Two-Stage Late Jurassic to Early Cretaceous Hydrothermal Activity in the Sakar Unit of Southeastern Bulgaria
Southeastern Bulgaria is composed of a variety of rocks from pre-Variscan (ca. 0.3 Ga) to pre-Alpine sensu lato (ca. 0.15 Ga) time. The Sakar Unit in this region comprises a series of granitoids and gneisses formed or metamorphosed during these events. It is cut by a series of post-Variscan hydrothe...
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doaj-6888b64b9d624326916bec4c72f4944c2020-11-25T02:52:32ZengMDPI AGMinerals2075-163X2020-03-0110326610.3390/min10030266min10030266Two-Stage Late Jurassic to Early Cretaceous Hydrothermal Activity in the Sakar Unit of Southeastern BulgariaKrzysztof Szopa0Anna Sałacińska1Ashley P. Gumsley2David Chew3Petko Petrov4Aleksandra Gawȩda5Anna Zagórska6Ewa Deput7Nikolay Gospodinov8Kamila Banasik9Institute of Earth Sciences, Faculty of Natural Sciences, University of Silesia in Katowice, Będzińska 60, 41-200 Sosnowiec, PolandInstitute of Geological Sciences PAS, 00-818 Warsaw, PolandInstitute of Earth Sciences, Faculty of Natural Sciences, University of Silesia in Katowice, Będzińska 60, 41-200 Sosnowiec, PolandDepartment of Geology, School of Natural Sciences, Trinity College Dublin, 2 Dublin, IrelandThe Earth and Man National Museum in Sofia, 1421 Sofia, BulgariaInstitute of Earth Sciences, Faculty of Natural Sciences, University of Silesia in Katowice, Będzińska 60, 41-200 Sosnowiec, PolandInstitute of Geological Sciences PAS, 00-818 Warsaw, PolandInstitute of Geological Sciences PAS, 00-818 Warsaw, PolandHristo Smirnenski 37-41, G, 51 Topolovgrad, BulgariaInstitute of Earth Sciences, Faculty of Natural Sciences, University of Silesia in Katowice, Będzińska 60, 41-200 Sosnowiec, PolandSoutheastern Bulgaria is composed of a variety of rocks from pre-Variscan (ca. 0.3 Ga) to pre-Alpine sensu lato (ca. 0.15 Ga) time. The Sakar Unit in this region comprises a series of granitoids and gneisses formed or metamorphosed during these events. It is cut by a series of post-Variscan hydrothermal veins, yet lacks pervasive Alpine deformation. It thus represents a key unit for detecting potential tectonism associated with the enigmatic Cimmerian Orogenic episode, but limited geochronology has been undertaken on this unit. Here we report age constraints on hydrothermal activity in the Sakar Pluton. The investigated veins contain mainly albite−actinolite−chlorite−apatite−titanite−quartz−tourmaline−epidote and accessory minerals. The most common accessory minerals are rutile and molybdenite. Apatite and titanite from the same vein were dated by U−Pb LA−ICP-MS geochronology. These dates are interpreted as crystallization ages and are 149 ± 7 Ma on apatite and 114 ± 1 Ma on titanite, respectively. These crystallization ages are the first to document two stages of hydrothermal activity during the late Jurassic to early Cretaceous, using U−Pb geochronology, and its association with the Cimmerian orogenesis. The Cimmerian tectono-thermal episode is well-documented further to the east in the Eastern Strandja Massif granitoids. However, these are the first documented ages from the western parts of the Strandja Massif, in the Sakar Unit. These ages also temporally overlap with previously published Ar−Ar and K−Ar cooling ages, and firmly establish that the Cimmerian orogeny in the studied area included both tectonic and hydrothermal activity. Such hydrothermal activity likely accounted for the intense albitization found in the Sakar Unit.https://www.mdpi.com/2075-163X/10/3/266geochronologyu–pb datingcimmerianapatitetitanitesakarbulgaria |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Krzysztof Szopa Anna Sałacińska Ashley P. Gumsley David Chew Petko Petrov Aleksandra Gawȩda Anna Zagórska Ewa Deput Nikolay Gospodinov Kamila Banasik |
spellingShingle |
Krzysztof Szopa Anna Sałacińska Ashley P. Gumsley David Chew Petko Petrov Aleksandra Gawȩda Anna Zagórska Ewa Deput Nikolay Gospodinov Kamila Banasik Two-Stage Late Jurassic to Early Cretaceous Hydrothermal Activity in the Sakar Unit of Southeastern Bulgaria Minerals geochronology u–pb dating cimmerian apatite titanite sakar bulgaria |
author_facet |
Krzysztof Szopa Anna Sałacińska Ashley P. Gumsley David Chew Petko Petrov Aleksandra Gawȩda Anna Zagórska Ewa Deput Nikolay Gospodinov Kamila Banasik |
author_sort |
Krzysztof Szopa |
title |
Two-Stage Late Jurassic to Early Cretaceous Hydrothermal Activity in the Sakar Unit of Southeastern Bulgaria |
title_short |
Two-Stage Late Jurassic to Early Cretaceous Hydrothermal Activity in the Sakar Unit of Southeastern Bulgaria |
title_full |
Two-Stage Late Jurassic to Early Cretaceous Hydrothermal Activity in the Sakar Unit of Southeastern Bulgaria |
title_fullStr |
Two-Stage Late Jurassic to Early Cretaceous Hydrothermal Activity in the Sakar Unit of Southeastern Bulgaria |
title_full_unstemmed |
Two-Stage Late Jurassic to Early Cretaceous Hydrothermal Activity in the Sakar Unit of Southeastern Bulgaria |
title_sort |
two-stage late jurassic to early cretaceous hydrothermal activity in the sakar unit of southeastern bulgaria |
publisher |
MDPI AG |
series |
Minerals |
issn |
2075-163X |
publishDate |
2020-03-01 |
description |
Southeastern Bulgaria is composed of a variety of rocks from pre-Variscan (ca. 0.3 Ga) to pre-Alpine sensu lato (ca. 0.15 Ga) time. The Sakar Unit in this region comprises a series of granitoids and gneisses formed or metamorphosed during these events. It is cut by a series of post-Variscan hydrothermal veins, yet lacks pervasive Alpine deformation. It thus represents a key unit for detecting potential tectonism associated with the enigmatic Cimmerian Orogenic episode, but limited geochronology has been undertaken on this unit. Here we report age constraints on hydrothermal activity in the Sakar Pluton. The investigated veins contain mainly albite−actinolite−chlorite−apatite−titanite−quartz−tourmaline−epidote and accessory minerals. The most common accessory minerals are rutile and molybdenite. Apatite and titanite from the same vein were dated by U−Pb LA−ICP-MS geochronology. These dates are interpreted as crystallization ages and are 149 ± 7 Ma on apatite and 114 ± 1 Ma on titanite, respectively. These crystallization ages are the first to document two stages of hydrothermal activity during the late Jurassic to early Cretaceous, using U−Pb geochronology, and its association with the Cimmerian orogenesis. The Cimmerian tectono-thermal episode is well-documented further to the east in the Eastern Strandja Massif granitoids. However, these are the first documented ages from the western parts of the Strandja Massif, in the Sakar Unit. These ages also temporally overlap with previously published Ar−Ar and K−Ar cooling ages, and firmly establish that the Cimmerian orogeny in the studied area included both tectonic and hydrothermal activity. Such hydrothermal activity likely accounted for the intense albitization found in the Sakar Unit. |
topic |
geochronology u–pb dating cimmerian apatite titanite sakar bulgaria |
url |
https://www.mdpi.com/2075-163X/10/3/266 |
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