temperature, pressure, and pressure of fluid in rock
The temperature of melting of rock depends on the chemical and mineralogical composition of the rock. Melting of rocks is complex and to understand it you need to know about eutectics and partial melts.
It depends upon nature of rock.
erosion and weathering heat and pressure melting and solidification
It depends on the rock. Different minerals have different melting points.
It depends on the rock type- different rock types have different melting temperatures (magma is molten rock) ie the rock called peridotite melts to produce basaltic magma. Other types of magma include rhyolitic and andesitic, which each come from different types of rock. And also it depends on the pressure at which the rock/magma is held at ie the deeper you go down into the earth, the higher a temperature would need to be to induce melting. It is too complicated to just say all magma has the same melting temperature, sorry.
decompression of rock
Melting causes an igneous rock to form into lava/magma.
When the temperature reaches the lowest melting point of the mineral or minerals of which the rock is made.That depends entirely on what type of rock you have, and what it's made up of. Different substances have different melting points. Igneous rock has the highest, which means they don't melt easily. You'd have to know what types of materials are in the rock and look up their respective melting points in a chemistry book, or online. There is no one single answer to your question.
There are three ways to melt rock to form lavas. You can use decompression, add volatiles, or conduction. All you need to do is use these strategies to get the rock to its melting point.
Water reduces the melting point of rock.
The melting of metamorphic or igneous rock forms magma.
I'm not sure if you mean melting rock or meltedrock, but melted rock is called lava, and if you knew what lava was, now you know what it really is!
Rock metamorphism does not involve melting and cooling from melt. A rock that has melted can only become an igneous rock.
Mineral composition of the rock, and the temperature and pressure it is exposed to, would determine the melting point of a particular rock.
An igneous rock
Yes. Rock can be liquified by raising its temperature to that of the melting point of the mineral constituent with the highest melting point.
by melting and cooling
By melting, then solidifying.
By melting and cooling