New Zealand fjord sediment records of Southern Hemisphere climate change and carbon cycling

Conceptual diagram depicting the flooding of a fjord basin by the postglacial rise in sea level (modified from Dlabola et al., 2015)

Fjords play a critical role in the global carbon cycle by storing large quantities of terrestrial organic carbon. It is estimated that, though they occupy <0.1% of Earth’s surface, annual fjord carbon burial accounts for 11% of the total annual global marine sequestration. Globally, these systems are a significant contributor to glacial-interglacial changes in atmospheric CO2, but very few continuous records that capture the entire sedimentary sequence from peak glacial to peak interglacial conditions have been compiled.

The lack of well-dated records limits our understanding of key sedimentary and biogeochemical processes and the impact that fjord systems have on the global system across key transitions from glacial to interglacial climates. New Zealand (NZ) fjord basins are ideal targets for scientific drilling: they have high sediment accumulation rates, interglacial and glacial sediments spanning at least the last ~20,000 years, accumulate marine and terrestrial sediments that enable paleoclimate proxy redundancy, have abundant terrestrial macrofossils for radiocarbon dating and host environmental processes that are directly linked to climate. 

Numerous sub-basins in three fiords have been identified that are potential candidates for scientific drilling based on seismic stratigraphic and sediment core data. From these sites, we propose to drill at least two basins within a single fjord to basement. A workshop in Doubtful Sound and at the University of Otago in New Zealand will determine primary drilling targets

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