关键词: Pb同位素, 沉积物自生组分, 岛弧风化, 东赤道太平洋, 第四纪

Abstract: Lead (Pb) isotopes serve as a critical tool for tracing theocean circulation and weathering evolution. Previous studies have primarily relied on low-resolution ferromanganese crusts. In recent years, investigations into the authigenic Pb isotopic compositions in sediments from the Atlantic and Indian Oceans have revealed variations in glacial activity and weathering inputs on orbital and millennial timescales, reflecting the sensitivity of regional weathering processes to climate change. These findings have provided important constraints for understanding the global marine Pb cycle and its interactions with the climate system. However, how deep water Pb isotopes respond to short-term climate changes in the Pacific remains poorly understood. This study focuses on deep-see sediments from ODP Site 1241 in the Eastern Equatorial Pacific (EEP) to explore the characteristics and sources of Pb isotopes over the past 150 ka. The results indicate that the Pb isotopic composition of deep water in study region is predominantly controlled by weathering inputs from the Andean volcanic arc and the Central American volcanic arc. Despite minimal overall variation in Pb isotope compositions over the past 150 ka and an absence of a clear glacial-interglacial pattern, a notable trend towards less radiogenic Pb isotope compositions during the MIS 4 and late Holocene may indicate a significant increase in the weathering of Central and South American arcs. Additional comparison with Pb isotopes of major water masses of the Pacific further demonstrates that the Pb isotopic composition of deep water in the EEP is primarily controlled by local sources rather than water mass mixing. These findings provide new insights into the global marine Pb cycle and highlight the importance of regional weathering processes in shaping deep-water Pb isotopic signatures. 

Key words: Pb isotopes, authigenic sediment components, arc weathering, Eastern Equatorial Pacific, Quaternary