South Asian Monsoon Wind Intensity During the Late Miocene to Early Pliocene From Maldives Drift Sediment

Abstract

Wireline log data from IODP Site U1467, located in the Maldives, were used to investigate the dynamics of South Asian Monsoon (SAM) wind intensity across the Late Miocene–Early Pliocene from approximately 8.4 to 3.2 Ma. We analyzed the High‐Resolution Laterolog Array (HRLA) resistivity record from lithologically homogeneous sedimentary Units II to IV of Hole E, which we interpret as a proxy for wind‐driven marine currents, consequently, monsoon wind strength. The astrochronological tuning of the existing magnetostratigraphic and biostratigraphic age model was performed by correlating the HRLA data with Northern Hemisphere summer insolation at 30°N latitude. The tuned record reveals that the intensity of SAM winds fluctuated at Milankovitch frequencies, predominantly driven by eccentricity‐modulated precession, with minimal influence from obliquity. On longer timescales, the orbitally‐paced SAM wind strength displays a reduced sensitivity to seasonal insolation forcing during the Late Miocene cooling period, followed by an increased insolation sensitivity at the Miocene–Pliocene boundary (∼5.3 Ma) and a further increase at ∼4 Ma approaching the middle‐Pliocene warm period. Durign this period summer insolation minima may result in very low monsoon intensity. While this pattern may reflect complex climatic interactions, our findings suggest a link between SAM wind intensity and global temperature trends, which are, in turn, related to increasing atmospheric CO2 concentrations.