Structure, stratigraphy and alteration of Cretaceous and Tertiary strata in the Gang Ranch area, British Columbia
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1990
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Abstract
The study area is located along the west side of the Fraser River, approximately 100 km west of the town of 100 Mile House. The Fraser Fault transects the study area, juxtaposing mid-Cretaceous and Eocene volcanic and sedimentary rocks on the west against Late Paleozoic to
Middle Jurassic subduction related rocks of the Cache Creek Complex on the east.
Mid-Cretaceous volcanic rocks in the study area can be correlated on the basis of lithology and geochemistry with the Spences Bridge Group, Spius Formation volcanic rocks which have been mapped on the east side of the Fraser Fault. A succession of Late Cretaceous volcanic and
sedimentary rocks unconformably overlies mid-Cretaceous Spius Formation flows. These rocks have been informally named the Churn Creek formation. Eocene volcanic rocks and sediments unconformably overlie both Churn Creek formation rocks and flows of the Spius Formation.
Folds of two different axial trends are present in the study area. West and southwest-trending folds occur in the Late Cretaceous rocks in the western part of the study area. The orientation of these folds agrees with a regional axis orientation that is well documented to the south in
sediments of the Tyaughton Trough. The formation of these folds is thought to be related to Late Cretaceous to Early Tertiary motion on the Yalakom Fault System which is located approximately 30 km southwest of the study area. Immediately west of the Fraser Fault, Eocene volcanic and sedimentary rocks are deformed by northwest-trending folds and reverse faults. Deformation of these rocks is attributed to wrench-fault
movement on the Fraser Fault.
Alteration of both Spius Fm. and Churn Creek fm. rocks is characterized by the low temperature alteration minerals, heulandite, mordenite, celadonite, and chlorite. Eocene volcanic and sedimentary rocks typically contain clinoptilolite, montmorillonite, celadonite and illite as
alteration products of volcanic glass and primary phases. The alteration in both Cretaceous and Eocene rocks is controlled predominantly by hydrothermal processes.
Description
Bibliography: p. 103-106.
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Green, K. C. (1990). Structure, stratigraphy and alteration of Cretaceous and Tertiary strata in the Gang Ranch area, British Columbia (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/22537