very slowly. There isn't really even a line that must be crossed which makes a sedimentary rock no longer a sedimentary rock. The process begins at burial, or perhaps even deposition, and is first called diagenesis. For the most part, diagenesis is the process that affects sediments in the conversion from loose particles to lithified mass, including recrystallization, neocrystallization (new minerals), and cementation. Diagenesis is dominantly a closed system process (well, semi-closed), meaning that the reactions do not involve the influx of lots of material from the outside (it is semi-closed because there is usually a lot of migration of material to the outside as the sediment pile dewaters). The appearance of minerals which are only stable at elevated temperatures (and/or pressures) is the usual division between diagenesis and metamorphism. that is, formation of minerals that cannot exist under near-surface conditions is the defining criterion for metamorphism rather than diagenesis. Lower temperature modifications to the sediment composition and mineralogy which result from a large flux of fluids are more rightly called alteration. Alteration can be thought of as metamorphism of sorts but that is a very gray area.
In one sense, diagenesis is a form of metamorphism, but it is generally not considered actual metamorphism by most people. It is usually considered still part of the sedimentation process. As a very general rule of thumb, things that occur under about 100 degrees C are typically thought of as diagenesis.
As the the "how", it is simply a case of change in pressure, temperature, and composition that causes the original mineralogy and texture of the sediment to undergo changes. the material gets pushed into a condition where the original mineralogy is no longer stable and thus changes to a more stable form.
Fundamentally, of course, that is even what happens when melting occurs. the liquid phase becomes more stable than the solid phase because of some changes in state (condition). Incipient melting would be an extreme instance of metamorphism, and there is even a bit of a gray area (a transition range) where a rock can be considered either or both metamorphic and igneous. In effect, only a small proportion of the rock mass would be igneous, with the remainder being metamorphic. As a bulk material, the rock tends to get called something like a migmatite or similar terms which indicate the presence of both melt and non-melt materials which have not generally segregated into distinct masses.
If you want your rock classification to be simple, where you only think of things in end-member terms, you are out of luck, because reality does not obey those on-off considerations.
There is no specific answer, inasmuch as there are different ways of achieving metamorphism. In general, metamorphism occurs when you do something to a rock that makes it substantially change its mineralogy, and/or texture, and/or fabric and/or bulk composition (which technically is metasomatism, but this is usually lumped in with metamorphism) in a (mostly) solid state. For a sedimentary rock, that would most likely happen either as a result of:
1) burial that subjected the rock to elevated pressure and temperature.
2) exposure to elevated temperature adjacent to an igneous intrusion.
3) extreme deformation and crushing along a fault.
Generally metamorphic rocks are same sedimentary rocks .In the section that tectonic shift slowly compress and push the rocks to ward up or down ,heat and pressure it combine the rocks together in very violent form even rock crystallize in form of quartz and ores that are contain sedimentary rocks deep inside during formation .
Answers & Comments
very slowly. There isn't really even a line that must be crossed which makes a sedimentary rock no longer a sedimentary rock. The process begins at burial, or perhaps even deposition, and is first called diagenesis. For the most part, diagenesis is the process that affects sediments in the conversion from loose particles to lithified mass, including recrystallization, neocrystallization (new minerals), and cementation. Diagenesis is dominantly a closed system process (well, semi-closed), meaning that the reactions do not involve the influx of lots of material from the outside (it is semi-closed because there is usually a lot of migration of material to the outside as the sediment pile dewaters). The appearance of minerals which are only stable at elevated temperatures (and/or pressures) is the usual division between diagenesis and metamorphism. that is, formation of minerals that cannot exist under near-surface conditions is the defining criterion for metamorphism rather than diagenesis. Lower temperature modifications to the sediment composition and mineralogy which result from a large flux of fluids are more rightly called alteration. Alteration can be thought of as metamorphism of sorts but that is a very gray area.
In one sense, diagenesis is a form of metamorphism, but it is generally not considered actual metamorphism by most people. It is usually considered still part of the sedimentation process. As a very general rule of thumb, things that occur under about 100 degrees C are typically thought of as diagenesis.
As the the "how", it is simply a case of change in pressure, temperature, and composition that causes the original mineralogy and texture of the sediment to undergo changes. the material gets pushed into a condition where the original mineralogy is no longer stable and thus changes to a more stable form.
Fundamentally, of course, that is even what happens when melting occurs. the liquid phase becomes more stable than the solid phase because of some changes in state (condition). Incipient melting would be an extreme instance of metamorphism, and there is even a bit of a gray area (a transition range) where a rock can be considered either or both metamorphic and igneous. In effect, only a small proportion of the rock mass would be igneous, with the remainder being metamorphic. As a bulk material, the rock tends to get called something like a migmatite or similar terms which indicate the presence of both melt and non-melt materials which have not generally segregated into distinct masses.
If you want your rock classification to be simple, where you only think of things in end-member terms, you are out of luck, because reality does not obey those on-off considerations.
There is no specific answer, inasmuch as there are different ways of achieving metamorphism. In general, metamorphism occurs when you do something to a rock that makes it substantially change its mineralogy, and/or texture, and/or fabric and/or bulk composition (which technically is metasomatism, but this is usually lumped in with metamorphism) in a (mostly) solid state. For a sedimentary rock, that would most likely happen either as a result of:
1) burial that subjected the rock to elevated pressure and temperature.
2) exposure to elevated temperature adjacent to an igneous intrusion.
3) extreme deformation and crushing along a fault.
4) extreme alteration by hydrothermal fluids.
Generally metamorphic rocks are same sedimentary rocks .In the section that tectonic shift slowly compress and push the rocks to ward up or down ,heat and pressure it combine the rocks together in very violent form even rock crystallize in form of quartz and ores that are contain sedimentary rocks deep inside during formation .
It doesn't. But part of a sedimentary bed can be rendered metamorphic by contact.
Intense heat and pressure cause re-crystallization.
yes
pressure and time