wiki:Canada in 3D: Concept Paper (EN)
Last modified 4 years ago Last modified on 04/05/16 19:00:32

Canada in 3D: Concept Paper

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Motivation

Geologic mapping has evolved fundamentally during the past decade. Instead of a fault line drawn on paper, faults are now geo-referenced data entries with relevant measured strikes and dips embedded. Instead of posting coloured geological map units on paper, specific digital formation polygons are telemetered from home offices to remote field camps as required by ongoing surveys. Instead of plastic mine models displayed in office foyers, digital prisms of ore bodies are projected within 3-D visualization rooms at any scale or from any user viewpoint. Instead of unfolding maps, digital geology draped over digital elevation models can be called up on an outcrop using field laptops or smart phone applications. Geologic mapping was fundamentally a 3-dimensional enterprise from its beginnings, but it is only recently that computing power and storage capacities have enabled its implementation and realization. Thus a “3-D map of Canada” is now achievable: an online and evergreen national geoscience library and compilation that would form the basis of a “next generation” visualization of the Canadian land mass.

Many countries already have 3-D geological models/maps prominently displayed on their product websites. For example, the British Geological Survey has about a dozen 3-D models and the surface geological map of the British Isles can be accessed anywhere within the UK using smart phone apps, during a day ramble along the coast or on a professional field trip in the Highlands. In a different example, Geoscience Australia offers crustal-scale 3-D models of historic mining regions based partly on deep seismic reflection profiles and airborne geophysical surveys. These models address a need to understand how ore bodies got to be where they are, by tracing deeply rooted mineralizing fluid plumbing systems that has been consistently identified as priority goals in recent forward-looking vision exercises by the Australian Academy of Science (the Uncover initiative). As a final example, the US Geological Survey website similarly offers hydrological models of key aquifers (http://gallery.usgs.gov/videos/350 or http://pubs.usgs.gov/sir/2004/5226/).

Approaches

The 3-D map of Canada will become a signature product for the country. It will display the most current state of knowledge of the geology of the Canadian landmass, and the underlying database will be a mosaic of existing 2D and 3D maps at various scales and resolutions, vertically and horizontally, produced by a variety of agencies. The foundation for this map already exists at the GSC and related provincial and territorial agencies, including (a) 3D method development in a variety of programs, (b) new map compilation strategies and related digital methods, and (c) new geological 2D and 3D mapping. The intention is not only to develop a 3D map for Canada, but enable frequent updates as new information becomes available, making it “evergreen”. It is anticipated that an initial low-resolution 3D map could be made rapidly, followed by more iterations in which the resolution increases as more detailed information becomes available and is incorporated, all the while adding to the inventory of geological knowledge in the database. Essential components to this will be new 2D maps for the surficial and bedrock geology of the country.

Such a 3-D map of Canada will need be achieved via two paths. At mining camp scale sufficient drill holes and mine workings may exist to construct data-driven map fragmetns where geological formations and rock types are explicitly mapped as deep as several kilometres. In remote areas and at regional scales and depths greater than a few kilometres, sufficient observations cannot exist and map fragments must be knowledge-driven, with geological formations inferred by manual interpretation, mathematical down-dip extrapolation of key surfaces, or from key physical properties such as magnetic properties. This latter is often called remote predictive mapping; at the surface it is typically done via airborne/satellite surveys, at depth it is done suing seismic and electromagnetic surveys.

Here we propose to explore the feasibility of developing a national 3D map for the geology of Canada. Two stages seem to be required: (1) assemble available 2D and 3D data in a GIS, and (2) build large-area 2D maps and a 3D model. A key activity will be prototyping surface-subsurface integration over a large area. Any such approach will need to build upon previous international, provincial and territorial efforts, adapting them as necessary to the unique Canadian national situation. The data base will be evergreen, and ideally served to a variety visualization vehicles, including potentially partner web sites. Ideally, some signature web portal might provide Google Earth-like functionality, by allowing the user to seamlessly ‘dive’ through the surface to any depth, and query as well as retrieve viewed information.

Possible outputs

Envisioned are three possible scenarios for a 3D geological map (and database) of Canada, which increase in complexity, resolution, and required effort and time. Underpinning all possibilities is a database that contains the necessary source products, such as essential input data and 2D and 3D maps, including new national surficial and bedrock geology compilations. The three options are sequentially dependent, i.e. option 3 requires option 2 to be in place, and similarly option 2 requires option 1 to be available.

  1. 2.5D Geology of Canada (map): 2D surficial and bedrock geology map compilations for Canada are draped on a topographic surface, associating a surface elevation with each point of geology. This will help confirm the validity of some geological boundaries, particularly in areas of relief. It will also provide a basis for subsurface extrapolation, and enable the geology to be incorporated into public-oriented applications, e.g. eco-tourism, as popular in some European countries. Major design decisions include the use of (a) existing 2D compilations (e.g. Wheeler, Fulton), or (b) development of new 2D compilations, likely by extending southwards the emerging compilations for the North.
  1. 3D geology of Canada (mosaic): develops an initial 3D model for Canada by (a) generating national-scale surfaces for key geological boundaries, and (b) extrapolating 3D volumes for each geological unit on the 2.5 maps and integrating these with the national surfaces. The latter might be achieved by inserting existing lower-resolution 3D models into the 2.5 map, or interpolating subsurface volumes from available data, such as drill holes or field observations. Importantly, irregularities between adjacent existing or interpolated subsurface bodies will not be resolved, i.e. 3D border discontinuities will remain. The end result will be a patchwork mosaic of irregularly connected 3D bodies sitting underneath 2.5D geological map compilations integrated with associated national-scale surfaces.
  1. 3D geology of Canada (compilation): same as option (2), but resolves discontinuities between adjacent subsurface geological bodies, potentially incorporating higher-resolution geological models and using carefully constrained geophysical inversions to extrapolate between existing 3D models.

Expected Benefits

Since publication of the last bedrock Geological Map of Canada in 1996, there have been profound advances in understanding the geology of Canada, as well as in related technologies. The wealth of new geoscience data indicates a new compilation is warranted. Technologic and scientific advances suggest a new compilation approach should be utilized, one that is database-driven and 3D-oriented, respectively. Such a digital map would increase Canada’s competitive edge by providing enhanced access to deeper integrated geoscience knowledge, and it could broker exploration of this knowledge from the national scale to provincial and territorial products. Multinational investors search for such knowledge from anywhere in the world and favour sophisticated Web accessible 3D data and knowledge.

Risks

Overall, the greatest unknown is the feasibility of first generating and then sustaining/maintaining a national 3D map of the geology of Canada and its underpinning database. Specifically:

  1. Does sufficient technologic capacity exist to integrate 2D and 3D geologic data seamlessly into a single, generally accessible GIS database? The fundamental IT and IM tools now exist, but have not yet been suitably adapted nor has access been offered to the general public.
  2. Is it scientifically justifiable to assemble 2D and 3D data uniformly across such diverse regions as the Canadian Arctic and southern provinces? This is a question of determining appropriate resolution, but also relative weighting of data- and knowledge-driven mapping.
  3. Determine the feasibility of generating new 3D maps by integrating surface observations, near-surface data, and deep geoscience data and derivative models of physical rock properties.
  4. Do effort requirements decrease significantly if this product is offered as a truly evergreen database and an interactive and re-usable map?

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