Turkish Journal of Earth Sciences

The Geochronological and Structurel Relationships Between metamorphic Sole and Surrounding Units of Taurus -Umman Ophiolitic Belt






The metamorphic rocks of the taurus-Umman ophiolitic belt occur as discontinuous tectonic slices at the base of the ophiolites, generally between the tectonites and volcanic and sedimentary unit and locally in the fault zones in the peridotites. They are represented essentially by amphibolites and in less quantity by mica shists, quartzites, epidotites and marbles. The geochronological data from the taurus and Oman ophiolites prove that the age of the metamorphism is generally around83-102 M. Y. By comparison with the Maastrichtian, general primary emplacement age on the continent, it is clear that the metamorphizm takes place in the oceanic environment, much before the obduction. ıt is surprising as a result of radiometric datings that cumulates are generally younger than the metamorphic rocks in the same ophioliyic massive. It is difficult the interpret. however, it can be concluded at least that the metamorphism occurs near the oceanic ridge during the young lithospheric period. Therefore it can be said that the metamophic rocks are formed probably from the volcanic and sedimentary rocks near the oceanic ridge but not from footwaal volcanic and sedimentary unit of which lowers parts give Upper Triassic age must be found far from the ridge. the lithological and structural characteristics of metamorphic rocks and their structural relations with the tectonites show that the metamorphism takes from by the dynamothermal effect of the hot base of the overthrusted lithosphere on the basic volcanic and pelagic sedimentary rocks. In the Pozantı-Karsantı ophiolites the fossil thrusting plane is reconstructed at N6E/38NE. The high angle ıt makeswith the fossil oceanic ridge plane (N70E) seems that the thrusting is developped from an oceanic fructure zone. In thsi configuration the younger age of the cumulates becomes explicable by the differences of evolutions of two litospheric block. Probably the cumulates continue to take form in the upper block and come on the same level with the older metamorphic rocks generated in the fructure zone.

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