Compaction – process by which sediments are pressed together under their own weight. Cementation – process by which dissolved minerals crystallize and glue particles of sediment together into one mass.

COMPACTION. The process by which sediments are pressed together under their own weight.

Cementation occurs when minerals such as quartz, calcite, and hematite are deposited between the pieces of sediment. 5. These minerals, acting as natural cements, hold the sediment together like glue, making a detrital sedimentary rock.

Four basic processes are involved in the formation of a clastic sedimentary rock: weathering (erosion)caused mainly by friction of waves, transportation where the sediment is carried along by a current, deposition and compaction where the sediment is squashed together to form a rock of this kind.

Most sedimentary rocks are made when mud, sand, or bits of rock are pressed together to form sediment. As the bits of sediment pile on top of each other, they form layers. Over time the weight of the top layers creates pressure on the lower layers and presses them together.

Cementation is the process in which sediments are glued together by minerals that are deposited by water.

Part of Hall of Planet Earth. There are three kinds of rock: igneous, sedimentary, and metamorphic. Igneous rocks form when molten rock (magma or lava) cools and solidifies.

Cementation is the process in which dissolved minerals crystallize and glue particles of sediment together.

Many minerals may become cements; the most common is silica (generally quartz), but calcite and other carbonates also undergo the process, as well as iron oxides, barite, anhydrite, zeolites, and clay minerals.

Formation of Sedimentary Rocks Sedimentary rocks are the product of 1) weathering of preexisting rocks, 2) transport of the weathering products, 3) deposition of the material, followed by 4) compaction, and 5) cementation of the sediment to form a rock.

The most important agents of metamorphism include temperature, pressure, and fluids.

AGENTS OF METAMORPHISM – The agents of metamorphism include heat, pressure (stress), and chemically active fluids.

The main factors that control metamorphic processes are:

• The mineral composition of the parent rock.
• The temperature at which metamorphism takes place.
• The amount and type of pressure during metamorphism.
• The types of fluids (mostly water) that are present during metamorphism.
• The amount of time available for metamorphism.

There are two main ways that lithification occurs: compaction and cementation. We will also touch on a third way that is important to some sediments, called recrystallization.

gneiss

Examples of Index Minerals The most widely used index minerals are, in ascending order of pressure/temperature, are biotite, the zeolites, chlorite, prehnite, biotite, hornblende, garnet, glaucophane, staurolite, sillimanite, and glaucophane.

The various types of foliated metamorphic rocks, listed in order of the grade or intensity of metamorphism and the type of foliation are slate, phyllite, schist, and gneiss (Figure 7.8)….7.2 Classification of Metamorphic Rocks.

Marble forms when limestone experiences metamorphism. Usually, this happens at a convergent tectonic plate boundary, but some marble forms when hot magma heats limestone or dolomite. The heat or pressure recrystallizes calcite in the rock, changing its texture.

One of the reasons why these stones can be shaped so easily is that they are not considered to be hard materials. Compared to limestone, marble is affected by more heat beneath the Earth’s surface. For this reason, marble tends to be more compacted than limestone and as a result, is harder.

Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite rock. Pure white marble is the result of metamorphism of a very pure (silicate-poor) limestone or dolomite protolith.