Syntectonic sedimentation history is a potential cause of differentiated accretionary wedge structures along the subduction margin. Recent efforts to model the role of sedimentation on wedge evolution have highlighted the importance of spatiotemporal history of sedimentation on the evolution of the wedge. Moreover, reconstruction of deformation history of the accretionary wedges using reflection seismic and borehole data has further substantiated the impact of sedimentation on wedge evolution. We conduct several numerical experiments using a high‐resolution dynamic 2‐D thermomechanical plate subduction model to systematically investigate and quantify different effects of sedimentation on accretionary wedge evolution. Models with sedimentation suggest migration of deformation to parts of the wedge lying outside the sedimentation zone leading to emergence/reactivation of out‐of‐sequence thrusts (OOSTs). Frequency and length of new thrust sheets are correlated with sedimentation in the trench. Models undergo a transition period of ~1.5 Myr following the onset of sedimentation, after which they continue to grow under a new steady state. Stabilization of the wedge and increased load on the oceanic plate due to sedimentation create conditions in which smaller wedge‐top basins combine to form a large and flat forearc basin. Last but not the least, emergence of OOST in models of accretionary wedges undergoing sedimentation provides important insights in to evolution of potentially tsunamigenic OOSTs like the Megasplay Fault seaward of the Kumano forearc basin.

We present a model for the dynamic formation of the forearc high of southern Anatolia where sedimentation in the forearc basin leads to thermally-activated deformation in the lower crust. Our thermo-mechanical models demonstrate that forearc sedimentation increases the temperature of the underlying crust by “blanketing” the heat flux and increasing Moho depth. Deformation switches from frictional to viscous with a higher strain rate led by increased temperature. Viscous deformation changes large-wavelength subsidence into coeval, short-wavelength uplift and subsidence. Models show that forearc highs are intrinsic to accretionary wedges and can grow dynamically and non-linearly at rates dependent on sediment accretion, sedimentation and temperature. The mechanism explains the uplift of the southern margin of the Central Anatolian Plateau and the Neogene vertical motions and upper-plate strain in the Anatolian margin along Central Cyprus. This system is analogous to forearc highs in other mature accretionary margins, like Cascadia, Lesser Antilles or Makran.

Quantitative constraints on soil organic matter (SOM) dynamics are essential for comprehensive understanding of the terrestrial carbon cycle. Deep soil carbon is of particular interest as it represents large stocks and its turnover times remain highly uncertain. In this study, SOM dynamics in both the top and deep soil across a climatic (average temperature ∼ 1-9 • C) gradient are determined using time-series (∼ 20 years) 14 C data from bulk soil and waterextractable organic carbon (WEOC). Analytical measurements reveal enrichment of bomb-derived radiocarbon in the deep soil layers on the bulk level during the last 2 decades. The WEOC pool is strongly enriched in bomb-derived carbon, indicating that it is a dynamic pool. Turnover time estimates of both the bulk and WEOC pool show that the latter cycles up to a magnitude faster than the former. The presence of bomb-derived carbon in the deep soil, as well as the rapidly turning WEOC pool across the climatic gradient, implies that there likely is a dynamic component of carbon in the deep soil. Precipitation and bedrock type appear to exert a stronger influence on soil C turnover time and stocks as compared to temperature.

Coastal oceans play a crucial role in the global carbon cycle, and are increasingly affected by anthropogenic forcing. Understanding carbon cycling in coastal environments is hindered by convoluted sources and myriad processes that vary over a range of spatial and temporal scales. In this study, we deconvolve the complex mosaic of organic carbon manifested in Chinese Marginal Sea (CMS) sediments using a novel numerical clustering algorithm based on 14 C and total OC content. Results reveal five regions that encompass geographically distinct depositional settings. Complementary statistical analyses reveal contrasting region-dependent controls on carbon dynamics and composition. Overall, clustering is shown to be highly effective in demarcating areas of distinct organic facies by disentangling intertwined organic geochemical patterns resulting from superimposed effects of OC provenance, reworking and deposition on a shelf region exhibiting pronounced spatial heterogeneity. This information will aid in constraining region-specific budgets of carbon burial and carbon cycle processes. Plain Language SummaryIn the context on ongoing climate change, it is crucial to understand how and where carbon is buried. Coastal oceans are very important areas for carbon burial globally, even though they only form a small part of the total ocean surface. These areas are very complex because there is carbon coming both from the land as well as the sea. By understanding where thecarbon from land and where the carbon from the sea ends up, we can better estimate carbon storage. This paper presents a clustering approach which uses the large dataset of carbon age and concentration in the Chinese marginal seas. The clustering approach shows where the carbon from land goes and how it is buried, which areas lose carbon and which areas bury carbon. This approach could also be used in the future on other datasets such as the Arctic Seas.