Upper Carboniferous Zhongwu Nongshan Group (C 3 )
It is mainly distributed in the southern foot of North Chaidan Mountains and
extends in the NWW direction. It consists of gray, gray-green, khaki and black
biotite Plagioclase schist, metamorphic sandstone, sericite phyllite, phyllite slate. It
has fault contact with the Upper Ordovician Tanjianshan Group (O 3 ). It is the main
stratum exposed by Reshuigou River.
Jurassic (J) stratum
It is distributed in the mouth of Datouyang Coal Mine, and mainly comprised of
grayish white, yellowish brown, yellowish green, brown conglomerate, sandstone,
shale coal seam and siderite concretion. It is generally formed by continuous
deposition with partial disconformity with Upper Jurassic Hongshuigou Formation.
It has fault contact with the underlying strata and local unconformable contact with
the Proterozoic Dakendaban Group or the Caledonian biotite granite. The visible
thickness exceeds 821 m.
– Quaternary strata
The Dachaidan Basin has been in a turbulent ascent since the Neogene period. In
particular, the northern Qaidam Mountains experienced strong uplifts than the
Luliang mountainous areas in the south of the Qaidam Basin. Due to relative
depression in the basin, a thick layer of Quaternary loose rocks is deposited in front
of each mountain. According to the geological-hydrogeological investigation and
the exposed strata in boreholes, the Quaternary loose deposits of different genesis
mainly include the Middle Pleistocene pro-glacial and alluvial deposits, Late
Pleistocene alluvial and pluvial deposits, and Holocene alluvial and lacustrine
deposits.
Middle Pleistocene stratum (Q 2
fgl−pl )
The stratum is mainly distributed on both sides of the modern riverbed of the
Baligou and Reshuigou Rivers. It gives rise to strips along the gully and cliffs of
10–30 m in the valley. It mainly consists of brownish yellow and brownish gray
muddy gravel and pebbles that are hardly sorted and poorly rounded. Some boulders are severely weathered. The main components include sandstone, granite,
quartzite and migmatite.
As exposed in the boreholes, the depth of the Baligou pluvial fan is about 76 m
in the mountain front and increases to about 100 m in the front edge. Due to the
limited depth of borehole, the formation is not fully exposed. The stratum has
pro-glacial and pluvial facies and looks yellow and khaki-yellow. The complex
components are hardly sorted and poorly rounded, wherein clay accounts for 15–
20% and sand 20%, and the rest are gravel and boulders.
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5 Application Cases
It is mainly distributed in the southern foot of North Chaidan Mountains and
extends in the NWW direction. It consists of gray, gray-green, khaki and black
biotite Plagioclase schist, metamorphic sandstone, sericite phyllite, phyllite slate. It
has fault contact with the Upper Ordovician Tanjianshan Group (O 3 ). It is the main
stratum exposed by Reshuigou River.
Jurassic (J) stratum
It is distributed in the mouth of Datouyang Coal Mine, and mainly comprised of
grayish white, yellowish brown, yellowish green, brown conglomerate, sandstone,
shale coal seam and siderite concretion. It is generally formed by continuous
deposition with partial disconformity with Upper Jurassic Hongshuigou Formation.
It has fault contact with the underlying strata and local unconformable contact with
the Proterozoic Dakendaban Group or the Caledonian biotite granite. The visible
thickness exceeds 821 m.
– Quaternary strata
The Dachaidan Basin has been in a turbulent ascent since the Neogene period. In
particular, the northern Qaidam Mountains experienced strong uplifts than the
Luliang mountainous areas in the south of the Qaidam Basin. Due to relative
depression in the basin, a thick layer of Quaternary loose rocks is deposited in front
of each mountain. According to the geological-hydrogeological investigation and
the exposed strata in boreholes, the Quaternary loose deposits of different genesis
mainly include the Middle Pleistocene pro-glacial and alluvial deposits, Late
Pleistocene alluvial and pluvial deposits, and Holocene alluvial and lacustrine
deposits.
Middle Pleistocene stratum (Q 2
fgl−pl )
The stratum is mainly distributed on both sides of the modern riverbed of the
Baligou and Reshuigou Rivers. It gives rise to strips along the gully and cliffs of
10–30 m in the valley. It mainly consists of brownish yellow and brownish gray
muddy gravel and pebbles that are hardly sorted and poorly rounded. Some boulders are severely weathered. The main components include sandstone, granite,
quartzite and migmatite.
As exposed in the boreholes, the depth of the Baligou pluvial fan is about 76 m
in the mountain front and increases to about 100 m in the front edge. Due to the
limited depth of borehole, the formation is not fully exposed. The stratum has
pro-glacial and pluvial facies and looks yellow and khaki-yellow. The complex
components are hardly sorted and poorly rounded, wherein clay accounts for 15–
20% and sand 20%, and the rest are gravel and boulders.
156
5 Application Cases