Post-Collisional, Potassic Volcanism in the Saga Area, Western Tibet: Implications for the Nature of the Mantle Source and Geodynamic Setting

Zhao, Hui1,2,3; Yang, Jingsui3; Liu, Fei3; Huang, Jian4; Zhang, Li5

2019-06

10.1007/s12583-019-1228-7

Journal of Earth Science   影响因子和分区

1674-487X

1867-111X

Post-collisional potassic and ultrapotassic volcanic rocks are widely distributed across the Tibetan Plateau, and they are considered to be indicators of evolving mantle dynamics. A suite of potassic basalts younger than 55 Ma from the Saga area of western Tibet has been reported. The geochemical characteristics of these rocks distinguish themselves from other potassic-ultrapotassic volcanic rocks in Tibet, such as positive Nb, Ta, and Ti anomalies and strong enrichment in large ion lithophile elements (LILE), suggesting that phlogopite, rutile and/or sphene might have originated from the mantle source. These basalts are also characterized by a very wide range of Sr-87/Sr-86 ratios (0.709 043-0.711 915) and relatively high Nd-143/Nd-144 ratios (0.512 426-0.512 470, epsilon(Nd)= -4.60 to -3.87). We propose a petrogenetic model for the Saga potassic rocks in which the lithospheric mantle source was infiltrated by a volatile-rich (H2O, CO2) and low-degree silicate melt derived from the asthenosphere in the Middle to Late Proterozoic. After the initial Indo-Asian collision, Neo-Tethyan slab breakoff resulted in the partial melting of the previously metasomatized lithospheric mantle and the formation of the Saga potassic rocks. It is likely that the eruption of these volcanic rocks lasted at least 10 Ma.

potassic volcanic rocks basalt Sr-Nd isotopes Saga area western Tibet

SCI ; CPCI-S

英语

第一

National Natural Science Foundation of China[41720104009] ; National Natural Science Foundation of China[41672063] ; National Natural Science Foundation of China[41773029]

Geology

Geosciences, Multidisciplinary

WOS:000471195700012

CHINA UNIV GEOSCIENCES, WUHAN

Web of Science

1.Southern Univ Sci & Technol, Harbin Inst Technol, Harbin 150001, Heilongjiang, Peoples R China
2.Southern Univ Sci & Technol, Dept Earth & Space Sci, Shenzhen 518055, Peoples R China
3.Chinese Acad Geol Sci, Inst Geol, Minist Nat Resources, Key Lab Deep Earth Dynam, Beijing 100037, Peoples R China
4.Yunnan Tuocheng Ind Co, Kunming 650051, Yunnan, Peoples R China
5.Chinese Acad Geol Sci, Inst Geophys & Geochem Explorat, Key Lab Geochem Cycling Carbon & Mercury Earths C, Langfang 065000, Peoples R China

Zhao, Hui,Yang, Jingsui,Liu, Fei,et al. Post-Collisional, Potassic Volcanism in the Saga Area, Western Tibet: Implications for the Nature of the Mantle Source and Geodynamic Setting[J]. Journal of Earth Science,2019,30(3):571-584.

Zhao, Hui,Yang, Jingsui,Liu, Fei,Huang, Jian,&Zhang, Li.(2019).Post-Collisional, Potassic Volcanism in the Saga Area, Western Tibet: Implications for the Nature of the Mantle Source and Geodynamic Setting.Journal of Earth Science,30(3),571-584.

Zhao, Hui,et al."Post-Collisional, Potassic Volcanism in the Saga Area, Western Tibet: Implications for the Nature of the Mantle Source and Geodynamic Setting".Journal of Earth Science 30.3(2019):571-584.