| Title | Mantle petrology, mineralogy and major elements geochemistry of the northern Cache Creek Terrane |
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| Author | Corriveau, A -S; Bédard, J H; Zagorevski, A ; Richer-Laflèche, M |
| Source | Margins through time: GAC-MAC 2016; Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts vol. 39, 2016 p. 14  Open Access |
| Links | Online - En ligne (complete volume - volume
complet, PDF, 1.3 MB)
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| Year | 2016 |
| Alt Series | Natural Resources Canada, Contribution Series 20190390 |
| Publisher | Geological Association of Canada |
| Meeting | GAC-MAC 2016; Whitehorse, YK; CA; June 1-3, 2016 |
| Document | serial |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Province | British Columbia; Yukon |
| Subjects | geochemistry; igneous and metamorphic petrology; Science and Technology; Nature and Environment; Cache Creek Terrane |
| Program | GEM2: Geo-mapping for Energy and Minerals Western Cordillera, Cache Creek Terrane |
| Released | 2016 06 01 |
| Abstract | The northern Cache Creek terrane extends for more than 500 km in northern British Columbia and southern Yukon. This composite terrane comprises mafic and ultramafic complexes and carbonate and chert
assemblages that have been interpreted by previous workers as components of accreted seamounts, spreading centers and rifted arc complexes. Our observations show that mantle facies are widespread and are generally structurally capped by brecciated
hypabyssal and volcanic rocks, most with arc affinities. Mafic and ultramafic cumulates occurrences are rare.
Variably serpentinized mantle rocks were sampled in southern Yukon (Jakes Corner area), and northern B.C. (Atlin, Nahlin area and Dease
Lake area). Ultramafic to gabbroic cumulates were found at King Mountain and in the Hardluck peak area. Foliated mantle harzburgite tectonite dominates, typically with 25-35% of porphyroclastic orthopyroxene and subordinate chromite. Orthopyroxenite
to rare websterite layers are interpreted to be transposed dykes. Subordinate dunite dykes and pods are common. Where present, gabbroic dykes are consanguineous with overlying volcanics.
Chromite is unzoned, with high Cr# from 32 to 58 and low
TiO2 and NiO contents. Olivine composition varies between Fo90 to Fo92 in the harzburgite and up to Fo94 in the dunite dykes. Enstatite and diopside respectively have Mg# of 91.3-91.6 and 92.9-94.2. They have low Al2O3 and Cr2O3 contents.
These
results suggest a large range in degree of partial melting (18- 32%) for these peridotites. Such extensive melting is consistent with the scarcity of clinopyroxene and the low modal proportions of orthopyroxene. The involvement of an arc component
during melting is suggested so as to explain the extensive melting. Resemblance between Cache Creek mantle rocks and arc-related mantle rocks supports this hypothesis; as does our data from Cache Creek cumulates, hypabyssal intrusions and volcanic
rocks. |
| GEOSCAN ID | 321665 |
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