what is lapolith? in which layer of earth it is present?
Answers
Answer:
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.
Lopoliths typically consist of large layered intrusions that range in age from Archean to Eocene. Examples include the Duluth gabbro, the Sudbury Igneous Complex of Ontario, the Bushveld igneous complex of South Africa, the Great Dyke in Zimbabwe, the Skaergaard complex of Greenland and the Humboldt lopolith of Nevada. The Sudbury occurrence has been attributed to an impact event and associated crustal melting.
Answer:
Lopoliths are saucer shaped concordant emplacements that lie parallel to the strata of intruded country rock.
Lopoliths are relatively small plutons that typically developed an upper surface that is concave downward. This sagging shape may be attributable to volume reduction when magmas crystallize. The weight of the overlying strata would cause collapse into the volume previously occupied by more voluminous liquid magma.
Lopoliths formed by a similar mechanism to laccoliths, but they are composed of dense, mafic magma that allows depression by the overlying strata on cooling. Many lopoliths contain layered gabbroic rocks. Some lopoliths are very large, with thicknesses of many kilometres. The Bushveldt lopolith in southern Africa is several hundred kilometres across and contains the richest platinum deposits known.
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