Hypogenic Caves in Provence (France).

Članek obravnava razvoj jam Adaouste in Champignons v francoski Provansi. Nove raziskave kažejo, da jami ni oblikovala meteorna voda, pač pa voda, ki je v arteških pogojih dotekala iz globin. V članku so obravnavane specifične jamske skalne oblike in sedimenti, ki podpirajo trditev o hipogenem razvoju jam.Two dry caves from French Provence (Adaouste and Champignons caves) were until now considered as »normal« caves having evolved under meteoric water flow conditions. A new approach gives evidence of a hypogenic origin from deep water uprising under artesian conditions. Specific morphologies and sediments associated with this hydrology are discussed

The Role of Condensation Corrosion in Thermal Speleogenesis. Study of a Hypogenic Sulfidic cCve in Aix-les-Bains, France

Condensation-corrosion is an active speleogenetical process in thermal caves where high thermal gradient drives air convection. Wall retreat rates are greater than in meteoric caves. Conversely, evaporation produces depositional processes by replacement of limestone by gypsum and by aerosol decantation leading to the formation of popcorns. The Chevalley Aven belongs to Aix-les-Bains thermal-sulfidic cave system. Condensation occurs at the contact of cool walls of large spheres; conversely, evaporation occurs at the output of the narrow passages where the air sinks down from the upper sphere. A weathered layer and biofilms are present where slow condensation occurs. Corrosion distribution varies according to thermal rock conductivity and causes the sphere to develop upwards, laterally, and divergent. This mor­phodynamic pattern favors the development of stacked spheres, isolated by narrow necks, and arranged in a bush-like pattern. This development is clearly active in the vadose zone above the thermal water table. We propose that some avens above wa­ter table hypogenic caves, like Villa Luz (Mexico), may be of condensation-corrosion origin instead of phreatic. Future de­velopment will collect physical and chemical data to calculate the condensation-corrosion budget and assess its role in cave developmen

New mineralogical record of guano-associated phosphates in Colombo Cave (Toirano, Liguria, Italy)

Colombo Cave is part of Toirano karst system and opens at 247 m a.s.l. The wide entrance passage was used during prehistoric times, and a 4.5 m deep archaeological excavation pit is located 10 m from the entrance. The main room is dominated by a large central rock pillar and the floor is completely covered by important ancient bat guano deposits. Samples were taken in separate containers and were representative of old guano deposits and a hard-yellow crust covering the guano heap. All samples were identified by XRD and SEM-EDS analysis. The results indicate that old guano samples were composed mainly of calcite, quartz, spheniscidite and minor amounts of xenotime (Y), monazite, zircon, and rutile. In particular, spheniscidite (NH4,K)(Fe3+,Al)2(PO4)2(OH)·2H2O forms from the reaction of ammonium-rich fresh guano leachates with probably clay sediments containing Fe and muscovite (source of K and Al) (Sauro et al., 2014). The mineral associations present in soft yellow and whitish crusts that cover guano were represented by gypsum CaSO4·2H2O, brushite Ca(HPO4)·2H2O, ardealite Ca2(HPO4)(SO4)·4H2O and newberyite Mg(HPO4)·3H2O. Brushite and ardealite occur as cryptocrystalline aggregates varying in color from white-ivory to yellow-ivory and form by the reaction of sulfuric and phosphoric acid with limestone rock (Hill & Forti, 1997; Puşcaş et al., 2014). Newberyite was less common and likely comes from the interaction of phosphates with Mg provided by the disaggregation of the dolomitic host rock. The identification of these minerals is important because they were never reported from Liguria. Further investigations will be conducted in order to understand the minerogenetic processes involved in these guano-associated minerals, and their evolution through time in the damp cave environment (Audra et al., 2019)

Cave and Karst evolution in the Alps and their relation to paleoclimate and paleotopography

Progress in the understanding of cave genesis processes, as well as the intensive research carried out in the Alps during the last decades, permit to summarize the latest knowledge about Alpine caves. The phreatic parts of cave systems develop close to the karst water table, which depends on the spring position, which in turn is generally related to the valley bottom. Thus, caves are directly linked with the geomorphic evolution of the surface and reflect valley deepening. The sediments deposited in the caves help to reconstruct the morphologic succession and the paleoclimatic evolution. Moreover, they are the only means to date the caves and thus the landscape evolution. Caves appear as soon as there is an emersion of limestone from the sea and a water table gradient. Mesozoic and early tertiary paleokarsts within the alpine range prove of these ancient emersions. Hydrothermal karst seems to be more widespread than previously presumed. This is mostly due to the fact that usually, hydrothermal caves are later reused (and reshaped) by meteoric waters

The contribution of condensation-corrosion in the morphological evolution of caves in semi-arid regions: preliminary investigations in the Kyrenia Range, Cyprus

The condensation-corrosion process occurs when airflow cools at the contact with colder cave walls. Condensed water becomes aggressive for soluble rocks and corrodes the walls. This process is particularly active close to cave entrances in high thermal gradient zones where external air enters caves. Condensation appears to be important where bat colonies are also present. Bat metabolism and guano decomposition release heat, vapour, and acids. Hence, bat colonies contribute to the increase of condensation- corrosion, especially by providing permanent moisture and chemical aggressiveness. Corrosive air convections produce rounded morphologies, such as ceiling channels, cupolas, and corroded older flowstones. This process has been overlooked in previous research, since related morphologies were often confused with those produced by early phreatic flow. Kyrenia Range in Cyprus has a semi-arid climate. All the studied caves developed along open-fractures. They are located both in recrystallized carbonates (limestone and dolostone, such as Smoky and Pigeons Caves), or in gypsum (First Day and Angry Bat Caves). We also studied a maze cave that acted as a spring in gypsum that initially developed under phreatic conditions, followed by an epiphreatic phase that allowed the development of notches (Fig Tree Cave, also named İncirli Show Cave). Due to the semi-arid climate, external air is very dry in summer, thus condensation seems to occur mainly in winter, when cave atmosphere instability allows large air exchanges between caves and surface atmosphere. In summer, evaporation prevails, allowing the development of popcorn lines in carbonate caves and massive gypsum crusts, stalagmites, and sidewalk rims in gypsum caves. However, the presence of a bat colony in a semi-confined chamber in Smoky Cave is probably the origin of the permanent moisture, also during the dry season, leading to a strong development of condensation-corrosion features such as ceiling cupolas, and possibly to the permanent activity of flowstones. In addition, we detected high concentrations of sulphur dioxide (SO2) and radon (Rn) in Fig Tree Cave, possibly related to the activity of the neighbouring overthrust. Based on the five studied caves in the Kyrenia Range and surroundings, the open-fracture caves in carbonates and gypsum have not undergone the typical initial phreatic stage, but have formed in a short time during Pleistocene as a result of the fast uplift of the range and were later reshaped by condensation-corrosion morphologies. Some gypsum caves may have formed entirely by this latter process, after initial minor fracture development. Cyprus is an outstanding area for studying the condensation-corrosion in caves, since a phreatic origin can be ruled out for most of the rounded morphologies. Prispevek kondenzacijske korozije pri razvoju jam v polsuhih območjih: predhodni rezultati v jamah Kirenijskega gorovja, CiperKondenzacijska korozija se pojavi ob stiku vlažnega zračnega toka s hladnimi jamskimi stenami. Pri tem na jamsko steno iz zraka kondenzira film vode, ki kemično korodira vodotopno kamnino. Proces je najbolj izrazit v bližini jamskih vhodov, kjer ob visokem temperaturnem gradientu zunanji zrak vstopa v jamo. Kondenzacijo in kondenzacijsko korozijo lahko pomembno povečajo kolonije netopirjev. Metabolizem netopirjev in razpadanje gvana sproščata toploto, vlago in kisline. Kondenzacijska korozija iz konvekcijskih tokov vlažnega zraka ustvarja zaobljene skalne oblike, kot so kupole, stropni kanali in korodirana siga. Kirenijsko gorovje na Cipru ima polsuho podnebje. Večina jam v tej raziskavi so odprte razpoke v prekristaljenem karbonatu (apnenec in dolomit) ali v sadri. Poleg teh obravnavamo tudi blodnjake v sadri, ki so se oblikovali v freatični coni in so v preteklosti delovali kot izviri. V njih najdemo stenske zajede, ki so nastale v epifreatični fazi. Ker je zrak poleti zelo suh, je kondenzacija omejena na zimski čas, ko se intenzivno izmenjuje zrak med jamsko in zunanjo atmosfero. Poleti prevladuje izhlapevanje, kar omogoča razvoj cvetačastih oblik v karbonatnih jamah ter sadrinih skorij, stalagmitov in stranskih obrob v jamah v sadri. Kolonija netopirjev v eni od polzaprtih dvoran v jami Smoky Cave verjetno vzdržuje visoko vlago tudi poleti. Posledica so močno izražene oblike kondenzacijske korozije (kupole) in stalna aktivna rast sige. V eni od jam smo izmerili visoko vsebnost SO2 in radona, ki je verjetno povezana z aktivno narivno tektoniko. Pet obravnavanih jam je tektonskega izvora in so verjetno nastale v kratkem obdobju hitrega dvigovanja v pleistocenu ter bile kasneje preoblikovane s kondenzacijsko korozijo. Nekatere jame v sadri so nastale skoraj izključno s kondenzacijsko korozijo, ki je preoblikovala prvotne majhne razpoke. Ciper je izjemno območje za podobne študije, saj lahko zaradi odsotnosti freatične faze večino zaobljenih jamskih oblik pripišemo kondenzacijski koroziji.Ključne besede: Vzhodno Sredozemlje, kondenzacijska korozija, gvano, Kirenijsko gorovje, jame v odprtih razpokah, hitri tektonski dvig, sadra, jamska mikroklima, pleistocen

Bat urea-derived minerals in arid environment. First identification of allantoin, C4H6N4O3, in Kahf Kharrat Najem Cave, United Arab Emirates

Kahf Kharrat Najem Cave is a small cave in United Arab Emirates (UAE) that hosts a bat colony which is the source of guano deposits and peculiar centimeter-long yellowish stalactites. The mineralogy and geochemistry of these deposits were analyzed using powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopic microanalysis (EDX), scanning electron microscope (SEM), and stable isotope composition (δ13C and δ15N). Urea CO(NH2)2 was found to be the main compound of these stalactites, while allantoin C4H6N4O3 was found to be an accessory urea byproduct. This paper is the first to mention allantoin in a cave environment. We also identified rare sulfate minerals (aphthitalite, alunite) and phosphates that probably correspond to the archerite-biphosphammite series. The occurrence of these rare bat-related minerals is due to the extremely dry conditions in the cave, which accounts for the extraordinary preservation of the guano deposits and allows for the crystallization of these very soluble minerals.Publisher PDFPeer reviewe

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Une monographie sur le massif de la Grigna (Côme, Italie) : "Il carsimo del Moncodeno" par A. Bini et A. Pellegrini, Geologia Insubrica, 1998

Audra Philippe. Une monographie sur le massif de la Grigna (Côme, Italie) : "Il carsimo del Moncodeno" par A. Bini et A. Pellegrini, Geologia Insubrica, 1998. In: Karstologia : revue de karstologie et de spéléologie physique, n°35, 1er semestre 2000. Le karst haut alpin du Kanin (Alpes juliennes, Slovénie-Italie) p. 63

Approche de la spéléogenèse des karsts alpins. Quelques exemples en France (Vercors, Chartreuse, Ile de Crémieu) et en Autriche (Tennengebirge)

Research has been carried out in the underground networks of certain alpine massifs, such as in the Tennengebirge, Ile de Crémieu, Vercors, Chartreuse. The main underground sediments are of paleoclimatic and hydrodynamic significiance, corresponding to hot, stable or in desequilibrium (flowstones, reworked weathered rocks) and cold environments (carbonated varves, glacial pebbles). Each massif has its own evolution, depending on its structural characteristics, its altitude, and its position in relation to successive base levels. Nevertheless there is a more global outline, with undercover karstifications having occured during the Paleocene and evolved into cone karsts, associated with horizontal cavities during the Miocene. From the Pliocene onwards, large horizontal networks were laid down. These were broken up with uplift and were reçut by the vertical "alpine" shafts. Thus, two fundamental successive conditions can be contrasted, the fluvio-karsts and the perched karsts. It would seem that large underground alpine networks, including horizontal perched levels and vertical conduits, can be closely linked to the plio-quaternary period. There formation can be explaines as a combination of progressive uplifts with fluvial or glacial allochtonous discharge inputs.Des recherches ont été entreprises dans les réseaux souterrains de quelques massifs alpins (Tennengebirge, Ile de Crémieu, Vercors, Chartreuse). Les principaux sédiments souterrains ont une signification paléoclimatique et hydrodynamique, correspondant à des milieux chauds, stables ou en rupture d'équilibre (concrétions, altérites remaniées), ou bien froids (varves carbonatées, galets glaciaires). Chaque massif possède sa propre évolution, dépendant avant tout de ses caractéristiques structurales, de son altitude et de sa position par rapport aux niveaux de base successifs. Néanmoins, une évolution globale s'esquisse, avec des karstifications sous couverture au Paléocène évoluant vers des karsts à buttes associés à des cavités horizontales au Miocène. A partir du Pliocène, de grands réseaux horizontaux se mettent en place. Ils seront démantelés par la surrection et recoupés par les réseaux verticaux "alpins". On oppose ainsi deux états fondamentaux successifs, les fluvio-karst et les karsts perchés. Il apparaît que les grands réseaux souterrains alpins, intégrant des niveaux horizontaux perchés et des conduits verticaux sont intimement liés à la période plio-quaternaire. Leur genèse s'explique par la combinaison des surrections progressives et des apports d'eaux allochtones, fluviátiles ou glaciaires.Audra Philippe. Approche de la spéléogenèse des karsts alpins. Quelques exemples en France (Vercors, Chartreuse, Ile de Crémieu) et en Autriche (Tennengebirge). In: Travaux du Laboratoire de Géographie Physique Appliquée, n°13, Février 1995 1994. pp. 47-61