Two centuries of the granite problem: Debates, evolution, and implications

<p indent="0mm">Granite (sensu lato) is one of the most abundant and geologically significant rock types on Earth, and its petrogenesis has long been a central focus of geological research. The enduring debate surrounding the “granite problem” has spanned more than two centuries, not only giving rise to multiple theoretical schools but also significantly advancing geological theories and analytical techniques. This study systematically reviews the historical progression of scientific debates on the granite problem and explores their profound implications for geological theories and the broader development of the discipline. We first review the five major stages of debate on the granite problem: from the late 18th-century confrontation between Neptunism and Plutonism, to the disputes between the metamorphic-origin and magmatic-origin schools from the 19th century to the mid-20th century, followed by the mid-19th to late 20th-century debate over the “space problem” between the autochthonous and allochthonous models, the mid-20th-century discussions between differentiationists and anatexis advocates on the origin and evolution of granitic magma, and finally, the 21st-century frontier debates on magma chambers versus magma mush reservoirs. This study focuses on key scientific questions arising from these debates, including the material and heat sources driving magma generation, the crustal melting versus differentiation processes of mantle-derived magmas, the emplacement and assembly of large intrusions, and the crystallization differentiation and melt extraction in crystal mush systems. We then summarize the scientific evolution of granite research and discuss the crucial roles of technological advancements, interdisciplinary collaboration, and social needs in driving further progress in granite research. Furthermore, we analyze how these debates have fostered theoretical innovations and methodological advancements, emphasizing the role of academic discourse in shaping future granite research and the importance of integrating global perspectives with regional investigations. Finally, we highlight that the granite problem holds fundamental significance not only for Earth sciences but also for planetary geology, offering unique insights into the formation and evolution of extraterrestrial bodies.