FROM MAGMATIC ARC TO POST-COLLISIONAL BACK ARC SETTING IN THE TAURIDE-ANATOLIDE PLATFORM (TAP): OVERVIEW OF THE CADOMIAN BASEMENT ROCKS IN TURKEY

A new geodynamic model is proposed to clarify the genesis of the Late Neoproterozoic - Early Cambrian meta-magmatic rocks cropped out in S Turkey. Cadomian basement rocks observed in peri-Gondwanan Turkey crop out in different Alpine tectonic terranes: Strandja, Istanbul Zonguldak Terrane (IZT), Tauride-Anatolide Platform (TAP) and South Anatolian Autochthone Belt (SAAB). Ediacaran magmatic arc and late to post-collisional igneous rocks in Turkey are mainly composed of meta-igneous rocks with a wide range of compositions. The oldest meta-magmatic rocks in the northern and western part of the country (Devrakani-Daday Massif-IZT, Bolu Massif-IZT and Menderes Massif-TAP, Derik-Mardin-SAAB) have ages of about 590-570 Ma that were predominantly obtained from the magmatic arc related granitic rocks (meta-tonalites/meta-granodiorites) and their volcanic equivalents (meta-andesitic/meta-rhyolites with rarely meta-basaltic lavas). From 560 to 545 Ma, igneous activity formed abundant I-type calc-alkaline late to post collisional granitic rocks and their felsic and mafic volcanic equivalents in the Strandja Massif, Menderes Massif-IZT, Taurides-TAP (Sandikli-İhsaniye-Afyon), SAAB-Bitlis Massif (Mutki-Genc). This was followed by 560-530 Ma continental back-arc mafic intrusions in the TAP and Menderes Massif. The Andean type arc-related igneous activity was followed by late to post-collisional magmatism during the initial stage of the extension in the marginal basin of peri-Gondwana that resulted in the lithospheric thinning associated with cataclastic deformation of the basement rocks at 545-530 Ma. As a result of early rifting between 560 and 530 Ma, lithospheric thinning in the continental crustal part of peri-Gondwana has resulted in opening a back-arc basin, where mafic magmatic products were generated along the northern edge of Gondwana just above the subducting Prototethys Ocean. The early Cambrian rifting may have resulted in separation of the arc-related intrusive and extrusive rocks from the post-collisional magmatic products of the peri-Gondwanan part of Turkey and hence the initial opening of an oceanic basin between the N and S of peri-Gondwanan part of Turkey. Similar tectonic scenarios have been suggested for other peri-Gondwanan terranes in Europe, Middle East, and eastern Asia.