The occurrence and relative stability of metamorphic allanite and monazite in metapelites of the Greater Himalayan Sequence (GHS) in the Dhauliganga valley, Garhwal Himalaya have been studied. The GHS is marked by kyanite grade metamorphism in the lower and middle structural levels and sillimanite grade metamorphism in the upper structural level. The occurrence of allanite is restricted to the lower structural level, while monazite occurs in the middle and upper structural levels. The allanite-out reaction occurred at ∼660 °C and 9.5 kbar. Monazite shows widely varying ThO2 content which can be explained mostly by brabantite substitution. The rocks of the GHS of the Dhauliganga valley display inverted metamorphic sequence and the allanite-out reaction is the result of prograde metamorphism.

中文翻译：

---

Garhwal喜马拉雅Dhauliganga山谷大喜马拉雅层序中Allanite和Monazite的赋存和稳定性

研究了大喜马拉雅层序（GHS）变质泥岩中变质褐铝石和独居石的赋存和相对稳定性，这些变质岩位于 Garhwal 喜马拉雅山 Dhauliganga 山谷。GHS的标志是中下构造层次蓝晶石级变质作用和上构造层次硅线石级变质作用。褐铝石的产状仅限于下层构造，而独居石则产于中上层构造​​。丙纶析出反应发生在~660 °C 和 9.5 kbar 下。独居石显示出变化很大的 ThO2 含量，这主要可以通过布拉班特取代来解释。Dhauliganga 河谷 GHS 的岩石显示出倒变质层序，并且出层石反应是顺变质作用的结果。