Cubley, Joel F., Pattison, David R.M. (2012) Metamorphism and deformation of the Grand Forks complex: implications for the exhumation history of the Shuswap core complex, southern British Columbia. Canadian Journal of Earth Sciences, 49 (11) 1329-1363 doi:10.1139/e2012-066
| Reference Type | Journal (article/letter/editorial) | ||
|---|---|---|---|
| Title | Metamorphism and deformation of the Grand Forks complex: implications for the exhumation history of the Shuswap core complex, southern British Columbia | ||
| Journal | Canadian Journal of Earth Sciences | ||
| Authors | Cubley, Joel F. | Author | |
| Pattison, David R.M. | Author | ||
| Year | 2012 (November) | Volume | 49 |
| Issue | 11 | ||
| Publisher | Canadian Science Publishing | ||
| DOI | doi:10.1139/e2012-066Search in ResearchGate | ||
| Generate Citation Formats | |||
| Mindat Ref. ID | 484789 | Long-form Identifier | mindat:1:5:484789:6 |
| GUID | 0 | ||
| Full Reference | Cubley, Joel F., Pattison, David R.M. (2012) Metamorphism and deformation of the Grand Forks complex: implications for the exhumation history of the Shuswap core complex, southern British Columbia. Canadian Journal of Earth Sciences, 49 (11) 1329-1363 doi:10.1139/e2012-066 | ||
| Plain Text | Cubley, Joel F., Pattison, David R.M. (2012) Metamorphism and deformation of the Grand Forks complex: implications for the exhumation history of the Shuswap core complex, southern British Columbia. Canadian Journal of Earth Sciences, 49 (11) 1329-1363 doi:10.1139/e2012-066 | ||
| In | (2012, November) Canadian Journal of Earth Sciences Vol. 49 (11) Canadian Science Publishing | ||
| Abstract/Notes | The Grand Forks complex (GFC) is an elongate, north–south-trending metamorphic core complex in the Shuswap domain of southeastern British Columbia. It comprises predominantly upper-amphibolite- to granulite-facies paragneisses, schists, orthogneisses, amphibolites, and calc-silicates of the Paleoproterozoic to Paleozoic Grand Forks Group. The GFC is juxtaposed against low-grade rocks of the Quesnel terrane across two bounding Eocene normal faults: the Kettle River fault (KRF) on the east flank and the Granby fault (GF) on the west flank. Peak metamorphic Sil + Kfs ± Grt ± Crd (Sil, sillimanite; Kfs, potassium feldspar; Grt, garnet; Crd, cordierite) assemblages in paragneiss and Hbl ± Opx ± Cpx (Hbl, hornblende; Opx, orthopyroxene; Cpx, clinopyroxene) assemblages in amphibolite in the GFC formed at 750 ± 25 °C, 5.6 ± 0.5 kbar (1 kbar = 100 MPa; 20 ± 2 km depth). Stratigraphically overlying Sil + St-bearing pelitic schists (St, staurolite) within the complex record peak conditions of 600 ± 15 °C, 5.5 ± 0.25 kbar. Crd + Ilm + Spl (Crd, cordierite; Ilm, ilmenite; Spl, spinel) and Crd + Qtz (Qtz, quartz) coronal textures in paragneiss, and Cpx + Opx + Pl + Mt (Pl, plagioclase; Mt, magnetite) symplectites in amphibolite, formed at 735 ± 20 °C, 3.3 ± 0.5 kbar, indicating high-temperature, near-isothermal decompression of the GFC of ∼2.3 ± 0.7 kbar (∼8.2 ± 2.5 km) from peak conditions. Transitional greenschist–amphibolite metamorphic assemblages in the hanging wall of the KRF indicate conditions of ∼425 ± 25 °C and 2.2 ± 0.6 kbar (∼8 ± 2 km depth), with local contact metamorphism around Jurassic intrusions as high as 630–650 °C at ∼2.5 ± 0.5 kbar. The pressure contrast across the Kettle River fault prior to greenschist facies displacement was ∼0.8 ± 0.7 kbar, for a vertical offset of ∼2.9 ± 2.5 km. This is similar to estimates for the Granby fault on the west flank of the GFC. The GFC therefore experienced a two-stage exhumation history: early high-temperature decompression at upper-amphibolite- to granulite-facies conditions, followed by low-temperature exhumation at greenschist-facies conditions owing to movement on the Eocene Granby and Kettle River faults. | ||
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