Fluid release from the subducted Cocos plate and partial melting of the crust deduced from magnetotelluric studies in southern Mexico: implications for the generation of volcanism and subduction dynamics

In order to study electrical conductivity phenomena that are associated with subduction related fluid release and melt production, magnetotelluric (MT) measurements were carried out in southern Mexico along two coast to coast profiles. The conductivity-depth distribution was obtained by simultaneous two-dimensional inversion of the transverse magnetic and transverse electric modes of the magnetotelluric transfer functions. The MT models demonstrate that the plate southern profile shows enhanced conductivity in the deep crust. The northern profile is dominated by an elongated conductive zone extending >250 km below the Trans-Mexican Volcanic Belt (TMVB). The isolated conductivity anomalies in the southern profile are interpreted as slab fluids stored in the overlying deep continental crust. These fluids were released by progressive metamorphic dehydration of the basaltic oceanic crust. The conductivity anomalies may be related to the main dehydration reactions at the zeolite → blueschist → eclogite facies transitions and the breakdown of chlorite. This relation allows the estimation of a geothermal gradient of ∼8.5°C/km for the top of the subducting plate. The same dehydration reactions may be recognized along the northern profile at the same position relative to the depth of the plate, but more inland due to a shallower dip, and merge near the volcanic front due to steep downbending of the plate. When the oceanic crust reaches a depth of 80–90 km, ascending fluids produce basaltic melts in the intervening hot subcontinental mantle wedge that give rise to the volcanic belt. Water-rich basalts may intrude into the lower continental crust leading to partial melting. The elongated highly conductive zone below the TMVB may therefore be caused by partial melts and fluids of various origins, ongoing migmatization, ascending basaltic and granitic melts, growing plutons as well as residual metamorphic fluids. Zones of extremely high conductance (>8000 S) in the continental crust on either MT profile might indicate extinct magmatism

Inferring interactivity from gaze patterns during triadic person-object-agent interactions

Observing others’ gaze informs us about relevant matters in the environment. Humans’ sensitivity to gaze cues and our ability to use this information to focus our own attention is crucial to learning, social coordination, and survival. Gaze can also be a deliberate social signal which captures and directs the gaze of others toward an object of interest. In the current study, we investigated whether the intention to actively communicate one’s own attentional focus can be inferred from the dynamics of gaze alone. We used a triadic gaze interaction paradigm based on the recently proposed classification of attentional states and respective gaze patterns in person-object-person interactions, the so-called “social gaze space (SGS).” Twenty-eight participants interacted with a computer controlled virtual agent while they assumed to interact with a real human. During the experiment, the virtual agent engaged in various gaze patterns which were determined by the agent’s attentional communicative state, as described by the concept of SGS. After each interaction, participants were asked to judge whether the other person was trying to deliberately interact with them. Results show that participants were able to infer the communicative intention solely from the agent’s gaze behavior. The results substantiate claims about the pivotal role of gaze in social coordination and relationship formation. Our results further reveal that social expectations are reflected in differential responses to the displayed gaze patterns and may be crucial for impression formation during gaze-based interaction. To the best of our knowledge, this is the first study to document the experience of interactivity in continuous and contingent triadic gaze interactions

Brief Report: Preferred Processing of Social Stimuli in Autism: A Perception Task

In this study we investigate whether persons with autism spectrum disorder (ASD) perceive social images differently than control participants (CON) in a graded perception task in which stimuli emerged from noise before dissipating into noise again. We presented either social stimuli (humans) or non-social stimuli (objects or animals). ASD were slower to recognize images during their emergence, but as fast as CON when indicating the dissipation of the image irrespective of its content. Social stimuli were recognized faster and remained discernable longer in both diagnostic groups. Thus, ASD participants show a largely intact preference for the processing of social images. An exploratory analysis of response subsets reveals subtle differences between groups that could be investigated in future studies

Erforschung des tieferen Untergrundes der Nordostdeutschen Senke - ein Beitrag der Magnetotellurik zur Untersuchung des praewestfalen Muttergesteinspotentials Abschlussbericht

The research project is terminated. The objective of obtaining information on the regional distribution of good-conducting layers in the deep subsurface of Northeastern Germany has been achieved by the evaluation of magnetotelluric measurements. By comparison with analogous results (e.g. offshore well G14 in the Baltic Sea, boreholes Proettlin 1 in northwestern Brandenburg and Muensterland 1 in North Rhine-Westphalia), the good-conducting horizons may indicate Cambrian and Ordovician black shale ('Skandinavische Alaunschiefer') in the area of Ruegen Island and the adjacent mainland up to the Anklam Fault, as well as Carboniferous black shale ('Hangende Alaunschiefer') to the southwest of the Lower Elbe Fault and in northern Brandenburg. Since these alum or black shale is to be considered as a potential (pre-Westphalian) hydrocarbon source rock, as has been uniquely proved by the results of the Deep Gas project (BGR, 1994) of the Federal Ministry for Education, Science, Research and Technology (BMBF), particular importance is entitled to their detection and to the localization of their regional and straticgraphic occurrence with respect to the hydrocarbon prospectivity assessment. As a result of the project activities, the survey region was subdivided according to the occurence of potential source rocks of different ages. Proposals were made for further magnetotellurc measurements in northwestern German areas of hydrocarbon prospectivity. (orig.)With mapsSIGLEAvailable from TIB Hannover: F97B1299+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman