Rb-Sr sphalerite data and implications for the source and timing of Pb-Zn deposits at the Caledonian margin in Sweden

The eastern Caledonian erosional front hosts the world-class Pb-Zn deposit at Laisvall (64 Mt mined) and Granberget mineralization, northern Sweden, along with several other smaller, related types of deposits consisting of impregnation mineralization of galena and sphalerite in clastic host rocks. Previous work have discussed the nature of the ore-forming processes and constraints for the timing of the mineralization, however, the mechanisms are still not fully understood and previous age determinations are ambiguous. The main challenge with obtaining reliable ages for the mineralization is the lack of minerals available for dating and the complex nature of the available isotope data. This thesis aims to improve the understanding for the ore-forming processes in the Laisvall type of deposit and, if possible, obtain an age for the mineralization by utilizing the crush-leach technique on disseminated sphalerite from Laisvall and Granberget with subsequent ID-TIMS isotope analysis. In general, the data is complex and our results does not provide a robust age for the mineralization. However, our data are in agreement with the hypothesis that ore-fluids with contrasting 87Sr/86Sr were mixing during the syn-ore forming stage. These results are opposing previous hypotheses which are favoring a post-ore disturbance causing scatter in the isotope data. Our data provide further support for hydrothermal circulation in response to orogenic tectonics at a regional scale, forming Pb-Zn mineralizations at multiple locations during a relatively short time-interval, either related to an event at ca. 540 Ma (related to the Timian orogeny) or at ca. 467 Ma (related to the Caledonian orogeny). Thus, these findings implicate that the Pb-Zn deposits in the Caledonian forefront was caused by a single, regional process. The results provide further insights to the genetic model for the Caledonian sediment hosted Pb-Zn deposits.Längs Kaledonidernas östra erosionsfront finns den världskända bly- och zinkfyndigheten vid Laisvall (totalt 64 miljoner ton bruten malm) och mineraliseringen vid Granberget samt flertalet mindre malmkroppar av impregnationstyp bestående av blyglans och zinkblände som kristalliserat i klastiska bergarter. I äldre litteratur har mineraliseringsprocesserna och tidsspannet för mineralisationen diskuterats, men processerna är fortfarande långt ifrån klargjorda och tidigare dateringar bör beaktas med viss skepsis. Den huvudsakliga utmaningen med att producera pålitliga dateringar av malmen är dels avsaknaden av daterbara mineral och dels det komplexa mönstret hos den data som befintliga geokronologiska metoder producerat. Målet med denna uppsats är att klargöra och fördjupa förståelsen för malmbildningsprocesserna vid Laisvall- och Granbergetmalmerna samt, om möjligt, datera malmen med hjälp av ID-TIMS isotopanalys av rubidium och strontium från zinkblände. Datan är överlag komplex och svårtolkad och våra resultat kan inte ge en precis och robust ålder för mineraliseringen. Datan styrker däremot hypotesen om att malmfluider med kontrasterande 87Sr/86Sr-isotopskvoter blandades i samband med malmgenesen. Dessa resultat står i motsats till tidigare hypoteser som argumenterar för att isotopsystemet skall ha blivit stört efter mineraliseringen avslutades. Vår data stödjer hypotesen om att bergskedjebildning kan ha gett upphov till hydrotermala fluider som cirkulerade på en regional nivå, vilket i sin tur ledde till bly- och zinkmineraliseringar på flertalet platser under ett relativt kort tidsintervall, relaterat till antingen den Timiska orogenesen (ca. 540 miljoner år sedan) eller ett tidigt stadium av den Kaledonska orogenesen (ca. 470 miljoner år sedan). Dessa resultat tyder på att blyoch zinkfyndigheterna längs den Kaledoniska bergskedjans rand har skapats av en ensam, regional process. I tillägg till detta bidrar också resultaten till en ökad kunskap och förståelse för Kaledoniska bly- och zinkmalmer i sedimentära moderbergarter

Mantelplymer : realitet eller ad hoc?

Mantle plumes are subject of a great discussion within the field of Geology. Do they really exist, and in that case, from where do they originate? The scope of this Bachelor thesis is to discuss the characteristics of mantle plumes and the arguments in favor of and against their proposed existence. The mantle plume hypothesis was first presented in 1971 by Jason Morgan, suggesting diapirs of hot rock were bringing heat from the Earth’s core to form hot spots on the surface of the Earth. The hypothesis has since that time gradually been elaborated and an increas-ing amount of data confirm that mantle plumes do exist and that they fuel the majority of the intraplate magmatism occurring in e.g. Hawaii, Tristan da Cunha and Reunion. In the attempts to evince the existence of mantle plumes, mainly three methods of analysis are used: seismic, geochemical analysis and different types of modelling. This literature review discusses the benefits and drawbacks of the above mentioned methods and the results they have spawned. Some critics consider the mantle plume characteristic magmatism being a consequence of melting in the shallow mantle as a result of varying chemical composition, small-scale convection, tectonic features and chemical stratification of the mantle due to subduction. Conclusively too much evidence agree with the mantle plume hy-pothesis for it to be ruled out. Some igneous provinces are results of mantle plumes while others require a different model of explanation. A working majority of the models produced by sceptics are more or less ad hoc and does not provide satisfying alternative explanations. Continued research should focus on studying the mantle plumes more closely to determine their origin and forming processes.Mantelplymer är ett mycket omdebatterat fenomen inom geologiämnet. Existerar de och var har de i så fall sitt ursprung? Detta kandidatarbete behandlar mantelplymens karaktäristika och de för- och motargu-ment för dess existens som finns i litteraturen. Hypotesen om mantelplymer uttrycktes första gången 1971 av Jason Morgan där det föreslogs att hett mantelmaterial förs från Jordens kärna till ytan där de bildar hotspots. Efterhand har hypotesen utvecklats och allt mer data pekar på att mantelplymer finns och att de gett upphov till majoriteten av magmatismen som sker inom plattor, exempelvis vid Hawaii, Tristan da Cunha och Reunion. I jakten på att försöka påvisa mantelplymer används främst tre typer av analysmetoder: seismik, geokemiska analyser och modelleringar av olika slag. I denna litteraturstudie diskuteras för- och nackdelar med dessa metoder, samt vilka resultat de gett upphov till. Det finns en inte helt oansenlig skara kritiker som anser att den magmatism som anses karaktäristisk för mantelplymer istället beror på uppsmältning i mantelns övre delar som ett resultat av varierande kemisk samman-sättning, småskalig mantelkonvektion, tektoniska svaghetszoner och kemisk stratifiering till följd av subduktion. Sammantaget talar en alltför stor mängd bevis för mantelplymhypotesen för att kunna avfärda den. Vissa magma-tiska provinser har uppkommit genom mantelplymer medan andra områden kräver alternativa förklaringsmodeller. Flertalet förklaringsmodeller framlagda av skeptiker är mer eller mindre ad hoc och ger inga tillfredsställande alter-nativa förklaringar. Fortsatt forskning bör fokusera på att studera mantelplymerna närmare för att kunna avgöra deras härkomst och bildningsprocesser

Quantitative powder diffraction using a (2+3) surface diffractometer and an area detector

X-ray diffractometers primarily designed for surface x-ray diffraction are often used to measure the diffraction from powders, textured materials, and fiber-texture samples in so-called $2\theta$ scans. Unlike high-energy powder diffraction only a fraction of the powder rings is typically measured and the data consists of many detector images across the $2\theta$ range. Such diffractometers typically scan in directions not possible on a conventional lab-diffractometer, which gives enhanced control of the scattering vector relative to the sample orientation. There are, however, very few examples where the measured intensity is directly used, such as for profile/Rietveld refinement, as is common with other powder diffraction data. Although the underlying physics is known, converting the data is time-consuming and the appropriate corrections are dispersed across several publications, often not with powder diffraction in mind. In this paper we present the angle calculations and correction factors required to calculate meaningful intensities for $2\theta$ scans with a (2+3)-type diffractometer and an area detector. We also discuss some of the limitations with respect to texture, refraction, and instrumental resolution, and what kind of information one can hope to obtain.Comment: Research paper, 15 pages, 12 figures, 3 table

Anisotropic strain variations during the confined growth of Au nanowires

The electrochemical growth of Au nanowires in a template of nano-porous anodic aluminum oxide was investigated in situ by means of grazing-incidence transmission small- and wide-angle x-ray scattering (GTSAXS and GTWAXS), x-ray fluorescence (XRF) and 2-dimensional surface optical reflectance (2D-SOR). The XRF and the overall intensity of the GTWAXS patterns as a function of time were used to monitor the progress of the electrodeposition. Furthermore, we extracted powder diffraction patterns in the direction of growth and in the direction of confinement to follow the evolution of the direction-dependent strain. Quite rapidly after the beginning of the electrodeposition, the strain became tensile in the vertical direction and compressive in the horizontal direction, which showed that the lattice deformation of the nanostructures can be artificially varied by an appropriate choice of the deposition time. By alternating sequences of electrodeposition to sequences of rest, we observed fluctuations of the lattice parameter in the direction of growth, attributed to stress caused by electromigration.. Furthermore, the porous domain size calculated from the GTSAXS patterns was used to monitor how homogeneously the pores were filled.Comment: Short communication manuscript. Four figure

Metastable Precursor Structures in Hydrogen-infused Super Duplex Stainless Steel Microstructure – An Operando Diffraction Experiment

We report the evolution of metastable precursor structures during hydrogen infusion in the near-surface region of a super duplex stainless steel. Grazing-incidence x-ray diffraction was employed to monitor, operando, the lattice degradation of the austenite and ferrite phases. Electrochemical hydrogen charging resulted in the splitting of the diffraction peaks of the austenite phase, suggesting the evolution of a metastable precursor structure. This may be explained by the formation of quasi-hydrides, which convert back into the austenite parent structure during hydrogen effusion. The ferrite showed less lattice deformation than the austenite and no phase transformation

In situ\textit{In situ} hydride breathing during the template-assisted electrodeposition of Pd nanowires

We investigated the structural evolution of electrochemically fabricated Pd nanowires $\textit{in situ}$ by means of grazing-incidence transmission small- and wide-angle x-ray scattering (GTSAXS and GTWAXS), x-ray fluorescence (XRF) and 2-dimensional surface optical reflectance (2D-SOR). This shows how electrodeposition and the hydrogen evolution reaction (HER) compete and interact during Pd electrodepositon. During the bottom-up growth of the nanowires, we show that $\beta$-phase Pd hydride is formed. Suspending the electrodeposition then leads to a phase transition from $\beta$- to $\alpha$-phase Pd hydride. Additionally, we find that grain coalescence later hinders the incorporation of hydrogen in the Pd unit cell. GTSAXS and 2D-SOR provide complementary information on the volume fraction of the pores occupied by Pd, while XRF was used to monitor the amount of Pd electrodeposited.Comment: 17 pages, 11 figures, 4 appendice

Exploring Hydride Formation in Stainless Steel Revisits Theory of Hydrogen Embrittlement

Various mechanisms have been proposed for hydrogen embrittlement, but the causation of hydrogen-induced material degradation has remained unclear. This work shows hydrogen embrittlement due to phase instability (decomposition). In-situ diffraction measurements revealed metastable hydrides formed in stainless steel, typically declared as a non-hydride forming material. Hydride formation is possible by increasing the hydrogen chemical potential during electrochemical charging and low defect formation energy of hydrogen interstitials. Our findings demonstrate that hydrogen-induced material degradation can only be understood if measured in situ and in real-time during the embrittlement process.Comment: 31 Pages, 18 Figures, Preprin

Multiplatform Analysis of 12 Cancer Types Reveals Molecular Classification within and across Tissues of Origin

Recent genomic analyses of pathologically-defined tumor types identify “within-a-tissue” disease subtypes. However, the extent to which genomic signatures are shared across tissues is still unclear. We performed an integrative analysis using five genome-wide platforms and one proteomic platform on 3,527 specimens from 12 cancer types, revealing a unified classification into 11 major subtypes. Five subtypes were nearly identical to their tissue-of-origin counterparts, but several distinct cancer types were found to converge into common subtypes. Lung squamous, head & neck, and a subset of bladder cancers coalesced into one subtype typified by TP53 alterations, TP63 amplifications, and high expression of immune and proliferation pathway genes. Of note, bladder cancers split into three pan-cancer subtypes. The multi-platform classification, while correlated with tissue-of-origin, provides independent information for predicting clinical outcomes. All datasets are available for data-mining from a unified resource to support further biological discoveries and insights into novel therapeutic strategies

Investigation into methods for N-trifluoromethylation of a key intermediate in the synthesis of an SGLT1 inhibitor and potential starting point for anti-diabetes drugs

Sodium-glucose transporters (SGLTs) are a group of membrane proteins involved in regulating blood-glucose levels. Compounds which inhibit SGLTs are therefore of interest in the development of new treatments for diabetes. The SGLT class is divided into SGLT1 and SGLT2, the primary difference between the two being where in the body they are expressed. Several SGLT2 inhibitors have been approved and are being used to treat diabetes in current clinical practice. No SGLT1 inhibitors have been approved as of yet but there are several under development at various pharmaceutical companies. In this work, methods to N-trifluoromethylate a key intermediate in the synthesis of an SGLT1 inhibitor and potential anti-diabetes drug were investigated. A previously reported procedure as well as potential alternatives were examined. Multiple methods were capable of producing the N-CF3 intermediate (confirmed by NMR and GC-MS analysis) but all inefficiently and in poor yields. Further research in this area is needed to improve the overall efficiency of the synthesis of the SGLT1 inhibitor

Investigation into methods for N-trifluoromethylation of a key intermediate in the synthesis of an SGLT1 inhibitor and potential starting point for anti-diabetes drugs

Sodium-glucose transporters (SGLTs) are a group of membrane proteins involved in regulating blood-glucose levels. Compounds which inhibit SGLTs are therefore of interest in the development of new treatments for diabetes. The SGLT class is divided into SGLT1 and SGLT2, the primary difference between the two being where in the body they are expressed. Several SGLT2 inhibitors have been approved and are being used to treat diabetes in current clinical practice. No SGLT1 inhibitors have been approved as of yet but there are several under development at various pharmaceutical companies. In this work, methods to N-trifluoromethylate a key intermediate in the synthesis of an SGLT1 inhibitor and potential anti-diabetes drug were investigated. A previously reported procedure as well as potential alternatives were examined. Multiple methods were capable of producing the N-CF3 intermediate (confirmed by NMR and GC-MS analysis) but all inefficiently and in poor yields. Further research in this area is needed to improve the overall efficiency of the synthesis of the SGLT1 inhibitor