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Isotropic three-dimensional (3-D) inversion has become a standard tool in the interpretation of magnetotelluric (MT) data. 3-D anisotropic inversion codes are under development, yet the number of unknowns increases by a factor of 6 rendering the problem extremely ill-posed. The presence of anisotropy is usually inferred from (i) spurious sequences of conductive and resistive bodies or (ii) comparison with two-dimensional anisotropic modelling approaches.Here, we investigate the 3-D structure of the Gawler Craton down to ∼250 km depth using 282 sites of the AusLAMP array located in the southern half of South Australia. Inversions of the MT impedance as phase tensors and real and imaginary parts result in diverging structures at depths > 70 km. We demonstrate that a unifying model that explains all data types similarly well is suggestive of an anisotropic resistivity structure at the base of the Gawler Craton lithosphere at depths of 120–210 km. Depth location and orientation of the anisotropy agree well with results from the analysis of seismic receiver functions. We suggest that electric anisotropy in the Gawler Craton is a result of lattice-preferred orientation of olivine crystals and metasomatic processes with macroscopic preferential orientation.Our results illustrate that inversion of phase tensor data is superior for the direct imaging of anisotropic resistivity contrasts in otherwise isotropic resistivity models; inversion models obtained with impedances may miss such structures. “Comparable” overall RMS misfits are often meaningless when comparing inversion results for various data types since sensitivities differ between data types. Reliable inversion results consistent with the entire data set can only be recovered if data fits are assessed systematically for all data representations. We also discuss the influence of error settings for phase tensors on the inversion.Our study also revealed that, if persistent across large areas, (i) parallel orientation of phase tensor major axes, (ii) constantly high phase tensor maximum phases or (iii) diverging directions of phase tensor major axes and induction arrows are suggestive of anisotropic structures and corresponding hypotheses should be evaluated.

West Tasmania has a complex geological history, including a Cambrian tectonic collision and related orogenesis, which formed ore deposits in a volcanic hosted massive sulfide (VHMS) setting. While the topography and dense vegetation covering the area presents challenges for on-ground investigations, the area is relatively well-studied such that 3D geological models are available. This contribution presents results of a broadband magnetotelluric (MT) 2D transect across the area (∼30 stations over a $ \sim 80\,{\rm km} $ ∼80kmline, deployed in early 2016) that enables a combined interpretation of regional-scale geoelectric and geological structures.After accounting for noise, distortion and geoelectric strike; we produce 2D resistivity models using OCCAM2D inversion. We infer low resistivity anomalies in the shallow ( $ \lt 3\,{\rm km} $ <3km), mid (3–8 km) and deeper crust. Along this MT transect the shallow and mid crust low resistivity zones correspond to major crustal faults. Deep low resistivity features in the east of the transect suggest fluid pathways associated with metamorphism along the western boundary of the Tyennan block during the Cambrian Tyennan Orogeny, while others potentially represent the metasomatism of lower crustal rocks and fluid pathways converging into the mid crust.

Heat flow data obtained in connection with geothermal resource exploration suggests anomalous upper crustal structure and processes in parts of central east Tasmania. The regional scale crustal geology of the Midlands of Tasmania is, however, mostly obscured at the surface by the Permo-Triassic sedimentary sequences of the Tasmania Basin together with extensive exposures of Jurassic dolerite. We investigate controls on undercover crustal processes in this region by combining long period and broadband magnetotelluric (MT) datasets in 3D inversions for the geoelectric structure; followed by an interpretation that is informed by aspects of the pre-existing 3D regional geological and geophysical model. The new 3D model allows improved resolution of low resistivity anomalies together with a qualitative appraisal of spatially variable model sensitivity. The most robust features ( $ \lt 1\,\Omega {\rm m} $ <1Ωm) in the 2–3 km depth interval occur where N–S and E–W faults intersect with a high point in the topography of the upper surface of a deep seated granite body. Enhancement of conductivity in this zone by clay, graphite or mineralisation, or a combination thereof, is likely. Other low resistivity features suggest that conductive pathways exist where major or multiple faults are present. These interpretations provide support for continued exploration in the Midlands of Tasmania for a variety of resources related to crustal fluids and fracturing.

When building 3D models of the subsurface, reconciling several geological and geophysical data of diverse nature, resolutions, coverage, or sensitivity, is challenging, both numerically and petrophysically. In this work, we propose a workflow for mapping selected geological features and characterise their uncertainty using a Bayesian Estimate Fusion algorithm. Different datasets such as 1D probabilistic models derived from geophysical data, drillholes and geological data are combined to produce probabilistic maps of selected geological boundaries, relying on petrophysical and geological assumptions. Leveraging large, high-quality geophysical datasets acquired in the eastern Gawler Craton in South Australia, we demonstrate the applicability of our approach with two examples: (1) we map in 3D the top of a stratigraphic unit in the cover, the Tregolana Shale, using 1D magnetotelluric (MT) and 1D Airborne Electromagnetic (AEM) probabilistic models, drill holes and surface geology; (2) we map the depth to basement using 1D probabilistic MT models, drill holes and interpreted structural information. Our results show that the different resolution, data sampling, depth of investigation and reliability of the utilised datasets can be combined in a complementary fashion, overcoming their respective limitations, to find solutions/models that satisfy all the datasets. We show that probabilistic workflows permit characterisation and reduce uncertainty when mapping the location of features of interest, but also permit the testing of geological hypotheses against other geophysical and geological data. These types of models are valuable to better characterise, interpret, and conceptualise the subsurface, enabling better exploration targeting and supporting efforts to discover new mineral deposits.

A long‐period magnetotelluric (MT) survey, with 39 sites covering an area of 270 by 150 km, has identified melt within the thinned lithosphere of Pleistocene‐Holocene Newer Volcanics Province (NVP) in southeast Australia, which has been variously attributed to mantle plume activity or edge‐driven mantle convection. Two‐dimensional inversions from the MT array imaged a low‐resistivity anomaly (10–30 Ω m) beneath the NVP at ~40–80 km depth, which is consistent with the presence of ~1.5–4% partial melt in the lithosphere, but inconsistent with elevated iron content, metasomatism products or a hot spot. The conductive zone is located within thin juvenile oceanic mantle lithosphere, which was accreted onto thicker Proterozoic continental mantle lithosphere. We propose that the NVP owes its origin to decompression melting within the asthenosphere, promoted by lithospheric thickness variations in conjunction with rapid shear, where asthenospheric material is drawn by shear flow at a “step” at the base of the lithosphere. Presence of large conductor in the lithospherePresence of partial melt underneath an intraplate volcanic field in AustraliaMagma genesis caused by decompression melting

The dominant north–south strike of the Palaeozoic outcrop of central Victoria has been well documented, but to the north, these rocks are covered by the Cainozoic sedimentary deposits of the Murray Basin. Two magnetotelluric surveys were completed to assist in extrapolation of the known structure and to identify possible new targets for mineral discovery. Supporting the results from previous seismic interpretations for the region, the 2D MT inversion models substantiate an intrazone thrust fault system of listric geometries in the Bendigo Zone connected in the mid-crust. With the zone boundary clearly defined the electrical resistivity structure is distinct between the major subdivisions, indicating a different tectonic evolution for the Bendigo and Melbourne Zones. However, the conductive overburden in the region poses complications for the generation of the 2D resistivity models. Static shifts and electrical anisotropy were identified as distortions in the dataset, with further processing needed to attain a complete picture of the underlying geology. The difficulties caused by galvanic distortion were allayed by using the phase tensor response in place of the distorted amplitude response. Phase tensor analysis of MT data has been completed subsequently, the results of which we present here, along with the original 2D inversion models, confirming that electrical anisotropy persists into the mantle.

In a previous combined QM/MM molecular dynamics (MD) study from our laboratory on the identity SN2 reaction between a chloride anion and an amino chloride in liquid dimethyl ether (DME), an increase in the free energy activation barrier was observed in the condensed phase when compared to the gas-phase activation energy. Here we reproduce these findings, but when comparing the condensed-phase potential of mean force (PMF) with the freeenergy profile in the gas phase (obtained from Monte Carlo simulations), we observe a smaller solvent effect on the activation barrier of the reaction. In a next step, we introduce an explicit description of electronic polarization in the MM (solvent) part of the system. A polarizable force field for liquid DME was developed based on the charge-on-spring (COS) model, which was calibrated to reproduce thermodynamic properties of the nonpolarizable model in classical MD simulations. The COS model was implemented into the MNDO/GROMOS interface in a special version of the QM/MM software ChemShell, which was used to investigate the effect of solvent polarization on the free energy profile of the reaction under study. A higher activation barrier was obtained using the polarizable solvent model than with the nonpolarizable force field, due to a better solvation of and a stronger polarization of solvent molecules around the separate reactants. The obtained PMFs were subjected to an energy-entropy decomposition of the relative solvation free energies of the reactant complex along the reaction coordinate, to investigate in a quantitative manner whether the solvent (polarization) effects are mainly due to favorable QM-MM (energetic) interactions.

We present a microiterative adiabatic scheme for quantum mechanical/molecular mechanical (QM/MM) energy minimization that fully optimizes the MM part in each QM macroiteration. This scheme is applicable not only to mechanical embedding but also to electrostatic and polarized embedding. The electrostatic QM/MM interactions in the microiterations are calculated from electrostatic potential charges fitted on the fly to the QM density. Corrections to the energy and gradient expressions ensure that macro- and microiterations are performed on the same energy surface. This results in excellent convergence properties and no loss of accuracy compared to standard optimization. We test our implementation on water clusters and on two enzymes using electrostatic embedding, as well as on a surface example using polarized embedding with a shell model. Our scheme is especially well-suited for systems containing large MM regions, since the computational effort for the optimization is almost independent of the MM system size. The microiterations reduce the number of required QM calculations typically by a factor of 2−10, depending on the system.

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We used the free-energy perturbation (FEP) method in quantum mechanics/molecular mechanics (QM/MM) calculations to compute the free-energy profile of the hydroxylation reaction in the enzyme p-hydroxybenzoate hydroxylase (PHBH). k statistics were employed to analyze the FEP sampling including estimation of the sampling error. Various approximations of the free-energy perturbation method were tested. We find that it is adequate not only to freeze the density of the QM part during the dynamics at frozen QM geometry but also to approximate this density by electrostatic-potential-fitted point charges. It is advisable to include all atoms of a QM/MM link in the perturbation. The results of QM/MM-FEP for PHBH are in good agreement with those of thermodynamic integration and umbrella sampling.

The experimental velocity distributions of NO desorbing from a NiO(100)‐surface are simulated using a time‐dependent wave packet method. Including the polar angle between the surface normal and the adsorbate molecular axis yields bimodal distributions in the correct velocity range and reasonable desorption probabilities if a resonance lifetime on the order of 25 fs is assumed. For two‐dimensional simulations, an angular‐independent charge‐transfer‐state was chosen as excited state in order to investigate the influence of the electronic ground‐state on the final state distributions. We compare our results with wave packet calculations using a representative ab initio angular‐dependent excited‐state potential energy surface using a three‐dimensional Hamiltonian.

Plants have adapted very efficiently to their natural light habitat. Artificial plant illumination, therefore, requires careful design. Not only the quantity of radiation per area or volume (intensity) but also the spectral quality has to match seasonal and diurnal variations of natural global radiation as close as possible. The GSF Research Center has developed a phytotron system especially devoted to plant stress research, where these requirements are of particular importance. The phytotron consists of seven closed chambers (4 walk-in size chambers, two medium and one small sun simulator). Our contribution oudines the basic design of the lighting and presents spectral data.

The air pollutant ozone is a potent abiotic inducer of defense-related enzymes such as pathogenesis-related proteins. Here we report on the accumulation of ß-1,3-glucanase and chitinase in Nicotiana tabacumL. treated with ozone and ultraviolet B radiation, singly and in combination, under a simulated sunlight spectrum. Ozone (0.16 μL·L−1, 2 × 5h) induced the basic isoforms of ß-1,3-glucanase in both, ozone-sensitive (Bel W3) and -tolerant (Bel B) cultivars, while chitinase was only affected in cv. Bel W3. Ultraviolet B radiation (7.5 MED) alone did not lead to ß-1,3-glucanase or chitinase induction. In combined treatments ultraviolet B increased the ozone-dependent lesion formation and reduced chitinase accumulation in the sensitive cv. Bel W3. Analysis of the intercellular washing fluid of ozone-treated plants revealed the accumulation of a major ozone-related protein (O3R-1) of 28 kDa within 32 h. Microsequence analysis of two tryptic peptides showed 100 % homology to acidic chitinase PR-3b. These results indicate that basic ß-1,3-glucanase and chitinase are distinctly regulated in ozone and ultraviolet B treated tobacco, and that ultraviolet B radiation with a similar UV edge as the solar spectrum does not lead to an accumulation of basic pathogenesis-related proteins.

Ecological plant experiments using artificial light sources require careful shaping of the spectral irradiance. This includes the steep UV-absorption characteristics resulting from the filtering of solar radiation by atmosphefic ozone. Borosilicate and soda-lime glass filters screen radiation very similarly to ozone. They have a high mechanical stability and are available in large filter sheets and are, therefore, suited for the simulation of future scenarios of enhanced solar UV-B radiation in large scale vegetation stress experiments. Although such filters meet many requirements of light engineering, there are limitations due to the slope of the UV-edge and due to solarisation effects. Thus, the interpretation of the artifical radiation spectra and their comparison to UV scenarios of decreasing stratospheric ozone need careful discussion. Different methods to classify spectra of artificial UV-radiation are presented, and a new classification by a cut-off wavelength of the UV-edge and its slope is introduced.

The central Australian Musgrave Province at the junction of the South, North and West Australian cratons has undergone and continues to retain evidence of significant whole-of-crust, and most likely ‘whole-of-lithosphere’ tectono-magmatic processes. The area is known for some of the largest geophysical anomalies related to significant Moho offsets of up to 15 km, which resulted from repeated intracratonic reworking since the Neoproterozoic. New magnetotelluric (MT) data have been collected across the Musgrave Province in Western Australia and South Australia as part of the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP). Station spacing was ∼50kmbetween 96 sites over an area of 500 × 700 km. Long-period MT impedance and tipper data over a bandwidth of 8 s to 10,000 s period have been inverted using a smooth 3D inverse algorithm. The 3D model shows two predominant resistivity trends. There are deep (>65km) north–south mantle conductors that we infer to be related to the Palaeo- to Mesoproterozoic north-trending arc-related rocks that experienced ultra-high temperature metamorphism and widespread magmatism during the Mesoproterozoic Musgravian Orogeny. These conductors are preserved in the crust south of the Musgrave Province. The upper mantle also contains a localised resistive zone that possibly represents generation of mafic- to ultramafic magmas during the c. 1090–1040 Ma Giles Event. The crust (<65kmdepth) contains strong east–west crustal conductors interpreted to reflect the east–west structural grain that initiated during the c. 1090–1040 Ma Giles Event and overprinted the older N–S-oriented mantle anomalies. These E–W crustal conductors coincide with magnetic anomalies that represent crustal-scale structures, and high gravity anomalies associated with significant Moho offsets resulting from further reactivation during the c. 630–520 Ma Petermann and c. 450–300 Ma Alice Springs orogenies.

Vom 23. bis zum 27. September fand in Bad Herrenalb das „Symposium für Theoretische Chemie”︁ statt. Es war das 37. dieser Symposien, die jährlich im deutschsprachigen Raum (seit einigen Jahren mit Englisch als Konferenzsprache) veranstaltet werden. Etwas über 250 Teilnehmer aus Deutschland, Österreich, der Schweiz und den angrenzenden Ländern fanden im „Haus der Kirche”︁ eine schöne Tagungsstätte und ein von der Heidelberger Theoretischen Chemie um Horst Köppel, Jochen Schirmer, Peter Schmelcher und Lorenz Cederbaum gut zusammengestelltes Programm vor.