GENERAL GEOLOGY

Detailed explanation-1: -In geology this refers to the changes in mineral assemblage and texture that result from subjecting a rock to pressures and temperatures different from those under which the rock originally formed. The original rock that has undergone metamorphism is called the protolith.

Detailed explanation-2: -A protolith (from Ancient Greek (prōto) ‘first’, and (líthos) ‘stone’) is the original, unmetamorphosed rock from which a given metamorphic rock is formed. For example, the protolith of a slate is a shale or mudstone.

Detailed explanation-3: -Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth’s surface. Sedimentary rocks often have distinctive layering or bedding.

Detailed explanation-4: -Metamorphic rock is the result of the transformation of an existing rock type, the protolith, in a process called metamorphism. The protolith is subjected to heat and pressure causing profound physical and chemical change. The protolith may be sedimentary rock, igneous rock, or another (older) metamorphic rock.

Detailed explanation-5: -Retrograde metamorphism (diaphthoresis, retrogressive metamorphism) is the mineralogical adjustment of relatively high-grade metamorphic rocks to temperatures lower than those of their initial metamorphism.