Geochemical, mineralogical, and textural data from tills in the Highland Valley Copper mine area, south-central British Columbia
Also released as Geological Survey of Canada Open File 8119
Although rocks of Quesnel terrane in the Intermontane Belt of south-central British Columbia have long-been known as prolific producers of porphyry mineralization, much of the bedrock in the region is covered by glacial sediments. Nonetheless, geochemical and mineralogical data, particularly from locally derived tills, can help detect deposits buried under Quaternary sediments. We collected till samples from 99 sites near the Highland Valley Copper mine for geochemical, indicator mineral, and grain size determinations to test the utility of the method at a site where the configuration and tenor of ore-grade porphyry Cu mineralization are known. Landform-scale features such as drumlins, flutings, crag-and-tails mapped on aerial photographs, outcrop-scale features such as striations, grooves, and rat tails measured in the field, and data from previous studies indicate a relatively simple regional Late Wisconsinan ice-flow history with generally southward sediment transport, making provenance determinations on subglacial tills relatively straightforward. Commonly a first derivative of bedrock, subglacial till is the ideal sample medium for till geochemical and mineralogical surveys. Most of our samples were taken from a regionally developed till facies interpreted as a subglacial till deposited by moving ice (well compacted, markedly fissile, massive, cobble-boulder diamicton with a relatively clay-rich matrix and abundant faceted and striated clasts). For comparison, we also collected from a more locally developed till facies interpreted as an ablation till (poorly compacted, non-fissile, massive cobble-boulder diamicton with a relatively clay-deficient matrix) that overlies the subglacial till. Quality assurance/quality control results indicate that, uncontrolled by analytical artefact, the geochemical and mineralogical results for the dataset presented herein are suitable for geological interpretations that will be considered in future publications.
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