Petrological Study as a Tool to Evaluate the Degradation of Speleothems in Touristic Caves, Castafiar de Ibor Cave, Caceres, Spain

In Castafiar cave the surface of most of the speleothems present dissolution and corrosion features. In touristic caves, this process has usually been related to the acidification of the atmospheric moisture caused by C02 from the breath of visitors. However, in Castafiar cave the process of corrosion has been also observed in rooms that are not visited by tourists. Petrological studies were carried out in the speleothems affected by surface corrosion in Castafiar cave. The results indicate that this process occurs not only at present time, but over a period of thousands of years, as evidenced by the presence of corrosion lines inside and on the surface of the speleothems. All this and the fact that Castafiar cave recovers very quickly from changes in the environmental parameters, indicates that the dissolution-corrosion process is slow and hence it is not related to the presence of visitors

Micritización de espeleotemas en ambiente meteórico vadoso (Cueva de Castañar de Ibor, Cáceres)

The aragonite and calcite speleothems of the Castañar de Ibor Cave show white and matt coatings that formed by micritization and dissolution of the initial crystals. These processes are also recognised in the inner part of the speleothems. Either in the inner or outher parts the result is the lost of brightness and transparency of the speleothems. Petrographically these coatings are seen as lines of micrite liked to dissolution processes that probably occurred because of the circulation of undersaturated fluids within the cave. At the moment no organic structures have been recognised in relation to the micritizated areas, indicating very probably that the process was inorganically driven

La cueva está viva y es un laboratorio natural

Peer reviewe

La política cambiaria y su impacto en las exportaciones no tradicionales de Colombia durante el proceso de apertura (1992-2001)

Al comienzo de la década de los 90 se iniciaron grandes transformaciones para la economía y la sociedad Colombiana y desde ese momento se ha venido viviendo en un mundo cada día más globalizado y sin barreras. Durante la mayor parte del siglos XX las restricciones a las exportaciones fueron la política estatal que predominaba para afrontar las dificultades cambiarias, el proteccionismo del gobierno hacia los productores colombianos contribuyó a frenar la exportación de productos con ventajas comparativas reales al introducir distorsiones en los precios relativos y por ende en la Tasa de Cambio Real aplicable a las exportaciones no tradicionales.Incluye bibliografí

Conservation Status and Challenges of the Atlantic Forest Birds of Paraguay

The Atlantic Forest, one of the most biodiverse biomes in the world, is also one of the most endangered. In Paraguay, its remnants are mostly fragmented and isolated. The Paraguay Biodiversity Corridor is an initiative that is being developed to generate and maintain connectivity of the main conservation areas. With the objective to analyze the bird richness and occurrence in each of the core areas of this corridor, we gathered published data, details of the management plans, and bird surveys recorded during 2015 and 2017 in these areas. In total, 557 bird species occur in the core areas of the Corridor, representing more than 80% of the birds of the country. San Rafael National Park and Mbaracayú Forest Nature Reserve are the richest areas, with 427 (70) and 408 (61) bird species (Atlantic forest endemics), respectively. These two areas also harbor more than 30 bird species of global conservation concern. Only 24% of the Corridor area is protected or sustainably managed, with only 10% under strict protection. The Corridor situated within this endangered biome encompasses some of the most important areas for bird conservation, but the situation of many of these areas is alarming as they are not protected or effectively managed to conserve their biodiversity. Restoration of connectivity, legal enforcement, and strengthening of authorities to combat deforestation on core areas, along with research focused on the impact contributed by human activities (selective logging, ecotoxicity exposure to agrochemicals) are key actions prioritized for the Upper Parana Atlantic forest (UPAF) Corridor.CONACYT - Consejo Nacional de Ciencia y TecnologíaPROCIENCI

Features and Origin of Red Clays in Castafiar Cave: A Touch of Colour

In Castaiiar Cave (Caceres, Spain), coatings of red clays cover the walls of the chambers, coexisting with diverse speleothems of aragonite, calcite, huntite and dolomite. The mineralogy of the clays is mainly illite, chlorite, kaolinite, smectite, quartz and Fe oxides and hydroxides such as goethite. They can be transported into the cave by infiltration waters or form by in situ alteration of the host rock: layers of dolomite rich in Fe and magnesite interbedded with greywackes and shales. Present-day hydrological conditions in the cave and conditions during the formation of speleothems have determined that the clays have not been transported by any flooding or seepage, but mostly staying in situ, and not included into carbonate crystal forms . Thus, most of the well-preserved speleothems are white and not stained, conforming an interesting chromatic contrast with the red clays that represent an additional attraction in this show cave

Dolomitización en sistemas kársticos actuales: el caso de la Cueva de Castañar de Ibor (Cáceres)

Deposits of recent dolomite in caves constitute one more setting that provide data in order to get one more approach to the "dolomite problem". The moon-milk deposits of the Castañar de Ibor Cave (Cáceres) include spheroidal dolomite which occurs associated with huntite that grows mostly on fibrous aragonite crystals. This study suggests that dolomite formed in relation to microbial films that developed on the aragonite crystals. Within these films, both dolomite and huntite formed, but also the wide presence of dolomite is due to transformation of huntite which is metastable. Magnesium is provided by the dissolution of Precambrian dolostones on which the cave developed

Geología de la cueva

Peer reviewe

The role of climate and aeolian dust input in calcrete formation in volcanic islands (Lanzarote and Fuerteventura, Spain)

[EN]Calcretes are widely described in non-marine settings with carbonates in their catchment, or vicinity areas, but in volcanic islands without carbonates in their substrate, calcretes are not very common. In Lanzarote and Fuerteventura Canary Islands, characterized by impressive volcanic landscapes, the sedimentary carbonate rocks are rare except for some recent marine and aeolian deposits. In these settings very well-developed calcretes cover large areas of the present landscape. The source of calcium required for the formation of these calcretes has not been discussed in much detail till now, although its role is critical to an understanding of the climatic conditions in which calcium was transported and fixed and of the calcrete formation processes. The petrological and geochemical studies (87Sr/86Sr ratios, δ13C, δ18O, major, trace and REE) carried out in this paper do confirm the important role of aeolian dust input in the formation of these calcretes. Canarian calcretes were mainly generated by pedogenic processes and are composed of various irregular carbonate lamina interbedded with fine clastic deposits. Our study indicates that these interbeddings were the result of several stages in which, during dry periods, aeolian dust deposition alternated with leaching and calcite precipitation during wetter periods when plants, insects and bacteria played an important role in carbonate precipitation. The δ18O (− 2.70 to + 2.22‰ VPDB) and δ13C (− 8.21 to + 0.24‰ VPDB) values indicate that calcretes were formed by pedogenic processes. Comparison of calculated ∆18O values for the Canary calcretes with continental mid-latitude calcrete values reflects the more homogeneous temperature regimes of calcrete formation in island (oceanic) settings. Calcrete87Sr/86Sr ratios (0.706357 to 0.709208) show strong affinity with those obtained in aeolian carbonate dust and marine deposits, and are relatively different from those obtained in basalts. REE, major and trace element concentrations show that Ca-bearing minerals from volcanic host rock contributed little to calcrete formation and most of the calcium was supplied by aeolian deposits such as the aeolian dust coming from the Sahara and Sahel or sand dunes