Upwelling of Mantle-derived Material in Southeast China: Evidence from Noble Gas Isotopes

Shallow groundwater collected in Chaozhou, Huizhou, and Guangzhou allowed testing of concentrations and the isotope ratios of noble gases. Based on the calculated noble gas temperature (NGT) and the ratio of noble gas isotopes, the recharge temperature, recharge source, and residence time of groundwater can be calculated. In addition, the contribution of noble gas components from different sources to the sample components can be assessed. In the Huizhou area, according to the 1/Xe vs. Ne/Xe and NGT data, the shallow sandstone-confined water samples in the Shiba area and the unconfined water samples of the Huangshadong are in different temperature ranges, indicating that they have different recharge sources, both in time or space. The He components in the samples are calculated to obtain the content of radiogenic 4He in the crust and to simulate the groundwater ages. The noble gas isotope ratios show the addition of mantle components into the basalt aquifers and sandstone aquifers in Chaozhou and Huizhou. Except for atmospheric and crustal sources, there is a certain proportion of mantle-derived components in the shallow underground cold water in Huizhou and Chaozhou. The noble gases in the Chaozhou groundwater have an obvious mantle signature, allowing speculation that there is a deep fluid carrying mantle characteristics. This upwelling of mantle-derived material might be caused by the India-Eurasia collision or that between the Philippine Sea Plate and the Eurasian Plate.