The development of folds in bedded chert and related rocks in the Malaguide Complex, southern Spain

Folds and folding mechanism in a chert sequence and related rocks of the Maláguide Complex (the uppermost tectonic unit of the Betic Zone) have been investigated. The geometric study shows that folds that developed in the chert sequence are usually angular in shape and asymmetric. Chevron and conjugate folds are common.Folding in bedded chert is explained in terms of a suggested model:

1. (1) Development of folds by kink and conjugate kinking.

2. (2) As the shortening increases, the interlimb angles decrease; in the kink folds this is caused by a reduction of the angle between the layers within the kink and the kink boundaries. There seems to be a relationship between this angle and the asymmetrical thinning-out in the limbs of many folds: the smaller is the angle between the kink boundary and the layers within the kink band, the larger is the reduction of the thickness in these layers.

Single limestone layers embedded in slate deform very probably by a buckling mechanism, implying tangential longitudinal strain and an additional flattening.     

Crystal bending in metamorphic calcite,and its relations to associated twinning

This paper deals with the incidence and geometry of lattice bending in calcite of naturally strained marble and possible relations in time to associated {01¯12} twinning, as revealed by microscopic examination with a universal stage. Microscopic technique and graphic treatment of data with a view to identifying the relation in time of bending to twinning, and possible glide mechanisms involved in the bending process are reviewed as a basis for present and subsequent investigation of this general topic.In most instances development of surviving thin e twins postdates bending of the host crystal (such twins everywhere are rationally oriented). Rarely (in contrast with experimental experience) some thin twins are slightly irrational (L_e lamellae) and apparently developed in the final stages of bending. Thick twins (a few tens of microns wide) on the other hand rather commonly predate or are synchronous with bending.The geometry of bending (external rotation) — especially for rotation less than 25° —commonly is compatible with models (based on experimental experience) of simple translation in the strained domains. The commonest translation system so identified is on {10¯11}, with sense of shear, where recognizable, either negative or positive. Translation on {02¯21} is relatively rare. Unexpectedly there is rather strong but not conclusive evidence of translation on {0001} parallel to an a axis. This mechanism, hitherto never identified with certainty, is now here documented unequivocally in a crystal of calcite experimentally strained at 300° C, 5 kb.     

Reconnaissance geochronology of basement rocks from the Amazonas and Maranhão Basins in Brazil

Rb/Sr whole rock as well as K/Ar whole rock and mineral age determinations have been carried out on drill core samples obtained from the crystalline basement underlying the Amazonas and Maranhão Basins in Brazil. The data confirm the existence of an ancient basement under the Upper and Middle Amazonas Basin. The primary age of the granitic rocks is estimated at about 1560 Ma which correlates with recent age data obtained on granitic rocks on both sides of the Amazonas syneclise. In some areas the K/Ar ages show a decrease probably due to the effect of the Nickerie thermal episode described previously in the Guayana Shield.In the basement of the interconnected Lower Amazonas and Maranhão Basins Late Precambrian (Caririan) metamorphism and igneous activity seems to have been pervasive. The data allow the continuation of the Brazilian age province known in northeastern Brazil under the Maranhão Basin, linking this province to the Brasilia-Paraguay orogenic belt of similar age.     

Location,location, location: changes in the diversity of animal resources exploited by Tardiglacial humans in northern Spain

Prey diversity of Homo sapiens in north Iberia exhibited shifts associated with climate warming after the Last Glacial Maximum, as deduced from animal remains obtained from Upper Palaeolithic caves in Asturias (northern Spain). Significant association of prey diversity and river proximity was found during adverse climate conditions, indicating opportunistic predation. A high increase of prey diversity was found when small animals (including fish) were taken into account in archaeological records, highlighting the importance of this type of prey in Palaeolithic diets. Copyright © 2009 John Wiley & Sons, Ltd.     

Regional Seas integrative studies,as a basis for an ecosystem-based approach to management: The case of the Bay of Biscay

Marine legislation world-wide has, as a recent final objective, the maintenance of a good environmental or ecological status for marine waters, habitats and resources. The concept of environmental status takes into account the structure, function and processes of marine ecosystems, bringing together physical, chemical, physiographic, geographic and climatic factors: subsequently, integrating such conditions, with anthropogenic impacts and activities undertaken in the area concerned. Such an approach is intended to permit an assessment of the environmental status at the ecosystem level, i.e. ‘ecosystem-based approach’, or ‘ecosystem-based management’.Such legislation emphasises the need for the development of methodologies, to assess environmental status. As such the knowledge acquired within Regional Seas, discussed at International Symposia and, finally, published as Special Issues, can serve as the basis for a regional ecosystem-based approach to management and the integrative assessment of marine systems. Hence, the Bay of Biscay is used in this contribution, as an example, to show past and present research, together with perspectives for the future. It is concluded that collaboration between institutions (marine research institutes, universities) and countries (France, Spain, Portugal, the United Kingdom and Ireland) could result in an interesting ‘case-study’, for the further implementation of the European Marine Strategy Framework Directive, at the level of this particular Regional Sea. In this way, the experience gained in the implementation of the Water Framework Directive within the ecoregion, together with the information collated in the eleven International Symposia of Oceanography of the Bay of Biscay, celebrated until now, can be very useful, for an ecosystem-based management approach for this Regional Sea.     

Trends in Abundance Indices of Fishes in Maryland’s Coastal Bays During 1972–2009

Maryland’s coastal bays provide habitat for juveniles of many commercially and recreationally important species of shellfish and finfish. Since 1972, the Maryland Department of Natural Resources has conducted the Maryland Coastal Bays Trawl and Seine Survey to monitor the populations of key species. The survey has undergone substantial spatial and methodological changes affecting the interpretation of simple indices of abundance. We developed generalized linear models to standardize the indices of abundance of five commonly caught fish species: Atlantic menhaden Brevoortia tyrannus, weakfish Cynoscion regalis, spot Leiostomus xanthurus, bay anchovy Anchoa mitchilli, and summer flounder Paralichthys dentatus. Density declined significantly since 1972 for menhaden, bay anchovy, and spot in at least one region within the coastal bays. The northern bays had significantly higher densities than the southern bays for all species. Changes in abundance indices of the five species examined were not related to sea grass coverage, temperature, salinity, nitrogen-to-phosphorus ratios, and other habitat variables but were likely a result of stock-wide recruitment processes.     

Technical, financial and location criteria for the design of land application system treatment

Conventional water treatments when downsized to cover the demands of small and scattered populations are costly and ineffective. In fact, many small towns cannot afford the high average treatment costs nor provide the skill and complex management requirements. Even when these facilities are available, waste water might not be properly treated. Land application system treatments (LAST) have been shown to be preferable on the basis of their technical effectiveness and financial viability. The recently approved Spanish regulations (RDL 1620/2007, pp 50369–50661) represent an opportunity for the implementation of well-designed LASTs. This paper presents an assessment methodology for the design of LASTs by combining technical, financial and location criteria. The method is applied to the design of LASTs to cover the water disposal demand of twelve municipalities located within the protected natural landscape, and surrounding areas of ‘El Rebollar’, Salamanca, Spain.