A new study by researchers from the Indian Institute of Science Education and Research (IISER) Pune has determined that a significant portion of the ocean floor in the Bay of Bengal is approximately 92 million years old. This finding provides a clearer timeline for the formation of the region.
Study Methodology
The study, conducted by Mohammad Ismaiel and Kolluru Sree Krishna, analyzed magnetic and seismic reflection data collected from the central Bay of Bengal seabed. The team used research ship-borne towing magnetic sensors to gather data and compared it with satellite models and seismic reflection imaging, which employs sound waves to map deep underground structures.
Challenges in Dating
Ismaiel explained that most of the crust in the region formed during the Cretaceous Normal Superchron, a period between 120 and 83 million years ago when Earth's magnetic field did not reverse frequently. This made age determination using standard methods difficult. Typically, ocean floor dating relies on magnetic stripes created by periodic magnetic field reversals. However, the team studied changes in the strength of Earth's magnetic field recorded in the rocks.
Key Findings
The researchers focused on identifying Q1, a globally recognized magnetic anomaly associated with a brief, intense fluctuation in Earth's magnetic field strength about 92 million years ago. By analyzing ship-borne magnetic profile data and magnetic regional models, they identified this internal time marker. The study area lies around 12 degrees North latitude, between the 85°E Ridge and the Ninetyeast Ridge.
Kolluru noted, "This is the first time that a 92 Ma age constraint has been provided for the Bay of Bengal region with more confidence." The team validated their findings by comparing them with data from other ocean basins, including regions near Antarctica.
Limitations and Future Research
Despite identifying the Q1 marker, the researchers could not confirm another marker, Q2, linked to an age of about 108 million years. They suggested that volcanic activity from the Kerguelen plume, which has generated massive amounts of volcanic rock for over 120 million years, may have obscured its signal. The study integrates magnetic readings and seismic images to reduce uncertainty, but Kolluru emphasized that higher-resolution geophysical surveys are needed to further improve understanding.
Significance
The findings offer a clearer picture of how the ocean floor in the Bay of Bengal formed and evolved over millions of years, based entirely on evidence recorded in Earth's magnetic field. This research also enhances understanding of the deep, dynamic forces that have shaped Earth's surface over geological time scales.
