Metamorphism of the Lower Palaeozoic rocks of the Lochmaben district, southern Scotland, 1:50K Sheet 10W

The pattern of regional metamorphism indicated by illite crystallinity has been used to interpret the tectonic and thermal history of the Lochmaben district of southern Scotland. The regional pattern is characterised by the sub-parallelism of isocrysts with the regional strike, and by changes in grade across the strike-parallel, tract-bounding faults. The late diagenetic grade of the oldest Gala Group strata, compared to the low anchizonal grade of the younger Hawick Group strata south of the Lauriston Fault is indicative of regional very low-grade metamorphism resulting from accretionary burial. Similar relationships have been recorded elsewhere along the Lauriston Fault. Uplift and block faulting prior to Permo-Carboniferous basin development is responsible for a restricted area of high anchizonal and epizonal strata in the north-east of the district, and late diagenetic zone strata along the eastern side of the Dumfries Basin.