TERTIARY OF ASSAM

Tertiary geology of Assam

• Assam, a northeastern Indian state, is well-known for its beautiful green tea plantations, unusual fauna, and colourful culture, as well as its distinctive geological characteristics.
• The state has a broad spectrum of tertiary geological formations that have helped shape its landscape and natural resources.
• The Tertiary period, which lasted from 65 million to 1.8 million years ago, was a significant time in Earth's history, defined by widespread tectonic activity, volcanism, and climatic change.
• Assam, located in the Eastern Himalayas' active tectonic zone, has been heavily impacted by tertiary events, resulting in the production of a variety of geological features such as sedimentary basins, fold mountains, and volcanic formations.
• The Assam Basin, a huge sedimentary basin spanning roughly 50,000 square kilometres, is one of Assam's most conspicuous tertiary geological features.
• The basin is filled with sedimentary rocks from the Tertiary Period, such as shales, sandstones, and limestones.
• These rocks are a major source of hydrocarbons, and the basin contains some of India's greatest oil and gas reserves, such as Digboi and Naharkatiya.
• Fold mountains, generated by the collision of the Indian and Eurasian tectonic plates, are another feature of Assam's tertiary geology.
• The Mikir Hills, a component of the Purvanchal Range, are an example of fold mountains.

• These hills are made up of tertiary sedimentary rocks that have been bent and shoved upward, resulting in a picturesque environment of steep hills, deep valleys, and swiftly moving rivers.
• Assam is also home to various volcanic formations, indicating a tertiary geological history.
• One example is the now-extinct Dieng Volcanic Complex in Karbi Anglong district.
• The complex is made up of many tertiary volcanic rocks, such as basalt, andesites, and rhyolites. These rocks give vital insights into the region's volcanic history and serve as a treasure trove for geologists and earth scientists.
• The last few million years of Assam's geology have also affected the state's natural riches and environmental control.
• The Assam Basin's sedimentary strata include not only hydrocarbons but also coal, limestone, and other minerals.
• However, these resources must be extracted in a sustainable manner, taking into account the environmental and social implications.
• Furthermore, tertiary geological structures such as fold mountains and volcanic formations have had an impact on the state's temperature, hydrology, and wildlife.
• For example, the Mikir Hills and other fold mountains operate as a barrier to monsoon winds, resulting in a distinct microclimate in the area.
• Similarly, volcanic structures have increased soil richness, allowing for the establishment of luxuriant vegetation as well as varied flora and animals.

IMAGE SOURCE (THUMBNAIL)