KEGS Ottawa February meeting
Monday, February 19, 4:30 pm
Speaker: Chris Galley, Post Doc uOttawa and Memorial Univ.
Title: Satellite-derived gravity data: from ocean wide bathymetric mapping to crustal scale modelling
Abstract: Most of our planet is covered in water, with only 20% of its bathymetric surface having been measured through shipborne acoustic methods (with resolutions of 20-100m). This leaves us to rely on a satellite-derived bathymetric model of the seafloor to fill in the remaining 80%, which boasts a resolution of 1-2 km. But how can a satellite, positioned approximately 800 km above Earth’s surface, collect data that can be modelled at that resolution? This talk will outline how satellite altimetry data is collected, and what steps have been taken to turn the altimetry data into free-air anomaly data that in turn is used to produce a bathymetric surface. However, the modelling of this gravity data doesn’t need to stop at the seafloor. Three-dimensional inversion modelling allows us to study petrological changes across the seafloor as well as resolving the depth of the Moho, the boundary between the lithospheric mantle and the crust. The talk will conclude with a case study of the Lau Basin, an actively forming back-arc basin north of New Zealand. The study’s gravity inversion modelling revealed changes in crustal composition and growth rates throughout the basin and along the volcanic arc.
Bio: Chris Galley is a geophysicist whose work has focused on the study of ancient and modern hydrothermal systems and their associated mineralization. Through the modelling of magnetic data, he has resolved the geometry of subseafloor hydrothermal convective systems and their near surface alteration and is presently modelling the structure of sediment hosted seafloor massive sulfide deposits off the East coast of the USA. His present studies also include crustal thickness modelling of the Lau Basin (a modern back-arc basin) and the Abitibi Greenstone Belt (an ancient back-arc basin) through gravity data inversion to determine the regional controls on volcanogenic massive sulfide mineralization. Chris presently holds postdoctoral positions at the University of Ottawa and Memorial University of Newfoundland. He received his PhD in Geophysics from Memorial University of Newfoundland in 2022, and his BSc. in Physics and Mathematics from the University of Victoria in 2015.
When: Monday, February 19, 4:30 pm
Where: at the GSC, Harrison Hall, Room, Room 177, 601 Booth St, Ottawa
Please note: In order to enter Harrison Hall, you will have to show some Canadian identification: a passport, permanent resident card, driver license, or health card. If you are a foreign student and have a residency visa, that should work too. Send me an email if you are not Canadian and have some questions about whether your identification will work. The reason for this extra complication is that Harrison Hall is inside the controlled area. Checking everyone’s id documents might take time – please try to get on site with some time to spare for the extra security procedure.
Upcoming KEGS Ottawa Presentations
Monday, March 18: Dennis Gamble, Notra Inc.,“UXO case history: From initial site assessment of the former Utopia, NB army base (370 km2) using a mineral exploration approach to develop an Unexploded Ordnance Site Model(SUM)”
Monday, April 15: Bob Grasty, GammaBob, “Experience building a worldwide network of calibration pads for ground and airborne gamma ray surveying”
For more information about:
- any upcoming KEGS Ottawa presentations, or
- if you know anyone who might be interested in presenting to our KEGS Ottawa group, or
- if you know anyone who should be included on the KEGS Ottawa email group,
- if you are on the KEGS email group and would like to unsubscribe from it,
please contact Luise Sander, SGL, luise@sgl.com.
The KEGS Ottawa group meets on the 3rd Monday of each month, usually at the GSC on Booth St. It is also possible to hold the presentations at other venues in Ottawa. We generally follow our presentation by adjourning socially to a nearby local establishment.
