Testing the correlation of marine bands of the Carboniferous Lower Limestone Formation (Midland Valley of Scotland) using foraminiferal quantitative biostratigraphy

Abstract

This study examines foraminifers from limestone horizons of the mainly Brigantian Lower Limestone Formation across the Midland Valley of Scotland (MVS), to determine more precisely the correlation of the limestone beds throughout the region and with the marine bands. Three quantitative biostratigraphical methods were applied to the foraminiferal dataset. The Ranking and Scaling method produced unusual mixed associations and a ranked optimum sequence, making it the least reliable. In contrast, the Unitary Associations (UA) and Constrained Optimization (CONOP) methods yielded more consistent sequences and correlations, especially the latter. The main conclusions drawn were: (i) The West Kirkton, First Abden and St Monans Brecciated limestones of the eastern MVS are considered the base of the Lower Limestone Formation; (ii) The Petershill Limestone is considered as the likely lateral equivalent of the Blackhall Limestone; (iii) the Seafield Tower, Charlestown Main and Middle Skateraw limestones can be correlated in the eastern MVS; (iv) the Abden Fauna (marine band) in central Fife, is confirmed just below the base of the Lower Limestone Formation in most sections; and (v) correlation of limestones below the Neilson Shell Band (marine band) in the eastern region is confirmed with the CONOP method, and in the western region with the Unitary Associations.