Geology Reference
In-Depth Information
Table 3: Distribution of Hydrogeological Units in the country and their potential
Geologic Age
Stratigraphic Unit
Rock Formation
States/Hydrogeological Characters
Consolidated Formations
Jurassic
Upper Cretaceous
to Eocene
Rajmahal Traps,
Deccan Traps.
Occur in West Bengal, Bihar, Madhya Pradesh, Gujarat,
Maharashtra, Andhra Pradesh and Karnataka.
Hydrogeological characteristics almost similar. Fractured
and Vesicular basaltic layers and inter-trappean
sedimentaries are productive.
Yield up to 5 lps.
Storativity: 1 to 4%. Hydraulic conductivity 5 to 15
m/day. Unconfined shallow aquifers and leaky-confined/
confined deeper aquifers.
Occur in all States.
These formations are devoid of primary porosity.
Weathering and denudation, structural weak planes and
fractures impart porosity and permeability in the rock
mass. Solution cavities (caverns) in carbonate rocks at
places, give rise to large ground water storage/circulation.
The ground water circulation is generally limited within
100 m depth. Storativity value of unconfined aquifer is
generally low (0.2% to 3%). Hydraulic conductivity varies
widely depending on fracture incidence (2 to 10 m/day).
Leaky confined/confined aquifers may be present in
layered formations. Granites and granite-gneisses are the
most productive aquifers.
Yield range 2 to 10 lps and more.
Basalts, Dolerites,
Diorites and other acidic derivatives
of Basaltic magma.
Pre-Cambrian
Cuddapahas
Delhi and
Equivalent
Systems.
(a) Consolidated Sandstones,
Shales, Conglomerates.
(b) Limestones, Dolomites
(c) Quartzites, Marbles
(d) Intrusive Granites and Malani
Volcanics.
Archaean
Archaean Complex
Dharwars, Aravalis
and Equivalent
formations.
(a) Granites, Gneisses, Charnokites
and Khondalites
(b) Schists, Slates, Phyllites
Granulites.
(c) Banded Haematite Quartzites
(Iron ore series)
( Contd )
 
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