Mineralogy of sediments in the Mariana Trench controlled by environmental conditions of the West Pacific since the Last Glacial Maximum

[Display omitted] •A sedimentary record from the “Challenger Deep” with a depth of 8.3 km is presented.•High illite/smectite ratios of clay minerals indicate increased dust inputs during the LGM.•The formation of authigenic minerals is attributed to the blooming of large diatoms.•The bulk and clay mineralogy of trench sediments is regulated by environmental conditions. The trench represents an important sink of sediments as a result of the “funneling effect”, however, the mineralogy of trench sediments and its response to environmental conditions is still not well understood. To fill this knowledge gap, we present a 3.2-m-long sedimentary record of core MT03, which was collected from the southern slope of the “Challenger Deep” in the Mariana Trench at a water depth of 8300 m. The results document that the minerals in the bulk sediments mainly include quartz, feldspar, mica, pyrite, apatite, and clay minerals. The clay minerals are mainly composed of smectite and illite, which are respectively derived from volcanic matter and Asian aeolian dust. At the bottom of the core, the increased aeolian input, which is reflected by high illite/smectite ratios, led to the blooming of diatoms and the formation of laminated diatom mats during the Last Glacial Maximum. During this period, the anaerobic oxidation of abundant organic matter led to an anoxic environment in the sediment where the authigenic pyrite precipitated. In the middle and upper sections of the core, the decrease in contents of organic carbon and authigenic pyrite indicates that the sedimentary environment became oxic, which is attributed to low productivity caused by reduced input of the aeolian dust in the deglacial period and Holocene. Therefore, our new findings indicate that the mineralogy of trench sediments is sensitive to the evolution of paleoclimate and paleoceanography, providing a new perspective to study the environmental evolution of the West Pacific.