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We take a sun sighting by turning the sun compass so that the sun casts a shadow though a small hole on to the fine line on the mirror, we then take a reading and record the time; this information is then put through some software to determine the X axis reading for the core sample.To obtain the Y axis reading, we simply add 90 degrees.Later on, back at the laboratory, we will carry out palaeointensity analysis on the samples.The amount of magnetisation trapped in the rock is almost linearly related to the ancient magnetic field strength; because of this relationship, we are able obtain estimates for the strength of the ancient field.A magnetic compass reading of the X axis is also taken for comparison; this is achieved by aligning the sun compass with the dip direction of the core and placing a magnetic compass against the axis of the mirror.The image below shows the X and Y axes over a plan view of the core sample/ specimen.There, Henry awaited us with his treasure – drawers full of samples, floppy drives full of measurement data and an enormous amount of additional knowledge and kindly allowed us to use his samples and data for our projects.The picture below shows the main part of the lab with the most elegant magnetometer in the centre.
After a month of literature review, our attention was fully caught by Canada, where (Neo-)Proterozoic dykes have been a focus of research for the last 30 years.2) The rock sample must be precisely orientated in x y and z, so that we can reproduce the orientation of the rock in the laboratory.This orientated reference frame is crucial if we want to determine the direction of the ancient geomagnetic field.Therefore, the two of us, accompanied by Andy Biggin, immediately and figuratively set sails to Canada to kick-start the first phase of our projects. Henry Halls’ studies of the Franklin- and Grenville-Dykes, our journey’s first stop had to be his lab at University of Toronto!While his studies focussed on determining the ancient field directions to gain knowledge about the palaeolocation of Laurentia, my research will deal mostly with palaeointensities of the Ediacaran period (635-541Ma).
It was great to see the lovely skyline and the CN Tower (shown in the picture below) while every other person was dressed in blue, thanks to a home game of the Toronto Blue Jays.