Protracted Magmatism and Mineralized Hydrothermal Activity at the Gibraltar Porphyry Copper-Molybdenum Deposit, British Columbia

2020 ◽  
Vol 115 (5) ◽  
pp. 1119-1136 ◽  
Author(s):  
Christopher Kobylinski ◽  
Keiko Hattori ◽  
Scott Smith ◽  
Alain Plouffe
Keyword(s):  
Mineral Exploration ◽  
Porphyry Copper ◽  
Hydrothermal Activity ◽  
White Mica ◽  
Late Triassic ◽  
American Continent ◽  
North American Continent ◽  
Porphyry Cu ◽  
The North ◽  
Molybdenum Deposit

Abstract The Gibraltar Cu-Mo deposit, with a total tonnage of 3.2 million tons (Mt) Cu, is located in the Canadian Cordillera and hosted by the Late Triassic Granite Mountain batholith. The batholith formed through multiple intrusions of tonalitic rocks over a period of ~25 m.y. beginning at 229.2 ± 4.4 Ma in the Quesnel island arc before the accretion of the arc to the North American continent. Late in its evolution, Cu fertile magmas intruded in the center of the batholith, during at least three events from 218.9 ± 3.1 to 205.8 ± 2.1 Ma. The fertile magmas were hotter and more mafic than older barren magmas. They generated magmatic-hydrothermal activity, forming potassic alteration and white mica alteration, and produced Cu mineralization as chalcopyrite-quartz veinlets and disseminated chalcopyrite. Zircon in the Cu-bearing tonalite intrusion (218.9 ± 3.1 Ma) shows high Ce4+/Ce3+ (681 ± 286 [2σ], n =15) compared to those from older barren intrusions (129 ± 56 [2σ], n = 118). Oxidation conditions for parental magmas are calculated using the compositions of zircon and amphibole. The magmas for Cu-bearing intrusions have an average of fayalite-magnetite-quartz buffer (FMQ) +1.7 ± 0.7 (2σ, n = 73), whereas those for older barren intrusions have slightly lower fO2 (avg FMQ +1.3 ± 0.5 [2σ], n = 108), although the values are overlapping for the two. The bulk rocks of Cu-bearing tonalite intrusions in the Granite Mountain batholith have low Sr/Y ratios (<22) independent of the degrees of alteration. The low ratios are also reflected by low Sr/Y in zircon, suggesting that the low Sr/Y ratios of bulk rocks represent those of unaltered rocks. The values are low compared to those associated with many other porphyry Cu deposits globally. The data suggest that igneous rocks elsewhere with low Sr/Y in bulk rocks may have a potential to host economic Cu deposits. Ratios of Ce/Nd and Ce/Ce* (=Ce/((NdN)2SmN)) in zircon are positively correlated with the Ce4+/Ce3+ in zircon from the Granite Mountain batholith. Since the former two ratios can be obtained solely from zircon composition, these ratios from detrital zircon may be useful in evaluating the occurrences of oxidized intrusions in regional mineral exploration.

scholarly journals Q fever in South Australia: an outbreak in a meat-works

1962 ◽  
Vol 60 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Margaret D. Beech ◽  
A. E. Duxbury ◽  
Peter Warner
Keyword(s):  
Q Fever ◽  
South Australia ◽  
Meteorological Conditions ◽  
American Continent ◽  
North American Continent ◽  
The Past ◽  
The North ◽  
Epidemiological Features ◽  
Very High ◽  
Abattoir Workers

This paper consists of an epidemiological study of 52 cases of Q fever occurring in metropolitan Adelaide in 1957 and also a description of the results of a survey of 516 sera obtained from abattoir workers.The only case occurring outside the abattoirs was a dairy farmer who probably became infected while visiting the abattoirs. If this were so the incubation period (35 days) of his disease would have been exceptionally long.The general features of the outbreak, which lasted several months, differed from those on the North American continent in that the latter occurred explosively within a few days with very high attack rates. The situation in the Adelaide abattoirs is similar to that in Brisbane, where the disease appears to be endemic. However, unlike in Adelaide, cases are commonly recognized outside the abattoirs in Brisbane.In the abattoirs the disease affected mainly inspectors, those working on killing beef, and those working on offal. Mutton workers were not so severely affected. However, all these groups had similar incidences of low titre antibodies suggesting that in the past Q fever spread equally in all killing departments. In departments not directly associated with slaughtering the incidence both of cases in 1957 and low titre antibodies was relatively small.It was suggested that the epidemiological features of Q fever in Adelaide could be explained by the irregular appearance of animals from infected herds situated perhaps in Queensland—a known endemic area. Perhaps the appearance of such animals in the Adelaide abattoirs might be governed by meteorological conditions such that they were prevented from going to the ordinarily most convenient slaughterhouse.

Francisco de Miranda in Russia

1950 ◽  
Vol 6 (04) ◽  
pp. 431-449 ◽  
Author(s):  
Joseph O. Baylen ◽  
Dorothy Woodward
Keyword(s):  
North American ◽  
American Continent ◽  
Grand Tour ◽  
North American Continent ◽  
The North ◽  
Austrian Minister

On September 26, 1786, Don Francisco de Miranda, adventurer and patriot, secured a passport from the Austrian Minister in Constantinople which enabled him to continue his “grand tour” to Russia. The nature of Miranda’s subsequent visit, and the extent to which his reception at the court of Catherine II influenced Spanish and Russian policy, assumes significance in the light of events on the North American continent immediately preceding and during his stay in Russia.

scholarly journals Identification of a Marine Green Alga Percursaria percursa from Hypersaline Springs in the Middle of the North American Continent

2005 ◽  
Vol 119 (1) ◽  
pp. 82 ◽  
Author(s):  
Kathleen L. Londry ◽  
Pascal H. Badiou ◽  
Stephen E. Grasby
Keyword(s):  
Green Alga ◽  
Microbial Mat ◽  
American Continent ◽  
North American Continent ◽  
The North ◽  
Western Shore ◽  
Dominant Member ◽  
Hypersaline Springs ◽  
First Time ◽  
North Western

The chlorophycean alga Percursaria percursa (Ulvaceae, Ulvales, Chlorophyceae), typical of marine inter-tidal zones, is reported for the first time from hypersaline springs located along the north-western shore of Lake Winnipegosis in Manitoba. Although not usually found inland, P. percursa is the dominant member of microbial mat communities that thrive in shallow pools at the outlets of hypersaline springs.

The Life History and Dispersal of the Bruce Spanworm, Operophtera bruceata (Hulst), (Lepidoptera: Geometridae)

1962 ◽  
Vol 94 (10) ◽  
pp. 1103-1107 ◽  
Author(s):  
C. E. Brown
Keyword(s):  
United States ◽  
Life History ◽  
The United States ◽  
American Continent ◽  
Forest Insect ◽  
North American Continent ◽  
The Third ◽  
The North ◽  
Insect Survey ◽  
Bruce Spanworm

The Bruce spanworrn, Operophtera bruceata (Hulst), is most common in the mid latitudes of the North American Continent; in Canada it occurs from Newfoundland to the interior of British Columbia (Prentice, In Press) and has been reported from Vermont and Wisconsin in the United States (Craighead, 1950.) Three outbreaks of this insect have been recorded in Alberta. The first occurred in 1903 (de Gryse, 1925) and was apparently of short duration. The second reported by Wolley Dod (1913) occurred in 1913 and denuded hundreds of acres of aspen poplar. Heavy defoliation in the third outbreak became evident in 1957 (Brown, 1957) but an examination of Forest Insect Survey records revealed that population buildup began about 1951. The outbreak continued to expand until 1958 and began to decline in 1959; by 1961 populations were again low except for one or two isolated areas where moderate to low populations persisted. At the peak of the outbreak in 1958 approximately 50,000 square miies were moderately or heavily infested and many more lightly infested.

The genus Crepidotus in Hawaii

1973 ◽  
Vol 51 (6) ◽  
pp. 1251-1254 ◽  
Author(s):  
Robert Ueki ◽  
Clifford W. Smith
Keyword(s):  
New Species ◽  
North American ◽  
American Continent ◽  
North American Continent ◽  
The North ◽  
One New Species

Ten species of the genus Crepidotus are described from Hawaii. They are Crepidotus alabamensis, C. amygdalosporus, C. appalachianensis, C. applanatus var. globigera, C. avellaneus, C. citrinus, C. mollis, C. nephrodes, and C. rhizomorphus. One new species, C. bakerae, is proposed. Keys and distinctive characters of each species are provided. It is suggested that most of the species came from the North American continent.

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