Peak Cenozoic warmth enabled deep-sea sand deposition.

Area of Science:

• Paleoclimatology
• Sedimentology
• Geology

Background:

• The early Eocene (56-48 million years ago) was a period of extreme warmth, high CO2, and high sea levels.
• Previous studies on early Eocene continental erosion and weathering relied on limited marine and basin settings.
• Understanding coarse siliciclastic deposition in deep-marine environments during this hothouse period is crucial.

Purpose of the Study:

• To evaluate the response of marine coarse siliciclastic systems to early Paleogene hothouse conditions.
• To investigate the distribution and drivers of sand-rich deep-marine depositional systems during the early Eocene.
• To assess the role of climate-driven sediment supply in deep-marine deposition.

Main Methods:

• Compilation of an inventory of documented sand-rich (turbidite) deep-marine depositional systems.
• Analysis of the geographic distribution of early Eocene turbidite systems across continental margins.
• Correlation of passive margin turbidite systems with known Eocene-age fluvial systems.

Main Results:

• Identified 59 instances of early Eocene turbidite systems globally, despite high sea levels.
• Found widespread sand-rich systems on both active (42 instances) and passive (17 instances) margins.
• Observed that 13 of 17 passive margin systems were linked to Eocene fluvial systems, indicating a clastic response to warming.

Conclusions:

• Deep-marine sedimentary basins provide valuable records of early Eocene climatic extremes.
• Climate-driven increases in sediment supply (e.g., rainfall, denudation) significantly influenced the global distribution and volume of coarse-grained deep-marine deposits.
• Eustasy and tectonism are important, but climate also plays a key role in sediment supply and deep-marine deposition.