Significance of Size in Occurrence, Distribution, Morphological Characteristics, Abundance, and Resource Evaluation of Polymetallic Nodules

Abstract

About 13,000 different sized nodules from 249 locations covering 75,000 km² relinquished Pioneer area in the Central Indian Basin (CIB) have been studied by assorting them in groups of 1 cm size intervals. The study shows systematic variation and inverse relationship of nodule size with the occurrence, distribution, grade, abundance, and Mn/Fe ratios. The study indicates that only 3–4 cm sized nodules in the first generation mine (FGM) site area are resources and have highest economical potential. The different sized nodules probably represent their formation under different environmental conditions which existed in the CIB.

Keywords:

• Abundance
• Central Indian Basin
• morphology
• nodule size
• polymetallic nodules
• resources

Acknowledgments

The authors thank Ms. Deepa Desai and Domnica Fernandes for the laboratory assistance, and Mr. Pramod Pawaskar and R.Uchil for preparing the figures. This is NIO (CSIR) contribution no. 5387.

Notes

CIB – Central Indian Basin.

()*-Number of operations used for determining the station averages.

**-3 Stations (totaling 82 nodules) were outside the Pioneer Area.

* = Out of 249 stations.

(): Total number of nodule types present.

Texture: r-rough, g-gritty, s-smooth.

Shape: R-rounded, ep-ellipsoidal/ elliptical, ds-discoidal, b-botryoidal, bl-bulged, f-flat, el-elongated, t-tabular, r-triangular/pyramidal, j-jointed, p-polynucleated, i-irregular, br-broken, bi-biological.

* = Out of 9,076 nodules.

* = Out of 9,076 nodules.

Tr = Traces (<100 gm), Av = average.