Ginés Angel and Ginés Joaquin 2007. Eogenetic karst, glacioeustatic cave pools and anchialine environments on Mallorca Island: a discussion of coastal speleogenesis. International Journal of Speleology, 36 (2), 57-67. Bologna (Italy). ISSN 0392-6672.
Coastal karst is characterized by special geomorphologic and hydrodynamic conditions as well as by peculiar sedimentary, geochemical, and biospeleological environments. Generally, the more distinctive karstic features produced near the coastline are strongly influenced by sea-level changes, which generate a broad set of interactions between littoral processes and karst development. The glacioeustatic rises and falls of sea level affected the littoral karst in different ways, namely: vertical and horizontal shifts in the shoreline position, changes in elevation of the local water table, and vertical displacements of the halocline. Most eogenetic karsts have been subjected over long time spans to repeated changes of a variety of vertically-zoned geochemical environments: vadose, phreatic meteoric-water, brackish mixing-waters and even marine water. Many coastal caves appear to be passively drowned by Holocene sea-level rise, and to contain glacioeustatic pools of varied size where the current water table intersects formerly air-filled chambers or passages. These coastal phreatic waters are controlled by sea level and fluctuate with tides. Significantly, features such as phreatic speleothems that are able to record ancient sea levels occur closely associated to the surface of the pools. The cave pools are brackish or even marine anchialine environments that contain remarkable communities of troglobitic stygofauna. All of these aspects can be studied in detail along the southern and eastern coast of Mallorca Island owing to the widespread outcrop of Upper Miocene calcarenites, in which the development of eogenetic karst features started approximately 6 Ma ago, at the end of Messinian times. Some outstanding coastal caves result and include the celebrated Coves del Drac (explored by E.A. Martel in 1896), the labyrinthine Cova des Pas de Vallgornera (more than 30 km in length) and the recently explored Cova de sa Gleda (whose submerged passages exceed 10 km, as shown by scuba-diving surveys). Careful observations and detailed mapping of caves in the Upper Miocene reef rocks of Mallorca permit a better understanding of the coastal speleogenetic processes involved in a typical eogenetic karst over time ranges greater than 1 Ma. The role played by recurrent glacioeustatic oscillations of sea level and the subsequent rises and falls of the water table are emphasized in our model. There are two associated mechanisms: the triggering of breakdown by the loss of buoyant support that follows each lowering of sea level (i.e., during glaciations or smaller cold events) and the later underwater solution of boulders and collapse debris (during high sea levels that correspond to interglacial events). Additionally, tidal fluctuations affecting groundwaters would enhance solutional enlargement of caves and vug-porosity connected to the sea, rather than conventional karstic flow through conduits that probably is not as important an agent in eogenetic speleogenesis.
Fairchild Ian John and McMillan Emily Anne 2007. Speleothems as indicators of wet and dry periods. International Journal of Speleology, 36 (2), 69-74. Bologna (Italy). ISSN 0392-6672.
Calcareous speleothems provide a record of dripwater composition which in turn is a function of climatic conditions. The historical focus of speleothem palaeoclimate studies has been on the derivation of palaeotemperatures through oxygen isotope studies. However, it is now realized that water availability is a more generally important control on their characteristics. Growth rate and growth morphology in principle should give rise to recognizable changes at low flow. However, accidental plumbing effects during aquifer evolution, can also lead to variations in water supply and it is not easy to distinguish these effects. In areas where there is a strong amount effect on the δ18O composition of atmospheric precipitation, the speleothem δ18O composition can be a direct (and inverse) function of rainfall. High-resolution methods are now available to distinguish the composition and relative abundance of winter and summer precipitation in speleothems which formed from drips of seasonally-varying composition. Two seasonally varying processes can be responsible for significant geochemical effects during the year. Seasonal (normally summer) dryness enhances CO2-degassing which leads to elevated δ13C, Mg/Ca and Sr/Ca in dripwaters, characteristics which are transferred to speleothems. The same effects can arise by enhanced degassing at low PCO2. High-resolution analysis can distinguish the seasonal processes and, where conducted at several time intervals, allows a more confident interpretation of longer-term records.
Tan Ming 2007. Climatic differences and similarities between Indian and East Asian Monsoon regions of China over the last millennium: a perspective based mainly on stalagmite records. International Journal of Speleology, 36 (2), 75-81 Bologna (Italy). ISSN 0392-6672
Cave sediments, especially stalagmites, have been providing absolute dated climate records that can extend from the present to over 500,000 years ago. Based on the reconstructed temperature time series, a comprehensive overview of the climatic differences and similarities between the Indian and the East Asian Monsoon regions of China over the last millennium is presented. Evidence from accurately dated and high-resolution records including stalagmites, ice cores and tree rings show that there was a “Medieval Warm Period” (around 1000 to 1400 AD) in north and east China where climate is dominated by the East Asian monsoon; whilst no such interval is evident in the records including stalagmites and ice cores from southwest China where climate is dominated by the Indian monsoon. However, both regions underwent a significant cooling during the Little Ice Age (around the mid 1500s to the 1800s). The result achieved here may allow a possibility of distinguishing the boundary between Indian monsoon and East Asian monsoon regions over the last millennium with increase of climate records, especially stalagmites that are mostly suitable for accurate U/Th dating and/or lamina counting.
Piccini Leonardo, Forti Paolo, Giulivo Italo and Mecchia Marco 2007. The polygenetic caves of Cuatro Ciénegas (Coahuila, Mexico): Morphology and speleogenesis. International Journal of Speleology, 36 (2), 83-92. Bologna (Italy). ISSN 0392-6672.
The Cuatro Ciénegas area is renown worldwide for its thermal springs, which feed a unique ecosystem consisting of many pools, lakes and marshes. The pools also represent a very important water resource in a region characterized by scarce rainfalls. Field investigation has emphasized the role of karst in the hydrogeology of the area. Only few and restricted forms of surface karst are represented; caves are mainly relics of old speleogenetic phases of thermal and bathyphreatic water flow.
Barton Hazel A., Taylor Nicholas M., Kreate Michael P., Springer Austin C., Oehrle Stuart A. and Bertog Janet L. 2007. The impact of host rock geochemistry on bacterial community structure in oligotrophic cave environments. International Journal of Speleology, 36 (2), 93-104. Bologna (Italy). ISSN 0392-6672.
Despite extremely starved conditions, caves contain surprisingly diverse microbial communities. Our research is geared toward understanding what ecosystems drivers are responsible for this high diversity. To asses the effect of rock fabric and mineralogy, we carried out a comparative geomicrobiology study within Carlsbad Cavern, New Mexico, USA. Samples were collected from two different geologic locations within the cave: WF1 in the Massive Member of the Capitan Formation and sF88 in the calcareous siltstones of the Yates Formation. We examined the organic content at each location using liquid chromatography mass spectroscopy and analyzed microbial community structure using molecular phylogenetic analyses. In order to assess whether microbial activity was leading to changes in the bedrock at each location, the samples were also examined by petrology, X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Our results suggest that on the chemically complex Yates Formation (sF88), the microbial community was significantly more diverse than on the limestone surfaces of the Capitan (WF1), despite a higher total number of cells on the latter. Further, the broader diversity of bacterial species at sF88 reflected a larger range of potential metabolic capabilities, presumably due to opportunities to use ions within the rock as nutrients and for chemolithotrophic energy production. The use of these ions at sF88 is supported by the formation of a corrosion residue, presumably through microbial scavenging activities. Our results suggest that rock fabric and mineralogy may be an important driver of ecosystem function and should be carefully reviewed when carrying out microbial community analysis in cave environments.
Smith Thomas and Olson Rick 2007. A Taxonomic Survey of Lamp Flora (Algae and Cyanobacteria) in Electrically Lit Passages within Mammoth Cave National Park, Kentucky. International Journal of Speleology, 36(2), 105-114. Bologna (Italy). ISSN 0392-6672.
A taxonomic survey of the lamp flora from electrically lit passages in Mammoth Cave, Mammoth Cave National Park, identified 28 species. Overall, cyanobacteria were dominant represented by 14 species (50% of the total), green algae had eight species (29%), and six diatoms species (21%) were present. There was not a correlation between species diversity and temperature, but there is a general trend of increasing diversity with warmer temperatures. There were two algal or cyanobacterial species identified in this study that overlapped with previous studies. There is a lack of continuity between previous studies only having one species identified in more than one study. This suggests a high algal turnover and possible colonization rates.
Book reviews
Jo De Waele Karst Hydrogeology and Geomorphology (Ford D.C. & Williams P., John Wiley & Sons Ltd., Chichester, UK, 562 pages, 2007 - paperback ISBN 978-0-470-84997-2).
Jo De Waele Archives of Climate Change in Karst. (Bogdan P. Onac, Tudor Tǎmaş, Silviu Constantin and Aurel Perşoiu (Eds.), Karst Waters Institute Special Publication 10, 246 pages, 2006 – ISBN 978-0- 9640258-9-2)
Malcolm Field Perspectives on Karst Geomorphology, Hydrology, and Geochemistry - A Tribute to Derek C. Ford and William B. White. (Russell S. Harmon and Carol M. Wicks (eds.), Geological Society of America, Special Paper 404, 366 pages, 2006 - ISBN 978-0-8137-2404-1)
Arrigo Cigna Acta Carsologica (new format). (Kranjc A. (Editor), Gabrovsek F. (Co-Editor), Karst Research Institute ZRC SAZU – ISSN 0583-6050)
Paolo Forti Hypogene Speleogenesis: hydrogeological and morphogenetic perspective. (Alexander Klimchouk, National Cave and Karst Research Institute Special Paper n. 1, 106 pages, 2007 – ISBN-10 0-9795422-0-0 – ISBN-13 978-0-9795422-0-6)
Paolo Forti Natural and anthropogenic Hazards in Karst Areas: Recognition, Analysis and Mitigation. (Parise M. & Gunn J. (eds), Geological Society of London, United Kingdom, Geological Society Special Publication 279, 202 pages, 2007 – ISBN 978-1-86239-224-3)
Jo De Waele Cave conservation and restoration (2006 Edition). (Hildreth-Werker V. & Werker J.C. (eds), National Speleological Society, United States of America, 600 pages, 2006 – ISBN 978-1-86239-224-3) |
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