当代地球科学的两个前缘领域一个是地球的早期历史，一个是地球的深部过程，这两个问题都与花岗质岩石紧密相关。花岗质岩石主要由石英、斜长石和碱性长石组成，并因此具有较低的密度。这种性质决定了花岗质岩石具有正的浮力，记录了很长的地球演化历史。因此，花岗岩类是地质学最复杂的话题之一，因为其源区岩石多种多样和形成过程非常复杂。本文的目的是帮助普通旅游者识别花岗质岩石及其重要意义。通常，花岗岩（狭义）被定义为由石英( >20%，按体积计算 )和长石（碱性长石大于斜长石）组成的深成岩。但是，地质学家常常将特征与花岗岩（狭义）类似的深成岩称为花岗质岩石或花岗岩类，也就是广义花岗岩。因此，花岗岩类是深成岩的一个大类，包括象花岗闪长岩、二长花岗岩、正长花岗岩、英云闪长岩等这样的岩石。火成岩的多样性不仅仅取决于岩浆作用过程，而且也取决于岩浆形成过程。岩浆的产生是源区岩石部分熔融的结果，因而火成岩的化学成分取决于源区成分、熔融温度和压力、挥发分以及熔融程度。尽管岩浆作用过程对火成岩的成分具有重要影响，花岗质岩石多样性的关键因素却是部分熔融作用。基于此，岩石学家更注意花岗质岩浆的起源而不是它们的演化。花岗质岩浆虽然起源于地壳，却是受地幔热引擎的驱动。因此，花岗质岩石也记录了大量地球深部过程的信息。
The earth's early history and geological processes at depths are the two frontiers of geosciences both of which related to granitic rocks (granitoid). Granitic rocks mainly consist of quartz, plagioclase and alkaline feldspar and hence have lower densities. This feature decides the granitic rocks have positive buoyancy and the long history records of the earth's evolution. Therefore, granitoid is one of the most difficult topics in geology due to its complex sources and formation processes. This paper is used to help general tourists to recognize granitic rocks and their importance. Generally, the term granite is defined as a pluton which consists of quarts (>20vol %) and feldspar (alkaline feldspar > plagioclase). However, geologists often call the rocks with features similar to the granite as granitic rocks or granitoid. Therefore, the granitoid is a big group of plutonic rocks including such as granodiorite, monzonite, syenogranite, tonalite, and so on. The igneous diversity is not only induced by the magmatic processes but also by the processes caused production of magmas. The generation of magma is resulted from partial melting of the source rocks and the igneous chemistry is the function of the source composition, melting temperature and pressure, volatile, and melting degree. Despite the important effects of magmatic processes on the igneous compositions, the partial melting is the key of the diversity for the granitic rocks. Based on this, the petrologists pay more attentions to the origin of magmas instead to the evolution of granitic magmas. The granitic magma generated in the crust, but the generation is driven by the mantle thermal engine. So, granitic rocks recorded a great of information about the geological processes in the depths of the earth.
.2007. An Overview of Granitoid[J]. Geological Review,53(Supp):180-230.