bluuebunny/crossref_metadata_2025 huggingface dataset:
Systematic Measurement Uncertainty of Critical Dimension Scanning Electron Microscope
Authors: Abe Hideaki , Kadowaki Motoki , Hamaguchi Akira , Ikeda Takahiro , Yamazaki Yuichiro
Published: June 2010

Critical dimension (CD) bias between a critical dimension scanning electron microscope (CD-SEM) and a reference tool is the most important error factor for more accurate CD measurement. The systematic measurement uncertainty was evaluated by experiment and electron beam simulation. The CD bias variation is caused by the change in secondary electron signal intensity. CD bias variation of an isolated 150 nm silicon substrate space pattern with space width change is 1.7 nm per 10 nm space width. The CD bias difference of the silicon substrate between with and without the native oxide layer is 30 nm at 150 nm space width. The CD bias change is 1.4 nm per 10 nm pattern height. This is caused by an interaction between space width and pattern height. We identified that measurement uncertainty includes not only random error but also systematic error in actual pattern shape, material, and layout variation quantitatively. The impact of systematic error on CD bias is very large compared with the metrology requirement for next-generation devices.
Projection Charged Particle Nanolithography and Nanopatterning
Authors: Loeschner Hans , Klein Christof , Platzgummer Elmar
Published: June 2010

The projection charged particle multi-beam techniques of IMS Nanofabrication are based on illuminating a programmable aperture plate system [APS; consisting of an aperture plate and a blanking plate with integrated complementary metal–oxide–semiconductor (CMOS) electronics] with a telecentric broad beam, to separate this beam into thousands of micrometer sized beams and to demagnify the beamlets thus formed to nanometer dimensions, using a projection charged particle optics with 200× reduction. Only beams which are unaffected by the blanking plate are projected to the substrate whereas beams which are slightly deflected are filtered out at a contrast aperture at the second cross-over of the projection optics. Proof-of-concept test systems were realized for these techniques. Inserting a 43k-APS providing 43 thousand programmable 12.5 nm sized beams complex patterns were realized in 20 ×20 µm2 exposure fields when using 10 keV H3
+ ions. For the electron multi-beam test system the beam at the APS was limited to 2 mm diameter, thus realizing 2500 programmable electron beams of 12.5 nm size and 50 keV energy within an exposure field of ca. 7 ×7 µm2. Application fields of projection charged particle multi-beam techniques are CHARPAN (Charged Particle Nanopatterning, with ion multi-beams), PML2 (Projection Mask-Less Lithography), and eMET (electron Mask Exposure Tool).
Non-Core–Shell Nanostructure Deposition on Focused-Ion-Beam Chemical Vapor Deposition
Authors: Kometani Reo , Warisawa Shin'ichi , Ishihara Sunao
Published: June 2010

Nano- and microstructures fabricated by focused-ion-beam chemical vapor deposition (FIB-CVD) have a core–shell structure caused by the scattering profiles of Ga ions and secondary electrons (SEs). This structural characteristic makes it difficult to design functions of nano-electromechanical devices. Therefore, non-core–shell structure deposition by the control of SE emission was examined to facilitate the function design of nanoelectromechanical devices. Non-core–shell structure deposition was achieved by applying voltage during carbon nanostructure growth. We also evaluated the growth characteristics of non-core–shell structure deposition. We found that the growth rate of a nanostructure did not change when voltage was applied. Furthermore, we evaluated the mechanical material characteristics (density and Young's modulus) of a non-core–shell structure by measuring of the resonant frequency shift of a Si cantilever using the electron beam method. We found that the non-core–shell structure had a high density (6.5 g/cm3) and a high Young's modulus (800 GPa). These results indicate that the technique for non-core–shell structure deposition is useful in achieving nanoelectromechanical devices.
Fundamental Studies on the Acid Generator to Improve the Resolution, Line Width Roughness, and Sensitivity Tradeoff under Ionizing Radiation
Authors: Utsumi Yoshiyuki , Irie Makiko , Komuro Yoshitaka , Matsuzawa Kensuke , Hada Hideo , Haga Takashi , Ogawa Satoshi
Published: June 2010

The effects of acid generation efficiency and other properties on the resolution, line width roughness (LWR), and sensitivity (RLS) tradeoff for extreme ultraviolet (EUV) photoresists were evaluated under electron beam (EB) exposure. The acid generators (AGs) introducing a trifluoromethyl group as an electron-withdrawing group on the sulfur atom had a much higher reduction potential than current AGs. We determined acid generation efficiency by the 13C-NMR method and standard titration. The dissolution inhibitory effect on the alkaline developer and the thermal property of the resist film using each AG were also evaluated. The RLS performance of resists containing AGs with a higher acid generation efficiency than conventional AGs was characterized using the relative Z-factor under EB exposure.
Development of New Positive-Tone Molecular Resists Based on Fullerene Derivatives for Extreme Ultraviolet Lithography
Authors: Oizumi Hiroaki , Tanaka Katsutomo , Kawakami Kiminori , Itani Toshiro
Published: June 2010

We have developed and evaluated new chemically amplified molecular resists based on fullerene derivatives with an excellent solubility in a standard alkali developer for extreme ultraviolet (EUV) lithography. We controlled the electron acceptability of fullerene derivatives and applied photo-acid generators (PAGs) with a high electron acceptability through ionization by EUV irradiation. As a result, sensitivities of positive-tone molecular resists based on fullerene derivatives were markedly improved, and we succeeded in obtaining good resolution, by applying an organic underlayer substrate without pattern collapse. Delineations of 45 nm half pitch (hp) and line width roughness (LWR) of 5.7 nm were achieved at an exposure dose of 12.5 mJ/cm2 on the organic underlayer.
Ultraviolet Electroluminescence Emission from n-Type ZnO/p-Type Si Crossed Nanowire Light-Emitting Diodes
Authors: Kim Kwangeun , Kang Jeongmin , Lee Myeongwon , Yoon Changjoon , Cho Kyoungah , Kim Sangsig
Published: June 2010

The optical characteristics of an n-type ZnO/p-type Si crossed nanowire (NW) light-emitting diode (LED) were investigated in this study. N-ZnO nanowires (NWs) were synthesized by thermal chemical vapor deposition, and p-Si NWs were fabricated by etching a single crystalline Si wafer. The p–n heterojunction LED formed by the cross of the n-ZnO and p-Si NWs selected from the NWs prepared in this work exhibited the current rectifying behavior with the turn-on voltage of 1.3 V. Our investigation of the photoluminescence spectrum of the as-grown n-ZnO NWs and electroluminescence spectrum of the n-ZnO/p-Si crossed NW LED reveals that both spectra have the same position of peaks at 390 nm. This result indicates that the UV emission from the crossed NW LED is mostly attributed to the band-to-band transition of electrons in the ZnO NW.
Effect of Silver Thickness on the Formation of Surface Plasmon Polaritons in Silver-Coated Silicon Nitride Photonic Crystal Slabs
Authors: Shyu Jia-Hong , Ou Neil , Chien Jui-Hsing , Lee Huang-Ming , Tai Chao-Yi , Wu Jong-Ching
Published: June 2010

A systematic study of the influence of silver film thickness on the transmittance spectra through a silicon nitride photonic crystal slab (SiN-PCS) coated with silver films of various thicknesses is presented. The transmission spectrum through a bare SiN-PCS reveals guided resonances. When an ultrathin silver film (<10 nm in thickness) is coated on a SiN-PCS, isolated silver nanoparticles are formed resulting in the suppression of guided resonances. In addition, a red shift is found in the optical transmittance spectra measured on SiN-PCS coated with a progressively thicker silver film. This may be attributed to the formation of localized surface plasmon resonances at the interface between silver nanoparticles and silicon nitride. A continuous texture is formed as the thickness of the silver film is increased up to 20 nm, resulting in a transition from localized surface plasmon resonances to surface plasmon polaritons. Furthermore, the surface plasmon polaritons that are formed externally (internally) are identified in SiN-PCS coated on one side (double sides) with a 20-nm-thick silver film.
Study of Backscattering Phenomenon from Drain Region of Silicon Decanano Diode Using Nonequilibrium Green's Function Approach
Authors: Tsutsumi Toshiyuki , Tomizawa Kazutaka
Published: June 2010

Scattering within a channel region of a decanano device has been focused on so far. However, it was found in our previous research that the backscattering from a drain region of such a decanano device markedly affects AC device characteristics. Therefore, we have investigated the backscattering phenomenon from the drain region of a silicon decanano diode at the level of electron wave behavior using nonequilibrium Green's function (NEGF) approach for the first time. The numerical experiment without scattering in the device reveals that there is an inevitable accumulation of electron charge near the drain in the channel, which might degrade the AC performance of the device, even without scattering in the device. Moreover, the numerical experiment with scattering in the device reveals that the backscattered (BS) ratio from the drain region increases with decreasing drain voltage. The amount of electron caused by scattering within the channel increases with increasing drain voltage, whereas the amount of electron caused by backscattering from the drain region increases with decreasing drain voltage. This is why the BS ratio from the drain region, which is an indicator of AC performance, increases with decreasing drain voltage. Since very low voltage operation is required for future ultralow power devices, the obtained result is very important and the analysis of the backscattering phenomenon from the drain region becomes more beneficial.
Single-Hole Charging and Discharging Phenomena in Carbon Nanotube Field-Effect-Transistor-Based Nonvolatile Memory
Authors: Ohori Takahiro , Nagaso Satoshi , Ohno Yasuhide , Maehashi Kenzo , Inoue Koichi , Matsumoto Kazuhiko
Published: June 2010

We have fabricated nonvolatile memory based on top-gated carbon nanotube field-effect transistors (CNTFETs). Two kinds of insulating films, SiN
x
and SiO2, were deposited to control the hysteresis characteristics after the removal of water molecules around the single-walled CNT channels. The interface between the SiN
x
and SiO2 films is expected to act as a charge storage node of nonvolatile memory. The fabricated CNTFET-based memory devices clearly exhibited not only a memory effect but also good retention characteristics for charge storage. Furthermore, single-hole charging and discharging phenomena were clearly observed in the CNTFET-based memory devices by reducing the number of carriers trapped in the interface between the SiN
x
and SiO2 films. These results indicate that the CNTFET-based nonvolatile memory can be potentially used to realize single-electron memory.
Transmission Electron Beam Drilling for Nanoscale Fabrication
Authors: Lin Tsan-Chu , Su Rui-Zhi , Lai Yu-cheng , Wang Dau-Chung , Wu Cen-Shawn
Published: June 2010

We demonstrated that a high-resolution focused electron beam can be used to fabricate metal nanostructures and devices on insulating membranes by nanosculpting metal films. This top-down focused electron beam drilling method works by the controlled ablation of materias to produce nanoscale devices with near-atomic the precision. In addition, we have fabricated a single-electron transistor (SET) on free-standing transparent Si3N4 membranes, which permits enables us to explore quantum tunneling effects in narrow-constriction structures. The produced SET exhibited distinct Coulomb-blockade current–voltage characteristics and gate-modulated current at 4.2 K. Its high resolution, geometrical flexibility, and yield make this fabrication method attractive for many applications including nanoelectronics and quantum devices.
Growth and Characterization of Telecommunication-Wavelength Quantum Dots Using Bi as a Surfactant
Authors: Okamoto Hiroshi , Tawara Takehiko , Gotoh Hideki , Kamada Hidehiko , Sogawa Tetsuomi
Published: June 2010

Telecommunication-wavelength quantum dots (QDs) were successfully grown by metalorganic vapor phase epitaxy using a novel growth method in which trimethylbismuth (TMBi) was supplied during the growth. Supplying TMBi during the growth was confirmed to have a surfactant effect, but did not result in the formation of a bismuth-containing alloy. Using this growth method, the photoluminescence intensity and wavelength of the QDs were much improved. It was found that the QD size was increased during the growth of the InGaAs covering layer; this effect partly resembled activated alloy phase separation reported for molecular-beam-epitaxy-grown QDs. For the realization of high density and multilayer QDs, we confirmed that a much higher V/III ratio than that of usual growth conditions and a strain-compensation structure are effective, respectively.
Preparation of ZnSe Nanocrystals Using Water-in-Oil Microemulsions
Authors: Kim Hyun Soo , Kim Jong Sung , Park Sang Joon
Published: June 2010

ZnSe nanocrystals were prepared using a safe and simple synthetic method by employing a sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/water/oil microemulsion system with aqueous ZnSO4 and Se2- solutions, and characterized by X-ray diffraction (XRD) analysis, photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM). To control the diameter of nanocrystals in the quantum confinement region, the synthesis was performed with different oil phases (heptane and cyclohexane) and various water-to-surfactant ratios, W ([H2O]/[surfactant]). Cubic zinc blende ZnSe nanocrystals were synthesized and their size was controlled in the range from 2.5 to 17 nm. The maximum PL efficiency was 14% for the smallest ZnSe nanocrystal.
Metrology of Wide Field of View Nano-Thickness Foils' Homogeneity by Conventional and Phase Contrast Soft X-ray Imaging
Authors: Faenov Anatoly , Pikuz Tatiana , Fukuda Yuji , Kando Masaki , Kotaki Hideyuki , Homma Takayuki , Kawase Keigo , Skobelev Igor , Gasilov Sergei , Kawachi Tetsuya , Daido Hiroyuki , Tajima Toshiki , Kato Yoshiaki , Bulanov Sergei
Published: June 2010

A tabletop ultra-bright, debris-free femtosecond-laser-driven cluster-based plasma soft X-ray source, which emits more than 1012 photons/(sr·pulse) in the spectral range 1–10 nm within a 4π sr solid angle was developed. Using such source in combination with a high dynamic range LiF crystal soft X-ray detector allows obtaining contact and propagation-based phase-contrast images of nanostructures with 700 nm spatial resolutions in a wide field of view. It was demonstrated that the high precision of used techniques enable distinguishing inhomogeneity of measured intensities of ultrathin foils in the order of ±3%. All of this opens a new approach for PBPC imaging and metrology of full areas of free-standing or mesh-supported nano-thickness foils, or other nanostructures.
Fluorescent UV-Curable Resists for UV Nanoimprint Lithography
Authors: Kobayashi Kei , Sakai Nobuji , Matsui Shinji , Nakagawa Masaru
Published: June 2010

We developed fluorescent UV-curable resists for UV nanoimprint lithography to readily detect residual layer thickness and analyze its profile in addition to pattern defects by fluorescence microscopy. A fluorescent dye of rhodamine 6G, 2-[6-(ethylamino)-3-(ethylimino)-2,7-dimethyl-3H-xanthen-9-yl]benzoic acid ethyl ester tetrafluoroborate 5a, showed sufficient durability of photobleaching in solution toward UV-light exposure at >350 nm in the absence and presence of a radical photoinitiator. The decrease of fluorescence intensity from the dye in a UV-cured thin film of a radical photopolymerization resin PAK-01 was suppressed at approximately 5% in comparison with the fluorescence intensity before UV-curing at an exposure dose of 1.0 J cm-2 monitored at 365 nm. It was confirmed that the fluorescence intensity of the UV-cured thin film showed a linear correlation to its thickness up to 100 nm. A dye-added PAK-01 resin was successfully available to UV nanoimprint. We demonstrated that the UV-cured thin film of the dye-containing resin was useful for facile confirmation and analysis of residual layer thickness in terms of its homogeneity.
Effects of Mold Side Wall Profile on Demolding Characteristics
Authors: Kawata Hiroaki , Kubo Kensuke , Watanabe Yuuta , Sakamoto Junji , Yasuda Masaaki , Hirai Yoshihiko
Published: June 2010

Silicon molds with various taper angles are fabricated and demolding forces are examined for the thermal imprinting of poly(methyl methacrylate) (PMMA) films on a silicon substrate. The silicon mold patterns are fabricated by a switching process, which consists of sequentially alternating etching and deposition steps. The side wall angle of mold trenches is controlled by adjusting deposition step time. The demolding force for the vertical mold is 0.35 MPa. The demolding forces for the inverse taper mold angle (taper angle, 92°) and the normal taper angle (taper angle, 83°) are 1.0 and 0.2 MPa, respectively. The residual PMMA thickness is not uniform. The surface profile of the PMMA film is also curved. Both the nonuniform residual PMMA thickness and the curved profile of the PMMA surface are caused by silicon wafer deformation. It is confirmed that the variation of PMMA surface height is proportional to the residual resist thickness.
Fabrication of a Hydrophilic Poly(dimethylsiloxane) Microporous Structure and Its Application to Portable Microfluidic Pump
Authors: Yang Wonseok , Nam Young Gyu , Lee Bong-Kee , Han Kyungsup , Kwon Tai Hun , Kim Dong Sung
Published: June 2010

In this paper, we present a simple and low-cost fabrication technique of a novel hydrophilic poly(dimethylsiloxane) (PDMS) microporous structure (or microsponge) based on a modified sugar leaching technique. A surfactant, Silwet L-77 enabled us to achieve the wettability conversion of PDMS from hydrophobic to hydrophilic. The wettability changes of PDMS surfaces and microsponges were characterized at various weight percentages of Silwet L-77 and it was found that a hydrophilic PDMS microsponge containing 0.6% of Silwet L-77 rapidly absorbed water droplets. The average porosity of the fabricated PDMS microsponges was measured as 0.55. We have successfully demonstrated the hydrophilic PDMS microsponge as a portable pump for a microfluidic device. The hydrophilic PDMS microsponge was firmly bonded at the inlet of a PDMS microchannel via oxygen plasma treatment. A water-phase sample was easily loaded into the hydrophilic PDMS microsponge and it was released and injected into the microchannel by simply pushing the microsponge.
Cell-Driven Three-Dimensional Manipulation of Microparts for a Microassembly
Authors: Hoshino Takayuki , Higashi Ayako , Konno Tomohiro , Ishihara Kazuhiko , Morishima Keisuke
Published: June 2010

Biological motility consisting of cell migration can be embedded in nano- and micro-mechanical systems. We have focused on the actin polymerization to employ its generative force as the driving force of a nano mechanical system. Cells are a self-sustaining full system which contains an energy supply and has self-organization of actin filaments. This self-organized driving force powered by the cells should be utilizable in a functionally designed nano or micro mechanical assembly. This paper describes locomotion of micro-parts driven by cell migration. A method to generate three-dimensional (3D) cell-driven operation of the micro-parts was investigated for a micro-assembly using two-dimensional (2D) cell-adhesive patterning of a substrate. Cyclic reattachment of cell membranes occurred on a discrete cell-adhesive portion within a 100-µm-pitch checkerboard pattern during cell migration. These movements of cells modulated the 2D cell migration to a 3D tilting movement of the micro-parts-on-cells and 180-µm-length micro-parts were successfully flipped by the cell migration power.
Direct Writing of Resist Patterns Using a Wire Nozzle Newly Developed for an Air-Pressure Dispenser
Authors: Ohtsuka Shinichiro , Horiuchi Toshiyuki
Published: June 2010

Direct writing of resist patterns using an air-pressure dispenser is expected as a low-cost patterning method for fabricating various microdevices. However, it was difficult to smoothly delineate fine resist patterns with a width of less than 100 µm when a commercial air-pressure dispenser system was used, because high-viscosity resists block fine dispenser nozzles, and low-viscosity resists spread after they are dispensed. For this reason, a new wire-nozzle dispenser was developed to write fine resist patterns with a width of less than 100 µm. The technology is especially suitable for customized small-scale productions. In the experiments, patterns were delineated onto wafers and copper-clad plastic substrates using the new wire-nozzle dispenser with an inner diameter of 100 µm and a wire diameter of 30 µm. As a result, straight line patterns with a minimum width of 50 µm were successfully delineated using a resist PMER P-LA900PM with a viscosity of 1500 mPa·s. Patterns circularly curved with a radius of 1 mm and a width of 130 µm were also smoothly delineated. In addition, microreactor patterns including a joint point and curved shapes were successfully written. Although the linewidths at the curved parts slightly differed from those at the straight parts, all the patterns were smoothly stitched. Moreover, complicated patterns with variously curved routes were also successfully delineated. It was verified that the newly developed wire nozzle was useful as a new dispenser tool.
Durability Enhancement of a Microelectromechanical System-Based Liquid Droplet Lens
Authors: Lee June Kyoo , Park Kyung-Woo , Kim Hak-Rin , Kong Seong Ho
Published: June 2010

In this paper, we propose methods to enhance the durability of a microelectromechanical system (MEMS)-based liquid droplet lens driven by electrowetting. The enhanced durability of the lens is achieved through not only improvement in quality of dielectric layer for electrowetting by minimizing concentration of coarse pinholes, but also mitigation of physical and electrostatic stresses by reforming lens cavity. Silicon dioxide layer is deposited using plasma enhanced chemical vapor deposition, splitting the process into several steps to minimize the pinhole concentration in the oxide layer. And the stresses-reduced cavity in a form of overturned tetra-angular truncated pyramid with rounded corners, which is based on simulated results, is proposed and realized using silicon wet etching processes combined into anisotropic and isotropic etching.
Progressive fold and fabric evolution associated with regional strain gradients: a case study from across a Scandian ductile thrust nappe, Scottish Caledonides
Authors: Alsop G. I. , Cheer D. A. , Strachan R. A. , Krabbendam M. , Kinny P. D. , Holdsworth R. E. , Leslie A. G.
Published: June 2010

Fold and fabric patterns developed within a major Caledonian thrust nappe in NW Scotland reflect a progressive increase in regional D
2
strain towards the basal ductile detachment. Within the upper greenschist to lower amphibolite facies thrust sheet, the main gently east-dipping foliations and SE-plunging transport-parallel lineations maintain a broadly similar orientation over
c
. 600 km
2
. Associated main phase, thrust-related folds (F
2
) are widely developed, and towards the base of the thrust sheet display progressive tightening and increasing curvilinearity of fold hinges ultimately resulting in sheath folds. Secondary folds (F
3
) are largely restricted to high-strain zones and are interpreted as flow perturbation folds formed during non-coaxial, top-to-the-NW ductile thrusting. These features are consistent with a structural model that incorporates plane strain pure-shear flattening with a superimposed and highly variable simple shear component focused into high-strain zones. The increase in strain over a distance of 30 km across strike is similar to the increasing deformation observed when structures are traced along strike to the north, and which are apparently related to proximity to basement-cover contacts. A U–Pb zircon age of 415±6 Ma obtained from a syn-D
2
meta-granite confirms that regional deformation occurred during the Scandian phase of the Caledonian orogeny.
Lateral variations and linkages in thrust geometry: the Traligill Transverse Zone, Assynt Culmination, Moine Thrust Belt, NW Scotland
Authors: Krabbendam M. , Leslie A. G.
Published: June 2010

Abrupt lateral changes in thrust geometry occur in many fold-and-thrust belts along so-called transverse zones, commonly related to pre-existing basement faults. However, the causative structures are usually concealed. We analyse here the Traligill Transverse Zone in the Assynt Culmination of the Caledonian Moine Thrust Belt, NW Scotland. This transverse zone trends sub-parallel to the WNW transport direction and is associated with en echelon faults cutting thrusts, discontinuity of thrust architecture and oblique fold-and-thrust structures. Thick thrust sheets north of the Transverse Zone contain thick basement slices; thrust sheets to the south are thin and involve a thin-bedded sequence. The Traligill Transverse Zone developed above the Loch Assynt Fault, a basement cross-fault, and reactivated Proterozoic ductile shearzone. Piercing point analysis shows that the cross-fault was active both before and after thrusting. Thrusting thus affected strata that were already disrupted by steep faults. The amplitude of the disturbance in fold-and-thrust architecture along the Traligill Transverse Zone is much greater than the vertical displacement along the fault; this is attributed to localized transpressional thrust-stacking. Other basement cross-faults and their relationship with lateral variations within the Moine Thrust Belt and in other thrust belts are discussed.
Regional-scale lateral variation and linkage in ductile thrust architecture: the Oykel Transverse Zone, and mullions, in the Moine Nappe, NW Scotland
Authors: Leslie A. G. , Krabbendam M. , Kimbell G. S. , Strachan R. A.
Published: June 2010

Sharp lateral changes in structural geometry of ductile thrust stacks are not widely reported. A regional-scale lateral culmination wall forms the southern boundary of the Cassley Culmination in Moine rocks in the Caledonides of Sutherland, Northern Scotland. This culmination wall is part of the Oykel Transverse Zone (OTZ), a kilometre-scale shear zone characterized by constrictional finite strain fabrics aligned sub-parallel to the regional WNW-directed thrust transport direction. Main phase folds and fabrics in the transverse zone hanging wall are folded by main phase folds and fabrics in the footwall, thus recording foreland-propagating ductile deformation. South of the Cassley Culmination, shortening occurred uniformly, without development of discrete subsidiary thrusts; distributed deformation (fold development) alternated with localized thrusting within the culmination. The classic ESE-plunging mullions at Oykel Bridge are an integral part of the OTZ and were generated by constriction aligned sub-parallel to the transport direction. Constriction is attributed to differential, transtensional movement across the OTZ during culmination development. Subsequent formation of the underlying Assynt Culmination further accentuated upward-bulging of the Cassley Culmination, amplifying the lateral change across the transverse zone. The OTZ aligns with a pronounced gravity gradient on the south-western side of the Lairg gravity low. Interpretive modelling relates this gradient to a buried basement ramp that possibly controlled the location of the transverse zone.
Relationships between the Loch Ailsh and Borralan alkaline intrusions and thrusting in the Moine Thrust zone, southern Assynt culmination, NW Scotland
Authors: Searle M. P. , Law R. D. , Dewey J. F. , Streule M. J.
Published: June 2010

The Moine Thrust zone of NW Scotland marks the Caledonian orogenic front and in the Assynt region consists of several west-vergent major thrust sheets (Moine, Ben More, Glencoul and Sole Thrust sheets) that place allochthonous rocks onto the Lewisian basement and Torridon Group cover in the west. Here we present two new balanced and restored sections across the Moine Thrust zone in the region of the Loch Ailsh and Loch Borralan alkali intrusions. Syenites and alkaline pyroxenites intrude up to Durness Group carbonates. Syenites are interpreted as cut by the Moine and Ben More Thrusts and therefore their intrusion age (
c
. 430 Ma) provides a maximum age constraint on cessation of motion along the Moine Thrust. We review and discuss several controversies, notably: (1) relationships between folding in the Ben More Thrust sheet (Sgonnan Mor folds) and fabric development associated with intrusion of the Loch Ailsh pluton and initiation of the Moine and Ben More Thrusts; (2) structural relationships around the Borralan intrusion, particularly the nature of its basal and lateral margins (intrusive or thrust-ramp); (3) the structural relationships of the Cam Loch and Benn Fhuarain klippen; and (4) the timing of motion of all thrust sheets in the southern Assynt culmination.
The Geological Structure of the North-West Highlands of Scotland
– revisited: Peach
et al.
100 years on
Authors: Butler Robert W. H.
Published: June 2010

Following years of sporadic debate, in the early 1880s consensus was reached that thrust tectonics explained hitherto controversial geological field relationships in NW Scotland. This spawned a major research effort there by the Geological Survey of Great Britain that culminated in a series of highly detailed geological maps, preliminary research papers and, eventually, the publication of a memoir to the region. These works became highly influential to early-20th century geoscience, especially structural geology. Not only did they provide the first major synthesis of thrust belt structure, they also provided the basis for descriptions of fault and shear zone processes and deductive methods for unravelling tectonic histories in metamorphic basement. A common misconception is that the results arose from mapping alone, without regard to extant models and theory and this approach is held up as an ideal for fieldwork. Yet the notebooks and writings of the surveyors show the application of learning not only from other research groups but also between themselves. As with modern mapping, the Survey team created interpretations that built on contemporary knowledge. This work in turn has driven subsequent research for over 100 years, in the NW Highlands and in deformed rocks throughout the world.
Predicting seismic properties from three-dimensional microstructures: a new look at an old quartzite
Authors: Lloyd Geoffrey E. , Law Richard D. , Mainprice David
Published: June 2010

The mylonitic Cambrian quartzites, Moine Thrust Zone, NW Scotland, have long been used to study microstructural and petrofabric evolution and to develop understanding of grain-scale processes accommodating large-scale displacements. Today, structural geology is entering a new age of understanding of the basic processes involved in microstructural evolution due to the emergence of novel instrumental techniques and theoretical models. It seems apposite therefore to re-evaluate the microstructure of one example of this classic quartz mylonite from the Stack of Glencoul, Assynt, using arguably the most important of these new techniques, electron backscattered diffraction (EBSD). The three-dimensional (3D) microstructure and petrofabric of this rock was analysed using EBSD, to: 1) corroborate previous optical and X-ray texture goniometry measurements; 2) investigate the potential for sampling and/or tectonic sectioning bias that may be introduced inadvertently into any petrofabric analysis; and 3) predict its seismic properties. It is found that microstructures do differ between orthogonal structural sections, leading to variations in strengths of different components in the overall petrofabric that might impact on seismic properties. The results emphasize the true 3D nature of microstructures and petrofabrics, which can be recognized and accommodated more readily by this new generation of analytical techniques.
Inclined transpression at the toe of an arcuate thrust: an example from the Precambrian ‘Mylonite Zone’ of the Sveconorwegian orogen
Authors: Viola Giulio , Henderson Iain C.
Published: June 2010

The ‘Mylonite Zone’ (MZ) forms a major, arcuate terrane boundary in the Precambrian Sveconorwegian orogen of SW Scandinavia. SE-directed thrusting along this curvilinear shear zone emplaced the higher-grade Idefjorden Terrane to the west onto the lower-grade Eastern Segment terrane to the east. Detailed structural characterization of the MZ mylonites in two different localities (Värmlandsnäs and Bua peninsulas) reveals a complex three-dimensional strain pattern. Inclined transpression is inferred on the basis of coexisting (and broadly coeval) foliation-parallel oblique shearing (resolvable in a strike-slip and dip-slip component) and across-foliation shortening. The former accommodated the transpressive component of the MZ, and its kinematics is either sinistral or dextral depending on the local strike of the MZ with respect to the regional thrust shortening vector. The latter led to pure-shear shortening perpendicular to the thrust sheet and subsequent lateral extrusion parallel to the mylonitic foliation via the development of antithetic displacements. No significant strain partitioning is observed at the meso-scale and strain is thus truly triclinic. The example described is an outstanding case of triclinic deformation, confirms theoretical analyses of complex strain models and adds valuable natural field constraints to our knowledge of deformation in the crust.
Peach and Horne: the British Association excursion to Assynt September 1912
Authors: Barber A. J.
Published: June 2010

At the meeting of the British Association held in Dundee in September 1912 a group of eminent European geologists, including most of the leading Alpine tectonic experts of the day, intrigued by the account of the structure of the NW Highlands given in the 1907 memoir, expressed a wish to see these structures for themselves. Peach and Horne were approached, and agreed to lead an excursion to the Assynt area following the meeting. The programme for the excursion followed an itinerary that many geological parties still follow today. On the final evening of the excursion Albert Heim (Zurich), the doyen of Alpine geologists, gave a vote of thanks to the leaders and Maurice Lugeon (Lausanne) composed
La Chanson du Moine Thrust
which the participants sung with great enthusiasm. Brief biographies are given of the participants, many of whom were already distinguished, while most of the junior participants, particularly those from the British Geological Survey, went on to pursue long and distinguished careers, making major contributions to our knowledge of Scottish geology.
Extensional tectonics in the North Atlantic Caledonides: a regional view
Authors: Fossen Haakon
Published: June 2010

Extensional structures characterize significant parts of the North Atlantic Caledonides. Silurian extensional deformation took place, particularly in the heated crust in the southern Greenland Caledonides, but the majority of the mapped extensional structures are Devonian (403–380 Ma). They formed by reactivation of low-angle Caledonian thrusts and by the formation of hinterland-dipping shear zones, of which the largest system is located in SW Norway and related to exhumation of the subducted margin of Baltica. The Devonian extension was concentrated to the central and southern part of the Caledonides, with maximum extension occurring in the area between the Western Gneiss Region of SW Norway and the Fjord Region of East Greenland. Kinematic data indicate that the main tectonic transport direction was toward the hinterland, and this pattern suggests that the main Devonian extension/transtension in the southern part of the North Atlantic region was postcontractional while strike-slip motions and possibly transpression occurred farther north. Late Devonian to enigmatic Early Carboniferous ages from UHP metamorphic assemblages in NE Greenland suggest that intracontinental subduction was going on in NE Greenland at a time when extensional deformation governed the rest of the orogenic belt.
On the difficulty of assigning crustal residence, magmatic protolith and metamorphic ages to Lewisian granulites: constraints from combined
in situ
U–Pb and Lu–Hf isotopes
Authors: Whitehouse M. J. , Kemp A. I. S.
Published: June 2010

Zircons from two granulite facies gneisses from the central region of the Lewisian Complex have been investigated by high spatial resolution ion-microprobe U–Pb dating and laser ablation combined Pb–Hf isotope methods. The ion-microprobe data reveal a complex pattern of zircon ages distributed along the concordia curve between the time of granulite facies metamorphism at
c
. 2.5 Ga and the oldest zircon in each sample (respectively 2.89 Ga and 3.04 Ga). This Pb-loss pattern complicates assignment of an unambiguous magmatic protolith age to the zircon although cathodoluminescence (CL) imaging is used to suggest a preferred age of
c
. 2.85 Ga for both samples, with older grains being inherited.
In situ
Hf isotopes show a larger spread in the sample containing older grains which is also consistent with inheritance and further suggests that several crust extraction events are represented in the inherited population. Comparison of Hf isotope compositions with plausible model evolution curves suggests that crustal precursors to the Lewisian granulites were derived from their mantle source at
c
. 3.05–3.2 Ga.

Supplementary material:

Analytical methods and data tables are available at:
http://www.geolsoc.org.uk/SUP18395
The Laxford Shear Zone: an end-Archaean terrane boundary?
Authors: Goodenough K. M. , Park R. G. , Krabbendam M. , Myers J. S. , Wheeler J. , Loughlin S. C. , Crowley Q. G. , Friend C. R. L. , Beach A. , Kinny P. D. , Graham R. H.
Published: June 2010

The Lewisian Gneiss Complex of northwestern Scotland consists of Archaean gneisses, variably reworked during the Proterozoic. It can be divided into three districts – a central granulite-facies district between districts of amphibolite-facies gneiss to the north and south. Recent work has interpreted these districts in terms of separate terranes, initiating a controversy that has implications for how Precambrian rocks are understood worldwide. The northern district of the Lewisian Gneiss Complex (the Rhiconich terrane) is separated from the central district (the Assynt terrane) by a broad ductile shear zone known as the Laxford Shear Zone. This paper reviews the geology of the Laxford Shear Zone, clarifying field relationships and discussing other evidence, to consider whether or not it does indeed represent a terrane boundary. A detailed review of field, geochemical and geochronological evidence supports the recognition of the separate Assynt and Rhiconich terranes. Mafic dykes (the Scourie Dyke Swarm) and granitoids, of Palaeoproterozoic age, occur on both sides of the Laxford Shear Zone and thus the terranes were most probably juxtaposed during the late Archaean to early Palaeoproterozoic Inverian event. Subsequently, the less-competent, more-hydrous amphibolite-facies gneisses of the Rhiconich terrane were affected by later Palaeoproterozoic (Laxfordian) deformation and partial melting, to a greater extent than the more-competent granulite-facies gneisses of the Assynt terrane.
The North‐West Highlands memoir: a century-old legacy for understanding Earth before Pangaea
Authors: Dalziel Ian W. D.
Published: June 2010

Benjamin Peach, John Horne and their co-workers recognized a century ago that the identical fauna and lithofacies of the lower Palaeozoic strata in the NW Highlands of Scotland and the North American craton could only be explained if they were: ‘part of one and the same geological and zoological province’. In this sense their work provided critical geological underpinning for the subsequent understanding of Mesozoic–Cenozoic seafloor spreading and continental drift. ‘Tectonic tracers’ such as the fragment of Laurentian craton in the NW Highlands of Scotland, provide the strongest evidence available for deciphering pre-Pangaea palaeogeography. The Laurentian craton appears to have left several such tectonic ‘calling cards’ in today's southern continents. Intriguingly, it is the presence in the Andean Precordillera of northwestern Argentina of an early Palaeozoic fauna identical to that of the NW Highlands that provides perhaps the most unequivocal geological clue to pre-Pangaea palaeogeography. Recent work in East Antarctic and Laurentian cratons has provided a positive test of the hypothesis that they were once juxtaposed prior to the Neoproterozoic opening of the Pacific Ocean basin. Geochronology and isotope geochemistry, supported by palaeomagnetic studies indicate that the Coats Land crustal block of East Antarctica at the head of the Weddell Sea is also a fragment of the Laurentian craton. These three ‘tectonic tracers’ permit tracking of the Laurentian craton in relation to the present southern continents from the Neoproterozoic break-up of the Rodinian supercontinent to the late Palaeozoic assembly of Pangaea.
Calcareous tufa as indicators of climatic variability: a case study from southern Tuscany (Italy)
Authors: Capezzuoli Enrico , Gandin Anna , Sandrelli Fabio
Published: June 2010

A carbonate terraced succession mainly consisting of fluvial/palustrine calcareous tufa and of lacustrine limestone was deposited during recent Quaternary in a limited segment of the Valdelsa fluvial pattern (southern Tuscany, Italy).

The radiometric data obtained from three carbonate terraces indicate that the depositional/erosional history of the Valdelsa succession during Late Pleistocene–Holocene, has been constrained by the same cyclic events observed in coeval detrital lacustrine successions of Central Italy. At least three of the Valdelsa carbonate Synthems and the interposed erosional phases can be correlated with the major climatic changes recognized in the European–Mediterranean area, from the Last Glacial Interstadial through the Younger Dryas to the Atlantic ‘Optimum Climatic’, the Sub-Boreal and finally at 2.5 ka the last Sub-Atlantic oscillation.

This climatic correlation and the radiometric data imply that the deposition of calcareous tufa in Valdelsa was mainly dependent on rainfall availability and, consequently, was active during the milder oscillations within the cold periods.
Calcium carbonate precipitation by cyanobacterial polysaccharides
Authors: Dittrich M. , Sibler S.
Published: June 2010

Cyanobacteria have been recognized as key players in the precipitation of calcium carbonate in marine and freshwater systems. These bacteria increase pH, (as a result of photosynthetic activity) and also produce extracellular polysaccharides, which act as binding sites for Ca
2+
and CO
3
2−
. Both processes influence the morphology and the mineralogy of the carbonate minerals. In order to clarify the role of polysaccharides of picocyanobacteria upon calcium carbonate precipitation, both their buffering capacity and ability to induce precipitation need to be investigated. In this experimental study, we characterized the polysaccharides of three unicellular autotrophic picocyanobacterial
Synechococcus
-type strains by potentiometric titration and infrared spectroscopy. Potentiometric titrations were conducted to determine the total buffering capacity. The nature and concentration of active sites of the polysaccharides was clarified with the aid of potentiometric titration and spectral analysis of an aqueous cellular suspension. Precipitation experiments with polysaccharides of different strains allowed an estimation of their potential to precipitate calcium carbonate. The results presented here indicate that polysaccharides from cyanobacteria have a strong potential to exchange protons with their surrounding environment. Precipitation experiments demonstrated that extracellular polysaccharides of all the strains studied able to precipitate calcium carbonate.
Microbial influence on macroenvironment chemical conditions in alkaline (tufa) streams: perspectives from
in vitro
experiments
Authors: Rogerson M. , Pedley H. M. , Middleton R.
Published: June 2010

Tufas represent a palaeoclimatic archive of potentially global significance. However, uncertainty remains over the exact process of calcite precipitation from these systems, inhibiting our ability to decipher the precise meaning of geochemical records. For example, field studies of alkaline stream systems are unable to disentangle the influence of temperature and photosynthesis on ambient hydrochemistry on diurnal and annual timescales. This report describes a series of flume experiments in which temperature and light conditions are manipulated separately. These experiments reveal that precipitation of calcite occurs preferentially under conditions of rising pH, and consequently at the night–day transition. The amplitude of diurnal changes is regulated by the buffering capacity (i.e. alkalinity) of the ambient water and by the daytime balance of photosynthesis and respiration. Respiration is shown to be strongly affected by temperature, whereas photosynthesis is found to be limited by nutrient and/or DIC availability making temperature impacts minor. Consequently, macroenvironment pH during both day and night-time tend to be higher under lower temperatures, in contrast to expectation. These observations may have potential implications for the isotopic geochemistry of tufa carbonate, promoting slightly lower δ
18
O, due to the carbonate ion effect, and more significantly negative δ
13
C, due to incorporation of respired CO
2
accumulated during the night. The observation that long periods of daylight are not necessarily needed for photosynthetically induced precipitation to occur confirm previous arguments that seasonal lamination requires either strong variability in ambient physicochemical activity or an ecological change in the microbial assemblage, and cannot be ascribed to reduced temperature and light intensity.