A study was made of rocks outcropping along a
road section in the vicinity of Hell's Gate, some 12 miles
south of Boston Bar, British Columbia. Biotite schists
belonging to the Hozameen group (Carboniferous or Permian
in age), were the oldest rocks found. The Custer granodiorite, a heterogeneous igneous body having the average
composition of a hornblende granodiorite, intrudes the
biotite schists. The age of the Caster granodiorite is
believed to be Upper Jurassic. Large numbers of pegmatite
and aplite dykes intrude the Custer granodiorite. Two
types of pegmatites, magmatic and metasomatic were distinguished. The Hell's date granodiorite, a uniform igneous
body of trondjhemitic composition, intrudes the Custer
granodiorite and also post dates the pegmatite and aplite
dykes. The age of the Hell's Qate granodiorite is believed
to be Upper Jurassic or possibly Lower Cretaceous. Sight
plagioclase porphyry dykes, classified into one of three
groups, (staple, multiple, and protoclastic types) were
found. The plagioclase porphyry dykes are believed to be
genetically related to the Hell's Gate granodiorite. Six
dykes having an andesitic composition were found; the dykes
have been classified into light colored and dark colored andesites. The rocks along the road section have been
intensively fractured. Faulting has taken place close to
the southern contact between the two granodiorites. The
narrow N-S trending outcrop of Custer granodiorite in the
area could possibly have been produced by faulting, and
its shape suggests a horst structure,
A study, using a method suggested by Gorai, was
made of the plagioclase twins occurring in the Hell's Gate
rocks. The conclusions drawn from this work largely
confirms the conclusions drawn from the field evidence. / Arts, Faculty of / Geography, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/41662 |
| Date | January 1955 |
| Creators | Morris, Peter Gerald |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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