b'Geophysics in the SurveysNewsGeological Survey of South Australia: Gravity at Wheal Ellen(a whealy good project)On Tuesday December 3, GSSAResources. The students used a CG5The main mine shaft lies just to the north Geophysicist Philip Heath and Cadetgravity meter and a Sokkia DGPS toof the dark blue portion of the grid.Grace Smith travelled to the historicsurvey the area, and learned how theThe gravity data have been tied to the Wheal Ellen mine with the NExUSacceleration due to gravity can varyAFGN via a new gravity survey point students to demonstrate the usearound mineral deposits. established at Mount Barker train of gravity in mineral exploration.The geology at Wheal Ellen strikesstation (Figure 2). The survey point was The NExUS (National Explorationroughly N-S, and gravity data wereestablished via ABA tie to the Burnside Undercover School) programme is aacquired along a single E-W traverse.Rugby Club AFGN point with two CG5 three-week course providing world- The position of the line was selected togravity meters. The survey point is class training in mineral exploration.cross immediately adjacent to the mainunmarked, but can be found at the There were around thirty students frommine shaft. Readings were acquired atMount Barker train station, immediately all around Australia learning a rangeintervals of 25 m. Data were processed atin front of the tap and next to a of geophysical techniques includingGSSA head office to produce a Sphericaldrainpipe, on the car park side of the magnetics, electrical techniques, seismic,Cap Bouguer Anomaly from which abuilding. In MGA coordinates, the site magnetotellurics, and gravity. 1st order trend was removed. The finalis at (approximately) 305212 m Easting, Silver, lead and zinc were mined at thegridded data are shown in Figure 1,6117747 m Northing, Zone 54. The site near Strathalbyn in the 1850s, andwhich displays an approximately 0.5mGalaverage observed gravity at the site (from the property is now owned by Hillgroveanomaly to the east of the main shaft.10 measurements) is 9796755.694 ms-2 in the AADG07 datum. The standard deviation is 0.153 ms-2As always, all gravity data is available upon request.Philip Heath Philip.heath@sa.gov.auFigure 2.The unmarked base station can be found at Mount Barker train station in front of a tap and adjacent to a drain pipe on the veranda. The Figure 1.Wheal Ellen historic mine and 1st order de-trended gravity traverse (AAGD07 SC BA). An approx.gravity meter on the right in this image is on top of 0.5 mGal gravity anomaly can be seen on the survey traverse to the east of the main mine shaft. the site.FEBRUARY 2020 PREVIEW 22'