The timing, composition, and petrogenesis of syn- to post-accretionary magmatism in the northern Cordilleran miogeocline, eastern Yukon and southwestern Northwest Territories ...

• Main Author: Rasmussen, Kirsten Louise
• Format: Text
• Language: English
• Published: University of British Columbia 2013
• Subjects: Yukon; Northwest Territories; Selwyn; Cassiar
• Online Access: https://dx.doi.org/10.14288/1.0071986; https://doi.library.ubc.ca/10.14288/1.0071986

Syn- to post-accretionary magmatic episodes of Cretaceous to Eocene age comprises the most voluminous magmatism in the northern Cordillera. Our understanding of the age, composition, and petrogenesis of this magmatism thus far, however, has been severely limited by a lack of robust geochronological, geochemical, and isotopic datasets for these rock units. This study fills the need for better temporal and compositional constraints on mainly Early to ‘mid’-Cretaceous (~115–90 Ma) magmatism in the Cassiar Terrane and eastern Selwyn Basin regions of the northern Cordilleran miogeocline. An extensive set of new U–Pb and ⁴⁰Ar/³⁹Ar age data, together with major and trace element geochemical analyses, radiogenic (Nd, Sr, Pb, and Hf) and stable (S and O) isotopic compositions, and detailed magmatic fluid compositional studies of intrusive rocks in the northern Cordillera are presented here. These results, and the integration of compiled datasets, have led to the identification of several new plutonic suites and ...