Magnetic Response to the Source‐To‐Sink Environmental Changes in the Bay of Bengal Since ∼60 ka

Abstract

The terrestrial magnetic minerals of marine sediments are utilized to track the climatic changes in the source area and the dynamic characteristics of sedimentation processes. However, due to the varied source‐to‐sink environments, the magnetic response to ambient climate cannot be generalized. Here, we conducted systematic environmental magnetic analyses on core CJ04‐50 from the Ninetyeast Ridge and investigated its magnetic response to source‐to‐sink environmental changes. Core CJ04‐50 covers the last 60 Kyr based on accelerator mass spectrometry (AMS) 14C dating and the relative paleointensity (RPI) record. Rare earth element (REE) results suggest that the terrestrial materials are fed by the Ganges‐Brahmaputra (G‐B) and Irrawaddy/Indo‐Burma Ranges. High/low magnetic mineral content corresponds to strong/weak terristrial input during the cold/warm period. This pattern differs from that in the East Asian marginal seas, which have a high magnetic mineral content in warm periods. It might be attributed to the heavier Indian summer monsoon (ISM) precipitation than that of East Asian summer monsoon. Excessive moisture (>1,500 mm/year) would not favor the formation and preservation of magnetic minerals in the source area during interglacials. By contrast, the enhanced physical weathering during glacials results in more magnetic contributions. A significant local magnetite dissolution occurred at the layer of Middle MIS 3, which may be caused by the non‐steady state diagenesis following deposition.