Date of Award
Master of Science (MS)
The Goldlund Mine is located in the Wabigoon Sub province of the Canadian Shield. Although the mine has been open sporadically since the late 1930's, little is known about the geochemistry and petrography of the deposit. The purpose of this study was to use petro graphic, geochemical, and physical data to document and better understand the host rock, alteration, and mineral ization of the deposit, and to develop a generalized model of formation.
Results showed that the host rocks of the gold mineral ization are albitized tonalite dikes. Gold, in native form and in gold-silver tellurides, occurs in quartz veins and in adjacent zones of metasomatic alteration within the tonalite.
Two texturally different phases of albitized tonalite exist. A light, fine- to medium-grained phase, which contains the majority of gold mineralization, is surrounded by a dark, fine-grained border phase.
Distinct alteration zones are present around quartz veins which fill tension fractures in the tonalite dikes. In addition to zones of visible alteration near the veins, cryptic zones farther from the veins were recog nized. Five alteration types recognized include: carbon atization, albitization, pyritization, desilicification, and dehydration. Geochemical data shows that carbon dioxide, sodium, calcium, and manganese were added to the tonalite from the veins, while iron, water, magnesium, and potassium were added to the veins from the tonalite. Corresponding mineralogical data suggests the breakdown of chlorite, biotite, and albite/quartz intergrowths, with formation of secondary carbonate, albite, pyrite, and vein quartz.
A three-stage paragenetic sequence was recognized: an early, high temperature stage, a middle, dominantly sulfide stage, and a late, low temperature gold and telluride stage. Native gold, petzite, calavarite, and altaite were deposited in the late, low temperature stage.
AFM, Q-Ab-Or, K-Na-Ca, Rb-Sr, Ti-Zr, Nb-Zr, and Y-Zr diagrams permit development of petrogenetic models for the intrusive rock types. The albitized tonalite dikes appear to have formed from a different magma source than the granite of the Crossecho Stock, the quartz monzonite stock, and the quartz-feldspar porphyries. The albitized tonalite dikes were probably derived by partial melting of amphibo lite and are syn-volcanic in age. The quartz-feldspar porphyries and quartz monzonite stock appear to be differentiated fractions of the magma of the Crossecho Stock and were intruded into the supracrustal assemblage during active plutonism of the Kenoran Orogeny.
The Crossecho Stock and other late intrusives appear to have acted as concentrating agents, supplying heat and volatiles which mobilized gold from the surrounding volcanic rocks with subsequent deposition in tension fractures of the albitized tonalite dikes.
Giddings, Steven D., "Petrology, mineralogy, and geochemistry of the Goldlund Gold Deposit, Northwestern Ontario" (1986). Theses and Dissertations. 107.