In situ LA‑ICP‑MS U-Pb titanite dating of Na-Ca metasomatism in orogenic belts: the North Pyrenean example

Abstract : In the Pyrenees, in association with the rotation of the Iberian plate around Europe during the Mid- Cretaceous, a Na-Ca metasomatism is recognized as a complementary record of the hydrothermal activity that led to Na-metasomatism (albitization) and talc-chlorite mineralization. It affected metasedimentary rocks as well as Hercynian granites. In situ laser ablation ICP-MS U-Pb analyses of titanite grains formed in albitites during metasomatism date the Na-Ca metasomatism between 110 and 92 Ma. The temperature of the Na-Ca metasomatism is estimated to be approximately 550 °C. Both the time constraints and temperature estimates suggest that the Na-Ca metasomatism is related to the low-P high-T North Pyrenean metamorphism.