Origin of Boron and Brine Evolution in Saline Springs in the Nangqen Basin, Southern Tibetan Plateau

Abstract

The Nangqen Basin is a typical shearing-extensional basin situated in the hinterland of the Tibetan Plateau. It contains abundant saline spring resources and abnormal trace element enrichments. The hydrochemical molar ratios (Na/Cl, B/Cl, and Br/Cl), H-O isotopes, and B isotopes of the saline spring were systematically measured to describe the evolution of brines and the origin of the boron. The sodium chloride coefficient of the water samples in this area is around 1.0 or slightly greater, which is characteristic of leached brines; the highest B/Cl value is 4.25 (greater than that of seawater). The Na/Cl, B/Cl, and Br/Cl values of the springs are clear indicators of a crustal origin. The18 O values of the spring waters range from −12.88‰ to −16.05‰, and the D values range from −100.91‰ to −132.98‰. Meanwhile the B content and B isotopes in the saline springs are in the ranges of 1.00 to 575.56 ppm and +3.55‰ to +29.59‰, respectively. It has been proven that the saline springs in the Nangqen Basin are a type of leached brine, suggesting that the saline springs have a terrestrial origin. The 11 B-B characteristics of the springs are similar to those observed in the Tibetan geothermal area, indicating that these two places have the same B source. Moreover, they have a crustal origin (marine carbonate rocks and volcanic rocks) instead of a deep mantle source.

Stable chlorine isotopes in saline springs from the Nangqen basin, Qinghai–Tibet Plateau: Brine genesis and evolution

“…11 B values of all samples are shown in tables 2 and 3 (Han et al 2018). The flow rates of the seven salt springs in this area are quite different, with the largest being 1.7 l/s and the smallest being 0.01 l/s.…”

“…For d 11 B, the d 11 B-B relationships were analysed and the results showed that the leaching from the surrounding rocks (marine carbonate rocks and volcanic rocks) are the main sources of the B isotopes in the saline springs. It is speculated that the saline springs in the Nangqen basin were leached from the underground salt layer during atmospheric precipitation or groundwater upwelling and then formed on the exposed surface (Han et al 2018). Table 2.…”

“…Table 2. Geochemical analysis of the saline springs, Nangqen basin, (cited from preliminary results, Han et al 2018).…”

“…The terrain of the Nangqen basin is very steep, causing a series of northwest-south-east fault zones. Many saline springs are exposed adjacent to the fault zones, and they are characterised by high salinities (salinity is greater than 150 g/l) and large distribution areas (10,000 km 2 ), which are most likely the result of the dissolution of the salt occurring underground (Han et al 2018). The study of the brine geochemistry can allow the geochemical information of the underground salt layer to be determined and help predict the salt formation and mineralisation.…”

Corrigendum to “Origin of Boron and Brine Evolution in Saline Springs in the Nangqen Basin, Southern Tibetan Plateau”

“…In the article titled "Origin of Boron and Brine Evolution in Saline Springs in the Nangqen Basin, Southern Tibetan Plateau" [1], there was an error in the order of the second and third affiliations. Additionally, the Laboratory name in the second affiliation should be changed from "Key Laboratory of Salt Lake Geology and Environment of Qinghai Province" to "Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes."…”