Dr. Brendan Reilly and team have generated a chronology and age uncertainty for the middle to upper Pleistocene from the Bengal Fan record, using a novel age-depth modeling approach from the International Ocean Drilling Program (IODP) Exp 354. Although IODP Exp. 352 consists of a series of seven drill site that date back to the Paleogene, this study focused on sediment deposits over the last 1.25 million years(lower Bengal Fan’s middle to upper Pleistocene depositional history),to determine the behavior of the fan during changes in sea level, climate and tectonic activity. 

Locations of Bay of Bengal and Bengal Fan archives, including the IODP Expedition 354 transect (orange), IODP Expedition 353 Site U1444 (blue), SO93 cores (yellow), ODP Leg 116 sites (pink), and ODP Leg 121 Site 758 (white).

The Bengal Fan is a deep-sea depositional fan, located in the sea of Bengal, created by the Himalayan’s erosional system. Meaning this fan contains the most complete record composed of eroded sediments from the Himalaya used to study the regional climate and tectonic history. Understanding the history of this system can help clarify some of the mysteries behind the Cenozoic uplift of the Himalayan Mountain range, development of the Asian Monsoonal systems, carbon sequestration by increased silicate weathering, and burial of organic carbon. Dr. Reilly’s new age-model for the evolution of the Bengal Fan is the first step to uncover these mysteries. Preliminary data already suggests the primary driver of changes in the Bengal Fan is from sea-level change from melting ice sheets. This is shown through the rapid growth of the fan during times when sea level increased due to erosional and depositional effects from melting ice sheets and glaciers.

Resulting sediment accumulation rates from the age-depth models. The LRO4 Benthic δ18O stack (Lisiecki & Raymo, 2005) with the magnetic polarity timescale (Channell et al., 2016) is plotted for reference, with greater δ18O values indicating times of increased ice volume, cooler deep ocean temperatures, and lower sea level. The blue shaded interval represents the time period where no turbidites were observed along the 8⁰ _N transect and 726 age control is best (Weber & Reilly, 2018). The gray shaded interval indicates the interval where the depocenter is focused on the western fan, asrecognized in seismic data (Bergmann et al., 2020; Schwenk & Spiess, 2009).

If you are interested in this paper, it can be found here Congratulations Brendan! We look forward to your continued work!