PT  - JOURNAL ARTICLE
AU  - Wang, Zhen
AU  - Shi, Yuruo
AU  - Yang, Tianshui
AU  - Anderson, J. Lawford
AU  - Hou, Chenyang
AU  - Kang, Yuelan
AU  - Peng, Wenxiao
AU  - Ma, Yiming
AU  - Bian, Weiwei
TI  - Constraints on the rollback of the Neo-Tethyan oceanic plate: Geochronology and geochemistry of volcanic rocks from the Dianzhong Formation, western Gangdese belt (Tibetan Plateau)
AID  - 10.2475/02.2022.10
DP  - 2022 Feb 01
TA  - American Journal of Science
PG  - 396--411
VI  - 322
IP  - 2
4099  - http://www.ajsonline.org/content/322/2/396.short
4100  - http://www.ajsonline.org/content/322/2/396.full
SO  - Am J Sci2022 Feb 01; 322
AB  - In this contribution, we report new U-Pb SHRIMP zircon ages and geochemical data for volcanic rocks from the Dianzhong Formation. The unit represents the lower part of the Linzizong volcanic succession located in the Shiquanhe area, western part of the Gangdese belt. Zircon U-Pb dating of three trachytes yields 206Pb/238U crystallization ages of 71.5±0.6 Ma, 70.8±1.0 Ma and 68.9±1.0 Ma. Whole rock major and trace element analyses indicate a main trend of calc-alkalic to high-potassic calc-alkalic, as well as an enrichment in large ion lithophile elements (LILEs), depletion in high field strength elements (HFSEs), with negative Nb, Ta and Ti anomalies. In addition, these volcanic rocks are enriched in LREE and depleted in HREE without a clear Eu anomaly. These geochemical features are similar to those of active continental margin volcanic rocks. In combination with previously published zircon U-Pb ages and geochemical data of the Dianzhong Formation, we suggest that the Linzizong volcanism started as early as the late Cretaceous (∼71 Ma) and the volcanic rocks of the Dianzhong Formation in the Shiquanhe area are the product of rollback of the Neo-Tethyan oceanic plate.