Lopolith

A lopolith is a large igneous intrusion which is lenticular in shape with a depressed central region. Lopoliths are generally concordant with the intruded strata with dike or funnel-shaped feeder bodies below the body. The term was first defined and used by Frank Fitch Grout during the early 1900s in describing the Duluth gabbro complex in northern Minnesota and adjacent Ontario.