Geochemistry of Major Oxides in Host Rocks in Vizianagarm Manganese Ores Belt (A.P.), India

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 SiO 2 over Al 2 O 3 ; 2) Dominance of K 2 O and CaO over Na 2 O; 3) Abnormally high concentration of phosphorus and a positive relationship of P 2 O 5 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 Al 2 O 3 , Ti, K 2 O and vice versa . High P 2 O 5 content in these manganese ores appears to be the result of precipitation from secondary manganese rich solutions containing dissolved phosphorus from the P 2 O 5 enriched host rocks. Another source of P 2 O 5 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.