scholarly journals Stratigraphic and structural setting of mineral deposits in the Brucejack Lake area, northwestern British Columbia

1994 ◽  
Author(s):  
A G S Davies ◽  
P D Lewis ◽  
A J Macdonald
Keyword(s):  
British Columbia ◽  
Mineral Deposits ◽  
Lake Area ◽  
Structural Setting

Carbonate-hosted lead–zinc occurrences in northeastern British Columbia with emphasis on the Robb Lake deposit

1978 ◽  
Vol 15 (11) ◽  
pp. 1737-1762 ◽  
Author(s):  
R. W. Macqueen ◽  
R. I. Thompson
Keyword(s):  
British Columbia ◽  
Hydrogen Sulphide ◽  
Middle Devonian ◽  
Mineral Deposits ◽  
Burial Depth ◽  
Sulphide Mineral ◽  
Lake Area ◽  
Sulphur Isotope ◽  
Platform Margin ◽  
Host Rocks

In the Rocky Mountains of northeastern British Columbia, a Lower and Middle Devonian platform carbonate succession of six formations and [Formula: see text] total thickness gives way laterally north and west to shales, siltstones, and carbonaceous limestones of the Besa River Formation, of deeper water origin. Promising mineralization, dominantly sphalerite with some galena, is located in carbonates near the platform margin, within the Muncho–McConnell–Stone, Pine Point – Sulphur Point, and Slave Point Formations. Mineralization is not obviously related to structure, unconformities, or evaporite solution. Sphalerite and galena are closely associated with white sparry dolomite and commonly accompanied by quartz and thermally altered reservoir bitumen. Sulphur isotope ratios of galena and sphalerite range from + 5.0 to + 17.5 δ34S‰, consistent with a reduced sulphate or petroleum-derived hydrogen sulphide source for sulphur.At Robb Lake, mineralization occurs within broadly conformable breccias in the Stone, Muncho–McConnell interval; sparry dolomite forms the breccia matrix; and bitumen is common although rare elsewhere in the interval. Maximum paleotemperatures of host carbonates at Robb Lake appear to have been about 200–230 °C, as determined by bitumen characteristics, fluid inclusion filling temperatures in quartz, and illite crystallinity from illite in Besa River Formation shales. The Paleozoic and Mesozoic sedimentary section in the region suggests that the Middle Devonian of the Robb Lake area reached a maximum burial depth of about 5 km during mid-Cretaceous time. Physical proximity of bitumen and sulphide mineral deposits suggests that similar processes were involved in petroleum maturation–migration, and metallic mineral precipitation. Besa River shales are seen as probable sources for both petroleum and metals; sulphide sources appear to have been hydrogen sulphide generated within carbonate host rocks. A genetic association of petroleum and metals implies that mineralization took place relatively late (?early Mesozoic), and under deep subsurface conditions.Ground preparation in the form of brecciation and fracturing is problematical; at Robb Lake it may be a consequence of hydraulic fracturing due to high pore pressures generated by dewatering of the fine clastic facies that envelope the host dolomites. A better knowledge of time of origin of these deposits will contribute greatly to an understanding of their genesis. Meanwhile, consideration of the burial and thermal history of the host rocks offers a useful framework within which the mineral deposits and their genesis may be assessed.

Rare earth element concentrations in Quaternary volcanic rocks of southwestern British Columbia

1984 ◽  
Vol 21 (6) ◽  
pp. 731-736 ◽  
Author(s):  
Nathan L. Green ◽  
Paul Henderson
Keyword(s):  
British Columbia ◽  
Earth Element ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Lake Area ◽  
Calc Alkaline ◽  
Lower Light ◽  
The Individual ◽  
High Level ◽  
Ree Patterns

A suite of hy-normative hawaiites, ne-normative mugearite, and calc-alkaline andesitic rocks from the Garibaldi Lake area exhibits fractionated, slightly concave-upward REE patterns (CeN/YbN = 4.5–15), heavy REE contents about 5–10 times the chondritic abundances, and no Eu anomalies. It is unlikely that the REE patterns provide information concerning partial melting conditions beneath southwestern British Columbia because they have probably been modified substantially by upper crustal processes including crustal contamination and (or) crystal fractionation. The REE contents of the Garibaldi Lake lavas are not incompatible with previous interpretations that (1) the hawaiites have undergone considerable fractionation of olivine, plagioclase, and clinopyroxene; and (2) the individual andesitic suites were derived from separate batches of chemically distinct magma that evolved along different high-level crystallization trends. In general, however, the andesites are characterized by lower light REE contents than the basaltic andesites. These differences in LREE abundances may reflect different amounts of LREE-rich accessory phases, such as apatite, sphene, or allanite, assimilated from the underlying quartz diorites.

Late Quaternary glacial and interglacial environments of the Nechako River - Cheslatta Lake area, central British Columbia

2001 ◽  
Vol 38 (4) ◽  
pp. 719-731 ◽  
Author(s):  
A Plouffe ◽  
V M Levson
Keyword(s):  
British Columbia ◽  
Late Quaternary ◽  
Late Glacial ◽  
Lake Area ◽  
Glacial Lakes ◽  
Ice Flow ◽  
Coast Mountains ◽  
Quaternary Stratigraphy ◽  
History Of ◽  
Quaternary History

The Quaternary stratigraphy of the Nechako River – Cheslatta Lake area of central British Columbia is described and interpreted to reconstruct the late Quaternary history of the region. Exposures of glacial and nonglacial sediments deposited prior to the last glaciation (Fraser) are limited to three sites. Pollen assemblages from pre-Fraser nonglacial sediments at two of these sites reveal forested conditions around 39 000 BP. During the advance phase of the Fraser Glaciation, glacial lakes were ponded when trunk glaciers blocked some tributary valleys. Early in the glaciation, the drainage was free in easterly draining valleys. Subsequently, the easterly drainage was blocked either locally by sediments and ice or as a result of impoundment of the Fraser River and its tributaries east of the study area. Ice generally moved east and northeast from accumulation zones in the Coast Mountains. Ice flow was influenced by topography. Major late-glacial lakes developed in the Nechako River valley and the Knewstubb Lake region because potential drainage routes were blocked by ice.

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