Yannis Kappelmann

Spatial distribution of recent sedimentary facies in an Indonesian carbonate complex - supply, transport and modification of skeletal material
from shelf- to island-scale 

In the context of rising sea level and changing environment, coral reef islands are in a vulnerable position. Their low-lying nature of often just few decimeters above mean sea-level is exposing these landforms to hydrodynamic energy and therefore potentially increased erosion rates. However, a balanced ratio of erosion and accretion may appear as a common characteristic of reef islands, underpinning their dynamic nature. To keep this balance (and therefore maintain existence of islands), a constant supply of suitable skeletal carbonate from surrounding reefs is highly important. Even though alterations in the sediment supply could have severe consequences, research from the past years has found reef islands to be potentially more robust than previously thought. Nonetheless, research also found dynamics to be regionally specific and unique. In the Spermonde Archipelago, located offshore Sulawesi in Indonesia little is known about processes that govern island dynamics.

My PhD project will therefore aim on the investigation of sediment dynamics in this Indonesian carbonate system. The DFG-funded HAnsea project, part of the SPP 1889 - Regional Sea Level Change & Society ‘SeaLevel’, will provide framework for this. I will evaluate sediment samples from the Spermonde Archipelago on different spatial scales, in order to learn about generation, transport and modification of skeletal carbonate. The final outcome will comprise knowledge about factors governing sediment production, effects of hydrodynamics on the sedimentary system and reconstruction of island-formation. For this, I will use basic sedimentary methods and evaluate the results statistically. Field work in Indonesia will be conducted as soon as personal safety is provided again and will complete data sets. Additionally, new samples for sea-level reconstructions from the study area will be obtained during the field campaign.