A reappraisal and 3D characterisation of fracture systems within the Devonian Orcadian Basin and its underlying basement: an onshore analogue for the Clair Group

The Orcadian Basin is a Devonian (Old Red Sandstone) sedimentary basin formed as a result of extensional tectonics after the end of the Caledonian Orogeny in onshore-offshore northeast Scotland. The Clair oil field lies in a smaller basin with similar types of continental sedimentation and it represents the largest remaining oilfield in the UKCS. Oil is found within Devonian-Carboniferous red beds of the Clair Group directly overlying crystalline basement rocks of the Rona Ridge. Recent work has shown that Lewisian Complex exposed in NW Scotland is excellent for assessing the nature and importance ofthe Rona Ridge basement fracture network. Here, geological evidence suggests that the Devonian rocks of the Orcadian Basin are also a suitable analogue for the Clair cover sequences to some degree and that a reappraisal of the deformation history of the Orcadian Basin is necessary to enhance the understanding of spatial and temporal characterization of structures in the subsurface. Faults, fault rocks, associated mineralization and deformation allow differentiation of three groups of structures within the Devonian Orcadian Basin: i. N-S, NW-SE, WNW-ESE trending faults showing little or no carbonate mineralisation (Group 1); ii. Metre- to kilometre-scale N-S to NE-SW trending folds and thrusts related to a highly heterogeneous regional inversion event, recognized locally throughout the field area, but especially on Orkney (Group 2); iii. dextral oblique NE-SW trending faults and sinistral E-W trending faults with widespread syn-deformational carbonate mineralisation (± base metal sulphides and bitumen) both along faults and in associated mineral veins (Group 3). Localized folds are associated with Group 3 structures due to reactivation of pre-existing faults. Crucially, these later folds are synchronous with carbonate and associated mineralisation events. Re-Os model ages of syn-deformational pyrite in two faults in the Caithness area (Dounreay) are 268.4 ± 4.9 & 266.4 ± 5.2 Ma (Permian). This is consistent with the field observation that Group 3 deformation is synchronous with the emplacement of ENE-WSW-trending lamprophyres of the Orkney Dyke Swarm (ca. 250 Ma based on K-Ar dating). Thus we suggest that Group 3 structures are synchronous with Permian rifting (NW-SE extension) which new faults and locally reactivated earlier structures. It appears that the Devonian rocks of the Orcadian basin were taken through the oil window at this time during a thermal event associated with regional alkaline basic igneous activity in Northern Britain. Scalability studies from 1D transect analysis show that fracture attributes (length and aperture)in the Devonian in Caithness (Scotland) are well described by a power-law distribution over 8 and 4 orders of magnitude. Also, 2D fracture connectivity is highly variable in the system and appears to be mainly associated with corridor structures at a large scale and on longer structures at the mesoscale. The onshore dataset shows sub-vertical fault intersections (3D) suggesting that horizontal drill orientation is favoured to vertical if these rocks were to be drilled as a reservoir

Polymorphs solvates and co-crystals of molecular materials

The scope of my research project is to produce and characterize new crystalline forms of organic compounds, focusing the attention on co-crystals and then transferring these notions on APIs to produce co-crystals of potential interest in the pharmaceutical field. In the first part of this work co-crystallization experiments were performed using as building blocks the family of aliphatic dicarboxylic acids HOOC-(CH2)n-COOH, with n= 2-8. This class of compounds has always been an object of study because it is characterized by an interesting phenomenon of alternation of melting points: the acids with an even number of carbon atoms show a melting point higher than those with an odd one. The acids were co-crystallized with four dipyridyl molecules (formed by two pyridine rings with a different number of bridging carbon atoms) through the formation of intermolecular interactions N•••(H)O. The bases used were: 4,4’-bipyridine (BPY), 1,2-bis(4-pyridyl)ethane (BPA), 1,2-(di-4-pyridyl)ethylene (BPE) and 1,2-bis(4-pyridyl)propane (BPP). The co-crystals obtained by solution synthesis were characterized by different solid-state techniques to determine the structure and to see how the melting points in co-crystals change. In the second part of this study we tried to obtain new crystal forms of compounds of pharmaceutical interest. The APIs studied are: O-desmethylvenlafaxine, Lidocaine, Nalidixic Acid and Sulfadiazine. Each API was subjected to Polymorph Screening and Salt/Co-crystal Screening experiments to identify new crystal forms characterized by different properties. In a typical Salt/Co-crystal Screening the sample was made to react with a co-former (solid or liquid) through different methods: crystallization by solution, grinding, kneading and solid-gas reactions. The new crystal forms obtained were characterized by different solid state techniques (X-ray single crystal diffraction, X-ray powder diffraction, Differential Scanning Calorimetry, Thermogravimetric Analysis, Evolved gas analysis, FT-IR – ATR, Solid State N.M.R)

Outcrop-scale manifestations of reactivation during multiple superimposed rifting and basin inversion events: the Devonian Orcadian Basin, northern Scotland

The Devonian Orcadian Basin in Scotland hosts extensional fault systems assumed to be related to the initial formation of the basin, with only limited post-Devonian inversion and reactivation. However, a recent detailed structural study across Caithness, underpinned by published Re–Os geochronology, shows that three phases of deformation are present. North–south- and NW–SE-trending Group 1 faults are related to Devonian ENE–WSW transtension associated with sinistral shear along the Great Glen Fault during the formation of the Orcadian Basin. Metre- to kilometre-scale north–south-trending Group 2 folds and thrusts are developed close to earlier sub-basin-bounding faults and reflect late Carboniferous–early Permian east–west inversion associated with dextral reactivation of the Great Glen Fault. The dominant Group 3 structures are dextral oblique NE–SW-trending and sinistral east–west-trending faults with widespread syndeformational carbonate mineralization (± pyrite and bitumen) and are dated using Re–Os geochronology as Permian (c. 267 Ma). Regional Permian NW–SE extension related to the development of the offshore West Orkney Basin was superimposed over pre-existing fault networks, leading to local oblique reactivation of Group 1 faults in complex localized zones of transtensional folding, faulting and inversion. The structural complexity in surface outcrops onshore therefore reflects both the local reactivation of pre-existing faults and the superimposition of obliquely oriented rifting episodes during basin development in the adjacent offshore areas

Supramolecular hierarchy among halogen and hydrogen bond donors in light-induced surface patterning

Halogen bonding, a noncovalent interaction possessing several unique features compared to the more familiar hydrogen bonding, is emerging as a powerful tool in functional materials design. Herein, we unambiguously show that one of these characteristic features, namely high directionality, renders halogen bonding the interaction of choice when developing azobenzene-containing supramolecular polymers for light-induced surface patterning. The study is conducted by using an extensive library of azobenzene molecules that differ only in terms of the bond-donor unit. We introduce a new tetrafluorophenol-containing azobenzene photoswitch capable of forming strong hydrogen bonds, and show that an iodoethynyl-containing azobenzene comes out on top of the supramolecular hierarchy to provide unprecedented photoinduced surface patterning efficiency. Specifically, the iodoethynyl motif seems highly promising in future development of polymeric optical and photoactive materials driven by halogen bonding

Surface-Relief Gratings in Halogen-Bonded Polymer–Azobenzene Complexes: A Concentration-Dependence Study

In recent years, supramolecular complexes comprising a poly(4-vinylpyridine) backbone and azobenzene-based halogen bond donors have emerged as a promising class of materials for the inscription of light-induced surface-relief gratings (SRGs). The studies up to date have focused on building supramolecular hierarchies, i.e., optimizing the polymer–azobenzene noncovalent interaction for efficient surface patterning. They have been conducted using systems with relatively low azobenzene content, and little is known about the concentration dependence of SRG formation in halogen-bonded polymer–azobenzene complexes. Herein, we bridge this gap, and study the concentration dependence of SRG formation using two halogen-bond-donating azobenzene derivatives, one functionalized with a tetrafluoroiodophenyl and the other with an iodoethynylphenyl group. Both have been previously identified as efficient molecules in driving the SRG formation. We cover a broad concentration range, starting from 10 mol % azobenzene content and going all the way up to equimolar degree of complexation. The complexes are studied as spin-coated thin films, and analyzed by optical microscopy, atomic force microscopy, and optical diffraction arising during the SRG formation. We obtained diffraction efficiencies as high as 35%, and modulation depths close to 400 nm, which are significantly higher than the values previously reported for halogen-bonded polymer–azobenzene complexes

Synthesis and Linker‐Controlled Self‐Assembly of Dendritic Amphiphiles with Branched Fluorinated Tails

Amphiphiles containing fluorinated segments tend to aggregate in the aqueous solution into structure of lower curvature than their hydrocarbon analogs due to their larger diameter. A benefit of supramolecular structures incorporating fluorine moieties is their high electron density, which can be viewed in cryo‐TEM with better contrast than their hydrogenated forms. A modular approach has been developed for the synthesis of a new family of nonionic branched amphiphiles consisting of oligoglycerol units (G2) as the hydrophilic part and a branched fluorinated (F27) hydrophobic part. The design of this hydrophobic moiety allows to achieve a higher fluorine density than the previously used straight‐chain perfluoroalkanes. Two different chemical approaches, amide, and triazole, are used to link the hydrophilic and hydrophobic segments. In addition, the aggregation behavior is investigated by dynamic light scattering (DLS) and cryo‐TEM. The measurements prove the formation of multivesicular (MVVs) and multilamellar (MLVs) vesicles as well as smaller unilamellar vesicles. Further, the cell viability test proves the low cell toxicity of these nanoarchitectures for potential biomedical applications

Fluorine-induced J-aggregation enhances emissive properties of a new NLO push–pull chromophore

A new fluorinated push–pull chromophore with good second-order NLO properties even in concentrated solution shows solid state intermolecular aryl–fluoroaryl interactions leading to J-aggregates with intense solid state luminescence

Hydro-mechanical simulation and analysis of induced seismicity for a hydraulic stimulation test at the Reykjanes geothermal field, Iceland

The combination of seismic analysis with advanced physics-based simulation provides an opportunity to further understand injection-induced fault reactivation, including the hydro-mechanical interplay between different faults and the rock where they reside. Here, this is investigated based on data from hydraulic stimulation of a well at the Reykjanes geothermal field. Central is the development of an interdisciplinary framework for integration of different data types towards a 3D, hydro-mechanical and faulted geothermal reservoir simulation model. This work shows how seismic interpretations can improve simulation models and, reciprocally, how fully coupled physics-based modeling can add to seismic interpretations in analysis of fault reactivation.publishedVersio

Vs30 and depth to bedrock estimates from integrating HVSR measurements and geology-slope approach in the Oslo area, Norway

In order to estimate well-constrained seismic hazard and risk on local scales, the knowledge of site amplification factors is one of several important requirements. Seismic hazard studies on national or regional scales generally provide the level of earthquake shaking only at bedrock conditions, thereby avoiding the difficulties that are caused through local site effects. Oftentimes, local site conditions are not well understood or even non-existent. In this study we investigate an efficient and non-invasive methodology to derive the local average shear wave velocity in the uppermost 30 m of the ground (Vs30). The Vs30 value is a useful parameter to define soil classes and soil amplification used in seismic hazard assessment and to extend the knowledge of the site to include the depth to basement rock. At the level of the municipality of Oslo, there is currently no map available that describes the Vs30, and as such any seismic risk study is lacking potentially critical information on local site amplification. The new proposed methodology includes the use of existing well databases (with knowledge on minimum basement depth), topographic slope derived from Digital Elevation Models (as a proxy for both depth to basement and Vs30, integrated with geological maps) and near-surface Quaternary geological maps. The Horizontal to Vertical Spectral Ratio (HVSR) method and a statistics-based geological mapping tool (COHIBA) are used to integrate the various sources of data estimates. Finally, we demonstrate our new methodology and workflow with data from three different regions within the Oslo municipality and propose an approach to conduct cost-efficient mapping for seismic site amplification on a general municipality scale

Fluorine-induced J-aggregation enhances emissive properties of a new NLO push-pull chromophore

A new fluorinated push-pull chromophore with good second-order NLO properties even in concentrated solution shows solid state intermolecular aryl-fluoroaryl interactions leading to J-aggregates with intense solid state luminescence. This journal is \ua9 the Partner Organisations 2014