The ribbed drapery of the Puerto Princesa Underground River (Palawan, Philippines): morphology and genesis

During the 2011 speleological expedition to the Puerto Princesa Underground River (Palawan, Philippines) a drapery characterized by several close-to-horizontal ribs has been noticed. Even without sampling and analyzing its internal growth layers, a detailed morphological study allowed to present a possible genetic model. The presented model helps to explain its evolution, which is mainly controlled by variation in water flow as a consequence of the Palawan climate. When validated by further analyses, the same genetic mechanism could define also the evolution of the very common but still unexplained complex flowstones, which exhibit several close-to-horizontal steps, widenings and narrowings along their growth axis

The Naica Project - A Multidisciplinary Study of the Largest Gypsum Crystals of the World

The caves of Naica (Chihuahua, Mexico) are perhaps the most famous mine caves of the world due to the presence of gigantic gypsum crystals. Nevertheless, very little research has been carried out on these crystals until now. An international multidisciplinary investigation started in 2006 with the aim not only to define the genesis and the age of the Naica gypsum crystals, but also to focus other important scientific aspects of these caves and to ensure a complete documentation and knowledge of these natural wonders which will not be accessible anymore in a few couple of years. The preliminary results of this, still in progress, research allow to date the giant crystals and to define the boundary conditions and the mechanisms which induced their development. For the first time pollens have been extracted from gypsum crystals and their analyses evidenced that some 35 Ky BP the Naica climate was cooler and more humid than today

Peculiar Minerogenetic Cave Environments of Mexico: The Cuatro Ciénegas Area

The karst area of Quatro Ciénegas (Coahuila, Mexico) represents an ideal site to study cave mineralogy, because it hosts caves of different age and genesis (karst, thermal, mine caves). Among the speleothems studied is worth to mention a nest of aragonite cave pearls found deep inside the Reforma mine characterized by the total absence of growing layers inside them. Despite only few studied caves (8), some 32 different cave minerals have been detected, one of which is new for the cavern environment (kingsmountite) and another one, still under study, which probably will result new for science. Due to the scientific interest of their chemical deposits it should be very important to protect in the future the natural cavities of the karst systems of Cuatro Ciénegas in order to preserve a scientific patrimony, actually only partially known

The Mineralogical Study on the Cueva de Las Vegas (Naica, Mexico)

The Cueva de las Velas is the last cave unveiled at -290 level within the Naica Mine; the cavity has been intercepted by a mine gallery at the beginning of 2005. One of its peculiarities is the widespread thick deposits of diagenetic minerals deposited over the cave walls before the beginning of the evolution of the giant gypsum crystals. These deposits consist of complex, often scarcely crystalline iron-manganese-lead oxides-hydroxides, but carbonates, sulphates and silicates are also present. Other minerals, mainly sulphates, started developing just after this area of the mine was dewatered some 20 years ago. Presently 17 different minerals have been observed, 5 of which (orientite, starkeyite, szmolnokite, szmikite and woodruffite) are completely new for the cavern environment. The study of these minerals, together with the presence of a completely new type of gypsum crystals, allowed to improve the knowledge on the speleogenetic evolution of this cave, which seems to be by far more complex than that of the other cavity of the -290 level.Its complexity is reflected by the activity of a larger number of different speleogenetic mechanisms. Among them are worth of mention the thermal corrosion/dissolution, the anhydrite-gypsum disequilibrium, the acid aggression, and the capillary migration and evaporation

THE STONE BOOK

The aesthetic value of a wild and/or tourist cave is well known everywhere. Anyway, presently only few people are aware that caves are the most important natural laboratories, in which it is possible to complete studies and researches that, in some cases, would be impossible in any other place. The caves are normally characterized by low energy and by the absence, or at least scarcity, of perturbing factors characterizing the external environments. Therefore, natural cavities may be regarded as perfect accumulation traps, preserving all the materials falling inside them. In the last half century the importance of cave deposits grew enormously in the field of paleoenvironmental and paleoclimatological studies, often allowing to reconstruct the chronology of the events a given environment underwent. From this point of view speleothems are by far the most important cave deposits, because their layered structure is always chronologically ordered and several techniques allow for an easy absolute dating of even a single event. Moreover, all these events may sometimes be restricted to a single year interval (or even less) on the basis of the speleothem growth layers. The speleothem’s layered structure makes reasonable to consider each of them a “stone book”, where each growing layer corresponds to a “page” of a multidisciplinary encyclopaedia. We are still unable to extract most of the information recorded by them. But in the near future, when we will be able to read all the pages of these “stone books”, their scientific importance will grow exponentially

Laser scanning technology for the hypogean survey: the case of Santa Barbara karst system (Sardinia, Italy)

The morphological knowledge of the territory, bothin its surface and subterranean aspects, is the main premise to all decision-making procedures as well as all planning and management activities. Knowledge takes shape into reliable precise and complete thematic cartography and databases, whichare necessary for anybody dealing withunderground contexts: speleologists, scientists, public administrations, managing authorities etc. Surveys in caves are normally carried out withtraditional techniques and instruments, whichare essential for a first representation but not enoughfor a pragmatic effective topographic approach. Laser scanning technique can be an alternative to the traditional systems. Laser scanning quickly acquires the shape of cavities as “point clouds” (x, y, z coordinates and colour values) and produces a highprecision database of the surveyed object. Laser scanning technology is therefore a feasible way to document caves in a precise exhaustive way, limiting risks relating to lack and/or inadequacy of data. The present paper explains the laser scanning survey carried out in San Giovanni mine near Iglesias (Sardinia, Italy), particularly in Santa Barbara and Santa Barbara 2 caves, the data post-processing and three-dimensional modelling of “point clouds” (operations performed witha dedicated software), and the use of the obtained digital model. Moreover, the paper describes the advantages of laser scanning for the hypogean survey in comparison to traditional methods and the future potentialities of a broad application of laser scanning instruments in caves.

Robertsite: un nuovo fosfato di grotta scoperto nella Tagusan Cave(Palawan – Filippine)

La Tagusan Cave è una cavità di attraversamento che si apre nel massiccio calcareo che ospita la famosa grotta Porto Pricesa Undergroud River nell’isola di Palawan (Filippine). Al suo interno sono state rivenute alcune pisoliti di colore nero che sono state campionate e quindi analizzate dal punto di vista tessiturale e mineralogico. Le analisi al microscopio ottico hanno evidenziato come queste pisoliti non siano omogenee ma siano costituite da un nucleo spesso costituito da una aggregazione di ooliti giallastre su cui si è depositata un’alternanza di sottili strati picei e rossastri. L’analisi mineralogica delle bande di accrescimento ha evidenziato la presenza, oltre a fosfati di calcio praticamente amorfi, di robertsite [Ca2Mn3(PO4)3O2•3H2O], un fosfato che non era mai stato segnalato prima in grotta. Sempre in queste bande, sulla base degli esami röntgenografici e delle analisi EDAX, si è ipotizzata la presenza anche di janggunite [Mn5-x(Mn,Fe)1-xO8(OH)6], di cui però non si è raggiunta la certezza. Nel nucleo invece è stato possibile identificare la presenza di strengite-Al [(Fe,Al) (PO4) •2H2O]. La genesi di queste particolari pisoliti è da mettere in relazione con i processi di digestione biologica del guano che all’inizio della loro evoluzione doveva essere abbondante nelle acque che fluivano nella grotta, mentre ora, l’apporto idrico è molto più scarso e proviene da stillicidi che hanno scarsa relazione con il guano medesimo.The Tagusan cave is a hydrologic tunnel in the karst massif hosting the famous Porto Pricesa Underground River in the Palawan Island (Philippines). It hosts some speleothems among which are worth to be cited some black pearls. A few of them have been sampled to be analyzed from the textural and mineralogical point of view. The optical microscope analyses put in evidence that the inner structure of these pearls is un-homogeneous, consisting of a nucleus often made by aggregates of yellowish oolites covered by alternated pitch-dark and reddish layers. The mineralogical analyses find out that the growing layers consist of amorphous phosphates and robertsite [Ca6Mn9(PO4)9O6(H2O)6•3(H2O)], which is here recognized, for the first time, as cave mineral. The x-ray patterns and the EDAX analyses suggest also the presence of janggunite [Mn5-x(Mn,Fe)1-xO8(OH)6], but no definitive proof of it has been yet achieved. Strengite-Al, [(Fe,Al)PO4•2H2O)] is the main component of the yellowish oolites in the pearl’s nucleus. The genesis of these peculiar cave pearls is strictly related to the biological digestion processes of the guano deposits. In fact at the beginning of their evolution the feeding water directly crossed guano deposits, while now the few still active dripping practically has no contact with it

La gradazione dei cristalli di gesso nella Cuevade las Espadas (Naica, Messico): un classico esempio di controllo della sovrasaturazione sui processi di nucleazioneJosè Marìa Calaforra, Paolo Forti, Fernando Gazquez, Laura Sanna

All’interno della Miniera di Naica (Chihuahua, Messico), la parte più interna e profonda della Cueva de las Espadas ospita una sequenza verticale di oltre 5 metri di cristalli di gesso, precipitati sulle pareti della galleria ad opera di fluidi ipogenici risalenti dalla profondità, le cui dimensioni risultano essere perfettamente gradate in modo diretto. Le analisi morfologiche, tessiturali e mineralogiche di questi cristalli, assieme ai dati relativi agli studi geochimici sulle inclusioni fluide in essi presenti, hanno permesso di dimostrare che il processo di gradazione dimensionale è stato controllato dall’oscillazione della falda freatica proprio in corrispondenza del livello di sviluppo della grotta e in un periodo di tempo compreso nell’arco degli ultimi 15.000 anni. Tale oscillazione, oltre ad aver permesso a parte della cavità di emergere a più riprese dalle acque termali, favorì l’instaurarsi di un’alternanza di fenomeni di evaporazione, che coinvolsero relativamente piccoli volumi di acqua a livello del “lago terminale”. A essi fecero seguito brevi periodi in cui le acque profonde risalenti riallagarono quasi totalmente quest’area. In questo contesto la sovrasaturazione risultò essere massima a livello dell’interfaccia acqua-aria e progressivamente registrò un calo verso le parti inferiori dove invece fu minima, limitando così la probabilità di nuova nucleazione e creando il gradiente osservato con una distribuzione continua di grossi individui nelle parti basse della parete che sfumano gradualmente verso l’alto in una densa concentrazione di cristalli più piccoli.In the Naica Mine (Chihuahua, Mexico), the deepest area of the Cueva de las Espadas hosts a 5 m high sequence of gypsum crystals. These crystals were deposited by hypogene uplifting fluids and their dimensions progressively decrease from the floor to the ceiling of the cave. The morphological, textural and mineralogical analyses of these crystals, together with the geochemical data on the fluid inclusions made possible to demonstrate that the dimensional gradation of these crystals was controlled by the swinging of the groundwater just at the level of the cavity and the development of these crystals occurred in the last 15,000 years. The swinging of the groundwater dried up the upper part of the Cueva de las Espadas several times thus inducing the evaporation of relatively small volumes of water confined in “terminal lake” just the deepest part of the cave. These periods were followed by short floods which brought the water practically to refill the whole cavity. The processes induced the supersaturation to be the highest at the air-water boundary and to lower progressively toward the bottom of the lake where it resulted the lowest thus hindering the probability of new nucleation. The result was that the biggest crystals developed on the lake’s bottom while the size of the crystals progressively lowered toward the ceiling