ON THE DISTRIBUTION AND DISPERSION OE ' PLATINUM IN THE SOILS OF THE TULAMEEN ULTRA . MAFIC COMPLEX , SOUTHERN BRITISH COLUMBIA
INTRODUCTION Exploration for platinum in British Columbia is hampered by a lack of data on its distribution and behavior in the surficial environment. To obtain some of the information required and suggest practical guidelines for exploration, this study, involving systematic sampling and analysis of soils and other media in the vicinity of a platinum deposit in the Tulameen district of southwestern British Columbia, was initiated in 1988 (Fletcher. 19x9). Preliminary results of work in progress are described. Tulameen River, approximately 25 kilometres west of Prince-The field area, on Grasshopper Mountain north of the ton, is divided into the main study area, on the southern slope of the mountain, and a second, smaller area near the summit (Figure 6.2-I). The lower part is accessible by pack trail from the Tulameen River road. Several kilometres of recently constructed drill road on the north and west sides of g e o l o g y , Tulameen ultramafic c o m p l e x. B. C. Figure 6-2-1, Location of the study areas and generalized (1) Nicola Group (2) syenogabhrn. (3) dunite. (4) olivine clinopyroxenite,(5) homblendr~linopqmxenite. (6)rnyloni-tic rocks. (7) Eagle granodiorile (modified after Nixon and Rublee. 1988). Grasshopper Mountain connect with the Lawless 'Creek forestry road and provide access from both the village of Tulameen and the Coquihalla Highway. BEDROCK GEOLOGY dissected dunite core of the Tulameen ultramafic complex, a Grasshopper Mountain is the northern segment o' the Late Triassic zoned Alaskan-type ultramafic-gabbroic intrusion within metasedimentary and metavolcanic rocks c,f the Upper Triassic Nicola Group. Geology of the complex, described by Findlay (1969) and Nixon and Rublea (1988). comprises a dunite core surrounded by crudely concentric shells of olivine clinopyroxenite, hornblende c h o p r o x-enite and gabbroic rocks ((Figure 6-2-1). The focus of the current study is within the dunite :ore. The dunite is typically Fine grained, extensively sepen-tinized, and weathers buff-brown on exposed surfaces "lati-num mineralization is restricted to chromite-rich dunite (Nixon e t a /. is best exposed in the summit region and in the sub\ertical randomly distributed massive to discontinuous pods, segre-gations. schlieren and disseminated grains. Schlierel are randomly distributed thrcmughout the dunite and are thought to represent foliation-concordant remnants of former cumu-late layers (Nixon and Rublee, 1988:1. Several cons of central region of the cor'? (Bohme, 19x7). but till-covered mineralization have beer1 defined within the well-exposed areas are largely untested. platinum-iron alloys and platinum antimonides …
Origin of the Tulameen ultramafic-gabbro complex, southern British Columbia
The Tulameen Complex is a composite ultramafic-gabbroic intrusion that outcrops over 22 sq. mi. (57 km2) in the Southern Cordillera of British Columbia. The complex intruded Upper Triassic metavolcanic and metasedimentary rocks of the Nicola Group, and on the basis of geologic relations and a K–Ar age determination (186 m.y.) is tentatively dated as Late Triassic.The principal ultramafic units — dunite, olivine clinopyroxenite, and hornblende clinopyroxenite — form an elongate, non-stratiform body whose irregular internal structure is best explained by deformation contemporaneous with crystallization of the rocks. The derivation of the ultramafic rocks is attributed to fractional crystallization of an ultrabasic magma. The gabbroic mass, which consists of syenogabbro and syenodiorite, partly borders and partly overlies the ultramafic body and was apparently intruded by it.The ultramafic and gabbroic parts of the complex probably formed from separate intrusions of different magmas, but the two suites have ...
Geology and genesis of ultrabasic nickel-copper-pyrrhotite deposits at the Pacific Nickel property, southwestern British Columbia
This paper deals with geology and genesis of some pipelike nickel-copper-pyrrhotite deposits on the property of Pacific Nickel Mines in southwestern British Columbia. These deposits occur almost exclusively within a stocklike ultrabasic mass one and a half miles across. The ultra-basic body consists essentially of pyroxenite with cores of peridotite, with hornblendic replacement phases, and with a remarkable reaction margin of pegmatitic hornblendite. The mineralization consists of disseminated and massive pyrrhotite with subordinate pentlandite and chalcopyrite among fresh olivine, bronzite, augite, and hornblende. The ultrabasics intermingle with, and partly cut, a larger batholithic mass of genetically related diorites of Late Mesozoic age. Both rocks and ore are cut by small ultrabasic and gabbroic dikes, and by veins and alteration zones. Some of the ore occurs as sulfidic olivine-rich cores or shells with bronzitic borders, forming remarkably zoned, steeply plunging pipe- or parsnip-shaped magnesian ultrabasic structures 100 feet or more in diameter. These features suggest replacement origin. The remainder of the ore forms massive sulfide-silicate bodies similar in size, attitude, and mineralogy to the zoned ones but more irregular in cross section and showing flow lines, banding, drag folds, sharp contacts, inclusions, and hornblendic reaction rims--all suggestive of injection origin.Genetic characteristics of other similar nickel deposits and rocks of the world are summarized and compared, then two theories are presented for genesis of the ore at Pacific Nickel. Magmatic segregation is suggested with injection of sulfides in an incipiently molten state (perhaps 700-800 degrees C) followed by minor replacement and reconstitution. Alternatively, a new twist is added to the hydrothermal replacement theory by suggesting that ascending water vapor above 650 degrees C could deposit the sulfides and, by removal or addition of silica, convert bronzite to olivine or vice versa to produce the zoned structures and other features.