Monitoring Catalytic 2-Propanol Oxidation over Co3O4 Nanowires via In Situ Photoluminescence Spectroscopy

Spectroscopic methods enabling real-time monitoring of dynamic surface processes are a prerequisite for identifying how a catalyst triggers a chemical reaction. We present an in situ photoluminescence spectroscopy approach for probing the thermo-catalytic 2-propanol oxidation over mesostructured Co3O4 nanowires. Under oxidative conditions, a distinct blue emission at ~420 nm is detected that increases with temperature up to 280 °C, with an intermediate maximum at 150 °C. Catalytic data gained under comparable conditions show that this course of photoluminescence intensity precisely follows the conversion of 2-propanol and the production of acetone. The blue emission is assigned to the radiative recombination of unbound acetone molecules, the n - π* transition of which is selectively excited by a wavelength of 270 nm. These findings open a pathway for studying thermo-catalytic processes via in situ photoluminescence spectroscopy thereby gaining information about the performance of the catalyst and the formation of intermediate products.

Contrasting Geomorphic and Stratigraphic Responses to Normal Fault Development During Single and Multi-Phase Rifting

Understanding the impact of tectonics on surface processes and the resultant stratigraphic evolution in multi-phase rifts is challenging, as patterns of erosion and deposition related to older phases of extension are overprinted by the subsequent extensional phases. In this study, we use a one-way coupled numerical modelling approach between a tectonic and a surface processes model to investigate topographic evolution, erosion and basin stratigraphy during single and multi-phase rifting. We compare the results from the single and the multi-phase rift experiments for a 5 Myr period during which they experience equal amounts of extension, but with the multi-phase experiment experiencing fault topography inherited from a previous phase of extension. Our results demonstrate a very dynamic evolution of the drainage network that occurs in response to fault growth and linkage and to depocentre overfilling and overspilling. We observe profound differences between topographic and depocenter development during single and multi-phase rifting with implications for sedimentary facies architecture. Our quantitative approach, enables us to better understand the impact of changing extension direction on the distribution of sediment source areas and the syn-rift stratigraphic development through time and space.

Contrasting transform and passive margin subsidence history and heat flow evolution: insights from 3D thermo-mechanical modelling

Transform and passive margins developed during the continental rifting and opening of oceanic basins are fundamental elements of plate tectonics. It has been suggested that inherited structures, plate divergence velocities and surface processes exert a first order control on the topographic and bathymetric evolution and thermal history of these margins and related sedimentary basins. Their complex spatial-temporal dynamics have remained controversial. Here, we conducted 3D magmatic-thermo-mechanical numerical experiments coupled with surface processes modelling to simulate the dynamics of continental rifting, continental transform fault zone formation and persistent oceanic transform faulting and zero-offset oceanic fracture zones development. Numerical modelling results allow to explain the first order observations from passive and transform margins, such as diachronous rifting, heat flow rise and cooling in individual depocenters and contrasting basin tectonics of extensional and transtensional origin. In addition, the models reproduce the rise of both marginal ridges and transform marginal plateaus and their interaction with erosion and sedimentation. Comparison of model results with observations from natural examples yield new insights into the tectono-sedimentary and thermal evolution of several key passive and transform continental margins worldwide.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5756555

Evolution of rift systems and their fault networks in response to surface processes

Continental rifting is responsible for the generation of major sedimentary basins, both during rift inception and during the formation of rifted continental margins. Geophysical and field studies revealed that rifts feature complex networks of normal faults but the factors controlling fault network properties and their evolution are still matter of debate. Here, we employ high-resolution 2D geodynamic models (ASPECT) including two-way coupling to a surface processes code (FastScape) to conduct 12 models of major rift types that are exposed to various degrees of erosion and sedimentation. We further present a novel quantitative fault analysis toolbox (Fatbox), which allows us to isolate fault growth patterns, the number of faults, and their length and displacement throughout rift history. Our analysis reveals that rift fault networks may evolve through five major phases: 1) distributed deformation and coalescence, 2) fault system growth, 3) fault system decline and basinward localization, 4) rift migration, and 5) breakup. These phases can be correlated to distinct rifted margin domains. Models of asymmetric rifting suggest rift migration is facilitated through both ductile and brittle deformation within a weak exhumation channel that rotates subhorizontally and remains active at low angles. In sedimentation-starved settings, this channel satisfies the conditions for serpentinization. We find that surface processes are not only able to enhance strain localization and to increase fault longevity but that they also reduce the total length of the fault system, prolong rift phases and delay continental breakup.

Land surface models significantly underestimate the impact of land-use changes on global evapotranspiration

Despite numerous assessments of the impact of land-use change (LUC) on terrestrial evapotranspiration (ET) that have been conducted using land surface models (LSMs), no attempts have been made to evaluate their performance in this regard globally. Errors in simulating LUC impacts on ET largely stem from LUC data interpretation (LI, i.e. mapping of gridded LUC data into annual plant function types) and model structure (MS, i.e. parameterization of land-surface processes). The objective of this study was to benchmark ET estimates from four LSMs using the Zhang-curve, a prototype of the Budyko framework that has been validated against global hydrological observations and used widely to quantify the impacts of LUC on ET. A framework was further proposed to quantify and attribute errors in estimated ET changes induced by LI or MS. Results showed that all LSMs underestimated ET changes by about 55%–78%, and 37%–48% of the error was attributable to LI, but only 11%–32% of the error was attributable to MS across the four LSMs. From a hydrological perspective, our analysis provided insights about the errors in estimated impacts of LUC on ET by LSMs. The results demonstrated that LUC data interpretation accounted for a larger fraction of errors than LSM structure. Therefore, there is an urgent need for the defining and development of consistent protocols for interpreting global LUC data for future assessments.