PLAGIOGRANITES FROM THE OPHIOLITE COMPLEXES OF DINARIDES AND VARDAR ZONE

• Main Authors: Vladimir Majer, Vesnica Garašić
• Format: Article
• Language: English
• Published: Faculty of Mining, Geology and Petroleum Engineering 2001-12-01
• Series: Rudarsko-geološko-naftni Zbornik
• Subjects: Plagiogranite; Ophiolite; CDOB; VZOB; Supra-subduction ocean ridge granite; Volcanic arc granite; Crystal-liquid differentiation process
• Online Access: http://hrcak.srce.hr/index.php?show=clanak&id_clanak_jezik=20561&lang=en

Geochemical dana of plagiogranites associated with ophiolite conplexes of Central Dinaride Ophiolite Belt (CDOB) and Vardar Zone Ophiolite Belt (VZOB) are presented. Plagiogranites occur as dikes or small intrusive bodies in the upper part of the gabbrodolerite or diabase section in the ophiolite sequence. On the basis of normative An-Ab-Or diagram most of studied plagiogranites are classified as trondhjemites. They are typically low in K2O, Rb and MgO and contain low to moderate Al2O3, but light SiO2 and Na2O. Their ocean ridge granite normalized patterns of trace elements displaying low contents of HFS and high contents of LIL elements are very similar to those of the volcanic arc granites. But assuming that in trace element pattern elevated K2O and Rb contents are result of alteration, the studied plagiogranites have also strong similarity with typical Troodos supra-subduction ocean ridge granite. The using of Peacock indeks reveals that they are characterized by calcic character what is typical for supra-subduction ocean ridge granite. The studied plagiogranites are probably formed in extensional conditions above a subduction zone and in terms of their origin the most probably related to crystal-liquid differentiation process.