The Qarhan
Salt Lake (QSL) in the Qaida
m Ba
sin in we
stern China i
s the large
st brine pota
sh depo
sit in the world. The for
mation of MgSO4-defificient evaporite
s in the QSL, whether fro
m the evaporation of river water
s with high Na+ and Cl− level
s, bacterial
sulfate reduction (BSR) in brine
s re
sulting in SO42− depletion, or the
mixing of the river and
spring water
s, re
main
s controver
sial. The δ34S value
s of 33 intercry
stalline brine
s and 10 gyp
su
m sa
mple
s fro
m a
sedi
ment core (ISL1A) collected in the QSL were pre
sented in thi
s study. Co
mbining the
se re
sult
s with previou
sly reported
major ionic concentration
s, total di
ssolved
solid
s (TDS) and δ34S value
s of difffferent water
s, and 87Sr/86Sr ratio
s of
sedi
ment
s, it wa
s concluded that (1) δ34S value
s of the intercry
stalline brine
s (+6.7‰ to +12.1‰) and gyp
su
m (+8.1‰ to +10.1‰)
sugge
sted that the BSR wa
s in
signifificant in the QSL. The
se value
s were do
minated by tho
se of inflflowing water
s and the evaporation proce
ss; (2) river water
s with high Na+ and Cl− level
s were unable to for
m MgSO4-defificient evaporite
s in the QSL. A
strong po
sitive correlation of Na and Cl equivalent
s coupled with high (Na+ + Cl−)/TDS ratio
s sugge
sted that the large a
mount of
solute
s in Gol
mud River water
s re
sult
s fro
m the di
ssolution of halite rather than the che
mical weathering of rock
s; and (3) the flflowing
sy
ste
m of the river and
spring in the pa
st 50 kyr wa
s si
milar to the
modern
supplying
system, and mixing of river and spring waters was responsible for the precipitation of evaporites in the QSL.