In the Borong Gneiss Dome and Malashan Gneiss Dome within the Tethyan Himalaya, zircon UPb ages and whole-rock geochemical data demonstrate that at least two episodes of leucogranite formed at 19.8–19.4 Ma and 18.6–18.5 Ma, respectively. Each of them contains at least two suites of granite: two-mica granite and garnet-bearing leucogranite. Although the two types of granites are characterized by distinct element geochemistry and mineral compositions, they show similar Sr-Nd-Hf isotope ratios and regular variations in the compositions of whole-rock elements. From two-mica granite to garnet-bearing leucogranite, SiO₂, Na₂O, Rb, Nb, and Ta contents and Rb/Sr ratios increase; in contrast, Al₂O₃, CaO, MgO, FeO, TiO₂, Sr, Ba, Eu, Zr, U, Th, light rare earth elements (LREEs) and Sc contents, as well as Zr/Hf and Nb/Ta ratios, decrease. Such systematic variations imply that two-mica granite and garnet-bearing leucogranite are cogenetic and that two-mica granite represents the more primary melt, whereas garnet-bearing leucogranite is a more evolved melt. During granitic magma evolution, fractional crystallization induces substantial changes in the melt structure and in turn major changes in the dissolution behavior of accessory phases (e.g., zircon, monazite, and apatite) and the geochemistry of key trace elements. Such changes might be the key factors that resulted in the subordinate W-Sn-Nb-Ta-Be anomalies in the more evolved granites, which implies that the Himalayan Cenozoic leucogranites have high potential to produce economic rare metal deposits.

在特提斯喜马拉雅山内的博龙片麻岩穹窿和马拉山片麻穹窿，锆石U Pb年龄和全岩地球化学数据表明，至少在19.8-19.4 Ma和18.6-18.5 Ma形成了至少两集白花岗岩。它们中的每一个都包含至少两套花岗岩：两云母花岗岩和含石榴石的白花岗岩。尽管这两种类型的花岗岩具有不同的元素地球化学和矿物组成，但它们显示出相似的 Sr-Nd-Hf 同位素比和全岩元素组成的规律变化。从二云母花岗岩到含石榴石的淡色花岗岩，SiO ₂、Na ₂ O、Rb、Nb、Ta含量和Rb/Sr比值增加；相比之下，Al ₂ O ₃、CaO、MgO、FeO、TiO₂、Sr、Ba、Eu、Zr、U、Th、轻稀土元素 (LREEs) 和 Sc 含量，以及 Zr/Hf 和 Nb/Ta 比值降低。这种系统变化意味着双云母花岗岩和含石榴石的暗色花岗岩是共生的，双云母花岗岩代表更初级的熔体，而含石榴石的暗色花岗岩是更进化的熔体。在花岗岩岩浆演化过程中，分步结晶导致熔体结构发生重大变化，进而导致副相（如锆石、独居石和磷灰石）的溶解行为和关键微量元素的地球化学发生重大变化。这种变化可能是导致演化程度较高的花岗岩中出现次要的W-Sn-Nb-Ta-Be异常的关键因素，这意味着喜马拉雅新生代淡色花岗岩具有很高的生产经济性稀有金属矿床的潜力。