Q: The important of field geological mapping? Posted bygeoamitJuly 24, 2020July 24, 2020Posted inQ&A Please answer in the “Leave a Reply” Section below Share this:TwitterFacebookMorePrintLinkedInRedditTelegramWhatsAppSkypeEmailLike this:Like Loading... Related
3 thoughts on “Q: The important of field geological mapping?”
The importance of field geological mapping is manifold in terms of mineral exploration and basic science:
1. Lithological and structural set up is identified which helps in finding localisation of mineral resource.
2. The stratigraphic set up of the area with age is known by mapping, essential for building litho and chronostratigraphy.
3.The geological evolution of the area is identified, whether a fold belt or a cratonic terrane.
4. Structural details to much extent is identified for the area under study which helps in identifying structural controls of localisation of mineral resources.
5. Alteration in lithology due to later influences of weathering, fluid actions, metamorphism, etc. processes, which in turn help identifying mineral resources concentration in the area.
6.Detailed geological mapping helps identifying minor and subtle changes in lithology and structure along with alteration zones in the rock types, thereby adding helpful data to the mineral resources exploration works.
7. Surface expressions of mineral resources such as mineral stains, alterations, oxidised and gossan zone are located in the area which are helpful in mineral resources survey works later on.
8.Genetic aspects of any mineral resource present in the area is identified by mapping in the field.
9. Origin and geological evolution of the area is understood with geological field mapping.
10. There is no alternative to field geological mapping and above points are only a few things which are told now.
The basic and first requirement in mineral exploration is the geological map. The topographical details with all geological features projected on it make a base map on which we can plan our future investigation. The Scale of the base geological map (R.F.) should depend on the objective of the survey or exploration namely Orientation/reconnaissance survey, detailed exploration or evaluation stage and accordingly the scale of mapping should change say for example 1:25000 or 1:10000 or 1:1000 or for Underground mapping it may be even 1:100.The accuracy of estimate will depend on the scale of the geological map.This is what required in addition to the details already given by Dr.D.B. Guha, above.
The smaller scale maps of larger area (1:5million, 1:2,50,000,1:2million,)give only general geological spectrum of the terrain and help in identifying the obvious geological potential (OGP) zones for different minerals availability in distinct geological set up like: Greenstone belt for Au, Cu Ag and other associated minerals, Ultramafic anorthosite layered complex for Ni, Cr, PGE etc., mineralization. Pipe rocks for diamond, high level residual weathering zones for bauxites /lateritic bauxite; nodular/shell limestone, phosphorite beds, manganese beds in marine strata etc., The geological mapping on 1: 50,000 and 1:25,000 will be the base map for the proposed area of exploration and help in planning for further follow up works. Whereas the larger scale of mapping (1:1000, 1:2000) of smaller area- helps to delineate the intricate features of mode of occurrence of particular mineral deposits in detail and the associated rock/ mineral assemblages in different geological set up, can be brought out. The delineation of structural fabrics in closed contact and hence the potential zones of concentration of mineral/ores loci could be deciphered which facilitate the planning for exploration / excavation techniques.
The close observation by mapping helps in delineation of hanging wall/ foot wall zones, the natural attitudes of formation which in turn helps in planning of boreholes drilling and other exploration / mining activities (Mining plan on 1:2000 or 1:1000-geology pits, stackyard, dumping yard, adits, driving path, office room, gunpowder room etc.,). Preparation of underground mapping on 1:100, 1:200, 1:500 and sampling, when the excavation is in progress, will help to locate the exact disposition of the ore lode. So the geological mapping is the basic prime importance in mineral/ ore exploration from the beginning, during the progress and till the end of excavation/ mining.