Oblique Collision and the Evolution of Large-Scale Trans- current Shear Zones in the Neoproterozoic Kaoko Belt (NW

sliced into blocks, which were incorporated into the Alpine (nappe and/or terrane) complexes and subsequently uplifted to a different degree during the Alpine collisional tectonic events. This polyorogenic history makes the reconstruction of the Hercynian structures rather difficult, but provides excellent expo sure of various levels of the Hercynian crust. The Hercynian granitic rocks occur in all three superunits of the CWC (the Tatricum, Veporicum and Gemericum) in various positions. In response to different geotectonic settings, different genetic types of granites were formed in the Western Carpathians over the time interval of 100 million years (360–250 Ma). Lower Carboniferous crustal thickening, Upper Carboniferous delamination, and Permian transtension resulted in S-, I- and A-type granite-forming events, respectively (Petrik and Kohut, 1997). A reconnaissance ammonium study was carried out on 40 selected representative Hercynian granitic rocks from the Western Carpathians. Ammonium was separated by distillation, using the classical method of Urano (1971), and its contents were determined at Philips TU 8670 VIS/NIR spectrophotometer. Although ammonium content of the Western Carpathians granites is rather variable, our research confirmed the commonly accepted opinion that the content of ammonium increases from more basic to more felsic granitic rocks, with the following mean values: diorites 17.8 ± 3.8 ppm, I-type granites 25.4 ± 8.7 ppm, S-type granites 36.0 ± 17.6 ppm. Not surprisingly, muscovite-bearing leucogranites within the Western Carpathians S-type granites have the highest values of ammonium (47.2 ± 18.4 ppm). However, most of the NH4 + data overlap and a general dividing line between I- and S-type granitic rocks cannot be drawn. Noteworthy are the local differences within independent Core Mountains, e.g., ammonium content in granites of the Velka Fatra Mts. is generally low (11–36 ppm, aver. 19.5 ppm) but rather high in the Male Karpaty Mts. (40–57 ppm, aver. 47.7 ppm). Interestingly, no principal differences were found between I/S type rocks albeit all ammonium values within each pluton are either low or high. Hall (1999) suggested that there is no significant correlation between NH 4