A Late Jurassic–Early Cretaceous metamorphic core complex, Strandja Massif, NW Turkey

Abstract

In the eastern part of the Strandja Massif constituting the east end of the Rhodope Massif, the amphibolite facies basement rocks intruded by Permian metagranites are juxtaposed against the greenschist facies cover metasediments of Triassic-Middle Jurassic protolith age. The distinct metamorphic break between the basement and cover rocks requires a missing metamorphic section. The boundary between the two groups of rocks is a ductile to brittle extensional shear zone with kinematic indicators exhibiting a top to the E/NE shear sense. Footwall rocks are cut by weakly metamorphosed and foliated granite bodies which are clearly distinguished from the Permian metagranites by their degree of deformation, cross-cutting relations and syn-tectonic/kinematic character. Also, hangingwall rocks were intruded by unmetamorphosed and weakly foliated leucogranites. 40 Ar/ 39 Ar data indicate that the ductile deformation from 156.5 to 143.2 Ma (Middle Oxfordian-Earliest Berriasian) developed during the syntectonic plutonism in the footwall. Deformation, and gradual/slower cooling-exhumation survived until to 123 Ma (Barremian). The mylonitic and brittle deformation in the detachment zone developed during OxfordianEarliest Berriasian time (155.7-142.6 Ma) and Early Valanginian-Aptian time (136-118.7 Ma), respectively. Our new field mapping and first 40 Ar/ 39 Ar ages demonstrate the existence of an extensional core complex of Late Jurassic-Early Cretaceous age not previously described in the Rhodope/Strandja massifs.

Biostratigraphy and tectonic significance of lowermost Cretaceous carbonate rocks of the Circum-Rhodope Belt (Chalkidhiki Peninsula and Thrace region, NE Greece)

“…Because this platform seals the accretion and obduction history and related tectono-metamorphic history of the eastern Vardar Zone and Circum-Rhodope Belt ophiolites, it provides stratigraphic constraint for the latest Jurassic-earliest Cretaceous Balkan orogenic event in both tectonic units. This constraint has strong implication for the regional consistency of the Balkan tectonic event also recorded between 162 and 134 Ma in the adjacent Strandzha Zone (Okay et al, 2001;Elmas et al, 2011;Sunal et al, 2011;see Fig. 1), as well as for Kraishte zone which overlies the Serbo-Macedonian Massif northerly, where the same event was recorded between 146 and 130 Ma (Kounov et al, 2010).…”

The phanerozoic palaeotectonics of Turkey. Part I: an inventory

“…Natal'in et al (2016) interpreted this boundary as a thrust, but we regard it as a low-angle normal fault, because it in places elides in the entire Triassic section. This normal fault may have been coeval with those that opened the Luda Kamčija Trough just to the north during the Pliensbachian-Toarcian interval in which deposition commenced with the Sinivir Formation (Tchoumatchenco et al 1992), although Elmas et al (2011) reported a considerable late Jurassic-early Cretaceous ( 40 Ar/ 39 Ar ages between 156 to 143 Ma) extension leading to the formation of an extensional metamorphic core complex in the northeastern Strandja. These two extensional events may be one protracted episode or two successive episodes of extension.…”

Two-Stage Late Jurassic to Early Cretaceous Hydrothermal Activity in the Sakar Unit of Southeastern Bulgaria

“…111 Ma [21,22,[24][25][26][27]. Similar late-Jurassic to early Cretaceous ages are also documented from the eastern part of the Strandja Zone, where a two-stage process of ductile and brittle deformation is documented by Elmas et al, [57], between ca. 156 and ca.…”