Geological Survey Of Canada Current Research Online No 2000 A16

The Nicola Horst in the southern intermontane belt, British Columbia, is a Tertiary fault-bounded structure that exposes relatively deep-seated metamorphic equivalents of Late Triassic Nicola Group volcanic & sedimentary rocks, intruded by plutons. Associated with the Nicola facies are undated conglomerate & schist units which are unlike any known facies of the Nicola Group but which resemble units of the pre-Nicola, pericratonic succession to the east. This paper presents preliminary results of field work conducted to better understand the evolution & contact relationships of the Nicola Horst and to examine whether the Horst provides evidence regarding the contact between the Nicola Group and the ancient North American cratonic rocks.

A well-exposed section about 250 metres wide below the high water line of the Jennings River, Teslin Lake map area in northern British Columbia shows part of the Teslin Fault and provides an opportunity to constrain the fault's kinematic history by direct ground observations. This report describes preliminary structural observations of this section of the Teslin Fault, including the rock types involved, mylonitic & ultramylonitic structures, and deformation. Indications of two main episodes of shearing are discussed.

The use of static global positioning system (GPS) equipment for accurate horizontal & vertical positioning in field geology operations at high latitudes is made difficult by the need to set up & operate a GPS reference station and limitations on the distance between the reference station & field GPS due to errors introduced by the ionosphere. Dual-frequency GPS receivers have the potential to eliminate these problems since they can eliminate ionospheric errors and thereby increase baseline lengths, thus potentially permitting the use of existing GPS reference stations. This paper describes the use of a dual-frequency receiver for establishing benchmarks along the Yukon River as a field trial of this technology. Field methods and post-processing of the data using GPS data from permanent receiving stations are described, and baseline results are presented. The derived benchmarks will be applied to a survey of fill thickness below the Yukon River.