Collisional tectonic setting

The rocks of the TCZ are interpreted to have erupted in a transtensional continental rifting environment in the Late Siiurian to Middle Devonian. In this tectonic environment A-type granites are expected, and indeed the reiativeiy high Zr, Nb, and Y content in these rocks support this. However, many other geochemicai aspects of these rocks, i.e., high Ba, Rb, Th and K, are more typical of the I-type magmas that commonly occur in collisional settings. 

Over the last decade considerable effort of the tectonics community has been directed towards the development of thermomechanical models that describe the collisional history and the internal dynamics of orogenic belts and continental plateaus (e.g., Beaumont et al. 2001, 2004 Koons et al. 2002). These models are commonly tested against thermobarometric, thermochronologic, and geochronologic data. However, by definition, these data sets only provide constraints on rates of rock uplift or exhumation the surface response to tectonic... 

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