The Genesis of the North Pennine Ore Deposits

Abstract

I. Introduction The North Pennine area of northern England, drained by the Tyne, Wear, and Tees and their tributaries, is a dissected plateau, uplifted along the Pennine fault-line to the west, and sloping gently down to the lowlands of East Durham. Its physiographic boundaries are, on the north, the main valley of the Tyne; on the west, the Pennine escarpment, overlooking the Vale of Eden; and on the south, the natural pass of Stainmoor. This region has been called the “Alston Block” by F. M. Trotter and S. E. Hollingworth (1928). Gently domed Carboniferous sediments resting on an eroded surface of closely folded Lower Palæozoic slates and volcanic rocks form the country-rock, and the area is structurally a fault-block, the limits of which correspond closely with the physiographic boundaries. The Carboniferous limestones, sandstones, shales, and coals have a total thickness of more than 5000 feet, and throughout their whole thickness rhythmic alternations of beds are well exhibited. In the Carboniferous Limestone series (S 1 -D 1 ), which is the lowest Carboniferous member, limestones predominate. Limestones are co-important with sandstones and shales in the overlying Yoredale series (D 1 -D 3 ), but are absent from the higher horizons. Coal seams alternating with sandstones and shales make up the Upper Carboniferous succession. As a result of the gentle outward inclination of the beds from the highest part of the dome, near Cross Fell, progressively higher horizons outcrop round the northern, eastern, and southern margins of the area. The Millstone Grit thus appears along the Tyne valley and over