Original paper

Structural criteria defining the Granite Mountain area in NW-Nevada as a target for mineral exploration

Kutina, Jan; Bowes, William A.

Global Tectonics and Metallogeny Volume 1 Number 4 (1982), p. 336 - 355

11 references

published: Dec 1, 1982

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ArtNo. ESP136000104005, Price: 19.00 €

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Abstract

Several of the most important ore deposits of the Western United States occur near the corners of four major lithospheric blocks of a size 530 x 600 km defined by intersections of deep-seated fracture zones trending E-W and N-S. Three of these intersections occur above a major structural boundary extending east-westerly through the upper mantle (shown in the contours of Pn velocities). Clusters of major ore deposits are known in two of these three intersections, one being located in Utah (containing the mining districts of Bingham, Tintic, Park City) and the other in Colorado (containing Climax, Urad-Henderson, Jamestown and others); the third intersection, also occurring above the same upper mantle boundary, is in NW-Nevada and has been defined as a target area potential for the discovery of major concentrations of metals. The 'Nevada intersection' is centered at about 40°020'N and 118°05'W, and includes major fracture zones trending E-W, N-S, NW-SE and NE-SW. They intersect not far from the western edge of the Cordilleran eugeosyncline. The igneous complex of Granite Mountain, consisting of multiple intrusive phases, originated near the center of the 'Nevada intersection'. An expressive east-west boundary appears both in the geology of Granite Mountain and its satellite image. An intrusive stock of monzogranite to granodiorite composition, mapped by Aaker and Rogowski (1 978) and Thurber (1982) in northern part of Granite Mountain, is also expressively elongated east,westerly, correlating with the course of a deep-seated, east-west trending fracture zone postulated by Kutina (1 969, 1980). Geochemical exploration by W. A. Bowes and co-workers has revealed a mineralized area about 4 km long, occurring in and around the stock, with copper and molybdenum fol lowed outward by a zone with lead, zinc, si lver and gold. Drilling performed along the southern edge of the stock penetrated Mo-Cu mineralization, described in a separate paper (Bowes, et al., this volume). A broad zone of an extensive potassium metasomatism, superimposed on a complex of dioritic and gabbroic rocks, extends for at least 2 km along the southern boundary of the stock and may indicate a more extensive mineralization.

Résumé

Plusieurs des plus importants gisements metalliferes de l 'Ouest des Etats Unis se trouvent a proximite des coins de quatre blocs lithospheriques majeurs de 530 x 600 km, definis par les intersections de fractures profondes orientees E-W et N-S. Trois de ces intersections se situent au dessus d'une discontinu ite majeure s'etendant d'Est en Ouest a travers Ie manteau superieur (exprime dans les contours des ondes Pn). Des groupements de depOts miniers majeurs sont connus dans deux de ces trois intersections. Une est localisee en Utah (contenant les district miniers de Bingham, Tintic, Park City) et I'autre dans Ie Colorado (contenant Climax, Urad-Henderson, Jamestown et d'autres...). La troisieme intersection, situee elle aussi au-dessus de la même discontinuite dans le manteau superieur, se trouve dans le NW-Nevada et a ete definie comme cible potentiel le pour la decouverte de concentrations majeures en metaux. eel'intersection du Nevada» est centree environ a 40° 20'N et 118°05'W, et comprend des zones de fractures majeures de directions E-W, NW-SE et NE-SW. Elles s'intersectent non loin de la bordure ouest du eugeosynclinal Cordilieran. Le complex igne de Granite Mountain, constitue par des phases intrusives multiples, a trouve origine pres du centre de intersection du Nevada. Un contact proeminent Est-Ouest apparait a la fois dans la geologie de Granite Mountain et sur l'image satellite correspondante. Un eestock» intrusif de composition monzogranite a granodiorite, cartographie par Aaker et Rogowski (1978) et par Thurber (1982) dans la partie nord de Granite Mountain, montre un allongement est-ouest prononce, et correspond au trace de la zone de fractures profondes Est-Ouest postulee par Kutina (1969, 1980). l'exploration geochimique par WA Bowes et ses collegues, a revele une zone mineralisee d'environ 4 km de long 336 (c) sondage realise le long de la bordure sud du «stock» a penetre la mineralisation Mo-Cu, et est decrit separement (Bowes et aI., meme volume). Une large zone de metasomatisme du potassium, affectant un complexe de roches dioritiques et gabbroiques, s'etend sur au moins 2 km le long de la bordure sud du «stock», et peut indiquer une mineralisation plus importante a plus grande profondeur.

Keywords

structuregranite mountainnevadamineral explorationusa