A Note on Chemical Composition and Origin of Ferromanganese Oxide Coated and Uncoated Pumice Samples from Central Indian Ocean Basin

Abstract

Pumice are explosive volcanic product, occur as uncoated or coated with ferromanganese (Fe-Mn) oxide and resides in association with ferromanganese nodules on the seabed in Central Indian Ocean Basin (CIOB). The older Fe-Mn oxide coated and younger uncoated pumice clasts were leached with 6N HCl to remove Fe-Mn oxide coatings as well as the calcium carbonate present within the vesicles. The main objective of the present study is to understand the origin of these pumice by utilizing their chemical composition. Both coated and uncoated pumice samples are rhyolite- and medium K calc-alkaline series. Major, trace, rare earth elements (ΣREE) concentration and chondrite-normalized REE patterns of both coated and uncoated pumice are nearly similar to each other suggesting a same source. Tectonomagmatic discrimination diagrams (Nb vs Y: Yb vs. Ta), triangular plot (TiO2-Zr-Y) and High Field Strength Element ratios (La/Ta- 25; Ta/Hf- 0.2; Nb/Ta- 9; Zr/Nb- 22 and Ba/Ta-1084) indicate volcanic arc origin. These were probably sourced from the nearest Indonesian volcanic arc and drifted to the CIOB by currents.

An Extensive Study on Physico-Chemical Parameters of Bay of Bengal and Central Indian Ocean Basin

“…IO is located to the south of the Adam's bridge and from southern extreme of Dondra Head (south point of Sri Lanka) to the North point of Poeloe Bras (5o44'N, 95o 04'E). Though there are reports of recording physico-chemical parameters at BOB [1][2][3][4][5] and CIOB, [6][7][8][9][10][11][12] they are scanty, scattered, sometimes in estuaries, tidal creeks or near shore, apart from limited number of sampling sites etc., To overcome this lacunae of information, the present investigations were carried out.…”