ALBERT

Description: In our meeting Dynamic Earth – from Alfred Wegener to today and beyond we will review how Wegener‘s findings evolved into to modern Earth system science including its impact on climate and the Earth surface, and how this system affects our daily life: where humans live, what risks we are exposed to, where we find our resources. In the meeting we will hold sessions that cover the entire geoscience spectrum (from mineral physics over solid earth geodynamics to the climate sciences) and that explore the consequences of Wegeners findings on how humans use our planet today (from energy and mineral resources over georisks to utilisation of the subsurface and materials for modern society). We have invited keynote speakers that are eminent international scientists in these fields. In events open to the general public we will get an account of Wegeners final trip to Greenland on the history of science of his hypothesis.

Description: Recent mobilisation of soil organic matter (SOM) in permafrost of the northern high latitudes is thought to have a significant impact on the carbon balance in the atmosphere. However, the environmental processes which influence SOM accumulation and remobilisation still need to be investigated more accurately. This study investigates the quantity and quality of SOM on Herschel Island in the western Canadian Arctic in relation to various landscape characteristics. To reach this goal, soil moisture, total organic carbon (TOC) and total nitrogen (TN) contents, stable carbon isotopes (∂¹³C) and TOC/TN ratios (C/N) were determined on 128 samples from twelve sediment cores reaching up to 250 cm depth. Drilling locations were chosen based on morphology, vegetation and soil properties and supported by satellite imagery and air photos. Seasonal thaw depths (active layer depths) correlate with ground disturbance and vegetation cover and lie between 20 and 100 cm. Well-preserved SOM is accumulated in the active layer and subjacent ice-rich permafrost of wet polygonal tundra. Uplands, hummocky tussock tundra and alluvial fans cover more than 50 % of the island and show heterogeneous SOM storage characteristics with considerable TOC contents being limited to the active layer. Disturbed areas with slope gradients greater than 6° show strong SOM degradation with low TOC contents throughout the active layer and permafrost strata. Linear regression and principal component analysis (PCA) shows that a decreasing SOM content is driven by increasing ground disturbance and reduced vegetation cover. Improved drainage decreases the preservation of SOM in the active layer. Future deepening of the active layer because of increasing temperatures and ground disturbance will remobilise SOM stored in ice-rich permafrost. This might increase carbon dioxide and methane emissions from permafrost landscapes.

Description: This work constitutes the preliminary results from the first phase of INTEGRATE, a project lying within the scope of the SPP: Mountain Building in 4-Dimensions (MB 4-D). Although the crustal and sub-crustal structures of the Alps are some of the best studied of any orogen in the world, different hypotheses still exist regarding plate architecture and the nature of the subduction system. Rheological configurations of the different crustal units and lithospheric mantle, isostasy in the orogen-foreland system, and variations of flexural rigidity along and across the mountain belt, at the present-day, poorly constrained with relation to spatial patterns of seismicity. The primary goal of INTEGRATE is to provide insights into these questions by generating a gravity constrained, 3D structural model of the Alps and their foreland basins, so that a lithospheric temperature field can be calculated and ultimately the distribution of deformation and seismicity derived across the whole region. Here we present a first 3D structural model of the entire Alpine orogen, constructed from an integration of all publicly available geoscientific observations on the study area. Our model will be constrained by gravity fields, and the results of previous models generated using similar techniques, in regions that overlap our study area, such as the Rhine Graben, the Molasse Basin and the Po Basin. Additionally, it will benefit from current efforts by the AlpArray Gravity research group to create high resolution terrestrial gravity fields of the region. A combined model such as this will provide estimates of flexural rigidity, loads, gravitational potential energy and stresses in the different crustal bodies and, additionally, allow testing of existing isostastic models of the lithosphere. These 3D models have the potential to be used as a reference for other types of data processing and are a crucial step forward in deciphering how deep-seated mass changes affect the evolution of an orogen.