Rimstone Pools Research Articles

Spomenik prirode "Klisura reke Panjice", opština Arilje - područje izuzetnih geomorfološko-hidroloških vrednosti

The gorge valley of Panjica river, in the part where there is Vodena pećina cave with a strong Karst spring, as well as a tufa accumulation with two attractive waterfalls, has been proposed for designation as a nature monument of geomorphological-hydrological character under the name "Nature Monument Panjica river gorge". The conserved natural phenomena are represented by abundance of surface and underground Karst forms, a gorge that in some segments has elements of a canyon valley with vertical valley sides, up to several tens of meters high, rich tufa deposits, waterfalls, a series of small overfalls, overflows, rimstone pools and cascades, and the caves Vodena and Rasovačka (Hajdučka). The area is also special in terms of important species and ecosystem diversity, above all 85 species of birds, of which 67 are breeding birds, and 72 species have the status of strictly protected, of which 16 species are on Annex I of the Birds Directive. All of the above makes this area unique and undoubtedly worth of its status.

Disentangling cryptic species in Parastenocarididae (Copepoda: Harpacticoida) with an integrative approach: the case of Stammericaris similior sp. nov. and Stammericaris destillans Bruno & Cottarelli 2017.

Stammericaris similior sp. nov. is described combining light microscopy, scanning electron microscopy, and genetic barcoding. The new species was collected from rimstone pools in Scrivilleri Cave, a cave in Sicily with so far unexplored microcrustacean fauna. The new species is particularly interesting because it is morphologically very similar to Stammericaris destillans, an epikarstic parastenocaridid endemic to a different Sicilian cave; however, the phylogenetic analysis based on the mitochondrial COI gene of sixteen parastenocaridids shows that these two Stammericaris are two distinct species, with an uncorrected p-distance of 22.9, and the sequences of Stammericaris similior sp. nov. cluster together in a well-supported monophyletic clade, with two different haplotypes. To our knowledge, the presence of different species of almost identical morphology had not been recorded before for the genus Stammericaris. The integrated molecular and morphological analysis, the latter conducted with the support of SEM, allows disentangling the affinities of the new species and identifying a few distinctive characters: the males of the new species are characterized by the caudal rami shorter than the anal somite; the morphology of the P3, which is thin and slightly arched, with three proximal spinules on exp-1; the peculiar structure of the P4 enp; the P4 basis ornamented with two spinules of different length, the one closest to the endopod being the shortest one, and a half-moon shaped lamella. The new species differs from S. destillans for its larger size, the presence of: three spinules, instead of two, on the P3 exp-1; the half-moon shaped lamella on the P4 basis; a row of spinules along the inner margin of P4 exp-1. We also provide data on the ecology and distribution of the new species, a list of the other copepod species collected, and a dichotomic key for the males of all species presently assigned to the genus.

Impact of visits on the microclimates of caves, Experimental evidence from Škocjan Caves

Tourism activities in caves can result in changes in the microclimates of caves. The natural microclimate in closed caves is constant due to the balance between cave air and cave walls, while in open caves exchanges with outside air influence the microclimate. Visits to caves, especially in closed smaller caves, can thus endanger the natural balance if the microclimate does not return to natural conditions quickly enough.Continuous monitoring of the temperature and concentration of carbon dioxide in Škocjan Caves enables the assessment of the impact of visits. For this purpose, we used data measured in the relatively closed Silent Cave, at the locations named Calvary (Kalvarija), Tent (Šotor), and Passage (Prehod) in 2016, and in the wide open Murmuring Cave, at the locations named Bridge (Most) and Rimstone Pools (Ponvice), in 2013. The outdoor air temperature, as measured at the Škocjan meteorological station on the surface plateau, was considered in both cases. Along the tourist part of Škocjan Caves, the most closed part of the cave in Silent Cave is the location at Calvary, when the entrance doors through an artificially dug tunnel are closed. During the visits, the microclimate is subjected to draughts through open doors and to anthropogenic emissions. The data suggest that the influence of draughts predominates over direct anthropogenic emissions. In winter or on cold days air flows upwards and through the tunnel out of the cave, whereas in summer or on warm days it flows downwards. In such cases, the CO2 concentration decreases markedly due to the downwards chimney effect as the concentration in the outside air is much lower than in the cave. The data show that the temperature overnight and towards morning always returns to its natural value even in this
 rather small location in the cave. The changes in CO2 concentration persist for a longer period, until the time of the first visit the next morning, when it is again perturbed by a new visit. The data on time courses support the theoretically estimated characteristic of the exponential decline of disturbances backward towards natural conditions, depending on the size of a cave and on the efficiency of exchanges with its walls. For tem­perature, this characteristic time tT is about three to six hours at the Calvary site. The return of CO2 to natural conditions tCO2 is longer and its estimate less reliable than the one for temperature. In the wide-open and large Murmuring Cave, the impact of visits is negligible throughout the year. In this part of the cave we can observe the influence of external daily and annual changes, the amplitudes of which get smaller, and their phase lags bigger, deeper in the cave.

Morphology, Mineralogy, and Chemistry of Ocherous Precipitate Aggregates Downstream of an Abandoned Mine Site

Mineral precipitates forming downstream of abandoned and/or uncontrolled mine sites generally act as scavengers for heavy metals, such as As and Sb, leaking from the sites. This study reports the morphology of ocherous precipitate aggregates downstream of Ayuta, an abandoned antimony mine site in Tochigi Prefecture, Japan, because its morphology differs significantly from those reported previously. The morphology of this aggregate consists of stacked, small terraces enclosed by numerous connected rimstone dams, although on a smaller scale compared to typical terrace landscapes. The rimstone pools contained ocherous spheroids precipitates at the bottom. Additionally, stream water and ocherous aggregates collected from the site were investigated for mineralogy and chemistry. As (0.07–0.17 μg/L) and Sb (0.02 μg/L) levels in the stream water were determined, and the distributions of As and Sb in the mineral phases of the precipitate were estimated using a sequential extraction procedure. The investigations revealed that As was adsorbed by iron-bearing ocherous precipitate aggregates, especially ferrihydrite that formed on the stream bank at concentrations, comparable to those reported by other studies (85 mg/kg). This adsorption contributed to the natural attenuation of As in the stream. Sb in the aggregate consisted of ultra-fine silt and clay-size particles of stibnite ore transported from the surrounding area and/or secondary minerals transported by groundwater and surface water.

The study of amphipods in rimstone pools of Akiyoshi-do Cave, Japan

Akiyoshi-do Cave is the largest show cave in Japan and has been recognised as a hotspot of cave animals due to their diversity in species. Human-induced alterations in the cave environment have been a significant concern catching the attention of tourists and managers. Previous studies indicated water quality alteration induced by tourism could affect the population densities of amphipods. However, no study went further than qualitative observation in terms of human impacts. This study targets two amphipods living in Akiyoshi-do Cave, Pseudocrangonyx akatsukai and Gammarus nipponensis and measures water characteristics in which they live. Results show that the population densities of the amphipods have decreased compared to the 1970s. Their living habitat has changed, probably induced by tourism.

Hydrogeochemical and isotopic evidence for flow paths of karst waters collected in the Heshang Cave, Central China

Understanding of hydrological processes in caves is important to help us interpret paleoclimate records from speleothems. In this study, we integrated hydrogeological and hydrogeochemical properties to characterize the hydraulic behavior of karst waters in the Heshang Cave, Central China. Using geological and topographical analyses, we identified regional watershed boundaries and hydrogeological connections that were controlled by anticlinal geometry and faults. Water samples were collected from the Heshang Cave and potential recharge sites. Geochemical data of c(Sr2+)/c(Ca2+) and c(Mg2+)/c(Ca2+) ratios suggest that the drainage system in Heshang Cave consists of two flow paths. For vadose waters, including drip water and rimstone pool water, c(Sr2+)/c(Ca2+) ratio ranges from 0.000 6 to 0.001 1, and c(Mg2+)/c(Ca2+) ratio ranges from 0.97 to 1.1, indicating that recharge was mainly from rainfall infiltration through the overlying Cambrian dolomite stratum. In contrast, slope current and underground river waters have higher c(Sr2+)/c(Ca2+) ratios (values from 0.002 2 to 0.002 8), and lower c(Mg2+)/c(Ca2+) ratios (values from 0.50 to 0.64). These waters show homogeneous isotopic composition (δ18O: −7.15‰–−6.95‰; δD: −52.73‰–−51.31‰), implying recharge of allogeneic water from the Xiaoer River via karst conduits that pass through Ordovician limestone and Cambrian dolomite stratum.

Nyctomyia biunguiculata, a new cavernicolous species of tribe Aedini (Diptera: Culicidae) from southern Thailand.

Nyctomyia biunguiculata, sp. n., is described from a unique male reared from a pupa (exuviae partially decomposed and over cleared) collected from a rimstone pool deep inside Wat Sumano cave located in Phatthalung Province of southern Thailand. The genitalia of the holotype are illustrated, and the species is compared with Nc. pholeocola, the type species of the genus described from a cave in another province of southern Thailand. The species has not been found outside the cave and appears to be a true troglobite.

In Karst Country, and: In the Deer Wallows

In Karst Country, and: In the Deer Wallows William Kelley Woolfitt (bio) In Karst Country Footnotes 1. Bats feasting in the stubble-fields on nights of swelter, mosquito-drone, sheets thrown back. 2. Under our back pasture, flow paths and rimstone pools, chambers branching and sponge-like and ramiform—a world where the sun and other luminaries are fables, where the flowers are stones. 3. That world coming near, breathing on us, in these fields rumpled and laced with ridges, fissures, sink-holes, and caverns. 4. Bats as emissaries, messages poured from bottles. 5. Bats unfurling like a parchment that’s both sturdy and delicate, both translucent and dark, “nearly of a London smoke color . . . deepening into blackness,” as Graceanna Lewis observes. Furless, their wing membranes are “so beautifully crimped by lines of blood-vessels . . . as to remind one of the India crape dresses our mothers used to wear.” 6. Bats threatened by our smoke, our filth. Isaac Weld recalls that Madison’s Cave was “covered with soot from . . . the pine torches” carried by the men who gave tours; its petrifactions were smoke-blackened. When Weld emerged, his “hands and clothes were smutted all over.” 7. The abandon of eating peaches, juice all over our faces. The pleasures of tasting, of savoring. Squirrels harvesting a mast-tree, bats eating moths. And water that gnaws stone. And neighbors who come for corn-shuckings or fodder-pulls, for loaded plates, stomping feet. [End Page 169] In the Deer Wallows Footnotes 1. Boy fleeing his chores, his father who peels a switch from the sarvisberry tree. 2. Apt to vanish when he’s sent to grub and seed, his truck-patch like those A. G. Bradley saw in the Blue Ridge: “small clearings . . . where scanty crops of corn, oats, or tobacco struggled with weeds and briars in stump-strewn enclosures, or beneath the giant skeletons of what had once been living trees, killed by girdling.” 3. Wishing to slip from sight, or grasp, or memory. Like a wooer’s note and ambrotype. Like flint knappers, mica crescents, spat-out bones, button-shanks from a soldier’s coat. 4. He eyes the earth for what’s keepable. Goes to his pallet, to brush meetings and the whipping-oak, with a walnut, or pebble, or dead bee in his fist. [End Page 170] William Kelley Woolfitt William Kelley Woolfitt is the author of two forthcoming books of poetry, Beauty Strip (Texas Review Press, 2014) and Charles of the Desert (Paraclete Press, 2016). His poems have appeared in the Threepenny Review, the Cincinnati Review, River Styx, and Radar Poetry. He teaches at Lee University in Cleveland, Tennessee. Copyright © 2014 Center for Literary Publishing

Water mites from caves of the Ha Giang province, northern Vietnam (Acari: Hydrachnidia).

Four species of water mites (Acari, Hydrachnidia) were collected in 2010 during an Italian speleological expedition to caves of the Ha Giang region in northern Vietnam from rimstone pools or other tiny accumulations of percolating water. Four taxa new to science are described, representing the families Torrenticolidae (Torrenticola anophthalma nov. sp., Stygotorrenticola coniseta nov. gen., nov. sp.), Limnesiidae (Raptorhydracarinae subfam. nov., Raptorhydracarus tomasini nov. gen., nov sp.) and Athienemanniidae (Africasia vietnamitica sp. nov.). Most of these taxa show striking morphological adaptations to subterranean life.

Natural and anthropogenic influences on the year-round temperature dynamics of air and water in Postojna show cave, Slovenia

Air and groundwater temperatures were measured in a rimstone pool in Postojna Cave, to advise evaluation of the impact of natural and anthropogenic influences related to heat being initially transmitted into cave air by visitors. Such heat can accumulate both in the rock mass and in water. Results show that attention must be paid to temperature changes of rimstone pool water rather than those of cave air, especially during the winter. Thanks to good ventilation deep inside the cave, short-term air temperature increases related to higher visitor numbers have not influenced flowstone precipitation or the cave fauna. However, this situation might change if winter visitor numbers increased greatly. This study does not support a suggested increase in winter visits (currently the tourism low-season) and reduction of summer visits (currently the tourism high-season).

Cave Pearls--The Integrated Product of Abiogenic and Biogenic Processes

Abstract Cave pearls, up to 8 cm long, collected from dried-out rimstone pools in Old Man Village cave on Grand Cayman, British West Indies, have nuclei (e.g., bone) that are encased by laminated cortices. These laminae are composed of trigonal prismatic calcite crystals, calcite crystal bushes, or particulate calcite that is formed of filamentous microbes (four morphotypes), spores (seven morphotypes), extracellular polymers (EPS), disorganized and organized calcite fiber crystals, and detrital calcite grains. Syntaxial overgrowths modified many of the fiber crystals and the trigonal calcite crystals. Thin, laterally discontinuous growth lines are formed of micrite that may have been precipitated in a microbial mat. Growth of the cave pearls involved abiogenic and biogenic processes. The trigonal calcite crystals and crystal bushes probably formed abiogenically whereas the particulate calcite laminae appear to have formed as microbes trapped and bound detrital grains to the surfaces of the cave pearls and indirectly mediated precipitation of the fiber crystals. Water flow into the rimstone pools, which was linked to local rainfall, controlled the influx of detrital grains, water chemistry, and microbe growth into the pools and hence, the growth of the cave pearls. Periods of low water influx led to stagnation of pool waters that seemed to trigger periods of rapid abiogenic calcite precipitation and curtail microbial colonization. High flow rates slowed abiogenic calcite precipitation, promoted microbe growth, and fed detrital materials into the pools. Despite the lightless environment of the cave, the evidence clearly shows that the microbes and their associated EPS played a critical role in the growth and development of the cave pearls.

Small-scale Terraces and Isolated Rimstone Pools on Stalagmites in Caves Exhibit Striking Similarity to Large-scale Terrace Landscapes at Hot Springs

We report on sinter terrace forms on the centimetre scale observed on the top and at the base of a stalagmite in Škocjanske jame (Škocjan caves). These exhibit connected rimstone dams, forming a net-like pattern with active water pools inside. The form is similar to those seen at the large travertine terraces, which form by precipitation of calcite from spring waters highly supersaturated with respect to calcite. In contrast to these patterns we have also found isolated sinter basins with dimensions of a few centimeter on stalagmite-like structures in the cave Dimnice, Slovenia. Similar basins a few meters wide are a tourist attraction in Pamukkale, Denizli, Turkey. The observed features have grown from supersaturated solutions of calcium carbonate in laminar flow. Large-scale landscapes originate under conditions of turbulent flow. Some ideas are presented why, in spite of the clear difference in flow, the shapes are similar on all scales.

The Road (review)

NEW APPALACHIAN BOOKS Reviews Cormac McCarthy. The Road. New York: Knopf, 2006. 256 pages. Hardback in dust jacket. $24.00 "Where men can't live godsfare no better. " Cormac McCarthy Cormac McCarthy has established a literary oeuvre such that each new work is judged not only for the story it tells but in relation to the body of work that precedes it. His literary style is marked by two outstanding traits: first is the unique poetic lyricism of his language and second is his ability to tell the untold tale with a style whereby major aspects of plot development are revealed by their absence. In his books, especially in his earlier works, there are passages which are outstanding for their sheer lyrical beauty. These passages hit some neuroaesthetic circuit in the brain and create the same type of experience as standing in front of a work of art in a museum. He writes with unexpectedly imagistic prose that comes at you intense with literary creativity. This made him a writer's writer, for many years widely acclaimed by the literati but unrecognized by the public at large. After his fourth book he moved from East Tennessee to Texas and shifted the setting of his books to that terrain. He then produced Blood Meridian which, along with Suttree are masterworks in realizing his ability to write with deeply moving lyrical beauty. With The Road he maintains his reputation as a consummate literary artist. In The Road there are passages which return to the style epitomized in his earlier books. In the very first passage in the book he describes a dream saying, they stood in a great stone room where lay a black and ancient lake. And on the far shore a creature that raised its dripping mouth from the rimstone pool and stared into the light with eyes dead white and sightless as the eggs of spiders. It swung its head low over the water as if to take the scent of what it could not see. Crouching there pale and naked and translucent, its alabaster bones cast up in shadow on the rocks behind it. Its bowels, its beating heart. The brain that pulsed in a dull glass bell. It swung its head from side to side and then 96 gave out a low moan and turned and lurched away and loped soundlessly into the dark. This beastly specter haunts the entire novel and reappears at the end as death takes its inexorable toll. Leaving key elements of the story untold, makes unusual demands upon the reader who gradually figures out what has happened. These untold parts become evident because, in many cases, they are major events in the lives of the characters and dramatically shape the flow of the book. Yet they are never mentioned or described in the text. In The Road the major event that determines the whole course of the book is one of these untold tales. It is an apocalyptic event: the earth is shrouded with perpetual clouds; ash is raining down from the sky; the ground is covered with ash; all the trees and plants are dead; there is no electricity, no gasoline, no automobiles, no agriculture, no animals; the earth is cold, the cities are deserted, and the population is decimated. The only food is what has been canned or preserved and the pickings are getting very slim. Yet he never describes the event. Was it nuclear? Was it volcanic? Was it meteors? What happened? You don't know, and you never find out. You can determine bits and pieces, there are clues. Perhaps, if you are a scientist, you can deduce from the descriptions of the weather and the conditions of the devastated landscape what type of catastrophe has happened. Nor does he give the names or the ages of any of the characters. There are only two main characters, an old man and his son. The boy is still playing with toys; the conversation between them is at a certain level. You know he is speaking to a boy, maybe about eight years old, just from the way they talk. The old man is constantly scavenging; he is trying to...

OVIPOSITION, EARLY DEVELOPMENT AND GROWTH OF THE CAVE SALAMANDER, EURYCEA LUCIFUGA: SURFACE AND SUBTERRANEAN INFLUENCES ON A TROGLOPHILIC SPECIES

We describe oviposition site, clutch characteristics and breeding phenology of a population of Eurycea lucifuga, the cave salamander, from SE Missouri, to understand the impact of biophysical and biotic conditions on a troglophilic species. In the field oviposition occurred in underground rimstone pools over 6 mo, with most reproduction occurring from August to October. Individual females deposited 1–31 eggs per pool, hatching approximately 10–20 d post-oviposition. Larvae remained in the pools as long as 6 mo before moving into the stream. We raised eggs and larvae of E. lucifuga in the lab and compared survival, growth, and development under three temperature regimes. Embryonic growth was slowest at cooler temperatures and produced larger larvae, while temperatures typical of summer surface stream temperatures resulted in high mortality. We suggest that the cool, predator free habitats of midwestern caves have allowed for a longer reproductive season in E. lucifuga, but that the unpredictable hydrology and limited food supply of these cave environments has expanded the breeding period and slowed embryonic and larval development.

Climate influence on geochemistry parameters of waters from Santana–Pérolas cave system, Brazil

A four-year study of water geochemistry and hydrology was performed in a relatively deep cave system (overlying bedrock thickness varies from 100 to 300 m) as part of two monitoring programs, from June 1990 to February 1992 and from March 2000 to March 2002. The pH, saturation index for calcite, Ca and SO 4 concentrations, and elemental ratios of Mg/Ca and Sr/Ca were measured in surface, well and drip waters throughout the system. Despite local hydrological and geological differences among sampling sites, the monitoring revealed significant synchronous intersite variations in these parameters that are related to seasonal changes in rainfall recharge, suggesting that element ratios of speleothems formed in deep caves are capable of recording short-term climate variations. Groundwater residence time appears to be the main factor affecting the water composition in the epikarst. Epikarstic waters are always undersaturated with respect to calcite but both saturation index (S.I.) and dissolved solids content increase substantially during drier periods because of longer residence times and longer interaction between meteoric water and limestone. By contrast, results from cave drips and rimstone pools indicate constant supersaturation for calcite and demonstrate that a major control on trace element ratios of waters in the deep vadose zone is the degree of prior calcite precipitation. This mechanism is more effective during drier periods when higher Mg/Ca and Sr/Ca values are observed in all drip and pool sites. However, variations do occur independently of the general trend of drip discharge, which suggest non-linear features in cave seepage water geochemistry. In addition, synchronous variations in SO 4 and Cl concentration indicate high connectivity between different water flow pathways characterized by similar response to interseasonal changes in vadose water level. Fluctuations in trace element ratios of cave streams appear to reflect increased contribution of waters flushed from the vadose fissure aquifer during very wet periods by a piston flow mechanism. Flushing episodes are also responsible for maintaining more positive saturation indices in streams even during periods of high river discharge. Our results suggest that trace elements are a potential proxy for past rainfall changes but they also reveal different scenarios for interpreting trace elements ratios of speleothems and freshwater tufa deposited in a deep cave systems located in tropical humid areas.

A geochemical evaluation of perennial spring activity and associated mineral precipitates at Expedition Fjord, Axel Heiberg Island, Canadian High Arctic

Two groups of perennial springs are observed in the Canadian High Arctic at Expedition Fjord on Axel Heiberg Island at Colour Peak and Gypsum Hill. Saline discharge (∼1.3–2.5 molal NaCl) produces a variety of calcite (travertine) and gypsum-rich precipitates. Saturation index calculations of the spring waters at Colour Peak suggest CO 2 degassing from the waters causes calcite precipitation. Gypsum precipitation dominates at Gypsum Hill, where spring waters have lower alkalinity and higher SO 4 concentrations. Mineral accumulations form both channel and rimstone pool morphologies as a result of varying slope conditions. At Colour Peak, confined flow in steep slope areas develop massive structures in contrast to more friable, porous accumulations in areas where waters fan out on shallower slopes; these morphological variations lead to corresponding varying apparent rates of mineral precipitation. Mineral precipitation at Gypsum Hill is far less notable as a result of lower discharge rates and annual degradation by icing formation. Microscopic observations and geochemical analyses of the channel precipitates at Colour Peak reveal alternating light (calcite spar) and dark (anhedral microcrystalline calcite combined with organic matter and non-carbonate minerals) laminae. Rimstone pools forming in lower sections of spring discharge are composed of accumulations of large euhedral calcite crystals interbedded with allochthonous inputs. High concentration of dissolved solids is responsible for slow travertine precipitation rates, which occurs during winter. This precipitation is further retarded during summer months by the introduction of crystal growth inhibitors such as Fe 3+ and deposition of organic matter and soil sediments.

Stable isotope study of cave percolation waters in subtropical Brazil: Implications for paleoclimate inferences from speleothems

We analyze the interannual monthly variability of oxygen isotope ratios in data from IAEA stations along the Atlantic coast of South America between 23° and 34° S to evaluate the influence of parameters such as temperature, rainfall amount and moisture source contribution on meteoric water recharging two karst systems in subtropical Brazil. In addition, a 2 year monitoring program performed on soil and cave drip and rimstone pool waters from sampling sites with contrasting discharge values and located at 100 and 300 m below the surface in the Santana Cave System (24°31′ S; 48°43′ W), is used to test the influence of hydrologic and geologic features on the temporal variations of seepage water δ 18O. Interannual monthly variations in δ 18O of rainfall reflect primarily regional changes in moisture source contribution related to seasonal shifts in atmospheric circulation from a more monsoonal regime in summer (negative values of δ 18O) to a more extratropical regime in winter (positive values of δ 18O). Variations in groundwater δ 18O indicate that the climatic signal of recent rainfall events is rapidly transmitted through the relatively deep karst aquifer to the cave drip waters, regardless of location of collection in the cave. In addition, the data also suggest that water replenishment in the system is triggered by the increase in hydraulic head during periods when recharge exceeds the storage capacity of the soil and epikarst reservoirs. Significant perturbations in the groundwater composition, characterized by more positive values of δ 18O, are probably connected to an increased Atlantic moisture contribution associated with extratropical precipitation. This implies that the δ 18O of speleothems from caves in this region may be a suitable proxy for studying tropical–extratropical interactions over South America, a feature that is intrinsically related to the global atmospheric circulation.

Influence of hydrological and climatic parameters on spatial-temporal variability of fluorescence intensity and DOC of karst percolation waters in the Santana Cave System, Southeastern Brazil

Fluorescence intensity (FI) and organic carbon concentration of groundwater percolating through soil and rock into the Santana Cave were monitored at eight different cave sites between 2000 and 2002 to investigate their relationships to climatic parameters, stalactite discharge and thickness of rock overlying the cave. FI values, compared among sampling sites, are inversely proportional to depth and directly proportional to discharge; in contrast, dissolved organic matter (DOC) shows no significant spatial variability. Time-series analysis demonstrated similarities in DOC trends of different waters, but no correlation was observed with FI trends. Combined evaluation of DOC of infiltration waters, rainfall data and chemical parameters of Fe, O 2, pH, Eh in soil solution indicate that peaks in DOC content coincide with more reduced conditions in the soil and have a lag time of 2–3 months after heavy showers. Variation of FI throughout the year occurs at all sampling sites but only higher drip discharge and rimstone pool waters were correlatable to rainfall events. FI of lower discharge sampling sites shows similar trends, but no relationship between drip discharge and rainfall variation was observed. Ranges and means of FI for all drip waters were significantly higher in the 2001–2002 period than in the preceding 2000–2001 period, which correlates with a 5.5 °C increase in mean austral winter temperatures in 2001. Hence, FI variations of karst waters that form carbonate speleothems under a humid subtropical climate may provide a useful proxy in paleoenvironmental reconstruction.

Sedimentology of Quaternary perched springline and paludal tufas: criteria for recognition, with examples from Guadalajara Province, Spain

AbstractOutcrop‐scale geometries and bed relationships of ambient temperature freshwater carbonates are poorly understood because many described tufas have been dismantled by erosion and present only part of a particular depositional model. At the field scale, four end‐member models encompass the tufa continuum: (1) perched springline; (2) paludal; (3) fluvial; and (4) lacustrine tufas. Individual bed types can occur with variable dominance within several of these models, but one or more beds are characteristically dominant only within a single tufa model, so it can be differentiated from relatively isolated outcrop fragments. Two models (perched springline tufas and paludal tufas) are known in outline only in the literature despite being present within the Quaternary deposits of most karstic regions. Perched springline tufas generally form lobate, fan‐shaped mound morphologies on hillslopes and develop from single or multiple spring resurgences. Mature deposits show a subhorizontal top and a steep face on the downflow side. The steep outer zones of tufa mounds may be developed into cascades with moss curtains or can be dominated by shallow rimstone pools according to face angle. Tufa deposits lying downslope of the mounds are usually detrital in nature, especially if some dismantling of the mound has occurred. The relatively thin subhorizontal lobe‐top deposits commonly contain organic‐rich deposits. Paludal tufas develop predominantly in waterlogged valley bottom situations, where line‐sourced waters emerge from valley side and bottom aquifers. Lime mud precipitation predominates in these sites. Mud is deposited as subhorizontal laminites that thin towards the valley axis and downstream of resurgences. Tufa spring‐mounds may form where lesser volumes of water are involved. Individual tussocks (phytoherm cushions) of grasses and rushes are the most diagnostic feature of the model, but sapropels and peats may be intercalated. Diagenesis in both models is rapid. Lithification of individual beds is virtually instantaneous and always occurs before the decay of the associated living vegetation. The resulting highly porous and permeable fabrics remain fresh in Holocene tufas, but aggrading neomorphism and partial spar infill of vegetation moulds is common in older deposits. Dissolution in many perched springline tufas is small scale. Many large cavities are primary, but with later coatings of speleothems. Early removal of organics from paludal tufas is responsible for autobrecciation and differential compaction.

Uranium-series Chronology and Environmental Applications of Speleothems

An increasing number of scientists recognize the value of speleothems1 as often extremely well-preserved archives of information about past climate, vegetation, hydrology, sea level, nuclide migration, water-rock interaction, landscape evolution, tectonics and human action. Well-constrained data are required to document past changes, reconstruct past patterns and predict future responses of the Earth system at a wide range of spatial and temporal scales. Speleothems are particularly useful in this regard because they can be found in many locations of the globe, sampled at high-resolution and reliably dated using high-precision uranium-series techniques. Speleothems are bodies of mineral material formed in caves as the result of chemical precipitation from groundwater flowing or dripping in a cave. Most speleothems are composed of calcite formed by slow degassing of CO2 from supersaturated groundwater, but aragonite and gypsum forms are also common, particularly near cave entrances where evaporative effects are important. A host of different speleothem types decorate the walls, ceilings and floors of caves, and their mineralogy and morphology is a function of fluid flow and chemistry of waters feeding a particular location as well as the ambient conditions (temperature, chemistry, light) in the air or water-filled void. Subaerial forms include the familiar stalagmites, stalactites, draperies, flowstones. Subaqueous forms include rimstone pools, “rafts,” mammillary calcite wall-coatings and “dog-tooth” spar. For an extensive review of the types of speleothem that have been observed, see Hill and Forti (1997). Speleothems are used in a multitude of ways to explore past environmental conditions, perhaps the most fundamental of which is their very presence or absence. Deposition of speleothems relies on sufficient water supply and soil CO2 to enable dissolution and transport of reactants in the vadose zone to underlying caves. In arid or glacial times, conditions may not have been favorable for speleothem formation. …