South Africa, India and Australia shared similar volcanic activity 3.5 billion years ago

Newswise — Cratons formed eons ago, representing primordial landmasses. Their examination unveils Earth's bygone operations, both within and on its surface. Preserving vestiges of our early planet, cratons harbor diverse rock collections, including greenstones and granites. Greenstones, predominantly consisting of underwater volcanic rocks with minor sedimentary formations, serve as invaluable records for studying ancient terrestrial processes. Recently, a study featured in Precambrian Research, led by Dr. Jaganmoy Jodder from the University of the Witwatersrand’s Evolutionary Studies Institute, reveals the Singhbhum Craton in India harbors exceptionally preserved volcanic and sedimentary rocks, dating back 3.5 billion years. Additionally, it shares a geological history akin to certain regions in South Africa and Australia.

A collaborative team comprising researchers from Wits University, UJ, and the Chinese Academy of Sciences, Beijing, explored volcanic and sedimentary rocks within the Daitari greenstone belt, situated in the Singhbhum Craton of India, with an estimated age of 3.5 billion years. Led by Jodder, the team conducted meticulous field investigations and employed precise Uranium-Lead (U-Pb) radiometric-age dating techniques to analyze the geological characteristics of these ancient greenstone rocks. Through their study, the researchers successfully established crucial geological timelines, shedding light on the tectonic evolution of the Daitari greenstones.

Jodder states, "The Daitari greenstone belt exhibits a comparable geological composition to the greenstones found in the Barberton and Nondweni regions of South Africa, as well as those in the Pilbara Craton of north-western Australia."

During the period spanning 3.5 to 3.3 billion years ago, sub-marine volcanic eruptions occurred frequently, leaving behind distinct features such as pillowed lava formations within the greenstone rocks found in the Singhbhum, Kaapvaal, and Pilbara cratons. Notably, the analysis of silicic rocks reveals the volcanic activity exhibited evidence of explosive processes in both sub-marine and sub-aerial environments.

"After the occurrence of silicic volcanism, sedimentary rocks, including sub-marine turbidity current deposits, were formed when the volcanic vent became submerged. By analyzing precise detrital U-Pb zircon data, we were able to estimate the age of these sub-marine sedimentary rocks to be approximately 3.5 billion years old."

The examination of ancient greenstones holds significance not only for comprehending a wide range of volcanic processes but also for the preservation of minor sedimentary rocks that originated in sub-marine environments.

Jodder emphasizes, "These volcano-sedimentary rocks offer valuable clues about habitable environments that existed on our young Earth. They can be seen as time capsules that contribute to our enhanced understanding of the evolutionary narrative of our planet during its early stages."

Jodder and the team of researchers propose that these ancient continents experienced geologically comparable processes approximately 3.5 billion years ago.

Jodder states, "Nevertheless, we cannot ascertain the exact paleo-geographic location of these ancient continents, and therefore, we cannot confirm whether they were once part of a supercontinent."

Jodder states, "The present research has contributed to a deeper comprehension of the ancient volcano-sedimentary rocks found in the Daitari region of India. This study has provided unique insights into the felsic magmatic processes that were prevalent in the Archaean cratons of India, South Africa, and Australia during the Palaeoarchaean era. It paves the way for further exploration of early Earth processes, offering new avenues for research."