OR/14/058 Modelled datasets

Arkley, S L B. 2014. Model metadata report for the Great Glen — Moray Firth GSI3D Faulted Bedrock Model. British Geological Survey Internal Report, OR/14/058.

Borehole data

No borehole data has been used in the construction of the model. Although there are a number within the area, the majority are either too shallow or not detailed enough to help with this model.

Map data

• Topographic map, 1:1 000 000 scale, clipped from the GDI, with attached world file.
• Onshore geological information, 625 000 bedrock, superficial and faults, clipped from the GDI.
• Offshore geological information, 250 000 bedrock and faults were clipped from the GDI. The data was re-projected to British National Grid to be compatible with the onshore datasets. The offshore map data does not colour up in GSI3D as it has different LEX- RCS units to those in the GVS/GLEG.

DTM data

The ‘Bald Earth’ DTM was extracted at 250 m resolution and is stored as a TIN within the GSI3D workspace. A model limitation is that bedrock units are drawn up to Bald Earth DTM rather than to the base of the superficial deposits (rockhead surface).

Existing section data

Currently 37 existing sections have been used: (Figure 6):

• The model is based on geological information shown in 9 sections imported from the GB_3D project. These sections were drawn by ‘regional geologists’ and have been largely unchanged, only minor edits were made in places to provide consistency, in addition to snapping to crossing sections and outcrops/subcrops.
• A section on the Moray-Buchan 250 000 map across the Moray Firth was scanned, saved as a raster and imported as a backdrop image to a section to help give some control on the thicknesses of units in that area. Sections on the onshore 50 000 maps are shallow and deemed not worth importing.
• An additional network of 13 sections was used to constrain the model.
• 4 Sections bound the model edges.
• 6 Fault helper sections were drawn where faults pinch out within the project.
• 4 Additional helper sections were needed to ensure there is a section passing through each polygon shown on the geological map such as several small Permian and Devonian outliers in the south-east of the model.

Figure 6 Cross-sections as seen in GSI3D window, left for original model. Close up view of cross sections, right. Note that many of the longer sections only contain data within the model area for Devonian and younger rocks: older strata from GB-3D lines have been removed as they have been superseded by more recent versions.

Figure 7 Cross-section GG_section_3 from GSI3D cross-section window showing Devonian and younger rocks, vertical exaggeration x5.

GVS and GLEG

The GVS and GLEG are used in the GB3D project.