The timing, composition, and petrogenesis of syn- to post-accretionary magmatism in the northern Cordilleran miogeocline, eastern Yukon and southwestern Northwest Territories
department or school: Science, Faculty of
department or school: Earth, Ocean and Atmospheric Sciences, Department of
data provider: DSpace
degree campus: UBCV
creator: Rasmussen, Kirsten Louise
issued: 2013-04-30T14:36:49Z
issued: 2013
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: 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 sub-suites, as well as modifications of previously defined plutonic suites. Inferences regarding the age and composition of the basement to the northern Cordilleran miogeocline have also been made based on mineralogical, geochemical, and isotopic interpretations of magma sources for crustally derived plutonic suites from across this region. These extensive datasets have also allowed a re-evaluation of previously proposed models for syn- to post-accretionary magmatic episodes, and have resulted in the proposal of modified tectono–magmatic models for the particularly voluminous Early to ‘mid’-Cretaceous magmatic episode. Finally, estimates of magmatic fluid compositions determined from apatite and biotite compositions (with respect to HF, HCl, and H₂O) and extended cooling histories indicated by U–Pb and ⁴⁰Ar/³⁹Ar geochronology, have been used to identify intrusive phases (locally and regionally) that are associated with reduced tungsten skarn mineralization, which comp…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/44391
note: THE TIMING, COMPOSITION, AND PETROGENESIS OF SYN- TO POST- ACCRETIONARY MAGMATISM IN THE NORTHERN CORDILLERAN MIOGEOCLINE, EASTERN YUKON AND SOUTHWESTERN NORTHWEST TERRITORIES by Kirsten Louise Rasmussen B.Sc., The University of Calgary, 2004 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Geological Sciences) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2013 © Kirsten Louise Rasmussen, 2013 ii ABSTRACT 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 sub-suites, as well as modifications of previously defined plutonic suites. Inferences regarding the age and composition of the basement to the northern Cordilleran miogeocline have also been made based on mineralogical, geochemical, and isotopic interpretations of magma sources for crustally derived plutonic suites from across this region. These extensive datasets have also allowed a re-evaluation of previously proposed models for syn- to post-accretionary magmatic episode…
has type: Thesis/Dissertation
date issued: 2013-05
is shown at: 10.14288/1.0071986
language: eng
degree discipline: Geological Sciences
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivs 3.0 Unported
rights URI: http://creativecommons.org/licenses/by-nc-nd/3.0/
scholar level: Graduate
type: Text
type: Dataset
identifier URI: http://hdl.handle.net/2429/44391