loading page

Ancient subcontinental ultra-depleted mantle-derived crust and its role in Phanerozoic magmatism of Central Asian Orogenic Belt
  • Huichuan Liu,
  • Gong-Jian Tang,
  • Weiming Fan
Huichuan Liu
College of Geosciences, China University of Petroleum, Beijing

Corresponding Author:[email protected]

Author Profile
Gong-Jian Tang
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences
Author Profile
Weiming Fan
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
Author Profile


Ultra-depleted mantle (UDM), characterized by Nd-Hf isotopically more depleted than mid-ocean ridge basalt, is ubiquitous beneath the oceanic crust, but no UDM has been reported underneath the continental crust. The Central Asian Orogenic Belt (CAOB) preserves large volumes of Phanerozoic granitoids with elevated εNd(t)–εHf(t) and is regarded as the largest site of Phanerozoic crustal growth on Earth. Ancient (ca. 1.7 Ga) subcontinental UDM with extremely high εNd(t)–εHf(t) values was identified beneath the CAOB for the first time based on finding of 1.7 Ga diorite intrusions with extremely high εNd(t), εHf(t) and δ18O values, and significant Nd-Hf isotope decoupling. Partial melting of 1.7 Ga subcontinental UDM produced widely distributed 1.7 Ga crust with ultrahigh εNd(t)–εHf(t) values, and subsequent episodic remelting of this crust generated the Phanerozoic high εNd(t)–εHf(t) granitoids in the CAOB. Phanerozoic crustal growth in accretionary orogens as exemplified by the CAOB may have been overestimated.