Eastern ghats

stratigraphy of India

1. Godavari river THE EASTERN GHATS

2. T he mountain ranges extend in the NE-SW direction along the eastern coast of Orissa to Tamil Nadu. The rocks exposure is the Archean rocks that are 50-80 Km in width. The chief rocks are: metamorphosed gneisses, Charnockites , Khondalites & Kodurites . Charnockites shows intrusive relationship with Khondalites . In these rocks garnet and sillimanite occur in abundance.

3. charnokites They shows intrusive relation with the country rock, and also shows foliated structure. They are acidic in nature and are characterized by the presence of bluish gray of quartz. Usually occur in most of mountain ranges of Eastern Ghats like Sheveroy hills, Nilgiri hills, and p alni hills

4. khondalites they are the Garnet- Silimanite -Schist They are named after the ‘ Khond ’ tribe of Andhra Pradesh. They are often banded and contain quartz, feldspar, and graphite. Khondalites are believed to have formed by plutonic metamorphism of argillaceous sediments. The felspathic Khondalites are thought to have originated by Granitization . On weathering these rocks give rise to laterite and bauxite Khondalites often contain graphite deposits of commercial importance. Argillaceous: of rocks or sediment) consisting of or containing clay

5. kodurites They are manganese rich gneisses. Composed of potash feldspar, manganese garnet, manganese pyroxene, quartz and Apatite. The Kodurite are the hybrid rocks by the assimilation of metamorphosed manganiferous sediment and acid igneous rocks. On weathering they give rise to Manganese ore diposits . Apatite: a widely occurring pale green to purple mineral, consisting of calcium phosphate with some fluorine, chlorine, and other elements. It is used in the manufacture of fertilizers.

6. Gondites it is a manganese bearing high grade metamorphic rock. It composed of quartz, spessartite , R hodonite , and small percentage of Apatite. They are formed by the plutonic metamorphism of sediments rich in Manganese oxide. Commonly found in Archean succession of Balaghat-chinwara area of Madhya Pradesh Spessartine : sometimes mistakenly referred to as  spessartite ,is a  nesosilicate ,  manganese   aluminium   garnet  species, Mn 2+ 3 Al 2 (SiO 4 ) 3 .  The mineral spessartine should not be confused with a type of  igneous rock  (a  lamprophyre ) called spessartite .

7. Rhodonite :  is a  manganese   inosilicate , ( Mn , Fe, Mg, Ca)SiO 3  and member of the  pyroxenoid  group of  minerals , crystallizing in the  triclinic  system. It commonly occurs as cleavable to compact masses with a rose-red color (the name comes from the Greek ῥόδος   rhodos , rosy), often tending to brown because of surface  oxidation .

8. Thank you This is Joseph R Lalfakawma