GENERAL GEOLOGY

Detailed explanation-1: -When a rock is both heated and squeezed during metamorphism, and the temperature change is enough for new minerals to form from existing ones, there is a strong tendency for new minerals to grow with their long axes perpendicular to the direction of squeezing. This is illustrated in Figure 7.2.

Detailed explanation-2: -Deep inside the Earth, intense heat and pressure can change rocks into entirely new metamorphic rocks. In fact, the conditions are so extreme, they can change the rock’s texture, color, and the shape of its crystals. Even the rock’s minerals are broken down and new ones are formed.

Detailed explanation-3: -Regional metamorphism takes place under high temperature and pressure conditions that may extend over large areas. Regional metamorphism results in intense alteration of the mineralogy and texture of rocks, usually to the point where original sedimentary structures are destroyed.

Detailed explanation-4: -Metamorphism occurs because some minerals are stable only under certain conditions of pressure and temperature. When pressure and temperature change, chemical reactions occur to cause the minerals in the rock to change to an assemblage that is stable at the new pressure and temperature conditions.