No.3

       Location (geographic coordinates): E102° 54' 13.172", N31° 6' 43.495"

       Geological period: Cenozoic

       Type of geological interests: Geomorphology

       Level of significance: International

       Geological description: The site comprises four contiguous snow-capped peaks: Dafeng Peak(Eldest Sister Peak), Erfeng Peak (Second Sister Peak), Sanfeng Peak (Third Sister Peak), and Yaomei Peak(Youngest Sister Peak), all of which are over 5,000 m in elevation. Among them, Yaomei Peak, at 6,247.80 meters, is the second highest peak in Sichuan and is known as the “Queen of the Mountains in Sichuan”. The mountain body of Yaomei Peak and Sanfeng Peak (5,355 m) is composed of granite, Erfeng Peak (5,276 m) is formed from quartzite and quartz sandstone, and Dafeng Peak (5,025 m) consists of limestone, sandstone, and slate.

       Approximately 220 to 190 million years ago, the compression of the Songpan-Garzê and other blocks against the Yangtze Block led to partial melting in the upper crust about 20 km deep in this region, forming the Daofu-Jinwan-Xiaojin-Heishui tectonic magmatic belt. The granitic bodies resulting from the intrusion of intermediate-acidic magma into the crust form the main body of Mt. Siguniang, establishing its material foundation. The differences in the lithology of the intrusions resulted in various forms of horn peaks due to Quaternary glacial erosion.

       The composite granite body that constitutes the main part of Mt. Siguniang is distributed around the central section of the Qionglai Mountains. This composite body is exposed on the surface in a near north-south orientation and intrudes into Paleozoic metamorphic sandstone, mudstone, carbonate rocks, volcanic rocks, and Triassic metamorphic sandstone. The body extends about 30 km north-south, 10–20 km east-west, with an area of approximately 420 km². It consists of several intrusive bodies of the Siguniangshan pluton and the Niuxingou pluton, which are in a pulsating contact relationship. The rock types are complex, including biotite granite, monzonite granite, orthogneiss, quartz monzonite, biotite-hornblende monzonite, hornblende monzonite, monzonite, quartz monzonite, and porphyritic monzodiorite. 

The extremely high peaks of Mt. Siguniang and distribution map of granites in the eastern Songpan-Garzê Terrane (after Roger et al., 2004; Zhang et al., 2006; Xiao et al., 2007; Yuan et al., 2010, 2011; Duan et al., 2013; Chen et al., 2017; Zheng et al., 2020; Zhou et al., 2020; Liu et al., 2021; Gao et al., 2023)

     Justification for International Significance: Mt. Siguniang is situated at a critical area where the Qinghai-Tibet Plateau abruptly drops into the Sichuan Basin, located at the junction of the Songpan-Garzê Terrane and the Yangtze Block in China. It provides a complete record of the uplift process and mechanisms of the Qinghai-Tibet Plateau. The composite granite body of Mt. Siguniang captures deep-seated dynamic information on the formation of the Songpan-Garzê Orogenic Belt, offering valuable insights into key issues such as the magmatic activity mechanisms of orogenic belts, crust-mantle interactions, crustal properties, and the evolution of orogenic belts.

Representative literature：
a) Pei, S., Niu, F., Ben-Zion, Y., Sun, Q., Liu, Y., Xue, X., ... & Shao, Z. (2019). Seismic velocity reduction and accelerated recovery due to earthquakes on the Longmenshan fault. Nature Geoscience, 12(5), 387-392.

b) Wang, J., Wang, W., Cao, B., Cui, H., Chen, X., Qiu, J., ... & Liao, J. (2023). Millennial-scale glacier fluctuations on the southeastern Tibetan Plateau during MIS 2. Earth and Planetary Science Letters, 601, 117903.

c) Pan, Y., & Shen, W. B. (2017). Contemporary crustal movement of southeastern Tibet: Constraints from dense GPS measurements. Scientific Reports, 7(1), 45348.

d) Zhao, H., Zhang, Y., Li, Q., Du, W., Zhang, Y., & Guo, Z. (2020). Early Jurassic I-type garnet leucogranite in the Siguniangshan pluton, eastern margin of the Songpan-Ganze terrane (NE Tibet), and its tectonic implications. Journal of Asian Earth Sciences, 188, 104079.

e) Xiao, L., Zhang, H. F., Clemens, J. D., Wang, Q. W., Kan, Z. Z., & Wang, K. M., et al. (2007). Late triassic granitoids of the eastern margin of the tibetan plateau: geochronology, petrogenesis and implications for tectonic evolution. Lithos, 96(3-4), 436-452.

f) Sigoyer, J. D., Vanderhaeghe, O., Duchene, S., & Billerot, A.. (2014). Generation and emplacement of triassic granitoids within the songpan ganze accretionary-orogenic wedge in a context of slab retreat accommodated by tear faulting, eastern tibetan plateau, china. Journal of Asian Earth Sciences, 88(jul.1), 192-216.