Why in the News?

Some recent study about the Singhbhum Craton in India, reveals that explosive volcanic eruptions were frequent around 3.5 billion years ago in regions that are also present in South Africa, and Australia.

What are Cratons?

Cratons are stable, ancient portions of the continental lithosphere, consisting of Earth’s two topmost layers—the crust and the uppermost mantle.
Cratons are typically found in the interiors of tectonic plates and are characterized by their ancient crystalline basement rock, often dating back to the Archean Eon.
Mantle plume events have played a significant role in the evolution of cratons.

The Singhbhum Craton is a geological region in India.
Location: It is located in eastern India, covering parts of the states of Jharkhand, Odisha, and West Bengal. The craton is separated from the Bastar Craton by the Mahanadi Graben and is in the vicinity of two Proterozoic mobile belts: the Satpura Mobile Belt and the Eastern Ghat Mobile Belt.
Geological features:
- The rocks in the Singhbhum Craton are predominantly of Archean age, ranging from Paleoarchean to Paleoproterozoic.
- It is a part of the larger Indian Shield, which is a stable continental crust that formed during the Archean Eon.
- The Singhbhum Craton is known for its abundant occurrences of Banded Iron Formations (BIFs), which are closely associated with basic volcanic and ultrabasic intrusive. The craton is also known for its iron ore deposits, which are found in the Iron Ore Group (IOG) and are closely associated with lavas and tuffs.
- The Singhbhum Craton has undergone regional metamorphism of the amphibolite facies and is believed to have evolved as a consequence of multiple phases of compressive deformation.
- The craton is made up of multiple pulses of discrete mantle plume events, resulting in a complex geological history.

The Archaean Eon, one of the two formal divisions of Precambrian time, began about 4 billion years ago and extended to the start of the Proterozoic Eon.
During this period, life on Earth was limited to simple single-celled organisms lacking nuclei, known as Prokaryota.
The atmosphere lacked oxygen, and the Earth’s crust had cooled enough to allow the formation of continents.
Volcanic activity was considerably higher than today, with numerous lava eruptions.
The oldest rock formations exposed on Earth are from the Archaean Eon.
The Archaean rock system includes Archaean Gneisses and Schists, which are the oldest metamorphosed rocks found in abundance in regions like the Dharwar district of Karnataka.

Submarine Mafic Volcanism: The prevalence of submarine mafic volcanic eruptions between 3.5 and 3.3 billion years ago is documented, enriching our understanding of ancient volcanic and sedimentary processes.
Geodynamic Insights: Comparative analysis enhances our comprehension of early Earth tectonic activities and surface/atmospheric processes during the Archaean.

Field Studies and Radiometric Dating: Detailed field-based studies coupled with uranium-lead radiometric-age dating were employed to establish geological timelines and understand magma crystallization.
Comparative Analysis: The geological similarities between the Singhbhum Craton and counterparts in South Africa and Australia were studied, focusing on volcanic eruption patterns.

Earth’s Formative Years: Insights into Earth’s early tectonic activities contribute significantly to understanding the planet’s formative years.
Habitable Conditions: Unique geological features, such as greenstone belts, provide invaluable information about early habitable conditions and the emergence of life.
Global Geodynamic Processes: Comparative studies across cratons worldwide facilitate the construction of comprehensive models elucidating ancient geodynamic processes prevalent during the Archaean.