变质岩形成时岩石(沉积岩、火成岩或以前的变质岩)在高压力和/或温度。压力和温度力的原子形成新矿物,从而一种新的岩石。它不是必要的支离破碎,但岩石,而变形通过*再结晶*到一个新的国家在应对压力和温度的材料重新组织。(再结晶)[1]不删除任何材料,它仅仅是一个物理重组紧凑的岩石。如果发生一些化学成分的变化,这叫做“交代”。(交代)[2]原子其实从岩石或形成的一部分,经常涉及水。好(岩石学家)[3]通常可以确定什么样的母岩,* *原岩,变质和到什么程度,但有时很难识别的区别。较低程度的变质,保存原始岩石的特性。例如你可以看到涟漪,甚至化石石板从源岩或变形结构,但在更高程度的metamorpism越来越难以想象母质的样子。片麻岩形成的砂岩和花岗岩可以非常相似lihology代表变质的条件,而不是原岩。 It can also be difficult to recognize a metamorphic rock. A weathered slate and shale or even granite and gneiss can appear very similar in the field. However, the processes to form the rocks are different and with a closer look at the minerals it can be possible to understand what kind of process that formed the rock. [![Metamorphic phases][4]][4] *(1, Blueschist facies 2, Eclogite facies 3, Prehnite-pumpellyite-facies 4, Greenschist facies 5, Amphibolite-facies 6, Granulite facies 7, Zeolite facies 8, Albite-epidote-hornfels facies 9, Hornblende-hornfels facies 10, Pyroxene-hornfels facies 11, Sanidinite facies)* The temperature and pressure determine what metamorphic rock you get, but the chemical composition is inherited from the protolith. Degrees of metamorphism are called metamorphic *facies*. This diagram shows at what depth and temperature a particular rock is formed. Igneous rocks are formed when a melt hardens to crystals and sedimentary rocks are formed from sediments. All rocks weather if exposed to water and air, and weathered material is transported by rivers to oceans where sandstone can be formed from the sand at the beach and shale from the finer sediments further away from the coast. Igneous rocks can be formed as hot magma intrudes the crust and slowly cools down and minerals are formed or form lava at volcanoes. This is known as the rock cycle and is one of the fundamental, but complicated, concepts in geology. You can read more about the rock cycle e.g. [here][5] to learn more about rock types and how they are formed. [1]: https://en.wikipedia.org/wiki/Recrystallization_(geology) [2]: https://en.wikipedia.org/wiki/Metasomatism [3]: https://en.wikipedia.org/wiki/Petrology [4]: https://i.stack.imgur.com/wcisW.png [5]: http://www.cotf.edu/ete/modules/msese/earthsysflr/rock.html