ABSTRACT
The abundance, distribution trends and
significance of the major oxides in the host rocks in Vizianagarm Manganese
Ores Belt (A.P.) (between N latitude 18°12' and 18°30' and E longitudes 83°20'
and 83°45'), 15 samples of host rocks from different localities of the area
under study were collected and analyzed for major oxides. We describe here in
major oxides geochemistry of host rocks and manganese ore deposits associated
with Precambrian Khondalite and Charnockite in Vizianagarm Manganese Ores Belt
(A.P.): 1) Preponderance of SiO2 over Al2O3;
2) Dominance of K2O and CaO over Na2O; 3) Abnormally high
concentration of phosphorus and a positive relationship of P2O5 with
CaO and Ti contents; 4) Manganese increases with increases of iron, lime and
soda and vice versa, 5) CaO increases with the increases of Al2O3,
Ti, K2O and vice versa. High P2O5content
in these manganese ores appears to be the result of precipitation from
secondary manganese rich solutions containing dissolved phosphorus from the P2O5 enriched
host rocks. Another source of P2O5 may be the
associated granitic and pegmatitic intrusions. Elements like K, Na, Ca, Mg, Co,
Ni, Pb and Zn etc. appear to be mostly concentrated in the Mn-minerals viz.
psilomelane, cryptomelane, hollandite and pyrolusite and related secondary
phases [1] and [2]. Stratigraphically, the study area includes
within a thick succession of Precambrian Group belonging to the Khondalite and
Charnockite Groups of Dharwar Supergroup, that form a part of Eastern Ghat
Complex of India. The manganiferous rocks that have been encountered in the
Vizianagarm Manganese Ores Belt (A.P.) India are known as Kodurites.