming events in the Chelopech area were previously well constrained by zircon U-Pb geochronology at 92.5-91 Ma. Here we provide the results of the first apatite fission-track (FT) together with biotite and amphibole Ar/Ar multiple single grain fusion analysis on the Late Cretaceous magmatic rocks associated with the Chelopech Au-Cu deposit. These rocks were sampled in aim to reveal the post-magmatic/metallogenic evolution of the area, which includes a Late Cretaceous-Paleocene (Late Alpine) compression followed by an Eocene-Miocene extension. The obtained results reveal at least three major cooling episodes since the Late Cretaceous. The Ar/Ar weighted mean ages of 92.12 
0.60 Ma (amphibole) and 89.17 0.34 Ma (biotite) are interpreted as representing the time of cooling below ca 300C after the emplacement of the sampled magmatic bodies. Four rock samples yield apatite FT ages between 48.6 4.1 Ma and 37.7 3.7 Ma. Modelling of the apatite fission track data using HeFTy software revealed two stages of rapid cooling below ca 120C - the first one between 52 and 45 Ma probably related to the syn- to post-Late Alpine thrusting denudation and the second one between 38 and 35 Ma triggered by the post-orogenic middle to late Eocene extension and exhumation.
