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Onshore heavy mineral placers of south Maharashtra, central west coast of India

DRS at CSIR-National Institute of Oceanography

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Title Onshore heavy mineral placers of south Maharashtra, central west coast of India
 
Creator Gujar, A.R.
Ambre, N.V.
Mislankar, P.G.
 
Subject Heavy minerals
Placers
Geographical distribution
Mineralogy
Geochemistry
Depositional environment
Potential resources
 
Description Heavy Mineral Placers from coastal sediments of south Maharashtra [105 km stretch from Vijaydurg (16 degrees 30 minutes N) in the North to Redi (15 degrees 43 minutes N) in the South] are studied to understand their distribution, environment of deposition, mineralogy, geochemistry and reserve potential. The sediments in the study area are mainly sandy, symmetrical to finely skewed, moderately well sorted to well sorted in nature and show the predominance of beach and river dune type of depositional environment. Heavy mineral percentage ranges upto 98.37% (average 26.96%). Heavy mineral composition consists of opaques, pyroxenes, amphiboles, rutile, tourmaline, kyanite, zircon, staurolite, titanite, olivine garnet, epidote, sillimanite etc., the light fraction is dominated by Quartz and feldspar. The opaques consist of ilmenite upto 43.07%, magnetite upto 58.15% and chromite upto 10.09%. The concentration of ilmenite, magnetite and chromite are higher in fine and very fine sand (-120 to 62.5 micron) and are relatively more abundant in the berm and dune regions (supratidal/backshore zone) compared to beach (intertidal/ foreshore zone). Ilmenites are fresh, their shapes varies from euhedral to rounded and shows minor degree of alternation to sphene and leucoxene along the borders. The TiO sub(2) percentage ranges between 38.89-50.69 % (average 44.0%). Magnetite is of two type titanomagnetite and magnetite. Titanomagnetites are relatively fresh and shows miner alteration to sphene along borders; where as magnetite shows alteration to hematite and also shows sign of weathering. Chemically in magnetite Fe sub(2) O sub(3) ranges between 31.2 to 48.0 % (average 38.3%). FeO percent ranges between 17.73 to 24.1 % (average 21.1%) and TiO2 % ranges between 14.31 to 23.98 % (average 21.1%). The chromite grains are rounded without any intergrowth and shows signatures of miner alteration along borders. In chromite Cr sub(2) O sub(3) content ranges between 32.06 to 47.52 % with an average of 36.99%. The chromite are of two type magnesio and iron rich. The transparent heavy minerals are represented by -pyroxene and amphibole group, kyanite, tourmaline, zircon, rutile, staurolite, titanite, olivine, sillimanite, garnet and epidote. Their assemblages is suggestive of their derivation from mixed source rocks. Comprising of igneous, high grade metamorphic and recycled kaladgis sediments. In the areas of significant heavy mineral concentrations (seven areas), the inferred reserves of heavy minerals to one meter of sand thickness are to the tune of 233 5.728 x 103 tonnes, ilmenite 556.199 x 10 tonnnes, magnetite 98.18 x 103 tonnes, chromite 113.573 x 10 sup(3) tonnes and non magnetite 683.199 x 10 sup(3) tonnes) and in the areas of limited concentration (five areas), the inferred reserves of heavy minerals to one meter sand thickness are to the tune of 31.959 x 101 tones.
 
Date 2008-01-31T07:03:33Z
2008-01-31T07:03:33Z
2007
 
Type Conference Article
 
Identifier National Seminar on Exploration, Exploitation, Enrichment and Environment of Coastal Placer Minerals (PLACER - 2007), eds. Loveson, V.J.; Sen, P.K.; Sinha, A. 3-26p.
http://drs.nio.org/drs/handle/2264/716
 
Language en
 
Publisher Macmillan, India