CALCRETE DEVELOPMENT AT THE JUNCTION BETWEEN THE MARTIN LIMESTONE AND THE RED HILL OOLITE (LOWER CARBONIFEROUS), SOUTH CUMBRIA

Abstract

SUMMARY The strata exposed at the junction between the Martin Limestone and Red Hill Oolite (Lower Carboniferous) from around the Leven Estuary, south Cumbria are described in detail. There is evidence that these rocks underwent a complex depositional and early diagenetic history. The sequence begins with a slight angular unconformity, previously undescribed. There follows up to 2 m of varied limestone including features diagnostic of calcretes and indicative of subaerial weathering. Evidence is presented to suggest that there was continued accumulation of sediments in the terrestrial environment while the calcretes were forming. The overlying limestone breccia, previously interpreted as marine, also contains evidence of subaerial weathering and is re-interpreted as a terrestrial deposit, perhaps as a result of mudflow. The sequence at the Martin Limestone/Red Hill Oolite boundary around the Leven Estuary is compared with sections elsewhere in south Cumbria and the conclusion is reached that local tectonic movements were responsible for the period of emergence described.