Occurrence and Hydrochemical Characteristics of Saline and Salty Springs in the Sichuan Basin of China

Water samples from saline and salty springs (geothermal wells, n=64) with TDS of 2-83 g/L and temperature of 19-95°C were collected in the Sichuan Basin to explore the factors controlling the occurrence of the springs and the differences in hydrochemistry. The saline and salty springs mostly emerge...

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Main Authors: Juan Guo, Xun Zhou, Yuqi Zhang, Mingming Ta, Yuan Wang
Format: Article
Language:English
Published: Wiley 2019-01-01
Series:Geofluids
Online Access:http://dx.doi.org/10.1155/2019/8671973
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author Juan Guo
Xun Zhou
Yuqi Zhang
Mingming Ta
Yuan Wang
author_facet Juan Guo
Xun Zhou
Yuqi Zhang
Mingming Ta
Yuan Wang
author_sort Juan Guo
collection DOAJ
description Water samples from saline and salty springs (geothermal wells, n=64) with TDS of 2-83 g/L and temperature of 19-95°C were collected in the Sichuan Basin to explore the factors controlling the occurrence of the springs and the differences in hydrochemistry. The saline and salty springs mostly emerge at the margin of the basin where fault zones or anticlines occur, which are clearly controlled by the regional tectonic trend. The springs are mainly of SO4-Na type in the western basin, SO4-Ca·Na and HCO3-Na type in the southwestern basin, Cl-Na and Cl·SO4-Na type in the northeastern basin, and SO4-Ca type in the eastern basin. Good correlation between Na and Cl, Ca and SO4, and Mg and SO4 suggests that the major ions of springs in the Sichuan Basin are from incongruent dissolution of halite, gypsum, dolomite, and magnesium sulfate minerals present in the outcropping Cretaceous and Triassic and Permian strata (sandstone, gypsum, or anhydrite layers or lens) in the western basin. The presence of marine carbonate (limestone and dolomite) interbedded with evaporites (gypsum and halite) in the eastern basin explains the good correlations between SO4 and Ca and between Na and Cl. The groundwater is continuously heated by geothermal heat flow. A conceptual model for the formation of the saline and salty springs is proposed that hypothesizes meteoric water infiltrates in the core of anticlines that occur in the carbonate rocks with fractures or in the fault zones. The water flows into the limbs of the anticlines or deep aquifers along fault planes. During its subsurface transport, incongruent dissolution of carbonates and evaporites (including anhydrite and halite) in the Lower and Middle Triassic strata occurs and the groundwater is heated. The discharge areas are often in the low-lying areas along the limbs of anticlines where carbonate rocks crop out, in the low-lying areas of local river valleys that cut noncarbonate rocks, or in the Yangtze Valley and its tributaries where groundwater flows upward through the Upper Triassic clastic rocks.
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spelling doaj-art-4b3eacf8c3bf4588bb5a147bbfb215642025-08-20T02:38:33ZengWileyGeofluids1468-81151468-81232019-01-01201910.1155/2019/86719738671973Occurrence and Hydrochemical Characteristics of Saline and Salty Springs in the Sichuan Basin of ChinaJuan Guo0Xun Zhou1Yuqi Zhang2Mingming Ta3Yuan Wang4School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, ChinaSchool of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, ChinaSchool of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, ChinaSchool of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, ChinaSchool of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, ChinaWater samples from saline and salty springs (geothermal wells, n=64) with TDS of 2-83 g/L and temperature of 19-95°C were collected in the Sichuan Basin to explore the factors controlling the occurrence of the springs and the differences in hydrochemistry. The saline and salty springs mostly emerge at the margin of the basin where fault zones or anticlines occur, which are clearly controlled by the regional tectonic trend. The springs are mainly of SO4-Na type in the western basin, SO4-Ca·Na and HCO3-Na type in the southwestern basin, Cl-Na and Cl·SO4-Na type in the northeastern basin, and SO4-Ca type in the eastern basin. Good correlation between Na and Cl, Ca and SO4, and Mg and SO4 suggests that the major ions of springs in the Sichuan Basin are from incongruent dissolution of halite, gypsum, dolomite, and magnesium sulfate minerals present in the outcropping Cretaceous and Triassic and Permian strata (sandstone, gypsum, or anhydrite layers or lens) in the western basin. The presence of marine carbonate (limestone and dolomite) interbedded with evaporites (gypsum and halite) in the eastern basin explains the good correlations between SO4 and Ca and between Na and Cl. The groundwater is continuously heated by geothermal heat flow. A conceptual model for the formation of the saline and salty springs is proposed that hypothesizes meteoric water infiltrates in the core of anticlines that occur in the carbonate rocks with fractures or in the fault zones. The water flows into the limbs of the anticlines or deep aquifers along fault planes. During its subsurface transport, incongruent dissolution of carbonates and evaporites (including anhydrite and halite) in the Lower and Middle Triassic strata occurs and the groundwater is heated. The discharge areas are often in the low-lying areas along the limbs of anticlines where carbonate rocks crop out, in the low-lying areas of local river valleys that cut noncarbonate rocks, or in the Yangtze Valley and its tributaries where groundwater flows upward through the Upper Triassic clastic rocks.http://dx.doi.org/10.1155/2019/8671973
spellingShingle Juan Guo
Xun Zhou
Yuqi Zhang
Mingming Ta
Yuan Wang
Occurrence and Hydrochemical Characteristics of Saline and Salty Springs in the Sichuan Basin of China
Geofluids
title Occurrence and Hydrochemical Characteristics of Saline and Salty Springs in the Sichuan Basin of China
title_full Occurrence and Hydrochemical Characteristics of Saline and Salty Springs in the Sichuan Basin of China
title_fullStr Occurrence and Hydrochemical Characteristics of Saline and Salty Springs in the Sichuan Basin of China
title_full_unstemmed Occurrence and Hydrochemical Characteristics of Saline and Salty Springs in the Sichuan Basin of China
title_short Occurrence and Hydrochemical Characteristics of Saline and Salty Springs in the Sichuan Basin of China
title_sort occurrence and hydrochemical characteristics of saline and salty springs in the sichuan basin of china
url http://dx.doi.org/10.1155/2019/8671973
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