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The Geological Mapping can be designated as the pioneer worker of all geological activities. Geological Mapping and Quaternary Geology Branch provides the baseline geoscientific expertise through field investigations, acquired field data and information, geological reports, geological and derivative maps. The report and maps are very important to evaluate the geological condition, mineral potential, present and future hazards etc of the area. Now a day, it is very important to acquire geological knowledge of an area to carry out sustainable development activities and any type of mineral exploration activities. It is also useful for the future development planning and sustainable infrastructure construction, combating hazards of an area especially for industrial growth and development, heavy construction, urban planning, roads and highway construction and all types of mineral exploration. Planners, developers, government, semi-government and non government organisations and researchers are the main users of the geological reports and maps for the sustainable developments of an area.

 

Responsibilities

 

1.        To prepare geological maps of the country at a usual scale of 1:50,000,

2.        To prepare geological report of an area or a structure,

3.        To carry out exploration works for surficial and near to surface economic mineral deposits,

4.        To develop a modern mapping technique suitable for the country,

5.        To establish the Quaternary Stratigraphy of the country,

6.        To carry out research works on the Quaternary events and episodes,

7.        To carry out investigation for fixing the base of the Quaternary Era,

8.        To carry out investigations on the geological hazards like river erosion, river course shifting, water stagnancy, river bed siltation etc,

9.        To investigate the neotectonic activities,

10.     To investigate primarily the arsenic contamination of an area,

11.     To extend geological supports to other government organizations, universities, NGOs, local government bodies etc,

12.     To share knowledge with the persons and organizations locally and internationally working in this field.

 

Achievements

 

Geological Maps & Reports

 

Mapping Branch initially started with 1:250 000 mapping scale to cover Bangladesh and mapped of an area 83 290 sq km. But in the 1980s, this branch soon realized to prepare geological map upazila-wise at a more usable scale of 1:50 000. Since than, this branch has so far been completed mapping of about  94 624 sq km areas in 1:50 000 scale. Besides preparation of maps, geological reports were also prepared and submitted.

 

 

Scale : 1 : 50 000

Mapped Area

(in Sq km)

1. Completed Mapped Area except Coastal Part

61 334

2. Completed Mapped Area of Coastal Part

33 290

Total Completed Mapped Area

94 624

3. Unmapped Area

52 946

 

During field investigation, other information on economic minerals deposits, causes of environmental degradation, hazards etc were also collected and reported. All the Geological Maps and Reports are available in the Data Centre of the Geological Survey of Bangladesh and can only be issued with due permission.

 

Economic Mineral Discovery

 

Being the pioneer investigator in an area, almost all the surficial and near-surficial economic mineral deposits have so far been discovered by the geologists of this branch. The important deposits are White clay, Glass sand, Heavy minerals, Peat, Transported coal, Pebbles & gravels, Construction sands, Brick clays etc. Country is getting benefit from those discoveries.

 

Activities

 

Present Activities

 

Geological survey of Bangladesh is presently implementing the project - “Geological exploration for the identification of mineral resources and the areas vulnerable to natural hazards in the coastal parts of Bangladesh. Geological Mapping and Quaternary Geology Branch is engaged with the project. The geoscientists of this branch are fulltime engaged in the coastal geological mapping to achieve the project objectives. The achievements till today are as follows-

 

A. Field Investigation - The entire coastal belt of Bangladesh, covering an area of 33 290 sq km, has been investigated regionally. During investigation, all the possible Geo-information as below as 100 meters have been tried to collect. Samples were collected systematically to perform various types of laboratory analyses. On the basis of the acquired data from regional investigation, few areas are selected for intensive study and sampling.

 

1. Geological Mapping – During field investigation, the prepared base maps consisting of geological map units, geomorphic features, land-water boundary, different types of infrastructures etc are corrected in the field.

2. Boring & Logging – About 550 lithological logs have been prepared through shallow boring up to 80 meters, mechanical boring up to 100 meters, auger boring and pitting through out the coastal belt. Moreover, about 50 Geophysical logging have been conducted in selected boreholes.

3. Sample Collection – More than 4000 sediment samples from different depths (up to 100 meters) below the surface have been collected for multi-dimensional laboratory analyses to unveil the hidden secrets of the coastal evolution. Besides regular sampling by the Mapping parties, intact samples, >1000 samples from 35 boreholes, up to a depth of 100 meters have been collected from different parts of the coastal belt of Bangladesh.

4. Fresh-water Aquifer Investigation – During the geological mapping in the coastal belt, the field parties noticed that the people of few areas, especially southwestern coastal part, are suffering intensively from drinking water. Both the surface and known sub-surface water sources are saline in this area. With the view to solve the problem, Geological Mapping Branch has undertaken a program to investigate the fresh water aquifer in the southwestern part of the coastal belt of Bangladesh to resolve the acute scarcity of Potable water. In the first phase the area under Koira, Paikgacha and Dacop upazilas of greater Khulna district has been investigated. Two potential fresh-water aquifers below 300 meters have been identified.

5. Economic Minerals Identification – During field survey, possible mineral deposits of economic importance have so far been identified in the coastal belt of Bangladesh.

 

 

Sl. No.

Type of deposits

Locality

1

Heavy minerals

(Radio-active Minerals)

In the beach deposits of Teknaf, Cox’sbazar sadar, Sonadia island, Materbari, Kutubdia island, Nijhumdwip, Bhola island, Kuakata and Kawar char.

2

Glass sand

In the valleys of Moheshkhali island, Pekua, Banskhali, Anowara and Chakaria

3

White clay

In small lenses of the hilly terrains of Ramu, Ukhia, Moheshkhali, Pekua, Banshkhali, Anowara and Chakaria

4

Tiles clay

In different areas of the Coastal Plain of Satkhira district

5

Peat

In the depressions of Gopalganj, Khulna, Bagerhat and Cox’sbazar districts (Pekua upazila) and  Kutubdia island

6

Construction sand

Teknaf, Cox’sbazar sadar, Moheshkhali, Pekua, Banshkhali, Anowara, Chakaria, Chittagong, Feni, Bhola and Barishal

7

Gravel and Construction Sands

Teknaf, Cox’bazar Sadar, Ukhia, Moheshkhali, Banshkhali,

8

Brick clay

In different areas of the Tidal floodplains of coastal area.

 

 

6. Identification of Hazards – The coastal belt of Bangladesh, due to its geographical position and geologic condition,experiences different types of hazards every year. Few of the potential hazards have been identified in the field which are listed below with locality-

 

 

Sl. No.

Type of deposits

Locality

1

Coastal and River erosion

Teknaf, Cox’bazar sadar, Kutubdia, Sandwip, Hatia, Lakhmipur, Chadpur, Sariatpur, Bhola, Kuakata, Pathorghata, Hizla, Muladi, Mehendiganj, Dacope etc.

2

Water logging

Noakhali, Chittagong, Patuakhali, Gopalganj, Madaripur, Bhagerhat,

Khulna and Satkhira                

3

Salinity (Ground and surface water)

Different parts of Khulna, Bhagerhat, Satkhira, Bhola, Patuakhali, Hatia, Begumganj, Banshkhali, Moheskhali etc,

4

Land slides

Hilly region of Chittagong and Cox’sbazar district.

5

Earthquake

Chittagong-Teknaf hilly region

6

Cyclone and Tidal surges

Teknaf, Cox’sbazar sadar, Kutubdia, Sandwip, Hatia, Lakhmipur, Sariatpur, Bhola, Kuakata, Pathorghata, Hizla, Muladi, Mehendiganj, Dacope, Pirozpur, Jalokhati and Barguna etc. along with the islands under Noakhali, Bhola, Patuakhali, Barisal districts

7

Land subsidence

Satkhira, Jessore, Mdaripur, Gopalganj, Sariatpur, Barghuna and Patuakhali.

 

B. Preparation of Geological and Derivative Maps – Preliminary Geological map of investigated areas have already been prepared in regional scale (1:250,000 scale) on the basis of extensive field survey and other primary data. The refinement of the Geological map and preparation of other derivative maps in suitable scale (1:50,000) are going on.

 

C. Laboratory Analyses – Different types of available laboratory analyses of selected samples, up to the depth of 100 meters, have been conducting to unveil the geological secrets and assess the economic potentiality of the coastal parts of Bangladesh. Besides regular Mineralogical, Grain-size and Chemical analyses, few specialized analyses have been continuing such as X-Ray Diffractogram for clay mineralogy, Palynological study for past vegetation history and Microfossil study for depositional environment.

 

D. Preparation of Geological Data Base- All the Geological and relevant data (Augur hole, Borehole, Pit section data and other information) from the field are being processed and recorded in different formats as Geological database of the Coastal belt. GIS, ROCKWORKS, SURFER etc software are used for data processing.

 

Future Activities

 

1.        To complete the nation-wide geological mapping program at 1 : 50 000 Scale,

2.        To complete the revised geological activities in relation with the 2-year extension of the on-going project “Geological exploration for the identification of mineral resources and the areas vulnerable to natural hazards in the coastal parts of Bangladesh”,

3.        3-year-long (2010-2013) research project, named ”Integrated geological mapping of the Chalanbil area to unveil the Quaternary records and climate changes”, has already been undertaken by this branch which  would hopefully be implemented within the stipulated time frame,

4.        To extend supports to Government, semi-government, NGO and other organizations in connection with Geological Mapping and information,

5.        To carry out special type of Quaternary Research,

6.        Development of Mapping Data-base will be Continued,

7.        To continue effort to construct a Quaternary Stratigraphy of Bangladesh,

8.        To establish an independent Quaternary Research Laboratory,

9.        To share acquired knowledge with the home and abroad researchers etc.