New Zealand: Magnetic anomaly beneath Lake Rotorua reveals ancient secrets
Nature
07.02.2024 New Zealand   14
New Zealand: Magnetic anomaly beneath Lake Rotorua reveals ancient secrets

In a major discovery, scientists have discovered a hidden hydrothermal system beneath the waters of Lake Rotorua, a site rich in Maori legends and perched atop a dormant volcanic crater on New Zealand's North Island.


This is the latest discovery not only adds a new dimension to the lake's extensive history, but also represents an important milestone in the understanding of underground geological phenomena.


Lake Rotorua known for its geothermal wonders such as bubbling mud pools, natural hot springs and shooting geysers, Lake Rotorua has long possessed the fiery power of the Earth. Despite intense geothermal activity, temperatures at the bottom of the lake remain relatively cool. Shallow in nature, with an average depth of about 10 m, it is part of the Taupo volcanic zone, formed by the collapse of a magma chamber after a volcanic eruption, resulting in the formation of the Rotorua caldera.


Researchers from the New Zealand research institute GNS Science have carefully mapped about 68% of the floor of Lake Rotorua, which covers an area of ​​55 square kilometers. Their efforts revealed eruption craters, the remains of an ancient river and a significant magnetic anomaly in the southern part of the lake.


For the first time, these discoveries confirm that the familiar hydrothermal activity observed on the mainland also extends to the submerged area of ​​Lake Rotorua .


The mapping project, carried out with assistance from the Royal New Zealand Navy, used advanced multi-beam echo sounder technology to reveal the physical features of the lake. Magnetic studies conducted during the exploration revealed an unexpected magnetic anomaly.


Although volcanic rocks typically exhibit strong positive magnetic responses due to magnetite, the anomaly identified indicates that hydrothermal fluids turned magnetite into pyrite , commonly known as fool's gold, which resulted in a noticeable decrease in the magnetic signal.


Cornel de Rond, lead scientist at GNS Science, compared the clarity of these recent maps to the feeling of seeing clearly for the first time. Detailed images showed a vibrant underwater landscape where heat, likely emanating from hot water, rises to the lake bed and the landscape is dotted with hydrothermal eruption craters.


Even though there is significant geothermal activity beneath the surface of Lake Rotorua, near its bottom the temperature is moderately cool, averaging about 14 degrees Celsius. The lake's vast volume ensures that heat emanating from the depths is effectively dissipated, thereby maintaining a stable overall temperature with minimal fluctuations.


As researchers continue to analyze the data, the secrets of Lake Rotorua's underwater world are being revealed may reveal additional wonders and enrich our understanding of the complex interactions of earth, water and forces beneath the earth's crust.

Source: timesofindia