In the Central Anatolian Crystalline Complex (CACC) the Late Cretaceous post-collisional granitic magmatism is followed by Eocene extension, resulting in formation of roughly E-W trending transtensional basins. Formation of these basins was accompanied by calc- alkaline- mildly alkaline volcanism. The volcanic rocks, mainly subaques lava flows and subareal domes are concentrated along these basins and associated with Middle Eocene (Bartonian) Mucur Formation. They are basic to intermediate and are classified as basalt, basaltic andesite and rarely alkali basalt and trachy-andesite. All studied samples are strongly and variably LREE enriched relative to chondrite with the (La/Sm)N ratio of 2.26- to 6.17. They have negative Nb-Ta and Ti anomalies in the primitive mantle normalized diagram, and are characterized by low Nb/La (0.21 to 0.62), Ce/Pb (3.70-34.90) and Nb/U ratios (1.11-30), which may indicate an interaction with the Late Cretaceous granitic host rocks in the course of their ascent.
The volcanic rocks display similar but variable ranges of Sr, Nd and Pb isotope values. Relatively high values of &epsilon / Nd (0.53 to 4.33) indicate an isotopically depleted mantle source. Combined trace element and isotope compositions of the Eocene samples suggest that they were derived from a heterogeneous lithospheric mantle source that had been metasomatized by subduction related agents such as fluids and/or melts during a previous geodynamic event.
Geochemistry and geotectonic setting point out that lithospheric delamination was the most likely mechanism to generate these calc-alkaline to mildly alkaline volcanic rocks in the CACC.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12613067/index.pdf |
| Date | 01 February 2011 |
| Creators | Geneli, Fatma |
| Contributors | Goncuoglu, M. Cemal |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
Page generated in 0.002 seconds