Effect of glacial-interglacial sea-level changes on the displacement and stress field in the forearc and along the plate interface of subduction zones

Combined seismological, space-geodetic and numerical studies have shown that the seismicity at subduction zones may be modulated by tides and glacier fluctuations on timescales of 1-100 a, because these changes in loads on Earth's surface are able to alter the stress field in the upper plate and along the plate interface. Here we use a two-dimensional finite-element model of a subduction zone to investigate how glacial-interglacial sea-level changes affect the forearc region and the plate interface. The model results show that a sea-level fall by 125m over 100 ka causes up to 0.7m of vertical displacement, with the maximum uplift occurring between the trench and the coast. The uplift signal induced by the sea-level fall decreases to zero similar to 20 km landward of the coastline. A subsequent sea-level rise by 125m over 20 ka causes subsidence, which is again most pronounced in the submarine part of the forearc. The sea-level changes cause horizontal displacements of up to 0.12 m, which are directed seaward during sea-level fall and landward during sea-level rise. With respect to the stress field, the sea-level changes lead to variations in the vertical stress and the shear stress of up to 1.23MPa and 0.4MPa, respectively. The shear stress variations are highest beneath the coast, i.e. in the area where the sea-level changes cause the strongest flexure. The resulting Coulomb stress changes on the plate interface are of the order of 0.2-0.5MPa and indicate that earthquakes are promoted during sea-level fall and delayed during sea-level rise. Our findings imply that eustatic sea-level changes during glacial-interglacial periods may have induced displacements and stress changes that were large enough to affect the seismic cycle of subduction thrusts.DFG/HA 3473/2-

Deformation of salt structures by ice-sheet loading: insights into the controlling parameters from numerical modelling

Subsurface salt flow is driven by differential loading, which is typically caused by tectonics or sedimentation. During glaciations, the weight of an ice sheet represents another source of differential loading. In salt-bearing basins affected by Pleistocene glaciations, such as the Central European Basin System, ice loading has been postulated as a trigger of young deformation at salt structures. Here, we present finite-element simulations (ABAQUS) with models based on a simplified 50-km long and 10-km-deep two-dimensional geological cross-section of a salt diapir subject to the load of a 300-m-thick ice sheet. The focus of our study is to evaluate the sensitivity of the model to material parameters, including linear and non-linear viscosity of the salt rocks and different elasticities. A spatially and temporarily variable pressure was applied to simulate ice loading. An ice advance towards the diapir causes lateral salt flow into the diapir and diapiric rise. Complete ice coverage leads to downward displacement of the diapir. After unloading, displacements are largely restored. The modelled displacements do not exceed few metres and are always larger in models with linear viscosity than in those with non-linear viscosity. Considering the low stresses caused by ice-sheet loading and the long time-scale, the application of linear viscosity seems appropriate. The elastic parameters also have a strong impact, with lower Young's moduli leading to larger deformation. The impact of both the viscosity and the elasticity highlights the importance of a careful parameter choice in numerical modelling, especially when aiming to replicate any real-world observations

Biomarker-Drug and Liquid Biopsy Co-development for Disease Staging and Targeted Therapy: Cornerstones for Alzheimer's Precision Medicine and Pharmacology.

Systems biology studies have demonstrated that different (epi)genetic and pathophysiological alterations may be mapped onto a single tumor's clinical phenotype thereby revealing commonalities shared by cancers with divergent phenotypes. The success of this approach in cancer based on analyses of traditional and emerging body fluid-based biomarkers has given rise to the concept of liquid biopsy enabling a non-invasive and widely accessible precision medicine approach and a significant paradigm shift in the management of cancer. Serial liquid biopsies offer clues about the evolution of cancer in individual patients across disease stages enabling the application of individualized genetically and biologically guided therapies. Moreover, liquid biopsy is contributing to the transformation of drug research and development strategies as well as supporting clinical practice allowing identification of subsets of patients who may enter pathway-based targeted therapies not dictated by clinical phenotypes alone. A similar liquid biopsy concept is emerging for Alzheimer's disease, in which blood-based biomarkers adaptable to each patient and stage of disease, may be used for positive and negative patient selection to facilitate establishment of high-value drug targets and counter-measures for drug resistance. Going beyond the "one marker, one drug" model, integrated applications of genomics, transcriptomics, proteomics, receptor expression and receptor cell biology and conformational status assessments during biomarker-drug co-development may lead to a new successful era for Alzheimer's disease therapeutics. We argue that the time is now for implementing a liquid biopsy-guided strategy for the development of drugs that precisely target Alzheimer's disease pathophysiology in individual patients

Composite faults in the Swiss Alps formed by the interplay of tectonics, gravitation and postglacial rebound: an integrated field and modelling study

Along the flanks of several valleys in the Swiss Alps, well-preserved fault scarps occur between 1900 and 2400 m altitude, which reveal uplift of the valley-side block relative to the mountain-side block. The height of these uphill-facing scarps varies between 0.5 m and more than 10 m along strike of the fault traces, which usually trend parallel to the valley axes. The formation of the scarps is generally attributed either to tectonic movements or gravitational slope instabilities. Here we combine field data and numerical experiments to show that the scarps may be of composite origin, i.e. that tectonic and gravitational processes as well as postglacial differential uplift may have contributed to their formation. Tectonic displacement may occur as the fault scarps run parallel to older tectonic faults. The tectonic component seems, however, to be minor as the studied valleys lack seismic activity. A large gravitational component, which is feasible owing to the steep dip of the schistosity and lithologic boundaries in the studied valleys, is indicated by the uneven morphology of the scarps, which is typical of slope movements. Postglacial differential uplift of the valley floor with respect to the summits provides a third feasible mechanism for scarp formation, as the scarps are postglacial in age and occur on the flanks of valleys that were filled with ice during the last glacial maximum. Finite-element experiments show that postglacial unloading and rebound can initiate slip on steeply dipping pre-existing weak zones and explain part of the observed scarp height. From our field and modelling results we conclude that the formation of uphill-facing scarps is primarily promoted by a steeply dipping schistosity striking parallel to the valley axes and, in addition, by mechanically weaker rocks in the valley with respect to the summits. Our findings imply that the identification of surface expressions related to active faults can be hindered by similar morphologic structures of non-tectonic origi

Klimawandel und Seismizität : Warum das Abschmelzen von Eis Erdbeben begünstigt

Durch den Klimawandel und die dadurch erfolgende Eisschmelze kann es in bisher stabilen Gebieten zu Erdbeben kommen. Prof. Dr. Andrea Hampel vom Institut für Geologie zeigt anhand von Modellierungen und Beispielen aus der geologischen Vergangenheit der Erde, wie Massenänderungen auf der Erdoberfläche die Spannungsverteilung beeinflussen können

Biomarker-Drug and Liquid Biopsy Co-development for Disease Staging and Targeted Therapy: Cornerstones for Alzheimer’s Precision Medicine and Pharmacology

Systems biology studies have demonstrated that different (epi)genetic and pathophysiological alterations may be mapped onto a single tumor’s clinical phenotype thereby revealing commonalities shared by cancers with divergent phenotypes. The success of this approach in cancer based on analyses of traditional and emerging body fluid-based biomarkers has given rise to the concept of liquid biopsy enabling a non-invasive and widely accessible precision medicine approach and a significant paradigm shift in the management of cancer. Serial liquid biopsies offer clues about the evolution of cancer in individual patients across disease stages enabling the application of individualized genetically and biologically guided therapies. Moreover, liquid biopsy is contributing to the transformation of drug research and development strategies as well as supporting clinical practice allowing identification of subsets of patients who may enter pathway-based targeted therapies not dictated by clinical phenotypes alone. A similar liquid biopsy concept is emerging for Alzheimer’s disease, in which blood-based biomarkers adaptable to each patient and stage of disease, may be used for positive and negative patient selection to facilitate establishment of high-value drug targets and counter-measures for drug resistance. Going beyond the “one marker, one drug” model, integrated applications of genomics, transcriptomics, proteomics, receptor expression and receptor cell biology and conformational status assessments during biomarker-drug co-development may lead to a new successful era for Alzheimer’s disease therapeutics. We argue that the time is now for implementing a liquid biopsy-guided strategy for the development of drugs that precisely target Alzheimer’s disease pathophysiology in individual patients

LGM ice extent and deglaciation history in the Gurktal and Lavantal Alps (eastern European Alps): first constraints from 10Be surface exposure dating of glacially polished quartz veins

Compared with the western European Alps, the ice extent during the Last Glacial Maximum (LGM) and the subsequent deglaciation history of the eastern Alps east of the Tauern Window remain less well constrained. Also, considerable discrepancies exist between the mapped LGM ice margin and the ice extent predicted by ice-sheet models. Here we present the first 10Be surface exposures ages from two regions east of the Tauern Window (the Gurktal and Lavantal Alps), which provide constraints on the LGM ice extent and the deglaciation history. Our results show that the deglaciation of the Gurktal Alps occurred between 16 and 14 ka, which agrees with the predictions from ice-sheet models. In contrast, the 10Be ages from the Lavantal Alps located farther east are either LGM in age or predate the LGM, indicating that these regions were ice free or only partially covered by LGM ice. This finding suggests that ice-sheet models may have overestimated the LGM ice extent in the easternmost Alps. In conclusion, our study highlights the need for more age data from the eastern Alps to refine the location of the LGM ice margin and the deglaciation history, which is also crucial for climate-evolution and postglacial-rebound models

Phases of Enhanced Exhumation During the Cretaceous and Cenozoic Orogenies in the Eastern European Alps: New Insights From Thermochronological Data and Thermokinematic Modeling

Austroalpine nappes in the Eastern European Alps have preserved the record of orogenies in the Cretaceous and Cenozoic but their cooling and exhumation history remains poorly constrained. Here we use low-temperature thermochronology and thermokinematic modeling to unravel the exhumation history of the Austroalpine nappes in the Gurktal Alps. Our data reveal marked differences between the exhumation of units located at different positions within the nappe stack and relative to the Adriatic indenter. Units located at a high structural level and farther away from the indenter cooled through the zircon fission track closure temperature in the Late Cretaceous and have resided at depths of ≤5–6 km since the Oligocene, as indicated by apatite fission track ages of 35–30 Ma. Thermokinematic modeling constrained that these units experienced enhanced exhumation (∼0.60 km/Ma) between ∼99 and ∼83 Ma due to syn- to late-orogenic Late Cretaceous extension. After a phase of slow exhumation (∼0.02 km/Ma), the exhumation rate increased to ∼0.16 km/Ma at ∼34 Ma due to the onset of the Europe-Adria collision. In contrast, zircon fission track ages from units at a lower structural level and near the indenter indicate cooling during the Eocene; apatite fission track ages cluster at ∼15 Ma. These units were rapidly exhumed (∼0.76 km/Ma) from ∼44 to ∼39 Ma during an Eocene phase of shortening prior to the Europe-Adria collision. After slow exhumation (∼0.13 km/Ma) between ∼39 and ∼18 Ma, the exhumation rate increased to ∼0.27 km/Ma in the wake of Miocene escape tectonics in the Eastern Alps

Spatial patterns of erosion and landscape evolution in a bivergent metamorphic core complex revealed by cosmogenic 10Be: The central Menderes Massif (western Turkey)

In extensional provinces with low-angle normal faulting (such as the Aegean region), both tectonic processes and erosion induce landscape change, but their interaction during the evolution of topography and relief accompanying continental extension has rarely been addressed. Here we present local and catchment-wide 10Be erosion rates that document the spatial pattern of erosion in the central Menderes Massif, a metamorphic core complex consisting of two asymmetric mountain ranges (Bozdağ and Aydın) bound by detachment faults and active grabens. Catchment-wide erosion rates on the northern flank of the Bozdağ Range are rather low (40–110 mm/k.y.) but reach values of >300 mm/k.y. on the steep southern escarpment—a pattern that reflects both topography and bedrock lithology. In the Aydın Range, erosion rates are generally higher, with mean erosion rates of ∼190 and ∼260 mm/k.y. on the northern and southern flank, respectively, and more variable along strike. In both ranges, erosion rates of ridge crests derived from amalgamated clasts are 30–90 mm/k.y. The difference between local and catchment-wide erosion rates indicates that topographic relief increases in most parts of the massif in response to ongoing fault-related uplift and concomitant river incision. Our findings document that tectonic processes exert a significant control on landscape evolution during active continental extension and are reflected in both the topographic signature and the spatial pattern of erosion. In the Menderes Massif, rock susceptibility to weathering and erosion is a dominant factor that controls the erosional contribution to rock exhumation, which varies spatially between ∼10% and ∼50%