M.Sc. Tezi Görüntüleme | |||||||||||||||||||||
|
|
||||||||||||||||||||
| Summary: Petrologic Features and Geotectonic Significance of Gabbroic Rocks in Bayburt Petekli-Yakupabdal Area (NE Turkey) Aim of this study is to explain petrology and geotectonic setting of gabbroic rocks of investigaton area which is located in southern zone of Eastern Pontides. Gabbroic rocks that compose subject of the study occur as ellipsoidal intrussive bodies and they are found in two different time stages as Atik Tepe Metagabbro and Beşkardeşler Gabbro. The metagabbros, the first of these intusions contain mainly plagioclase and amphibole, olivine, aktinolite-talc and clorite crystals while more fresh and second of these intrussive bodies, gabbros are formed basically plagioclase and olivine, amphibole and clorite minerals. Distrubution of these gabbroic and other magmatic exposures which are consentient with the main fault system of the investigation area is the proof of the transportation of magmatism products by the faults. After reclamation of these field and petrography observations, major, trace and rare earth element content of the gabbroic rocks are determined and interpereted. As regards to first valuation, these rocks fall with the gabbro area in total alcali versus silica triangular diagram. The main characteristic magma serie of gabbroic rocks is calc-alcaline. In primitive mantle normalized spiderdiagram they show enriched LILE and nearly normal and slightly depleted HFSE pattern, negative Ti, Nb, anomalies. In MORB normalized spiderdiagram these gabbroic rocks display enriched LILE and depleted HFSE trend while enriched LREE and less enriched and slightly depleted HREE pattern in chondrite normalized rare earth element spiderdiagram. With their major, trace and rare earth element contents of these gabbroic intrussive bodies reflect to a subduction zone geotectonic setting. In respect of these characteristics they must be derivative of a basic magma related with subduction zone fluids. These gabbroic rocks, together with metomorphic base rock that including these intrussive bodies, compose lower part of magmatic arc litosphere.
Key Words: Gabbro, metagabbro, gabbroic rocks, subduction zone, subduction zone magmatism, Eastern Pontides. | |||||||||||||||||||||