Cave Turbidites

Turbidites are uncommon in caves, but are more common as palaeokarst deposits. Marine carbonate turbidites, called cay­manites, are the most common cave and palaeokarst turbidites, but marine non-carbonate turbidites, freshwater carbonate turbidites and freshwater non-carbonate turbidites are also de­posited in caves and preserved in palaeokarst sequences. One of the most complex sequences of cave turbidites occurs in the Wellington Caves Phosphate Mine in Australia. Cave turbidites form in ponded water in caves and may be triggered by floods and highintensity rain events. While caymanites are most likely to form during marine transgressions, they can be emplaced by tsunami. Freshwater cave turbidites are most likely to form in flooded hypogene caves located in the seasonally wet tropics and in areas withirregular highintensity rainfall events

Detailed Morphologicial Studies in Netopirjev rov, Predjama Cave: A Hypogene Segment of Slovenian Cave.

Netopirjev Rov, part of the upper level of Jana near Predjama Cave, is not a former fluvial cave passage but a complex void made up of coalesced, structurally guided elongate cavities with cupolas and a range of speleogens normally associated with hy­pogene caves. These cavities were initially separate and later became integrated by the breakdown of their common walls. The main chamber consists of at least two coalesced voids while an apparent bend, a pseudobend, towards the northern end of Netopirjev Rov results from the breakdown of the com­mon wall near the ends of two adjacent elongate cavities. It is proposed that this section of cave was excavated by the action of water rising from below (per-ascensum speleogenesis), but the nature and source of this water remains unclear

Dating ancient caves and related palaeokarst

 There are few cases of open caves that have been reliably dated to ages greater than 65 Ma. This does not mean that such caves are extremely rare, rather it is difficult to reliably establish that a cave, or palaeokarst related to a cave, is this old. Relative dating methods such as: - regional stratigraphic, lithostratigraphic, biostratigraphic, relative climatic, relative isotopic, morphostratigraphic, and regional geomorphic are very useful. They suffer however from significant difficulties, and their results lack the impact of a crisp numerical date. While many of the methods used to date younger caves will not work over the required age range, some isotopic methods and palaeomagnetic methods have been applied with varying degrees of success. While finding something to date and having it dated is difficult enough, producing the date is rarely the end of the story. The difficult issue is not the date or relative correlation itself, but what the date or correlation means. Demonstrating that caves are ancient seems to rapidly become beset with the old adage that “extraordinary claims require extraordinary proof”. The presence of a well-dated or correlated sediment in a cave does not necessarily mean that the cave is that old or older. Perhaps the dated material was stored somewhere in the surrounding environment and deposited much more recently in the cave. A lava flow in a cave must be demonstrated conclusively to be a flow, not a dyke or a pile of weathered boulders washed into the cave. It must be conclusively shown that dated minerals were precipitated in the cave and not transported from elsewhere. There seems little doubt that in the future more ancient caves, or ancient sections of caves, will be identified and that as a result our perception of the age of caves in general will change. R.A.L. Osborne: Datiranje starih jam in z njimi povezanega paleokrasa Je le nekaj primerov odprtih jam, ki bi imele zanesljivo določeno starost nad 65 milijonov let. To ne pomeni, da so take jame izredno redke, ampak da je težko zanesljivo ugotoviti, da so oziroma paleokras, povezan z njimi, res tako stare. Relativne metode datiranja, kot so regionalno stratigrafsaka, litostratigrafska, biostratigrafska, relativno klimatološka, relativno izotopska, morfostratigrafska in regionalno geomorfološka, so zelo uporabne. Imajo pa pomembne pomanjkljivosti, saj njihovi izsledki ne temelje na jasnih številčnih podatkih. Medtem, ko marsikatera od metod, ki so uporabne za datiranje mlajših jam, ni uporabna za omenjeno starost, pa je bilo uporabljenih več izotopskih in paleomagnetnih metod z različnim uspehom. Težko je najti snov za datiranje in jo datirati, a sama starost še ni konec zgodbe. Težava ni z datiranjem ali s korelacijo, ampak v tem, kaj starost oziroma korelacija pomenita. Dokazovanje, da so jame stare, je hitro odpravljeno s pregovorom »Izredni izsledki zahtevajo izredne dokaze«. Dobro datirani ali korelirani sedimenti v jami še ne pomenijo, da je jama toliko stara ali starejša. Morda je bilo datirano gradivo odloženo nekje v okolici in šele mnogo kasneje preneseno v jamo. Lavin tok v jami mora biti neizpodbitno določen kot lavin tok, ne pa da je dyke ali balvani, prenešeni v jamo. Neizpodbitno mora biti dokazano, da so bili datirani minerali izločeni v jami in ne preneseni od nekod drugod. Nedvomno bo v bodoče spoznanih več starih jam ali njihovih delov in zaradi tega se bo tudi naše pojmovanje o starosti jam v celoti spremenilo.  

Significance and Monitoring

Za vsak program monitoringa v jamah je nujno potreben predhodni popis vseh bistvenih lastnosti nekega procesa. Monitoring ni sam sebi namen, pač pa je del integriranega procesa, osnovanega na bistvenih lastnostih upravljalskega procesa. Nujno je, da vemo, kaj v jami je res pomembno, da poznamo pogoje, v katerih lahko to pomembnost ohranimo in, da so tako ohranjeni pogoji celota vseh pomembnih dejavnikov. Na primer, če ne poznamo mehanizma odlaganja blatnih sedimentov, potem monitoring stanja kapnikov ne bo preprečil ponovnega odlaganja blata, ki smo ga sicer odstranili s pranjem pod visokim pritiskom. Podobno nima nobenega smisla merjenje temperature, če je prah glavna gro‘nja pomembnim elementom. Edini način, po katerem spoznamo, da je monitoring uspešen je ta, da merimo značilnosti in celovitost pomembnih elementov. Sicer lahko zberemo veliko pomembnih podatkov, najpomembnejše oblike pa nam medtem propadejo. Zato se mora monitoring nanašati na nujne okoliščine, pri katerih še lahko ohranimo bistvene značilnosti ter na sprotno stanje in celovitost pomembnih značilnosti.An inventory survey followed by a significance assessment process, are essential precursors to any cave monitoring program. Monitoring must not be seen as an end in itself, but as part of an integrated, significance- based management process. It is essential to know what is significant, the conditions necessary to maintain its significance and that the condition and integrity of significant elements are being maintained. For instance, if the significance of a mud deposit is not known, monitoring the condition of speleothems will not stop the mud deposit from being destroyed by high-pressure water cleaning. Similarly, there is little point in monitoring temperature if dust is the main threat to the significant elements. The only way to know that monitoring of environmental conditions is effective is to monitor the ongoing condition and integrity of the significant elements themselves. Without this, lots of interesting data could be collected while the most important features of the cave are lost. Monitoring should therefore address the conditions necessary for the maintenance of significance and the ongoing condition and integrity of significant elements

The World’s Oldest Caves: - How -Did They Survive and What Can They Tell Us?

Parts of an open cave system we can walk around in today are more than three hundred million years old. Common sense tells even enthusiasts like me that open caves this old should not still exist, but they do! Their survival can be partly explained by extremely slow rates of surface lowering, but this is not sufficient by itself. Isolation by burial and relative vertical displacement by faults are probably also required. Now one very old set of caves have been found, are there more of them? What can they tell us

The Troubles with Cupolas

Kupole so korozijske tvorbe v obliki kupol, znane tako s krasa v apnencih kot tudi v anhidritih. Medtem ko je bilo v literaturi precej razpravljanja o verjetnem nastanku in pomenu teh oblik, pa je zelo malo podrobnih opisov teh oblik ter definicij tega pojma. Zato je s kupolami precej težav: Kaj je kupola? Kje se kupole pojavljajo? Kakšne so kupole? Ali so kupole povezane z določenimi drugimi oblikami? Ali so kupole oblike v stropu ali oblike, ki jih je strop prerezal? Kako kupole nastajajo? Kako lahko rešimo ta vprašanja? V prispevku je veliko odgovorov na ta vprašanja, toda večji del terenskih raziskav in teoretičnega dela bo treba šele opraviti. Najpomembnejša so podrobna terenska opazovanja in merjenja kupol ter tistih oblik, ki so z njimi povezane. Tako bo mogoče rešiti vprašanje kupol in tako bo mogoče izvedeti še več o nenavadnih jamah, v katerih se kupole pojavljajo.Cupolas are dome-shaped solution cavities that occur in karst caves, and have been described in both limestone and gypsum karst. While there has been considerable discussion in the literature concerning the likely origin and significance of these features, there has been little in the way of detailed description of the features themselves and little attention has been given to the definition of the term. Consequently, there are a number of troubles with cupolas: - What is a cupola? Where do cupolas occur? What are cupolas like? Do cupolas occur with particular types of speleogens? Are cupolas features of ceilings or features intersected by ceilings? How do cupolas form? But how can these troubles be resolved? Tentative answers are given here to many of these questions but a great deal of basic field observation and theoretical work is required to solve them. The most important step would be more field observation and measurement of cupolas and of the particular suite of speleogens that occur with them. The troubles with cupolas can be solved and in the process we will come to understand a great deal more about the unusual caves in which they occur

Understanding the Origin and Evolution of Jenolan Caves: The Next Steps

The dating of cave and surficial sediments by Osborne et al. (2006) indicated that some sections of Jenolan Caves, particularly the large chambers, formed in the Early Carboniferous before deposition of sediments dated at 340 Ma. The dating also identified younger mass-flow sediments, dated at 303Ma and secondary fine illite, dated at 258 Ma and 240 Ma indicating burial of the caves under the Sydney Basin. These dates meant that a new chronology for cave development at Jenolan is required to supersede that of Osborne (1996b). Construction of this chronology raises new questions: Did the paragenetic conduits form before deposition or after stripping of the Sydney Basin? Caymanites (marine carbonate turbidite palaeokarst) appear to be older than 340 Ma, but does this make palaeogeographic sense? The Early Carboniferous dates give us a beginning for the history of the present caves at Jenolan, but much of the story is missing. Many obvious features in the caves have not been studied. Present knowledge of the developmental history, palaeokarst and sediment stratigraphy, morphology and mineralogy of tourist caves at Jenolan Caves is insufficient to support sound conservation, management, development and interpretation. The next step in understanding Jenolan Caves is a structured program of dating, geological, mineralogical and geomorphic studies

Sulfate and Phosphate Speleothems at Jenolan Caves, New South Wales, Australia

Sulfate and phosphate deposits at Jenolan Caves occur in a variety of forms and compositions including crusts, ‘flowers’ and fibrous masses of gypsum (selenite), and clusters of boss-like speleothems (potatoes) of ardealite (calcium sulphate, phosphate hydrate) with associated gypsum. This boss-like morphology of ardealite does not appear to have been previously described in the literature and this is the first report of ardealite in New South Wales. Gypsum var. selenite occurs in close association with pyrite-bearing palaeokarst, while the ardealite gypsum association appears to relate to deposits of mineralised bat guano. Isotope studies confirm that the two gypsum suites have separate sources of sulfur, one from the weathering of pyrite (-1.4 to +4.9 δ34S) for gypsum (selenite) and the other from alteration of bat guano (+11.4 to +12.9 δ34S) for the ardealite and gypsum crusts

Sulfate and Phosphate Speleothems at Jenolan Caves, New South Wales, Australia

Sulfate and phosphate deposits at Jenolan Caves occur in a variety of forms and compositions including crusts, ‘flowers’ and fibrous masses of gypsum (selenite), and clusters of boss-like speleothems (potatoes) of ardealite (calcium sulphate, phosphate hydrate) with associated gypsum. This boss-like morphology of ardealite does not appear to have been previously described in the literature and this is the first report of ardealite in New South Wales. Gypsum var. selenite occurs in close association with pyrite-bearing palaeokarst, while the ardealite gypsum association appears to relate to deposits of mineralised bat guano. Isotope studies confirm that the two gypsum suites have separate sources of sulfur, one from the weathering of pyrite (-1.4 to +4.9 δ34S) for gypsum (selenite) and the other from alteration of bat guano (+11.4 to +12.9 δ34S) for the ardealite and gypsum crusts

Caves and karst-like features in Proterozoic gneiss and Cambrian granite, southern and central Sri Lanka: An introduction

There has been little study of the geology and geomorphologyof the caves and karst-like features developed in the Proterozoicgneiss and Cambrian granite of Sri Lanka. This lack of studyis surprising given that caves and rockshelters in these rockscontain significant archaeological and cultural sites. Caves andkarren, both mimicking those developed in carbonate rocks,have formed both in gneiss, which is the dominant rock type ofthe Proterozoic crust of the island and in granite. In addition tooverhangs, boulder caves, soil pipes and tectonic caves, tunnelcaves, arch caves and block breakdown caves of significant sizeare developed in siliceous rocks in Sri Lanka. While metamorphoseddolomites are interfoliated within the gneissic suite,simple removal of carbonate by solution from within the surroundingrock cannot account for all or most of the speleogenesisobserved. While spalling and breakdown are responsiblefor cave enlargement cave initiation is probably due to eitherphreatic solution of silicates and/or phantom rock processes.Speleothems and cave minerals including silicates, phosphates,gypsum, carbonates and niter are found in the caves. Activesilicate speleothems are not restricted to joints and fissures andsuggest that solution of silicates is currently occurring withinthe body of the rock in the vadose zone. While guano is thelikely source of the phosphate, sulfate and nitrate, the sourceof the calcium in the carbonates remains unclear. Caves in theintrusive and metamorphic rocks of Sri Lanka are enigmatic.They are unexpectedly similar in appearance to their carbonatekarst counterparts. Continuing research will allow them tohold a mirror to our understanding of speleogenesis, mineralizationand sedimentation in carbonate karst caves