Magnetic fabrics and their relationship with the emplacement of the Piracaia pluton,SE Brazil

Magnetic fabric and rock-magnetism studies were performed on the four units of the 578 ± 3-Ma-old Piracaia pluton (NW of São Paulo State, southern Brazil). This intrusion is roughly elliptical (~32 km²), composed of (i) coarse-grained monzodiorite (MZD-c), (ii) fine-grained monzodiorite (MZD-f), which is predominant in the pluton, (iii) monzonite heterogeneous (MZN-het), and (iv) quartz syenite (Qz-Sy). Magnetic fabrics were determined by applying both anisotropy of low-field magnetic susceptibility (AMS) and anisotropy of anhysteretic remanent magnetization (AARM). The two fabrics are coaxial. The parallelism between AMS and AARM tensors excludes the presence of a single domain (SD) effect on the AMS fabric of the units. Several rock-magnetism experiments performed in one specimen from each sampled units show that for all of them, the magnetic susceptibility and magnetic fabrics are carried by magnetite grains, which was also observed in the thin sections. Foliations and lineations in the units were successfully determined by applying magnetic methods. Most of the magnetic foliations are steeply dipping or vertical in all units and are roughly parallel to the foliation measured in the field and in the country rocks. In contrast, the magnetic lineations present mostly low plunges for the whole pluton. However, for eight sites, they are steep up to vertical. Thin-section analyses show that rocks from the Piracaia pluton were affected by the regional strain during and after emplacement since magmatic foliation evolves to solid-state fabric in the north of the pluton, indicating that magnetic fabrics in this area of the pluton are related to this strain. Otherwise, the lack of solid-state deformation at outcrop scale and in thin sections precludes deformation in the SW of the pluton. This evidence allows us to interpret the observed magnetic fabrics as primary in origin (magmatic) acquired when the rocks were solidified as a result of magma flow, in which steeply plunging magnetic lineation suggests that a feeder zone could underlie this area.     

A test of independence for stratigraphic sequences with respect to embedded Markov chains

Identification of cyclic sequences gives valuable insight into depositional associations of stratigraphic facies. An embedded Markov chain is a reasonable general model for facies transitions. But a model with independent random occurrences of facies is not an appropriate null hypothesis to be tested to show the presence of cycles because of definitional restriction in transition observations to only those between different facies. This is a common stratigraphic situation and the problem has been raised recently by several authors. We present here a test statistic for null hypothesis derived from the concept of partial independence and inherent to the model of embedded Markov processes.     

Analyses of the Relationship Between Mucous Aggregates and Phytoplankton Communities in the Gulf of Trieste (Northern Adriatic Sea) by Multivariate Techniques

Abstract. Multivariate techniques (cluster analysis and Principal Component Analysis) applied on phytoplankton data collected in June, July, August, and September 1990, 1991, 1992, and 1993 in the Gulf of Trieste (Northern Adriatic Sea) highlighted a clear temporal pattern from 1990 to 1993. In the summer of 1991, phytoplankton communities showed a dramatic increase in the dinoflagellatddiatom ratio. In particular, during June and July 1991 only few specimens of diatoms ( Cylindrorhecu closreriurn. Probosciu alata, Nirzschio longissimu , and Nitzschiu spp.) were collected; this confirmed the diatom scarcity in the phytoplankton communities before and during the appearance of large mucous aggregates (mucilage) in July 1991 in the Gulf of Trieste. The differences observed between the structure of the phytoplankton communities inside the aggregates and in the ambient waters suggested two hypotheses: 1) the aggregates were not produced in the gulf, but were carried ints the gulf by the eastern bordering current; 2) the aggregates were produced by a few, scarce species with a high exudate production that are capable of quickly reaching a high reproductive rate within the aggregates.     

Spatialities of ageing: The co-construction and co-evolution of old age and space

This editorial introduction to the themed issue is divided into four parts. We begin with outlining five reasons for more sustained attention to ageing and old age in human geography and go onto discuss two major challenges for geographical inquiry into ageing and later life. One of these is examining embodiment in ways that keep both its social/cultural aspects and its biological/physiological dimensions in sharp focus; the other concerns the challenge of considering time, or rather spatiotemporality, in all its facets. With regard to the latter we argue that the life-course concept can be helpful in this regard, especially if attention is paid to transitions as well as to slow, difficult-to-identify forms of change and if life-courses are understood in terms of folds. Thinking in these terms opens up a perspective according to which ageing and space can be analysed as entwined becomings. We conclude by positioning the contributions in this issue vis-à-vis the perspective developed in this piece.     

Characterization of environmental impact on resources, using strategic assessment of environmental impact and management of natural spaces of “Las Batuecas-Sierra de Francia” and “Quilamas” (Salamanca, Spain)

A new procedure is proposed for joint strategic environmental assessment and environmental impact assessment using simultaneous characterizations in the protected natural area studied to analyse the importance and extent of the impact of human activities within this area on the various natural resources. GIS techniques were used to define territorial models, including environmental information criteria in thematic layers to facilitate environmental diagnosis in the early planning stages in the areas of concern or of higher quality for conservation at different working levels (municipal, district, provincial or national). Traditional conventional environmental impact assessment methods were improved, using spatial analysis to compare scenarios based on the spatial and temporal variability of the impacts identified and their evaluation. This method was applied to the natural space of Las Batuecas-S. de Francia and Quilamas, where in an initial stage the different anthropogenic activities (landfills, etc.) with the potential to cause direct (sewage waters, etc.) or indirect (leachate, etc.) impacts were identified, using checklists and double-entry matrices to analyse actions likely to cause impacts, developing the cartography and identifying environmental impacts potentially damaging to the natural environment. Next, thematic and interpretive mappings were drawn up (surface water quality, aquifer vulnerability to pollution and vulnerability to municipal solid waste) to assess the effects upon resources (water, soil, air, etc.). Finally, by overlapping the impact identification and vulnerability mappings (municipal solid waste, pollution of aquifers and surface water quality) the impact characterization mapping was obtained, showing the absorption capacity of the different sectors to help the responsible bodies set out preventive and/or corrective measures. The essence of this paper is, in methodological terms, its use of two methods simultaneously (strategic environmental assessment and environmental impact assessment) in a protected natural area, allowing it to be extrapolated to any area where territorial management and planning studies need to be carried out.     

Analysis of trends and sudden changes in long-term environmental data from King George Island (Antarctica): relationships between global climatic oscillations and local system response

The Western Antarctic Peninsula is one of the most rapidly warming regions on earth. It is therefore important to analyze long-term trends and inter-annual patterns of change in major environmental parameters to understand the process underlying climate change in Western Antarctica. Since many polar long-term data series are fragmented and cannot be analysed with common time series analysis tools, we present statistical approaches that can deal with missing values. We applied U-statistics after Pettit and Buishand to detect abrupt changes, dynamic factor analysis to detect functional relationships, and additive modelling to detect patterns in time related to climatic cycles such as the Southern Annular Mode and El Niño Southern Oscillation in a long-term environmental data set from King George Island (WAP), covering 20 years. Our results not only reveal sudden changes for sea surface temperature and salinity, but also clear patterns in all investigated variables (sea surface temperature, salinity, suspended particulate matter and Chlorophyll a) that can directly be related to climatic cycles. Our results complement previous findings on climate related changes in the King George Island Region and provide insight into the environmental conditions and climatic drivers of system change in the study area. Hence, our statistical analyses may prove valuable for other polar environmental data sets and contribute to a better understanding of the regional variability of climate change and its impact on coastal systems.