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

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

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

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

A study of the immunity of FM discriminators to 2 pi frequency impulses

Frequency impulse response of selected FM discriminator

Cumulative luminosity functions of the X-ray point source population in M31

We present preliminary results from a detailed analysis of the X-ray point sources in the XMM-Newton survey of M31. These sources are expected to be mostly X-ray binaries. We have so far studied 225 of the 535 sources found by automated source detection. Only sources which were present in all three EPIC images were considered. X-ray binaries are identified by their energy spectrum and power density spectrum. Unlike in other surveys we have obtained source luminosities from freely fit emission models. We present uncorrected luminosity functions of the sources analysed so far.Comment: 2 pages, 1 figure. To appear in proceedings of IAUS23

A universal GRB photon energy-peak luminosity relation

The energetics and emission mechanism of GRBs are not well understood. Here we demonstrate that the instantaneous peak flux or equivalent isotropic peak luminosity, L_iso ergs s^-1, rather than the integrated fluence or equivalent isotropic energy, E_iso ergs, underpins the known high-energy correlations. Using new spectral/temporal parameters calculated for 101 bursts with redshifts from BATSE, BeppoSAX, HETE-II and Swift we describe a parameter space which characterises the apparently diverse properties of the prompt emission. We show that a source frame characteristic-photon-energy/peak luminosity ratio, K_z, can be constructed which is constant within a factor of 2 for all bursts whatever their duration, spectrum, luminosity and the instrumentation used to detect them. The new parameterization embodies the Amati relation but indicates that some correlation between E_peak and E_iso follows as a direct mathematical inference from the Band function and that a simple transformation of E_iso to L_iso yields a universal high energy correlation for GRBs. The existence of K_z indicates that the mechanism responsible for the prompt emission from all GRBs is probably predominantly thermal.Comment: Submitted to Ap

A search for thermal X-ray signatures in Gamma-Ray Bursts I: Swift bursts with optical supernovae

The X-ray spectra of Gamma-Ray Bursts can generally be described by an absorbed power law. The landmark discovery of thermal X-ray emission in addition to the power law in the unusual GRB 060218, followed by a similar discovery in GRB 100316D, showed that during the first thousand seconds after trigger the soft X-ray spectra can be complex. Both the origin and prevalence of such spectral components still evade understanding, particularly after the discovery of thermal X-ray emission in the classical GRB 090618. Possibly most importantly, these three objects are all associated with optical supernovae, begging the question of whether the thermal X-ray components could be a result of the GRB-SN connection, possibly in the shock breakout. We therefore performed a search for blackbody components in the early Swift X-ray spectra of 11 GRBs that have or may have associated optical supernovae, accurately recovering the thermal components reported in the literature for GRBs 060218, 090618 and 100316D. We present the discovery of a cooling blackbody in GRB 101219B/SN2010ma, and in four further GRB-SNe we find an improvement in the fit with a blackbody which we deem possible blackbody candidates due to case-specific caveats. All the possible new blackbody components we report lie at the high end of the luminosity and radius distribution. GRB 101219B appears to bridge the gap between the low-luminosity and the classical GRB-SNe with thermal emission, and following the blackbody evolution we derive an expansion velocity for this source of order 0.4c. We discuss potential origins for the thermal X-ray emission in our sample, including a cocoon model which we find can accommodate the more extreme physical parameters implied by many of our model fits.Comment: 16 pages, 6 figures, accepted for MNRA