Bedrock GS13D models from interpreted data in geologically complex Carboniferous terrains : a work in progress from the Clyde catchment area, Midland Valley of Scotland

Millward, D.; Stephenson, D.. 2011 Bedrock GS13D models from interpreted data in geologically complex Carboniferous terrains : a work in progress from the Clyde catchment area, Midland Valley of Scotland. Nottingham, UK, British Geological Survey, 58pp. (IR/11/052) (Unpublished)

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Abstract/Summary

This report describes the construction of 3D bedrock geological models of the Mississippian (Visean) Clyde Plateau Volcanic Formation (CPV), a succession of basaltic to trachytic lavas in the Midland Valley of Scotland using GSI3D version 2011 Bedrock. These lavas form a range of picturesque hills around the margin of the River Clyde catchment to the north, west and south of Glasgow. The modelling has formed part of the BGS Geology and Landscape Scotland’s 3D modelling programme of the Clyde catchment, and is a contribution to the Clyde-Urban Super-Project (CUSP). The horseshoe-shaped outcrop of the CPV was divided into 4 areas for modelling. To the north of Glasgow the Campsie Fells block comprises an area of c. 285 km2 and the model consists of 23 geological units, 73 faults and 64 cross-sections. To the west of this the Kilpatrick Hills block model of an area of 145 km2 has 9 geological units, 45 faults and 34 cross-sections. West of Glasgow is the Renfrewshire Hills block, an area of 650 km2, with 18 geological units, 87 faults and 90 cross-sections. South of Glasgow is the Southern Hills block, some 530 km2 There are few boreholes in the area and the models have been constructed mostly using outcrop data and published cross-sections as a starting point for constructing the fence-diagram. Also, a methodology was devised and tested successfully for the modelling of funnel-shaped intrusions which is appropriate for the multitude of small plugs, vents and necks that cut the sequence in the Midland Valley. Despite shortcomings in the quality of the calculated surfaces, the modelling has shown that GSI3D can cope with many aspects of complex Carboniferous geology as found in the Midland Valley of Scotland. However, as many of the stratigraphical surfaces in these models are marred by calculation errors, the models must not be regarded as finished products, which await improvements to the GSI3D engine, currently in progress. , with 8 geological units, 64 faults and 45 cross-sections. The scale for each of the models is nominally 1:50 000. Though the focus of the modelling was on selected divisions of the CPV, enveloping formations were also included. Most importantly here is the 3-fold division of the Inverclyde Group beneath the volcanic succession, and the overlying units within the Strathclyde, Clackmannan and Scottish Coal Measures groups, as appropriate. The models show the following significant geological features: The overstepping relationship of the base of the volcanic succession on the underlying Clyde Sandstone, Ballagan and Kinnesswood formations; A transpressional ‘pop-up’ duplex structure developed within a restraining bend on the dextral strike-slip Campsie West Fault, provides a mechanism for formation of the unconformity at the base of the volcanic succession; The localised distribution of lava and pyroclastic units and their spatial relationship with the linear vent-swarms.

Item Type:	Publication - Report
Programmes:	BGS Programmes 2010 > Geology and Landscape (Scotland)
Funders/Sponsors:	NERC
Additional Information. Not used in RCUK Gateway to Research.:	This item has been internally reviewed but not externally peer-reviewed. Report made open to all August 2012
Date made live:	29 Aug 2012 10:41 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/19394

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