105 research outputs found
Ultrahigh-pressure metamorphism in the magnesite + aragonite stability field: evidence from two impure marbles from the Dabie-Sulu UHPM belt.
Two magnesite-bearing impure dolomitic marbles from the DabieSulu ultrahigh-pressure (UHP) region have been investigated to clarify if they had actually attained PT conditions outside the dolomite stability field, limited by the reaction dolomite = aragonite + magnesite, and to test their potential for recording (U)HP conditions. In both cases, the silicate mineral assemblage records conditions around the terminal amphibole breakdown reaction: amphibole + aragonite +/- quartz = clinopyroxene + talc, which is a good geobarometer between at least 2.0 and 2.6 GPa. At higher pressures, the terminal breakdown of talc to clinopyroxene + coesite is the last PT milestone below 4 GPa recordable by the silicate assemblage, but evidence of former coesite is ambiguous. The dolomite dissociation curve becomes strongly divariant in Fe-bearing marbles and may thus be attainable during cold subduction near the 5 degrees C km-1geotherm. At least one of the samples (from Xinyan village, near Taihu, Dabie Shan) preserved relicts of both magnesite and aragonite and most likely attained conditions within the aragonite + magnesite stability field. For the second sample from Sanqingge village in the Sulu terrane, no certain evidence has been found in this study. Impure dolomitic marbles have considerable potential to preserve (ultra)high-pressure relicts. Particularly, massive impure marbles that have not been pervasively infiltrated by fluids during exhumation are considered to preserve high-pressure relicts better than metapelites, paragneisses and orthogneisses, and perhaps almost as well as eclogites or metaperidotites. The inconspicuous mineral assemblage clinopyroxene + talc or quartz (after former coesite) may in fact record UHP conditions.GeologySCI(E)EI8ARTICLE135-483
Dioctahedral mixed K-Na-micas and paragonite in diagenetic to low-temperature metamorphic terrains: bulk rock chemical, thermodynamic and textural constraints
Abstract
Metamorphic mineral assemblages in low-temperature metaclastic rocks often contain paragonite and/or its precursor metastable phase (mixed K-Na-white mica). Relationships between the bulk rock major element chemistries and the formation of paragonite at seven localities from Central and SE-Europe were studied, comparing the bulk chemical characteristics with mineral assemblage, mineral chemical and metamorphic petrological data. Considerable overlaps between the projection fields of bulk chemistries of the Pg-free and Pg-bearing metaclastic rocks indicate significant differences between the actual (as analyzed) and effective bulk chemical compositions. Where inherited, clastic, inert phases/constituents were excluded, it was found that a decrease in Na/(Na+Al*) and in K/(K+Al*) ratios of rocks favors the formation and occurrence of Pg and its precursor phases (Al* denotes here the atomic quantity of aluminum in feldspars, white micas and “pure” hydrous or anhydrous aluminosilicates). In contrast to earlier suggestions, enrichment in Na and/or an increase in Na/K ratio by themselves do not lead to formation of paragonite. Bulk rock chemistries favorable to formation of paragonite and its precursor phases are characterized by enrichment in Al and depletion in Na, K, Ca (and also, Mg and Fe2+). Such bulk rock chemistries are characteristic of chemically “mature” (strongly weathered) source rocks of the pelites and may also be formed by synand post-sedimentary magmatism-related hydrothermal (leaching) activity. What part of the whole rock is active in determining the effective bulk chemistry was investigated by textural examination of diagenetic and anchizone-grade samples. It is hypothesized that although solid phases act as local sources and sinks, transport of elements such as Na through the grain boundaries have much larger communication distances. Sodium-rich white micas nucleate heterogeneously using existing phyllosilicates as templates and are distributed widely on the thin section scale. The results of modeling by THERMOCALC suggest that paragonite preferably forms at higher pressures in low-T metapelites. The stability fields of Pg-bearing assemblages increase, the Pg-in reaction line is shifted towards lower pressures, while the stability field of the Chl-Ms-Ab-Qtz assemblage decreases and is shifted towards higher temperatures with increasing Al* content and decreasing Na/(Na+Al*) and K/(K+Al*) ratios
Positive Affect Predicts Cerebral Glucose Metabolism in Late Middle-aged Adults.
Positive affect is associated with a number of health benefits; however, few studies have examined the relationship between positive affect and cerebral glucose metabolism, a key energy source for neuronal function and a possible index of brain health. We sought to determine if positive affect was associated with cerebral glucose metabolism in late middle-aged adults (n = 133). Participants completed the positive affect subscale of the Center for Epidemiological Studies Depression Scale at two time points over a two-year period and underwent 18F-fluorodeoxyglucose-positron emission tomography scanning. After controlling for age, sex, perceived health status, depressive symptoms, anti-depressant use, family history of Alzheimer’s disease, APOE ε4 status and interval between visits, positive affect was associated with greater cerebral glucose metabolism across para-/limbic, frontal, temporal and parietal regions. Our findings provide evidence that positive affect in late midlife is associated with greater brain health in regions involved in affective processing and also known to be susceptible to early neuropathological processes. The current findings may have implications for interventions aimed at increasing positive affect to attenuate early neuropathological changes in at-risk individuals
Moving Forward in Fostering Humour: Towards Training Lighter Forms of Humour in Multicultural Contexts
The following theoretical position paper has the aim to outline two important future directions of humour intervention research. Firstly, existing humour trainings have not differentiated explicitly between different uses of humour or humour that may be virtuous or not. Within the realm of Positive Psychology, all virtuous forms of humour need to be identified and interventions developed that aim at fostering these benevolent/lighter forms. Secondly, most humour trainings have been adapted and conducted in one cultural context. Future trainings should consider cross-cultural perspectives to allow for comparative research and practice. Thus, the current paper first gives an overview on the extant literature on the distinction between lighter and darker forms of humour, as well as showing how humour can serve the virtues proposed by Peterson and Seligman (2004). Then, we elaborate on the findings on humour and well-being, as well as findings on existing humour interventions. The second section starts with open questions and hypotheses on how a new generation of trainings targeting lighter forms of humour could look like. Then, we discuss (potential) cultural differences in humour and how this may affect the design of interventions. When aiming for cross-cultural adaptations of the same humour program, several challenges have to be overcome, such as the term “humour” not having the same meaning in every culture, and cultural rules on what can be laughed at
High-pressure/low-temperature metamorphism of basalts in Lavrion (Greece): Implications for the preservation of peak metamorphic assemblages in blueschists and greenschists
Pressure-temperature evolution of eclogites from the Kechros complex in the Eastern Rhodope (NE Greece)
Pseudosection modelling for a selected eclogite body from the Koralpe (Hohl), Eastern Alps.
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Metamorphic reprocessing of a serpentinized carbonate-bearing peridotite after detachment from the mantle wedge: A P-T path constrained from textures and phase diagrams in the system CaO-MgO-Al2O3-SiO2-CO2-H2O
Is the homo ludens cheerful and serious at the same time? An empirical study of Hugo Rahner's notion of Ernstheiterkeit
The theologian Hugo Rahner argued that the homo ludens is a man of ‘Ernstheiterkeit’ (seriouscheerfulness), a person who can smile under tears but also recognizes the gravity in all earthly cheerfulness. The primary aim of this study was to test the validity of this notion: Do homines ludentes exist? Two hundred sixty-three adult subjects were measured for (1) seriousness and cheerfulness and (2) playfulness. Results provided unequivocal support for Rahner’s thesis. Numerous subjects scored high in both seriousness and cheerfulness thus confirming the existence of homines ludentes. It was further found that these subjects were among those scoring highest in playfulness. Subjects scoring high in cheerfulness but low in seriousness were, however, even more closely associated with playfulness. The scores for homines ludentes did not differ from the rest of the subjects in the creative and dynamic facets of playfulness. The importance of developing empirical research to investigate hypotheses derived from non-scientific concepts is discussed
Character and dealing with laughter: The relation of self- and peer-reported strengths of character with gelotophobia, gelotophilia, and katagelasticism
We hypothesized that gelotophobia (the fear of being laughed at), gelotophilia (the joy of being laughed at), and katagelasticism (the joy of laughing at others) relate differently to character strengths. In Study 1 (N = 5,134), self-assessed gelotophobia was primarily negatively related to strengths (especially to lower hope, zest, and love), whereas only modesty yielded positive relations. Gelotophilia demonstrated mainly positive relations with humor, zest, and social intelligence. Katagelasticism existed widely unrelated from character strengths with humor demonstrating the comparatively highest coefficients. Study 2 consisted of N = 249 participants who provided self- and peer-ratings of strengths and self-reports on the three dispositions. The results converged well with those from Study 1. When comparing self- and peer-reports, those higher in gelotophobia under-estimated and those higher in gelotophilia over-estimated their virtuousness, whereas those higher in katagelasticism seemed to have a realistic appraisal of their strengths. Peer-rated (low) hope and modesty contributed to the prediction of gelotophobia beyond self-reports. The same was true for low modesty, creativity, low bravery, and authenticity for gelotophilia and for low love of learning regarding katagelasticism. Results suggest that there is a stable relation between the way people deal with ridicule and laughing and their virtuousness
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