409 research outputs found

    Cretaceous age, composition, and microstructure of pseudotachylyte in the Otago Schist, New Zealand

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    At Tucker Hill, in Central Otago, New Zealand, a series of pseudotachylyte veins are hosted in quartzofeldspathic schist. Chilled margins, microlites, flow banding, and the crystallisation of mineral phases absent from the host rock provide unequivocal evidence for melting during pseudotachylyte formation. Whole rock analyses of pseudotachylyte reveal c. 3 enrichment of K2O, Ba, and Rb, and similar depletion of Na2O, CaO, Sr, and Eu, as compared to host schist. Formation age of pseudotachylyte is 95.9±1.8 Ma as measured by total fusion 40Ar/39Ar analyses. Stepwise heating of pseudotachylyte matrix yields an excellently defined 40Ar/39Ar plateau age of 96.0±0.3 Ma. These well-defined ages are attributed to the presence of potassium feldspar, low abundance of inherited lithic material from the host rock, and few fluid inclusions containing extraneous Ar. We propose that formation of these pseudotachylyte veins was related to Cretaceous extensional uplift and exhumation of the Otago Schist

    High-resolution X-ray texture goniometry

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    High-resolution X-ray texture goniometry (HRXTG) significantly improves peak/background ratios and allows for the determination of crystallographic preferred fabrics of small regions (2) in heterogeneously deformed rocks. The basic instrument is a commercially available automated single-crystal X-ray diffractometer equipped with a Mo source. A stage for transmission mode was constructed that is driven by the original motors, so the unit is fully computer controlled. Absorption corrections are calculated, which removes the need for generally difficult to obtain empirical corrections. This, combined with equipment optimization, enables us to use small irradiated volumes of rocks with variable compositions. The advantage of HRXTG in heterogeneously deformed rocks is demonstrated in a cleaved mudstone. Analysis of 2 areas in a 2 cm bed showing a gradation from micaceous sandstone to slate reveals that fabric intensity of both mica and chlorite increases significantly (dM from 0.64 to 1.03 and from 0.45 to 0.78, respectively), without appreciable change in the oblate shape (kM) of the fabric. Thus, HRXTG can record a strain state at the mm-scale of heterogeneously deformed rocks.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31487/1/0000409.pd

    TEM and AEM constraints on the origin and significance of chlorite-mica stacks in slates: an example from Central Wales, U.K.

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    Chlorite-mica stacks (grains of intergrown chlorite and white mica) in a matrix of fine-grained white mica and chlorite have been studied using XRD, SEM, EMPA, TEM and AEM methods. The stacks occur in a weakly cleaved Llandoverian mudstone, central Wales, which has a white mica (illite) crystallinity index of 0.35[deg] [Delta]2[phi] corresponding to the lower anchizone. White mica occurs as packets (100 A to 8 [mu]m thick) interleaved with dominant chlorite packets in stacks, with both apparent coherent interfaces or cross-cutting small angle boundaries with chlorite layers. It is well-crystallized 2M1 polytype with phengitic composition and low paragonite component [Na/(Na + K) 2 crystals surround stacks and occur within chlorite, and white mica is Ti-rich compared to matrix white mica.Fine-grained white mica and chlorite in the matrix have two different orientations: one parallel to hedding and one parallel to cleavage, which is approximately 30-50[deg] to bedding. Matrix white mica is predominantly a 2M1 polytype, but some cleavage-parallel white mica is 3T and some bedding-parallel white mica is 1Ma. It is Na-rich [(Na/(Na + K) ~ 0.14-0.42] and relatively heterogeneous; some discrete paragonite and phengitic muscovite are observed to coexist in the cleavage orientation. Matrix white mica and chlorite each contain less Fe than corresponding white mica and chlorite in stacks. Both matrix and stack chlorite are one-layer polytypes.The data imply that chlorite in the stacks is largely derived from the replacement of volcanogenic biotite and other ferromagnesian minerals (probably via intermediate expandable trioctahedral phyllosilicates). Most intergrowths of chlorite and mica in stacks formed by mica replacement of chlorite and altered biotite along cleavage fissures. Subsequent deformation caused further modification of pre-existing chlorite-mica stacks whereas partial dissolution of stacks and bedding-parallel matrix phyllosilicates resulted in the formation of cleavage-parallel phyllosilicates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31427/1/0000345.pd

    Transdiagnostic Ecological Momentary Intervention for Improving Self-Esteem in Youth Exposed to Childhood Adversity:The SELFIE Randomized Clinical Trial

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    Importance: Targeting low self-esteem in youth exposed to childhood adversity is a promising strategy for preventing adult mental disorders. Ecological momentary interventions (EMIs) allow for the delivery of youth-friendly, adaptive interventions for improving self-esteem, but robust trial-based evidence is pending.Objective: To examine the efficacy of SELFIE, a novel transdiagnostic, blended EMI for improving self-esteem plus care as usual (CAU) compared with CAU only.Design, Setting, and Participants: This was a 2-arm, parallel-group, assessor-blinded, randomized clinical trial conducted from December 2018 to December 2022. The study took place at Dutch secondary mental health services and within the general population and included youth (aged 12-26 years) with low self-esteem (Rosenberg Self-Esteem Scale [RSES] <26) exposed to childhood adversity.Interventions: A novel blended EMI (3 face-to-face sessions, email contacts, app-based, adaptive EMI) plus CAU or CAU only.Main Outcomes and Measures: The primary outcome was RSES self-esteem at postintervention and 6-month follow-up. Secondary outcomes included positive and negative self-esteem, schematic self-beliefs, momentary self-esteem and affect, general psychopathology, quality of life, observer-rated symptoms, and functioning.Results: A total of 174 participants (mean [SD] age, 20.7 [3.1] years; 154 female [89%]) were included in the intention-to-treat sample, who were primarily exposed to childhood emotional abuse or neglect, verbal or indirect bullying, and/or parental conflict. At postintervention, 153 participants (87.9%) and, at follow-up, 140 participants (80.5%), provided primary outcome data. RSES self-esteem was, on average, higher in the experimental condition (blended EMI + CAU) than in the control condition (CAU) across both postintervention and follow-up as a primary outcome (B = 2.32; 95% CI, 1.14-3.50; P < .001; Cohen d-type effect size [hereafter, Cohen d] = 0.54). Small to moderate effect sizes were observed suggestive of beneficial effects on positive (B = 3.85; 95% CI, 1.83-5.88; P < .001; Cohen d = 0.53) and negative (B = −3.78; 95% CI, −6.59 to −0.98; P = .008; Cohen d = −0.38) self-esteem, positive (B = 1.58; 95% CI, 0.41-2.75; P = .008; Cohen d = 0.38) and negative (B = −1.71; 95% CI, −2.93 to −0.48; P = .006; Cohen d = −0.39) schematic self-beliefs, momentary self-esteem (B = 0.29; 95% CI, 0.01-0.57; P = .04; Cohen d = 0.24), momentary positive affect (B = 0.23; 95% CI, 0.01-0.45; P = .04; Cohen d = 0.20), momentary negative affect (B = −0.33; 95% CI, −0.59 to −0.03, P = .01, Cohen d = −0.27), general psychopathology (B = −17.62; 95% CI, −33.03 to −2.21; P = .03; Cohen d = −0.34), and quality of life (B = 1.16; 95% CI, 0.18-2.13; P = .02; Cohen d = 0.33) across postintervention and follow-up. No beneficial effects on symptoms and functioning were observed.Conclusions and Relevance: A transdiagnostic, blended EMI demonstrated efficacy on the primary outcome of self-esteem and signaled beneficial effects on several secondary outcomes. Further work should focus on implementing this novel EMI in routine public mental health provision.Trial Registration Dutch Trial Register Identifier: NL7129(NTR7475

    Contradictions of slate formation resolved?

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62973/1/392348a0.pd

    Note on analysis of quartz grain dimensions in foliated greywackes

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    Quarzkorn-Abmessungen aus Grauwacken wurden auf ein internes Referenzsystem (reference aspect ratio, RAR) bezogen und mit Hilfe der linearen Regressionsanalyse der reduzierten Hauptachse (reduced major axis, RMA) ausgewertet. Das verwendete statistische Verfahren unterscheidet im Gegensatz zur Methode der kleinsten Quadrate nicht zwischen abhängigen und unabhängigen Variablen. Die Anwendung der RMX-Methode in Verbindung mit den RAR-Meßwerten kann sehr hilfreich für Vergleiche innerhalb geschieferter Grauwacken sein, bei denen unterschiedliche Prozesse in Korngrößenbereich wirksam waren wie etwa Drucklösung und Festkörper-Rotation. Die RAR/RMA-Analyse erfaßt Kornregelungen und ist daher auch einsetzbar für die Klassifikation von Schieferungen. Darüber hinaus wird die Anwendung der RAR/RMA-Analyse für die Bestimmung der Deformation diskutiert. Robin strain-Werte werden mit arithmetischen und harmonischen Mittelwerten der RAR-Analyse verglichen. Es zeigt sich, daß das arithmetische Mittel des RAR ein vernünftiges Maß für die longitudinale Deformation darstellt. Quartz grain dimensions, measured parallel to an internal reference system (reference aspect ratio, RAR), were analyzed using the »reduced major axis« (RMA) linear regression analysis. In contrast to least-squares analysis, this statistical technique does not distinguish between dependent and independent variables. Application of the RMA analysis in conjunction with RAR values can be most useful for comparisons between foliated greywackes in which different grain scale processes, such as pressure solution and rigid-body rotation, were active. The RAR/RMA analysis reflects grain alignment and is therefore also useful for cleavage classification. In addition to the above, the application of RAR/RMA analysis for the determination of strain is discussed. Robin strains are compared with the arithmetic and harmonic means from RAR's and it is concluded that the arithmetic mean RAR produces a reasonable estimate of longitudinal strain in these rocks. Les dimensions des grains de quartz, mesurés parallèlement à un système de référence interne (»reference aspect ratio«: RAR) ont été traitées par la méthode de la régression linéaire (»reduced major axis«: RMA). Contrairement à la méthode des moindres carrés, cette technique statistique ne fait pas de distinction entre les variables dépendantes et indépendantes. L'application de ce type de méthode s'avère très utile à la comparaison de grauwackes schisteuses dans lesquelles les dimensions des grains peuvent être la conséquence de processus différents, tels que la dissolution (pressure solution) et la rotation. L'analyse RAR/RMA traduit l'alignement des grains et peut, de ce fait, être utilisée aussi à l'appréciation du type de schistosité. D'autre part, l'auteur discute l'application de l'analyse RAR/RMA à la détermination de la déformation finie. Si on compare les déformations »Robin« aux moyennes arithmétique et harmonique des RAR, on peut conclure que les moyennes RAR arithmétiques fournissent une estimation raisonnable de la déformation longitudinale. Помимо интернациона льной системы RAR, разме ры зерен кварца анализи ровали с помощью регр ессивного анализа «Изменение о сновных осей» — RMA. В отличие от анализа ме тодом наименьшего кв адратов, при названном статис тическом методе разл ичия между зависимыми и не зависимыми переменн ыми не учитываются. Компл ексное применение RAR иPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47848/1/531_2005_Article_BF01821068.pd

    Defective Connective Tissue Remodeling in Smad3 Mice Leads to Accelerated Aneurysmal Growth Through Disturbed Downstream TGF-β Signaling

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    Aneurysm-osteoarthritis syndrome characterized by unpredictable aortic aneurysm formation, is caused by SMAD3 mutations. SMAD3 is part of the SMAD2/3/4 transcription factor, essential for TGF-β-activated transcription. Although TGF-β-related gene mutations result in aneurysms, the underlying mechanism is unknown. Here, we examined aneurysm formation and progression in Smad3−/− animals. Smad3−/− animals developed aortic aneurysms rapidly, resulting in premature death. Aortic wall immunohistochemistry showed no increase in extracellular matrix and collagen accumulation, nor loss of vascular smooth muscle cells (VSMCs) but instead revealed medial elastin disruption and adventitial inflammation. Remarkably, matrix metalloproteases (MMPs) were not activated in VSMCs, but rather specifically in inflammatory areas. Although Smad3−/− aortas showed increased nuclear pSmad2 and pErk, indicating TGF-β receptor activation, downstream TGF-β-activated target genes were not upregulated. Increased pSmad2 and pErk staining in pre-aneurysmal Smad3−/− aortas implied that aortic damage and TGF-β receptor-activated signaling precede aortic inflammation. Finally, impaired downstream TGF-β activated transcription resulted in increased Smad3−/− VSMC proliferation. Smad3 deficiency leads to imbalanced activation of downstream genes, no activation of MMPs in VSMCs, and immune responses resulting in rapid aortic wall dilatation and rupture. Our findings uncover new possibil
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