Petrological characteristics of dharwar system in India

 • The Dharwar System, also known as the Dharwar Craton, is a geological formation in southern India that consists of ancient rocks formed between 2.5 to 3.6 billion years ago.

• Petrologically, these rocks are predominantly composed of granitic and gneissic formations, with significant occurrences of metavolcanic rocks, such as greenstone belts, and metasedimentary rocks, including quartzites and schists.
• The Dharwar System also contains mineral deposits such as gold, iron, manganese, and copper, making it economically significant.
•  Additionally, it exhibits evidence of regional metamorphism and deformation, indicating tectonic activity during its formation.

The petrological characteristics of rocks within the Dharwar System vary widely due to the complex geological history of the region. However, some common petrological characteristics include:

1. Granitic and Gneissic Rocks: These rocks are abundant in the Dharwar System and are characterized by their coarse-grained texture and interlocking mineral grains. They often exhibit banding or layering due to metamorphic processes.

2. Metavolcanic Rocks: Greenstone belts are common within the Dharwar System, composed of metavolcanic rocks such as basalt, andesite, and rhyolite. These rocks may contain minerals like chlorite, serpentine, and amphiboles due to alteration processes.

3. Metasedimentary Rocks: Metasedimentary rocks like quartzites, schists, and phyllites are present, indicating the sedimentary origin of some formations within the Dharwar System. These rocks may show evidence of metamorphism, such as recrystallization and foliation.

4. Mineral Deposits: The Dharwar System hosts significant mineral deposits including gold, iron, manganese, copper, and other base metals. These deposits are often associated with specific rock types and structural features within the craton.

5. Metamorphism and Deformation: Regional metamorphism and deformation are widespread within the Dharwar System, leading to the development of foliation, folding, and shearing in rocks. Metamorphic grades vary from low to high, indicating different degrees of temperature and pressure conditions during geological history.

Overall, the Dharwar System exhibits a complex assemblage of rocks with diverse petrological characteristics, reflecting its long and dynamic geological evolution.