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Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That wilting coefficient, wilting point is the soil moisture content at which plants wilt [16].?

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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
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Your search for oscillation (Keyword) returned 55 results for the whole karstbase:
Showing 1 to 15 of 55
Phreatische Fauna in Ljubljansko polje (Ljubljana-Ebene, Jugoslavien); ihre oekologische Verteilung und zoogeographische Beziehungen., 1981, Sket Boris, Velkovrh Franci
The phreatic basin of Ljubljansko polje (polje = plain, field) recharges its water supply mainly from the Sava river-bed and at a few other locations where connections with karstic subterranean waters might exist and only up to 15% from precipitation. An important zone of infiltration in the river-bed is the bottom and not the bank which is to a large extent watertight due to organic debris (rests of Sphaerotilus e.g.). The main water-body moves about 10 m/day, there are however some local jets with far higher speeds. Yearly amplitudes of water temperatures are high near the river but in the centre of the plain only a couple of centigrades. Oxygen saturation is in the open river-water 100%, dropping to 40-60% just 1 m into the phreatic. True stygopsammal animals are represented here only by a few species and specimen in spite of the fact, that the interstices in the gravel are mostly filled with finer sediments. Remarkable is also the scarcity of Nematodes and the near absence of Acarina (compare with Danielopol 1976). Only a few specimen of the river benthos (Chironomidae, Tipulidae, Leuctra supp., Baets spp.) penetrate the interstitial water (compare with Ruffo 1961, Danielopol 1976) and only Naididae are more frequent there. However, many epigean animals occur in interstitial waters in the periodically flooded gravel-banks; one can explain this with oscillations of the water level. Some epigean animals (creno- and troglophilic) are quite regularly represented in the phreatic near the river, but have not been found in the river-bed. The distribution of phreatic species within the studied water-body seems to be controlled mainly by the presence of food supplies and the consequent competition among species. The same is true for the speed of the water current and some other factors which are less easily defined. The characteristics of the substratum as well as O2-saturation and other characteristics of the water seem to have little influence on the fauna. The energetically (food-) rich neighbourhood of the river is inhabited by a number of species in quite dense populations while the central parts of the phreatic water body exhibit a great poverty of species and of specimen. However, some species live here, which don't occur in the presence of larger food supplies and of greater competition (Niphargus serbicus). The higher current speed seems to prevent settlement of some species (Cyclopoida, Proasellus deminutus) while some are bound to such habitats (Proasellus vulgaris). Some species exhibit a high degree of euryvalency inside the stygopsephale habitats (Niphargus longidactylus e.g.), while some are highly specialized. Some of them form dense populations (comparatively dense even in energetically poor places) while others exhibit even in most favourable conditions very low densities (Niphargus jovanovici multipennatus). The present fauna is zoogeographically very diverse. Some species are distributed throughout Europe; some reach from Central Europe to the borders of Dinaride Karst (Bogidiella albertimagni) and some even penetrate it (Trichodrilus pragensis, Acanthocyclops kiefer). Bogidiella semidenticulata. Niphargus pectinicauda, Hadziella deminuta seem to be limited to the higher reaches of the Sava River. All of the above mentioned animals live regularly in interstitial waters and only sporadically in karstic hypogean waters. Niphargus stygius is here the only animal of a certainly karstic provenience; inside the plain it is limited to a completely special habitat. It is very likely that the entire Proasellus-deminutusgroup has developed in interstitial waters of larger plains which are in contact with karstic areas; some species penetrated from the plains into the karst rather than the reverse. To the contrary (judging from the distribution of the genera) karstic waters seem to be the cradle of Hauffenia and Hadziella. Such a sharp delimitation between cave- and interstitial fauna resp. in this area is very noteworthy. Both faunas live here in abundance and in close contact. It is very probable that particularly high competition and specialization of both faunas, caused by their richness and diversity, prevent mixing of species.

Quelques aspects du karst en Chine, 1985, Tricart, J.
Some characteristic features of karst in China Karst terrain is widespread in China: some 2,000,000km2, corresponding to 20-25% of the whole surface of the country. It occurs at very different altitudes and under quite different climates, from the region of Zhoukoudian, where has been found the skull of the Pekin Man, to the Tibet Plateau, where there is presently permafrost conditions, and up to southern tropical moist China, near Canton and Guilin. Recent chinese investigations have proved that most karst features are old. In Southern China a tropical karst (tower-karst or "mogotes" karst) is associated with lacustrine deposits containing the well-known Hipparion Fauna, of Miocene age. Its predates the intensive uplift of the Himalaya and of the Tibet, which has begun during the Pliocene and has continued during all the Pleistocene. The same fossils have been found in this tropical karst in present permafrost areas, above 5,000m. In the region of Guilin (Guangxi Province), this tropical karst has been described. There is evidence for the former existence of a covered karst, where limestones and dolomitic limestones were covered by a thick layer of reddish residual clays, with limonite. This mantle has been stripped during different periods of drier and probably cooler climate, has suggested by pollen spectra. In some places, these residual products have been trapped into pits, cracks, and caves. We have observed a small quantity of red clay painting limestone stalactites and sinters (Chuanshan and Leng Yin Yen Caves, in the surroundings of Guilin). They present sometimes a mining interest and some extractive industries are presently active (limonite, cassierite, etc.). Many caves have been surveyed by the Institute of Karst geology, in Guilin. Some have been equiped for tourism, around Guilin. All these caves are old. Some radiocarbon dating of speleothems yield ages of 33,000 year BP. The famous carving of the Leng Yen Cave have not been affected by calcite deposition from dripping since at least 500 years. The large caves that have been surveyed should correspond to a long evolution span. Along the Lijiang River, at least two terraces can be observed. They are built with gravels and pebbles, covered with thinner sand and loam, suggesting climatic changes, also attested by the changes of fauna and vegetation. These past cooler periods are characterised by an opened vegetation, with the striping of the old weathering cover of the former tropical karst. These karst terrains have been investigated in China for management purposes. Groundwater oscillations have frequently resulted in land subsidences damaging buildings, and in dramatic collapses destroying fields, roads. Sometimes, underground collapse plugged caves and dammed underground rivers, resulting in floodings. The caves are frequently used as reservoirs for irrigation and power plants.

Niveaux marins, chronologie isotopique et karstification en rpublique dominicaine, 1993, Diaz_del_olmo F. , Camara_artigas R.
The study of marine levels and the karstification of coral reefs on the Santo Domingo coast emphasizes qua-ternary dynamics linked to climatic variations and eustatic oscillations. The evolution proposed here includes the last 400 000 years (U/Th limit) and shows the importance of stages 1, 5 and 7 (interglacial stages) in the layout of coral reefs. As far as karstifiction is concerned, the differences observed between ancient and more recent times can be accounted for by a tendancy to the drying out of the intertropical morphoclimatic system.

The astronomical theory of climate and the age of the Brunhes-Matuyama magnetic reversal, 1994, Bassinot Fc, Labeyrie Ld, Vincent E, Quidelleur X, Shackleton Nj, Lancelot Y,
Below oxygen isotope stage 16, the orbitally derived time-scale developed by Shackleton et al. [1] from ODP site 677 in the equatorial Pacific differs significantly from previous ones [e.g., 2-5], yielding estimated ages for the last Earth magnetic reversals that are 5-7% older than the K/Ar values [6-8] but are in good agreement with recent Ar/Ar dating [9-11]. These results suggest that in the lower Brunhes and upper Matuyama chronozones most deep-sea climatic records retrieved so far apparently missed or misinterpreted several oscillations predicted by the astronomical theory of climate. To test this hypothesis, we studied a high-resolution oxygen isotope record from giant piston core MD900963 (Maldives area, tropical Indian Ocean) in which precession-related oscillations in [delta]18O are particularly well expressed, owing to the superimposition of a local salinity signal on the global ice volume signal [12]. Three additional precession-related cycles are observed in oxygen isotope stages 17 and 18 of core MD900963, compared to the composite curves [4,13], and stage 21 clearly presents three precession oscillations, as predicted by Shackleton et al. [1]. The precession peaks found in the [delta]18O record from core MD900963 are in excellent agreement with climatic oscillations predicted by the astronomical theory of climate. Our [delta]18O record therefore permits the development of an accurate astronomical time-scale. Based on our age model, the Brunhes-Matuyama reversal is dated at 775 10 ka, in good agreement with the age estimate of 780 ka obtained by Shackleton et al. [1] and recent radiochronological Ar/Ar datings on lavas [9-11]. We developed a new low-latitude, Upper Pleistocene [delta]18O reference record by stacking and tuning the [delta]18O records from core MD900963 and site 677 to orbital forcing functions

Etapes et facteurs de la splogense dans le sud-est de la France, 1995, Blanc, J. J.
The examination of karstic erosion surfaces and of some caves presents three stages of unequal duration in the speleogenesis processes : 1) Oldest paleokarsts linked to a tropical and oxydizing climate (Cretaceous, Eocene, Oligocene and Miocene) are affected by the tectonic effects in relation with the western European and liguro-provencal riftings, the mediterranean opening phases and the main karstic levelling. 2) The Messinian crisis, characterized by a significant lowering of the water-table level, is responsible for a major vertical network development and the first canyon sinking phase; hence the erosion of the high surfaces and the drying up of networks. The formation of new over-sized karst is the result of this evolution. 3) From Pliocene (5.3 My) to Quaternary and present time (passive mediterranean margins), the karstic evolution tends towards new drainages and volumes adjusted to the next climatic and eustatic control, with several oscillations and discontinuities. After a compression period, there is a slowing down of the tectogenesis. We can observe orientation flow changes and speleogenesis induced by cold and wet climatic phases. From Tardiglacial times, speleogenesis mechanisms have slowed down.

CYCLOSTRATIGRAPHY OF MIDDLE DEVONIAN CARBONATES OF THE EASTERN GREAT-BASIN, 1995, Elrick M,
Middle Devonian carbonates (250-430 m thick) of the eastern Great Basin were deposited along a low energy, westward-thickening, distally steepened ramp. Four third-order sequences can be correlated across the ramp-to-basin transition and are composed of meter-scale, upward-shallowing carbonate cycles (or parasequences). Peritidal cycles (shallow subtidal facies capped by tidal-flat laminites) constitute 90% of all measured cycles and are present across the entire ramp. The peritidal cycles are regressive- and transgressive-prone (upward-deepening followed by upward-shallowing facies trends). Approximately 80% of the peritidal cycle caps show evidence of prolonged subaerial exposure including sediment-filled dissolution cavities, horizontal to vertical desiccation cracks, rubble and karst breccias, and pedogenic alteration; locally these features are present down to 2 m below the cycle caps. Subtidal cycles (capped by shallow subtidal facies) are present along the middle-outer ramp and ramp margin and indicate incomplete shallowing. submerged subtidal cycles (64% of all subtidal cycles) are composed of deeper subtidal facies overlain by shallow subtidal facies. Exposed subtidal cycles are composed of deeper subtidal facies overlain by shallow subtidal facies that are capped by features indicative of prolonged subaerial exposure (dissolution cavities and brecciation). Average peritidal and subtidal cycle durations are between approximately 50 and 130 k.y. (fourth- to fifth-order). The combined evidence of abundant exposure-capped peritidal and subtidal cycles, transgressive-prone cycles, and subtidal cycles correlative with updip peritidal cycles indicates that the cycles formed in response to fourth- to fifth-order, glacio-eustatic sea-level oscillations. Sea-level oscillations of relatively low magnitude (< 10 m) are suggested by the abundance of peritidal cycles, the lack of widely varying, water-depth-dependent facies within individual cycles, and the presence of noncyclic stratigraphic intervals within intrashelf-basin, slope, and basin facies. Noncyclic intervals represent missed subtidal beats when the seafloor lay too deep to record the effects of the short-term sea-level oscillations. Exposure surfaces at the tops of peritidal and subtidal cycles represent one, or more likely several, missed sea-level oscillations when the platform lay above fluctuating sea level, but the amplitude of fourth- to fifth-order sea-level oscillation(s) were not high enough to flood the ramp. The large number of missed beats (exposure-capped cycles), specifically in Sequences 2 and 4, results in Fischer plots that show poorly developed rising and falling limbs (subdued wave-like patterns); consequently the Fischer plots: are of limited use as a correlation tool for these particular depositional sequences. The abundance of missed beats also explains why Milankovitch-type cycle ratios (similar to 5:1 or similar to 4:1) are not observed and why such ratios would not be expected along many peritidal-cycle-dominated carbonate platforms

The influence of climatic change on exposure surface development: a case study from the Late Dinantian of England and Wales, 1996, Vanstone Simon,
Exposure surfaces represent an integral part of Asbian-Brigantian cyclothemic platform carbonates in England and Wales. These are characterized by the association of clay palaeosols, calcrete and palaeokarst and in most instances would appear to have been polygenetic. Alternating calcrete-karst stratigraphies associated with individual exposure surfaces indicate that the climate changed from semi-arid to humid to semi-arid conditions during each sea-level fall/rise cycle. Lowstand intervals were humid and resulted in karstification of the cyclothem-top sediments and the formation of a mineral soil. In contrast, regressive/transgressive phases were semi-arid and resulted in calcretization of the emergent platform carbonates. The influence that climatic cyclicity had upon exposure surface development was modulated by variations in platform bathymetry, subsidence and spatial climatic variation, and platforms exhibit their own individual record of what was essentially an idealized sequence of events. As with the sea-level oscillations responsible for cyclothemic sedimentation, the climatic cyclicity is thought to be the product of orbital forcing and probably reflects either eccentricity-driven shifts in the locus of monsoonal precipitation, or precession-driven variations in monsoonal intensity. If precessional in origin, exposure surface development represents a single minimum to minimum excursion, some 20 ka in duration, whereas if eccentricity-driven this may have been appreciably longer. Nevertheless, the immature nature of the exposure surfaces suggests that emergence was probably only of the order of a few tens of thousands of years

High-resolution temporal record of Holocene ground-water chemistry; tracing links between climate and hydrology, 1996, Banner Jl, Musgrove M, Asmerom Y, Edwards Rl, Hoff Ja,
Strontium isotope analysis of precisely dated calcite growth layers in Holocene speleothems from Barbados, West Indies, reveals high-resolution temporal variations in ground-water composition and may provide a new approach to documenting the links between climate variability and fluctuations in the hydrologic cycle such as recharge rates and flow paths. The speleothems grew in a cave that developed in a fresh-water aquifer in uplifted Pleistocene reef limestones. Three periods of ground-water Sr isotope evolution are observed: 87 Sr/ 86 Sr values decreased from 6 to 4 ka, increased from 4 to 1 ka, and decreased again after 1 ka. The Sr isotope oscillations appear to record periodic variations in the relative Sr fluxes to ground water from exchangeable soil sites vs. carbonate mineral reactions, as reflected in 87 Sr/ 86 Sr values of modern Barbados ground waters. A hydrologic model that explains changes in ground-water flow routes in karst aquifers as a function of amount of rainfall recharge can account for the speleothem Sr isotope record. Independent Holocene climate records that indicate a major period of aridity at around 1.3-1.1 ka in the American tropics correspond with periodic variations in rainfall on Barbados that are predicted by this hydrologic model

Interprtation morphomtrique et splo_gense : exemple de rseaux karstiques de Basse-Provence (directions de galeries, modle et maillage structural), 1997, Blanc Jeanjoseph, Monteau Raymond
Successive tectonic phases on limestone massifs are at the origin of a fracturation grid with several pattern dimensions, and linear or organized drain directions. Mechanical reactivations are observed from Oligocene until Plio-Quaternary on a former "pyreneo-provenale" structure (Eocene). Statistical analysis of gallery and fracture directions, cave levels and descent stages (overdeepening) show several erosional stages occurring after the formation of the Antevindobonian erosional surface. The active speleogenesis during Oligocene and Miocene was controlled by tectonics in connection with European rifting and mediterranean opening. In Messinian a short and significant lowering of mediterranean base level (and water table) made drastic erosion and created vertical pits. The horizontal cave level dug during the stabilization phase of Pliocene, now perched over underground rivers, shows a new overdeepening because of glacio-eustatic Quaternary oscillations. Compressive or distensive mechanical reactivations (Upper Miocene, Pliocene, Quaternary) modified the drainage and consequently the cave organization: self-piracy, confluence and diffluence. In the endokarst, the drainage inversion can be detected in late Upper continental Miocene and early Messinian (6,5 Ma), in correlation with the tilting and extension of the continental margin. Five caves in Provence are studied: Sabre, Petit Saint-Cassien, Rampins, Planesselve river, and Tete du Cade networks.

Geochemistry and water dynamics: Application to short time-scale flood phenomena in a small Mediterranean catchment .1. Alkalis, alkali-earths and Sr isotopes, 1997, Benothman D, Luck Jm, Tournoud Mg,
We report major, trace elements and Sr isotope data for water samples taken regularly during a four-day-long September flood of a Mediterranean river, the Vene (Herault, S. France). The objective is to combine all these data into a dynamic model that describes the origin(s) and movements of waters and their loads. This river drains the runoff from a small, mainly carbonate, partly karstified watershed with Miocene and Jurassic lithologies. The watershed is also impacted by both agricultural and urban activities. Both the dissolved and the particulate loads were analyzed. Concentrations of the dissolved components show major remobilization of almost all elements during the first few hours of the flood (water treatment plants and aerosol scavenging), followed by a sharp concentration decrease. Some major species return to their previous summer values (Ca, HCO3) while others reach low 'background' levels (Na, K, Cl, SO4). Some trace elements (Rb, Sr, Cs) show similar behaviour but (Ba) appears somewhat unaffected. Trace element concentrations and ratios define two main periods (three in the suspended particulate matter). Ratios do not allow distinguishing between the three main sources for the dissolved load in the first period (Miocene, Jurassic, water treatment plants), but clearly show the Jurassic karst influence later on. The Sr-87/Sr-86 Of the suspended particulate matter is more variable and more radiogenic than in the dissolved phase. Variations in concentration ratios and Sr isotope composition in particulates indicate the large and variable contribution of Miocene silicates with some carbonate. However, there is a need for another component with [Rb]/[Sr] higher than bedrocks, internal or external to the watershed, possibly due to differential erosion. Dissolved Ca and Mg fluxes during the flood were calculated at 0.26 ton and 0.029 ton/km(2), respectively. Even though the carbonate nature of the watershed restricts variability in Sr isotope composition in the dissolved load, we distinguish several endmembers: seawater(approximate to marine rain), Miocene marls, Jurassic limestones, water treatment plants (and possibly another attributable to fertilizers). Combined with major and trace element variational Sr isotope fluctuations indicate time-varying proportions of different water endmembers at the outflow and suggest a general dynamic model. Based on PCA (principal component analysis), a 3D representation allows to visualize the geochemical evolution of the Vene waters. In particular, Sr isotopes clearly indicate that the inflow of karstic waters during the flood was not continuous but occurred as a series of marked oscillations between flowing waters with chemical signature of Miocene lithologies and increasing flushes of deeper waters that interacted with Jurassic lithologies. (C) 1997 Elsevier Science B.V

Drip flow variations under a stalactite of the Pere Noel cave (Belgium). Evidence of seasonal variations and air pressure constraints, 1998, Genty D, Deflandre G,
The study of drip rate and seepage water electrical conductivity (hereafter called conductivity) under one stalactite in the Pere Noel cave (Belgium), with data produced from an automatic station since 1991, demonstrates several previously unobserved features: (1) measurement of drop volume shows that, for 94% of the time series, drop volume is constant (= 0.14 ml), but when discharge exceeds 48.2 drips min(-1), drop volume decreases, probably because of secondary drop formation; (2) the interannual drip rate variation is correlated to the annual water excess and its correlant, rainfall (R-2 = 0.98; exponential model); this result introduces a new improvement in the understanding of the previously investigated relationships between stalagmite annual laminae thickness and mean annual rainfall; (3) the drip rate shows a well marked seasonality: it increases abruptly in late fall or early winter and decreases slowly during spring, summer and fall. Increased discharge is accompanied by an increase in conductivity, which suggests that the flushed water is more mineralized and was stored in the karst aquifer for several months; (4) superimposed on these seasonal variations, there are two kinds of flow regimes which are driven by the atmospheric pressure: (i) a 'wiggles regime', whose duration is 1-7 days in length and which is inversely proportional to the air pressure wiggles; it is explained by either a ''shut-off faucet'' process due to the rock formation stress, or to a change in the two-phases flow component proportions (air/water); (ii) an 'unstable regime' characterized by abrupt switches (<2 h) or oscillations with variable periodicities, from a few minutes to a few hours. These occur when the drip rate reaches a threshold (i.e. 240 drops 10 min(-1)); the chaotic behaviour of this phenomenon is discussed. (C) 1998 Elsevier Science B.V. All rights reserved

Contribution to knowledge of gypsum karstology, PhD thesis, 1998, Calaforra Chordi, J. M.

The objective of this study was not to establish a definitive judgement regarding a topic for which very little previous information was available, but rather to open new routes for research into karst by means of a particularized analysis of some of the factors involved in the speleogenesis of gypsiferous materials. The main obstacle to the attainment of this goal has been the scientific community's lack of interest in karst in gypsum, particularly in our country, until the nineteen eighties. To overcome this neglect it was decided, in my opinion quite correctly, to extend the bounds of the study as far as possible, so that the information obtained from the contrast found between the most important worldwide zones of karst in gypsum could be applied to the gypsiferous karst in our country, and in particular, to the most significant, the karst in gypsum of Sorbas.
This is the justification for the numerous references in the text to the gypsiferous karst and cavities in gypsum that are most relevant in Spain (Sorbas, Gobantes, Vallada, Archidona, Estremera, Baena, the Ebro Basin, Estella, Beuda, Borreda, etc.) and also to the best-known gypsiferous karsts worldwide (Podolia, Secchia, Venna del Gesso Romagnolo, Sicily and New Mexico). By means of these comparisons, the initial lack of information has been overcome.
The study is based on three central tenets, which are interrelated and make up the first three chapters of this report. The first consideration was to attempt to characterize the particular typology of gypsiferous karst from the geological (both stratigraphic and structural) point of view. This chapter also provides an introduction to each of the gypsiferous karsts examined. The second chapter is dedicated to the geomorphology of gypsiferous karst, under both superficial and subterranean aspects. It is important to note that the study of a gypsiferous karst from the speleological point of view is something that may seem somewhat unusual; however, this is one of the points of principle of this paper, the attempt to recover the true meaning of a word that has historically been unfairly condemned by a large part of the Spanish scientific community. Thirdly, a detailed study has been made of the hydrochemistry of the most important gypsiferous karsts in our region, together with the presentation of a specific analytical methodology for the treatment of the hydrochemical data applicable to the gypsiferous karst.
Geological characterization of gypsum karst
In the characterization of karst in gypsum, the intention was to cover virtually all the possibilities from the stratigraphic and structural standpoints. Thus, there is a description of widely varying gypsiferous karsts, made up of Triassic to Miocene materials, some with a complex tectonic configuration and others hardly affected by folding. The gypsiferous karsts described, and their most significant geological characteristics, are as follows:
Karst in gypsum at Sorbas (Almeria): composed of Miocene gypsiferous levels with the essential characteristic of very continuous marly interstrata between the layers of gypsum, which decisively affect the speleogenesis of the area. The gypsum layers have an average thickness of about 10 m and, together with the fracturing in the zone, determine the development of the gypsiferous cavities. These are mainly selenitic gypsum - occasionally with a crystal size of over 2 m - and their texture also has a geomorphologic and hydrogeologic influence. This area is little affected by folding and so the tectonic influence of speleogenesis is reduced to the configuration of the fracturing.
The Triassic of Antequera (Malaga): this is, fundamentally, the gypsiferous outcrop at Gobantes-Meliones, originating in the Triassic and located within the well-known "Trias" of Antequera. It is made up of very chaotic gypsiferous materials containing a large quantity of heterometric blocks of varied composition; the formation may be defined as a Miocene olitostromic gypsiferous breccia that is affected by important diapiric phenomena. The presence of hypersoluble salts at depth is significant in the modification of the hydrochemical characteristics of the water and in the speleogenetic development of the karst.
The Triassic of Vallada (Valencia): Triassic materials outcrop in the Vallada area; these mainly correspond to the K5 and K4 formations of the Valencia Group, massive gypsum and gypsiferous clays. The influence of dolomitic intercalations in the sequence is crucial to the speleogenesis of the area and this, together with intense tectonic activity, has led to the development in this sector of the deepest gypsiferous cavity in the world: the "Tunel dels Sumidors". As in the above case, the presence of hypersoluble salts at depth and the varied lithology influence the variations in the hydrodynamics and hydrochemistry of the gypsiferous aquifer.
Other Spanish gypsum karsts: this heading covers a group of gypsiferous areas and cavities of significant interest from the speleogenetic standpoint. They include the area of Estremera (Madrid), with Miocene gypsiferous clays and massive gypsum arranged along a large horizontal layer; this has produced the development of the only gypsiferous cavity in Spain with maze configuration, the Pedro Fernandez cave. The study of this cave has important hydrogeological implications with respect to speleogenesis in gypsum in phreatic conditions. The Baena (Cordoba) sector, in terms of its lithology, is comparable to the "Trias de Antequera". Here, the cavities developed in gypsiferous conglomerates, following structural discontinuities have enabled contact between carbonate and gypsiferous levels, and so we may speak of a mixed karstification: a karst in calcareous rocks and gypsum. The karst of Archidona (Malaga) is similar to that of the Gobantes-Meliones group and is significant because of the geomorphologic evolution of the karst, which is related to the diapiric ascent of the area and the formation of karstic ravines. The karst in the Miocene and Oligocene gypsum of the Ebro Basin (Zaragoza), has been taken as a characteristic example of a gypsiferous karst developed under an alluvial cover, with the corresponding geomorphological implications in the evolution of the surface landforms. In the gypsiferous area of Borreda (Barcelona), the presence of anhydritic levels in the sequence might have influenced the speleogenesis of its cavities. The cavity of La Mosquera, in Beuda (Girona), developed in massive Paleogene gypsum. This is the only Spanish example of a phreatic gypsiferous cavity developed in saccaroid gypsum, which is related to the particular subterranean morphology discovered. Finally, this group includes other Spanish gypsiferous outcrops visited during the preparation of this report, the references to which may be found in the relevant chapters.
Karst in gypsum in Europe and America: In order to complete the study of karst in gypsum, and with the idea of using all the available data on the karstology of gypsiferous materials for comparative studies of data for our country, a complementary activity was to define the most significant geological characteristics of the most important gypsiferous karsts in the world. An outstanding example is the gypsiferous karst at Podolia (Ukraine), developed in microcrystalline Miocene gypsum which has undergone block tectonics related to the collapse of the Precarpatic foredeep. This gypsum provides interesting data on speleogenesis in gypsiferous materials, as its evolution is related to the confining of the only gypsiferous stratum (of 10 to 20 m depth) producing interconnected labyrinthine galleries of over 100 km in length. Another well-known karst in gypsum is the one located at "Venna del Gesso Romagnolo" (Italy), in the Bologna region, with a lithology that is very similar to that which developed at Sorbas, but with the difference that it underwent more intense tectonics with folding and fracturing of the Tertiary sediments of the Po basin. In the same Italian province, in "L'alta Val di Sec-chia", there are outcrops of karstified Triassic materials which correspond to the formation of Burano, composed of gypsum and anhydrite with hypersoluble salts at depth and very notable diapiric phenomena. The study of this area has been used for a comparative analysis - geomorphology and hydrogeochemistry - with the Spanish gypsiferous karsts developed in Triassic levels. The third Italian gypsiferous karst to be considered is the one developed in Sicily, which has extensive Messinian outcrops of microcrystalline and selenitic gypsum as well as a great variety of lithologic types within the gypsiferous sequence, which we term the "gessoso solfifera" sequence. This gypsiferous karst is especially interesting from the geomorphologic standpoint due to the great quantity and variety of present superficial karstic forms. This has also served as a guide for the study of Spanish gypsiferous karsts. Finally, considering the relation between climatology and the development of karstic forms, we have also studied the karst in gypsum in New Mexico, where there is an extensive outcrop of Permian gypsum, both micro and macrocrystalline, situated on a large platform almost unaffected by deformation, and where the conditions of aridity are very similar to those found in the gypsiferous karst of Sorbas.
Geomorphological characterization of gypsum karst
From the geomorphological standpoint, the intention is to give an overview of the great variety of karstic forms developed in gypsum, traditionally considered less important than those developed in carbonate areas. This report shows this is not the case.
The theory of Convergence of Forms has been shown to be an efficient tool for the study of the morphology of karst in gypsum. Here, its principles have been used to provide genetic explanations for various gypsiferous forms derived from carbonate studies, and for the reverse case. In fact, studying a karst in gypsum is like having available a geomorphological laboratory where not only are the processes faster but they are also applicable to the karstology of carbonate rocks.
A large number of minor karstic forms (Karren) have been identified. The most important factors conditioning their formation are the texture of the rock, climatology and the presence of overlying deposits. The first, particularly, is largely responsible for determining the abundance of certain forms with respect to others. Thus, Rillenkarren, Trittkarren and small "kamenitzas" are more frequently found in microcrystalline and sandstone gypsum (for example, karst in gypsum in Sicily (Italy) and Va-llada (Valencia, Spain). Others seem to be more exclusive to selenitic gypsum, such as exfoliation microkarren, or are closely related to the climatology of the area (Spitzkarren develops from the alteration of gypsum in semiarid conditions). Others are related either to the presence of developed soil cover (Rundkarren, using Convergence of Forms), or to their specific situation (candelas and Wallkarren around dolines and sinkholes) or to the microtexture of the gypsum and the orientation of the 010 and 111 crystalline planes and twinning planes for the development of nanokarren.
The tumuli are the most peculiar forms of the Sorbas karst in gypsum, though they have also been identified in other gypsiferous karsts (Bolonia, New Mexico, Vallada, etc.). These are subcircular domes of the most superficial layer of the gypsum. Their formation has been related to processes of precipitation-solution and of capillary movement through the gypsiferous matrix. Their extensive development is largely determined by the climatology of the area and by the structural organization. It is therefore clear that the best examples are found in the karst of Sorbas due to the abrupt changes in temperature and humidity that occur in a semiarid climate, and because of the horizontality of the gypsiferous sequence.
Karst in gypsum and its larger exokarstic forms, apart from being climatically determined, also depend on the structural state and lithological determinants of the area. Thus, it is possible to differentiate between gypsiferous karsts where the lithology, together with erosive breakup, is more important (Sorbas and New Mexico) and others where confining hydraulic conditions persist (Estremera and Podolia). In other cases, tectonics has played a significant modelling role, and there is a clear possibility of an inversion of the relief (Bolonia or Sicily) or of the effect of diapiric processes (Secchia, Vallada, Antequera). The typological diversity of the dolines is obviously also related to these premisses. Another example is the relation existing between carbonate precipitation and gypsum solution, as evidenced in contrasting examples (Bolonia versus Sorbas).
Subterranean karstic forms have been examined from a double perspective: the morphology of the passages and the mineralization within the cavities. With respect to the former, a noteworthy example is the interstratification karst of Sorbas, where subterranean channels have developed during two well-differentiated phases, the phreatic and the vadose. The first was responsible for the formation of the small proto-galleries, currently relicts that are observable as false dome channels in the bottom of the gypsiferous strata. The second, with an erosive character, enabled the breakup of the marly interstrata and the formation of the large galleries found today. Other aspects considered include the speleogenetic influence of the presence of calcareous intercalations in the gypsiferous sequence (Vallada karst), gypsiferous agglomerates (Baena karst), anhydrite (Rotgers karst), suffusion processes (Sorbas karst) and the importance of condensation.
Spelothemes in gypsiferous cavities have been approached with special concern for gypsiferous speleothemes, in particular those which, due to their genetic peculiarity or to the lack of previous knowledge about them, are most significant. Among these are gypsum balls, with phenomena of solution, detritic filling, capillarity and evaporation; gypsum hole stalagmites, where the precipitation-solution of the gypsum controlling the formation of the central orifice is related to the previous deposit of carbonate speleothemes; gypsum trays that mark the levels of maximum evaporation; gypsum dust, determined by abrupt changes in temperature and humidity in areas near the exterior of gypsiferous cavities. All of these are characteristic of, and practically exclusive to, gypsiferous karsts in semiarid ztenes such as Sorbas and New Mexico.
Karst in gypsum has been morphologically classified with reference to the previously-mentioned criteria: the presence and typology of epigean karstic forms, both macro and microform; the typology of hypogean karstic forms (passages) and the type of speleothemes within the cavities (gypsiferous or carbonate). All these variables are clearly influenced by climatology, and so a study of the geomorphology of gypsiferous karst is seen to be an efficient tool for the analysis of the paleoclimatology of an area.
Hydrogeochemical characterization of gypsum karst
The hydrogeochemical characterization of karst in gypsum was approached in two stages. The first one was intended to establish themodels to be applied to the hydrochemistry approach, while the second provided various examples of hydrochemical studies carried out in gypsiferous karsts.
The theoretical framework which has been shown to be most accurate with respect to the formulation of chemical equilibria in water related to gypsiferous karst is the Virial Theory and the Pitzer equations.
For this study, we used a simplification of these equations as far as the second virial coefficient by means of a simple, polynomial variation to obtain the equilibrium state of the water with respect to the gypsum, for an ionic strength value greater than 0.1 m and temperatures of between 0.5 and 40 "C. This was the case of the gypsiferous karsts found to be related to hypersaline water at depth (Vallada, Gobantes-Meliones, Poiano). In the remaining situations, where the ionic strength was below 0.1 m, only the theory of ionic matching was used.
The hydrochemical study of the gypsiferous karst of Gobantes-Meliones (Malaga) led to the hypothesis of the possible influence of hypersaline water on karstification in gypsum. Using theoretical examples of the mixing of water derived both from hypersaline water and from water related only to the gypsiferous karst, it was shown that above a percentage content of 0.1:0.9 of saline and sulphated water, the mixture is subsaturated with respect to gypsum and other minerals. On reaching percentages greater than 0.5:0.5, values of oversaturation are again found. This could mean that the contact between sulphated and hypersaline water is a karstification zone in gypsum at depth.
In the gypsiferous karst at Salinas-Fuente Camacho (Granada), a study has been made of the hydrochemical influence of dolomitic levels in the sequence by means of the analysis of the hydrochemical routes between hydraulically-connected points. The generic case of mass transfer in this gypsiferous aquifer implies a precipitation of calcite which is in-congruent with dolomitic solution, proving that the process of dedolomitization in gypsiferous aquifers with an abundance of dolomitic rocks can be an effective process. In situations of high salinity, with contributions of hypersaline water, the process may be inverted, such as occurs in coastal carbonate aquifers influenced by the fresh-saltwater interface.
The gypsiferous aquifer of Sorbas-Tabernas (Almeria) provides the best case of karstification in gypsum in Spain; the hydrochemical study carried out has been used as an example of karstification in gypsum completely uninfluenced by sodium-chloride facies. It is shown, from the hydrochemical similarities between the different sectors, that the uniformity of the flow from the system main spring (Los Molinos) responds to the delayed hydraulic input through the overlying post-evaporitic materials and to the pelitic intercalations of the gypsiferous sequence. The aquifer is partially semiconfined, a situation which is comparable to the onset of the karstification stage, while the area of the Sorbas karst, strictly speaking, bears no hydriaulic relation to the rest of the system, behaving like a free aquifer intrinsically related to the epikarstic zone. This fact is demonstrated by the hydrochemical differences between the main spring and those related to gypsiferous cavities.
Apart from the general study of the Sorbas-Tabemas aquifer, a study was also made of the hydrochemical-time variations within cavities, and in particular within the Cueva del Agua, where it is possible to observe particular processes affecting karstification in gypsum, such as the precipitation of carbonates on the floor of the cavity which produce, in that area, a greater solution of gypsum (the phenomenon of hyperkarstification). Furthermore, the temporal evolution of the chemistry of the cavity, along 800 m of subterranean flow through its interior, shows the existence of inertial sectors where the variations were less abrupt. Only in the case of particular sectors, related to sporadic hydriaulic contributions or to the proximity to points of access., was a notable seasonal influence detected.
A similar hydrochemical study was carried out in the karst of Vallada (Valencia), along the cavity of the Tunel dels Sumidors. The chemistry here was compared with that of the springs of Brolladors (whose water rapidly infiltrates into the cavity) and Saraella (a saline resurgence of the whole system). Unexpected increases in the ionic content of certain salts (sulphates and chlorides) were detected during periods of increased flow; these were interpreted as the effect of the recharging of the Saraella spring arising from the immediate contribution of rapidly circulating sulfated water coming from the cavity and the subsequent mobilization of interstitial water with an ionic content higher than the characteristic level of the spring.
We present as a hypothesis the idea that, in addition to the hydrogeochemical processes described that can affect the evolution of a gypsiferous karst, the processes of sulphate reduction also influence karstification in gypsum, at least during the earliest stages. Some examples such as the presence of gypsum with abundant organic matter reprecipitated into phreatic channels (Sorbas) or veins of sulphur related to gypsiferous karsts (Podolia, Sicily) lend support to this idea.
Studies of the solution-erosion of gypsum have been performed by physical methods (tablets and M.E.M.) showing that the solution-erosion of gypsum within cavities is minimal (0.03 mm/ year) compared to that existing in the exterior (0.3 mm/year). The speleogenetic effect of condensation within the cavities has also been shown, with solution-erosion rates of 0.005 mm/year to be like the equivalent surface lowering. These data correspond to the karst in gypsum at Sorbas, where, additionally, a study about the time variation of the solution-erosion was carried out. It was found that the process is not continuous but clearly sporadic. During periods of torrential rain, the solution-erosion ranges from a weight loss of 400 mg/cm2/year on the surface of the karst to 75 mg/cm2/year inside the caves, while during the rest of the year the weight loss was barely 1 mg/cm2/year. The physical methods were compared with the results obtained from chemical methods, and it was found that, in general, higher values were obtained with the former (10-20% higher when weighted for the rainfall during the measuring periods). Thus it is reasonable to consider that the erosive process is more marked than was at first assumed.
In total, three cavity tracing experiments were carried out, all with fluoresceine, two of them in Cueva del Agua in Sorbas (during periods of high and low water levels) and the other in Tunel dels Sumidors in Vallada. At the first site, the comparison of the two tracing tests reveals a differential hydrodynamic behaviour of the cavity for the two contrasting situations; periods of high water input and periods of low rainfall. This behaviour is characteristic of well developed karstic aquifers, where the hydrodynamic effect of the circulation of water through small channels or, in this case, through the gypsiferous matrix and interbedded marly layers, seems to be more important under conditions of low hydraulic input than when rainfall is abundant. The two situations tested seem to confirm that the Cueva del Agua system, an epikarstic aquifer, which is representative of karstification in gypsum, has scarce retentive power and so large volumes of precipitation are totally discharged via the spring within a few days. However, the explanation of the small but continuous flow from the base of the cavity requires the inclusion of other factors in the interpretation. In this case, the flow seems to be fairly independent of rainfall and attributable to other processes, in addition to the previously described ones, such as the retentive power of the gypsiferous matrix and the marly interstrata. These might include the high degree of condensation measured over long periods, both on the surface of the karst in gypsum and within the cavities. In the case of the Tunel dels Sumidors, a highly irregular response was found, despite the fact that the coefficient of dispersivity was found to be 0.4. This value is similar to that obtained for the karst in gypsum at Sorbas in response to low water conditions, and so, here too, one might assume the influence of greater than expected flow-retaining processes, between the entry and exit points. Doubtless the karstic system of the Tunel dels Sumidors is more complex than was initially expected and in fact, the irregularity reflected by the fluoresceine concentration curve over time implies the existence of other factors to explain the diversity of the relative maxima obtained. Firstly, the presence of numerous Triassic clay intercalations might delay the flow, in addition to retaining a certain quantity of fluoresceine by ionic exchange. There is also a possibility that the flow is dispersed through a network of small conduits and pores, due to the permeability of the gypsiferous matrix. Finally, we cannot discount the possible existence of a deep-level input which, in this case, would be responsible for the variation in the flow and the chemical composition. This set of suppositions, as a whole, would explain the fact that the response of the spring to tracing is so irregular, even though we cannot achieve a definition of the qualitative influence of each one on the hydrodynamics of the system.
In order to verify some of the above hypotheses, particularly those referring to the process of condensation within cavities, an experiment was designed, consisting of a microtracing test at some points where condensation had been detected within the Cueva del Agua at Sorbas. The test produced a range of condensation flow speed values of 0.2 to 30 cm/hour and shows that, in those sections where the presence of condensation flow is visually apparent, there is a rapid dispersion of the colourant. However, it also shows that at points where there is no apparent condensation the process also occurs, but at a lower rate of efficiency. The importance of condensation within cavities has two aspects; firstly, speleogenetic, with the development of solution forms (cupolas) and deposit forms (capillarity boxwork); and secondly, hydrogeological, as this is the reason why certain processes (strong changes in temperature and humidity, multiple routes of airflow exchange with the exterior) may in themselves constitute a hydraulic contribution, of slight importance, but sufficient to explain a large part of the base flow (0.2 - 0.8 L/s) of a whole cavity system such as the Cueva del Agua in semiarid conditions.
With the intention of completing the analyses carried out in various karsts in gypsum, instruments were installed in the Cueva del Agua at Sorbas to measure, by continuous registration, some important physico-chemical parameters that might provide additional data on the hydro-geologic behaviour of this gypsiferous karst, especially at the level of the epikarstic zone. The parameters of temperature and water conductivity were considered most important, due to their singular behaviour patterns. During the experiment there were two periods of rainfall that modified the chemistry of the cavity, one of 30 mm in two days and another of 200 mm (almost the annual total) in four days. In the second case, which was much more extreme, a very significant increase in water temperature (up to 7 °C during the initial period of high water flow) was detected, while conductivity fell. But suddenly, when the minimum conductivity was reached, the temperature dropped sharply by 6-7 °C to return to the base temperature of the cavity. Subsequently, the temperature again stabilized at about 7 °C above the data recorded during the dry period. This behaviour pattern was not detected when the rainfall was slight. The explanation for this dual behaviour observed is fundamentally based on the quantity of rainfall and on the differences between the exterior air temperature, the temperature of interstitial water and the temperature recorded in the spring during high water flow. When water temperature in the cavity during high water flow is higher than the base temperature recorded in the period immediately before, it means that the interstitial water does not mobilize. However, when at any time the two temperatures coincide, one might suppose that there might have existed a process of mobilization of the water previously resident in the rock, by a piston effect, but in the unsaturated zone. On the other hand, the temporal variations of these parameters during the months following periods of high rainfall have enabled us to detect the existence of distinct periods during the return to normal cavity conditions. By carefully examining the decrease curve of water temperature inside the cavity while conductivity regained its maximum stable value, two periods may be differentiated. The first may be termed the "inertial influence period", when the rainfall occurring removes all signs of natural variation in the cavity. Thus, the daily external influences are not clearly detectable and the curve is downward-sloping and asymptotic with no significant oscillations. In the second period, which ends with the total stabilization of the parameter at the level of the initial conditions, the asymptotic descent is seen to be affected by daily temperature variations. This is termed the "inertial recovery period", during which external variations start to have an effect on the interior of the cavity such that there is a progressive increase in the amplitude of the daily variation in water temperature, air temperature and relative humidity. This behaviour pattern of variation of these parameters during periods of high rainfall, might be extended to all karstic systems, varying only in magnitude and temporal extent.


High-resolution sequence stratigraphic correlation in the Upper Jurassic (Kimmeridgian)-Upper Cretaceous (Cenomanian) peritidal carbonate deposits (Western Taurides, Turkey), 1999, Altiner D, Yilmaz Io, Ozgul N, Akcar N, Bayazitoglu M, Gaziulusoy Ze,
Upper Jurassic (Kimmeridgian)- Upper Cretaceous (Cenomanian) inner platform carbonates in the Western Taurides are composed of metre-scale upward-shallowing cyclic deposits (parasequences) and important karstic surfaces capping some of the cycles. Peritidal cycles (shallow subtidal facies capped by tidal-Aat laminites or fenestrate limestones) are regressive- and transgressive-prone (upward-deepening followed by upward-shallowing facies trends). Subtidal cycles are of two types and indicate incomplete shallowing. Submerged subtidal cycles are composed of deeper subtidal facies overlain by shallow subtidal facies. Exposed subtidal cycles consist of deeper subtidal facies overlain by shallow subtidal facies that are capped by features indicative of prolonged subaerial exposure. Subtidal facies occur characteristically in the Jurassic, while peritidal cycles are typical for the Lower Cretaceous of the region. Within the foraminiferal and dasyclad algal biostratigraphic framework, four karst breccia levels are recognized as the boundaries of major second-order cycles, introduced for the first time in this study. These levels correspond to the Kimmeridgian-Portlandian boundary, mid-Early Valanginian, mid-Early Aptian and mid-Cenomanian and represent important sea level falls which affected the distribution of foraminiferal fauna and dasyclad flora of the Taurus carbonate platform. Within the Kimmeridgian-Cenomanian interval 26 third-order sequences (types and 2) are recognized. These sequences are the records of eustatic sea level fluctuations rather than the records of local tectonic events because the boundaries of the sequences representing 1-4 Ma intervals are correlative with global sea level falls. Third-order sequences and metre-scale cyclic deposits are the major units used for long-distance, high-resolution sequence stratigraphic correlation in the Western Taurides. Metre-scale cyclic deposits (parasequences) in the Cretaceous show genetical stacking patterns within third-order sequences and correspond to fourth-order sequences representing 100-200 ka. These cycles are possibly the E2 signal (126 ka) of the orbital eccentricity cycles of the Milankovitch band. The slight deviation of values, calculated for parasequences. from the mean value of eccentricity cycles can be explained by the currently imprecise geochronology established in the Cretaceous and missed sea level oscillations when the platform lay above fluctuating sea level. Copyright (C) 1999 John Wiley & Sons, Ltd

A high-resolution proxy record of rainfall and ENSO since AD 1550 from layering in stalagmites from Anjohibe Cave, Madagascar, 1999, Brook Ga, Rafter Ma, Railsback Lb, Sheen Sw, Lundberg J,
Two stalagmites from Anjohibe Cave have annual layers made up of inclusion-rich calcite over inclusion-free calcite or of darker aragonite over clear aragonite. Geochemical evidence indicates that the basal units are deposited slowly in the wet season and the upper units more rapidly in the dry season. For the period with rainfall and temperature data (ad 1951-1992), layer thickness correlates well with the Southern Oscillation Index (SOI), as well as rainfall, water surplus, and actual evapotranspiration (AET) at nearby Majunga. Com parison of the layer record for one stalagmite with 1866-1994 SOI data indicates that layer thickness correlates best with the frequency and intensity of warm, low-phase SO (El Nino) events, not with average SOI conditions. In addition, the 415-year layer thickness time-series from that speleothem agrees remarkably well with historical records of El Nino frequency, with Galapagos (Ecuador) coral records of sea-surface temperature in the eastern Pacific, and with accumulation rates on the Quelccaya Ice Cap of Peru, which are lower at times of high El Nino frequency

Spectral analysis of a 1000-year stalagmite lamina-thickness record from Shihua Cavern, Beijing, China, and its climatic significance, 1999, Qin Xiaoguang, Tan Ming, Liu Tungsheng, Wang Xianfeng, Li Tieying, Lu Jinpo,
Stalagmite laminae provide a high-resolution geological record of climate change. In this paper, moving spectral analysis is used to analyse a stalagmite lamina thickness record to study climatic variability. It was found that the dominant cycles of the lamina thickness sequence are 2, 3.3, 5-6, 10-12, 14-18, 133 and 194 years. Some of the cycles are the same as the cycles of modern climatic indices, such as the QBO (Quasi Biennial Oscillation) of 2 years, the QTO (Quasi Triple-year Oscillation) cycle of about 3.5 years, the QFO (Quasi Five-year Oscillation) cycle of 5-6 years and the QEO (Quasi Eleven-year Oscillation) cycle of 11 years. It was also found that there are different dominant cycles in different time periods. Usually, the dominant cycles are stronger in wet periods when the microlaminae are thicker. In dry periods, the microlaminae are thinner and the power of the dominant cycles is also weaker. Another feature is that the power of the dominant cycles and their long-term periods and frequencies appear to change. These phenomena are important for understanding the climatic changes in Beijing area over the last 1 ka

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