Abstract:

“Canyon and Danxia” is a composite landscape formed by both internal and external geological processes, and has great landscape and scientific value. The Lamu river in Hualong county (Qinghai Province) is a primary tributary of the Yellow River, where typical angular unconformity and Danxia landform are developed. This makes Hualong a suitable area for studying the Qinghai-Tibetan Plateau uplift and the Yellow River evolution. Aiming at elucidating its morphology, genesis, and chronology, this field study focuses on the rock formation, strata and tectonic setting of “Canyon and Danxia” landform. We systematically concluded the driving force and formation processes of the landscape in the Lamu canyon, and discussed its implications to the Qinghai-Tibetan Plateau uplift and the Yellow River evolution. The Lamu canyon is composed of the Neoproterozoic Hualong Complex gneiss (~900 Ma) and Paleogene Xining Group red glutenite (~54 Ma) with an angular unconformity. The Danxia landform in the canyon was developed when the Qinghai-Tibetan Plateau started uplifting at 8 Ma. After the Hualong Basin was cut by the Yellow River at 1.1 Ma, the canyon developed “Canyon and Danxia” landform via continuous river incision and gravitational collapse. The canyon is precipitous and the Danxia landform is lifelike, which are typical, unique and rare national-class geoheritage. It has important research value on the uplift of the Qinghai-Tibetan Plateau, the evolution of the Yellow River, and the Cenozoic climate and environment.

Key words: Geoheritage, Danxia landform, Canyon, Hualong Complex, Yellow River Valley, Hualong county, northeastern margin of the Qinghai-Tibetan Plateau