TITLE:
A Petrological, Geochemical, and Geochronological Study of Shuikou Ultrabasic Rock Mass in Wuding County, Yunnan Province, China
AUTHORS:
Bin Yang, Zizheng Wang, Qing Zhou, Xiaoliang Cui, Shengwei Wang
KEYWORDS:
Shuikou Rock Mass, Petrological Characteristics, Geochemical Characteristics, Geochronology, Wuding County, Yunnan Province
JOURNAL NAME:
Open Journal of Geology,
Vol.12 No.8,
August
17,
2022
ABSTRACT: Geotectonically, the Shuikou ultrabasic-basic rock mass is located on the western margin of the Yangtze Platform. As revealed by field geological surveys, the Shuikou rock mass intrudes into the quartz sandstones of the Sinian Chengjiang Formation (Zac). It is dominated by pyroxenites and can be roughly divided into four lithofacies zones, namely gabbros at the outermost periphery and fine-, medium-, and coarse-grained pyroxenites from margin to center. With the transition from pyroxenites to gabbros, the Shuikou rock mass features gradual enrichment in silica and alkali overall, an increase in ΣREE and (La/Yb)N ratio, and a decrease in δEu values and Eu/Sm ratio, indicating that the Shuikou rock mass was formed from the continuous differentiation and crystallization of consanguineous magma and that low-degree partial melting occurred meanwhile. According to the U-Pb baddeleyite geochronology, the crystallization age of the Shuikou rock mass is 210.7 ± 3 Ma (MSWD = 1.01). Based on this, as well as the analysis of geochemical characteristics, the Shuikou rock mass occurred in a continental intraplate tensional environment, this is closely related to the activities of the Emeishan mantle plume during the same period.