Shankhadeep Baul / Earth & Environmental Sciences / Faculty Mentor: Majie Fan
Loess deposits are key repositories of Earth’s past environment, climate, and surface processes. Here we compare the middle Cenozoic and late Paleozoic loessites to understand the climate conditions that generated abundant silt grains and strong wind systems. The latest Eocene-early Oligocene loess in the western USA and China occurred during the rise of the North America Cordillera or Tibetan Plateau and late Eocene-early Oligocene global cooling. Similarly, the Permian loessites were deposited on the supercontinent Pangea during the uplift of the Ancestral Rockies and Central Pangean Mountains and the late Paleozoic ice age. Therefore, both deposits coincided with mountain uplift and climate cooling. Glaciation in the equatorial region during the late Paleozoic was the major mechanism of silt production, with some contribution from river erosion and transport as an intermediate process. Middle Cenozoic loess in the western USA was likely recycled from fluvial sediments with great volcaniclastic input. Loess of the same age in China was associated with desertification and the role river played in silt generation remains uncertain.
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