THE OCHIL FAULT AND THE KINCARDINE BASIN - KEY STRUCTURES IN THE TECTONIC EVOLUTION OF THE MIDLAND VALLEY OF SCOTLAND

The Ochil Fault, one of the most prominent tectonic features in the Mi dland Valley of Scotland, juxtaposes Lower Devonian volcanic rocks aga inst late Westphalian strata, implying a possible vertical displacemen t of up to 4 km. The Kincardine Basin in its hanging-wall, although ac tively subsiding during the greater part of the Silesian, trends gener ally N-S, perpendicular to the Ochil Fault, and its Silesian sedimenta ry record shows little sign of tectonic control by that fault. It is p roposed that the Ochil Fault was initiated, possibly as a sinistral st rike-slip feature, in the Devonian, but acted as a sidewall fault duri ng the early evolution of the Kincardine Basin, attributed to extensio n on a hypothetical pre-Brigantian fault along the Bo'ness Line on the east side of the basin until late Namurian times, when active extensi on ceased. Both faults were probably buried during late Namurian and W estphalian times. Reactivation of the Ochil Fault during end-Carbonife rous N-S extension, dated by quartz-dolerite emplacement, was responsi ble for probably at least 2 km displacement, including the presently v isible footwall uplift. It is suggested that the hanging wall may have contained a Permian basin, now removed.