Multi-elemental Statistical Features of Early Paleogene Sediments from
the Mid-latitude Eastern Indian Ocean
Abstract
The early Paleogene is characterized by a “hothouse” environment with
repetitive transient warming events known as “hyperthermals.” While
these paleoenvironmental changes are well-documented in the Pacific and
Atlantic Oceans, records of such changes in the Indian Ocean are
limited. Here, we present a new dataset of bulk chemical composition and
stable isotopic ratios of the late Paleocene–middle Eocene sediments on
the Exmouth Plateau in the mid-latitude eastern Indian Ocean. The bulk
δ13C and δ18O suggest a warming period called the Early Eocene Climate
Optimum (EECO) and cooling towards the middle Eocene in a long-term
perspective. From a short-term perspective, we identified at least five
hyperthermals (PETM, H2, I1, J, and ETM3) in the studied sections. We
identified six independent components (ICs) corresponding to sediment
source materials and post-depositional processes by applying independent
component analyses (ICA) to the bulk chemical composition data. The
time-series behavior of IC3 indicates an increase in detrital material
or a decrease in carbonate rain flux during both long-term (EECO) and
short-term (hyperthermal) warming. Additionally, the rise in IC2 implies
an increased population of high consumers in the oceanic ecosystem
during warming events around the Exmouth Plateau. Other ICs (IC1, IC4,
IC5, and IC6), indicators of diagenetic processes and post-depositional
remobilization of elements, showed excursions across hyperthermal
horizons. These observations indicate that changes in the redox state of
pore or bottom water in the Exmouth Plateau are associated with
hyperthermals.