b'Data trends Data trendsTim Keeping Associate Editorfor geophysical datamanagement and analysistechnical-standards@aseg.org.auRemanence mapping using tilt angles and MMTsLast year the Geological Survey of South Australia released several grids with the latest state TMI grid. The cryptic BigT and BigE grids were derived using Petar Stavrev and Daniela Gerovskas method of magnitude magnetic transforms (MMTs) for correcting horizontal position of magnetic anomalies, an alternative to the RTP (Gerovska and Arazo-Bravo, 2006, Stavrev and Gerovska, 2006).Figure 1.Coompana MMT remanence.Rainer Wackerle of Intrepid Geophysics has explored combining the BigT withapplied to the Coompana area of SouthReferencesTilt Derivative to detect remanence.Australia. An area well known for a BigT is his nickname for the sum oflarge negative magnetisation anomaly,Gerovska, D. and M. J. Arazo-Bravo, squares of first order componentsalso known as the Giant Skull, since a2006. Calculation of magnitude of T(MI), or the Total Field of thedetailed airborne survey in 2015. Themagnetic transforms with high Analytic Signal (Tx*Tx + Ty*Ty + Tz*Tz).blunt application used raster arithmeticcentricity and low dependence on Remanence is a timely topic since Jimto colour black any points of coincidingthe magnetization vector direction. Hanneson recently demonstrated in thisnegative RTP and positive BigT (Figure1).Geophysics 71 (5): 121130. DOI: magazine the importance of even minorAccording to Rainer This works quitehttps://doi.org/10.1190/1.2335516remanence (Hanneson and Baxter,well on sharp (near surface) anomaliesHanneson J.E. and C. N. Baxter, 2022). but fails in basin areas. My thresholds are2022. Discovery of the Havieron DC based, e.g., if the RTP tilt is smallerGold-Copper deposit, WA, Rainers advice is that when onlythan -X and BigT tilt is larger than +Y it isPreview, 219: 42-47, DOI: induced magnetisation is present, theclassified as remanent. 10.1080/14432471.2022.2103941curvature of an RTP and BigT shouldStavrev,P. and Gerovska, D., 2006. Inversion be in synchronicity and if not, there is aAs previously stated, my bluntof elongated magnetic anomalies likelihood of remanence. Therefore whereapplication is simply to illustrate theusing magnitude transforms, the RTP tilt (curvature) is negative andpossibilities of where remanenceGeophysical Prospecting, 54: 153166the BigT tilt is positive there is (possible)could be included in your geologicalHanneson J.E. and C. N. Baxter, remanence. model or where to search for2022. Discovery of the Havieron remanent rocks, and hopefully this isGold-Copper deposit, WA, Following the Intrepid cookbook andanother inroad to progressing pastPreview, 219: 42-47, DOI: example scripts, the method has beenjust magnetic susceptibility in models. 10.1080/14432471.2022.210394141 PREVIEW DECEMBER 2022'