Late Pleistocene stratum (Q 3 )
It is widely distributed in the piedmont alluvial-pluvial fan and gullies. It can be
divided into pluvial deposits (Q 3
pl
) and alluvial-pluvial deposits (Q 3
al−pl ) according to
the genesis.
Pluvial deposits (Q 3
pl
) are mainly distributed in the rear edge of the piedmont
pluvial fan. As exposed in boreholes, they are 50–70 m thick in the rear edge
thickness and gradually increase to about 100 m in the front edge. They mainly
consist of sienna gravel and pebbles that hardly sorted, poorly rounded, and mostly
angular or sub-angular. Without clear layers, the complex components include are
sandstone, limestone, granite, and quartzite. Found in each borehole, this stratum
serves as the main aquifer of the pluvial fan, providing appropriate space for
groundwater endowment.
Alluvial-pluvial deposits (Q 3
al−pl ) are mainly distributed in the front edge of the
piedmont alluvial-pluvial fan and dominated by pluvial deposits. According to the
ground mapping and borehole data, from the mountain front to the front edge of the
fan, the deposits gradually change from gravel and pebbles to sand gravel and
gravel-contained coarse sand and their thickness also increases from 30–50 to 60–
80 m. The stratum is khaki-yellow and brown-yellow. The deposits are easy to sort,
and generally rounded, and largely sub-angular and sub-rounded. Better roundness
is observed near the front edge of the fan, creating horizontal bedding. The stratum
is the main aquifer for groundwater in the Baligou alluvial fan.
Holocene stratum (Q 4 )
The stratum is widely distributed in the study area, ranging from modern riverbed to
lake basin center. It can be divided into alluvial-pluvial deposits (Q 4
al−pl ),
alluvial-lacustrine deposits (Q 4
al−l ) and lacustrine deposits (Q 4
f ).
Alluvial-pluvial deposits (Q 4
al−pl ) are mainly found in terraces I–III of the
modern riverbed of the Baligou and Reshuigou Rivers, as well as the floodplains.
They are asymmetrically distributed and gradually thinned from the center of the
valley to the two sides. The thickness, restricted by the topography, varies from
place to place, ad generally ranges from 5 to 20 m. The main components include
sand gravel and gravel. Gray-yellow medium and coarse sand and fine sand are on
the top and gray-yellow gravel at the bottom, which presents a binary structure. The
gravel is imbricated and inclined on a flat surface, and forms obvious horizontal
bedding. It is well rounded to sub-angular and sub-rounded shape.
Alluvial-lacustrine deposits (Q 4
al−l ) are mainly distributed in the fine soil plain
belt at the front edge of the Balikou alluvial-pluvial fan. They gradually change
from grey and grey-black medium and coarse gravelly sand to sandy loam, mild
clay and clay, and form horizontal bedding.
Lacustrine deposits (Q 4
f ) are mainly distributed in the lacustrine plain in the
basin, and comprised of gray and grey-black fine sand, sandy loam, mild clay,
humus and silt. They are often found contiguous.
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It is widely distributed in the piedmont alluvial-pluvial fan and gullies. It can be
divided into pluvial deposits (Q 3
pl
) and alluvial-pluvial deposits (Q 3
al−pl ) according to
the genesis.
Pluvial deposits (Q 3
pl
) are mainly distributed in the rear edge of the piedmont
pluvial fan. As exposed in boreholes, they are 50–70 m thick in the rear edge
thickness and gradually increase to about 100 m in the front edge. They mainly
consist of sienna gravel and pebbles that hardly sorted, poorly rounded, and mostly
angular or sub-angular. Without clear layers, the complex components include are
sandstone, limestone, granite, and quartzite. Found in each borehole, this stratum
serves as the main aquifer of the pluvial fan, providing appropriate space for
groundwater endowment.
Alluvial-pluvial deposits (Q 3
al−pl ) are mainly distributed in the front edge of the
piedmont alluvial-pluvial fan and dominated by pluvial deposits. According to the
ground mapping and borehole data, from the mountain front to the front edge of the
fan, the deposits gradually change from gravel and pebbles to sand gravel and
gravel-contained coarse sand and their thickness also increases from 30–50 to 60–
80 m. The stratum is khaki-yellow and brown-yellow. The deposits are easy to sort,
and generally rounded, and largely sub-angular and sub-rounded. Better roundness
is observed near the front edge of the fan, creating horizontal bedding. The stratum
is the main aquifer for groundwater in the Baligou alluvial fan.
Holocene stratum (Q 4 )
The stratum is widely distributed in the study area, ranging from modern riverbed to
lake basin center. It can be divided into alluvial-pluvial deposits (Q 4
al−pl ),
alluvial-lacustrine deposits (Q 4
al−l ) and lacustrine deposits (Q 4
f ).
Alluvial-pluvial deposits (Q 4
al−pl ) are mainly found in terraces I–III of the
modern riverbed of the Baligou and Reshuigou Rivers, as well as the floodplains.
They are asymmetrically distributed and gradually thinned from the center of the
valley to the two sides. The thickness, restricted by the topography, varies from
place to place, ad generally ranges from 5 to 20 m. The main components include
sand gravel and gravel. Gray-yellow medium and coarse sand and fine sand are on
the top and gray-yellow gravel at the bottom, which presents a binary structure. The
gravel is imbricated and inclined on a flat surface, and forms obvious horizontal
bedding. It is well rounded to sub-angular and sub-rounded shape.
Alluvial-lacustrine deposits (Q 4
al−l ) are mainly distributed in the fine soil plain
belt at the front edge of the Balikou alluvial-pluvial fan. They gradually change
from grey and grey-black medium and coarse gravelly sand to sandy loam, mild
clay and clay, and form horizontal bedding.
Lacustrine deposits (Q 4
f ) are mainly distributed in the lacustrine plain in the
basin, and comprised of gray and grey-black fine sand, sandy loam, mild clay,
humus and silt. They are often found contiguous.
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