Date of Award
Spring 5-2014
Degree Type
Thesis
Degree Name
M.S.
Degree Program
Geology
Department
Earth and Environmental Sciences
Major Professor
Dr. William Simmons
Second Advisor
Mr. Alexander Falster
Third Advisor
Dr. Karen Webber
Abstract
The Usakos pegmatite, Namibia, is a highly evolved, rare-element LCT-type pegmatite. The pegmatite is emplaced in metasedimentary rocks of the Kuiseb formation. Ca and Al enrichment at the contact, B mineralization in the country rock and Sr mineralization in the core of the pegmatite are all evidence of interaction of the pegmatite melt and hosting country rock. K/Rb ratios within mica and feldspar are very low indicating a highly evolved melt. Tourmaline has a fractionation trend from Fe-rich at contact and intermediate areas to Fe-depleted in core regions and pockets. Columbite tantalite group minerals show a similar trend in fractionation, with columbite-(Fe) found near the pegmatite country rock contact and tantalite-(Mn) found in the core region. Trace element geochemistry from samples of pegmatite-country rock contact is enriched in light rare earth elements. Whole rock geochemistry provides evidence of the geochemically evolved nature of the pegmatite forming melt.
Recommended Citation
Grassi, Leah R., "A Geochemical Investigation of the Usakos Gem Tourmaline Pegmatite, Namibia" (2014). University of New Orleans Theses and Dissertations. 1803.
https://scholarworks.uno.edu/td/1803
Rights
The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.