Dual Nd isotopic archives in fossil teeth reveal bottom-current control of rare-earth element enrichment in deep-sea sediments.

Dual Nd isotopic signatures in fossil teeth reveal that Antarctic bottom water controls the distribution of REY-enriched deep-sea sediments.

• Why it matters: Understanding the mechanisms behind REY enrichment in deep-sea sediments is crucial for resource exploration and deciphering past ocean circulation patterns. The link between Antarctic bottom water expansion and REY deposits has remained unclear.
• What they did: In situ elemental and neodymium isotopic analyses were performed on apatites from Oligocene-Miocene sediments along the North Pacific AABW pathway, focusing on the isotopic composition of different tooth layers.
• The result: Findings show that 90% of REY resides in inner dentin, with Nd isotopic signatures indicating the outer layer reflects the fish’s environment and the inner dentin records depositional conditions, supporting AABW’s role in transporting and sorting fossil teeth and influencing REY sediment enrichment.