Chafe, Alexander N. (2015) Direct dating and characterization of the Pope's Hill REE occurrence. Masters thesis, Memorial University of Newfoundland.
- Accepted Version
Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
The Pope’s Hill (PH) rare earth element (REE) occurrence, located in central Labrador, is a syenite-hosted, highly enriched unit with whole-rock geochemical analyses indicating REE contents ranging from <1 to 22 weight percent. Samples of ore, altered host rock, and unaltered country rock, were collected throughout the occurrence in order to: 1) determine which phases concentrate the REE and also quantify their abundances and distribution in the ore; 2) determine the host rock emplacement age; 3) determine the timing of the subsequent hydrothermal alteration and REE mineralization; and 4) constrain the source of the REE using in situ LA-ICPMS and ID-TIMS U-Pb geochronology and in situ Sm-Nd isotopes using LA-MC-ICPMS in monazite. The REE-enrichment occurs in millimeter- to decimeter-scale pods that are locally discontinuous and consist of primary and secondary REE minerals including a variety of silicate, phosphate, carbonate, and niobate phases; the most abundant being allanite-(Ce), monazite-(Ce), britholite-(Ce), and an unnamed LREE-enriched mineral similar in composition to titanite. ID-TIMS geochronology reveals monazite dates from ~1090 to 940 Ma that coincide with Grenvillian metamorphism and plutonism during continent-continent collision suggesting that locally derived REE in the PH syenite crystalized into primary REE-silicates either before or during Grenvillian events. Microtextures in thin section indicate that secondary non-silicate REE minerals were produced by the breakdown of primary REE-silicates, suggesting either hydrothermal fluid alteration, or metamorphism.
|Item Type:||Thesis (Masters)|
|Additional Information:||Includes bibliographical references (pages 106-111).|
|Keywords:||Rare earth elements, SEM-MLA, Labrador, Titanite|
|Department(s):||Science, Faculty of > Earth Sciences|
|Geographic Location:||Newfoundland and Labrador--Labrador|
|Library of Congress Subject Heading:||Rare earth metals--Newfoundland and Labrador--Labrador; Geochronometry--Newfoundland and Labrador--Labrador; Metamorphism (Geology)--Newfoundland and Labrador--Labrador; Mineralogy, Determinative--Newfoundland and Labrador--Labrador|
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