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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 shear plane is a plane along which failure of material occurs by shearing.?

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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 atlantic (Keyword) returned 59 results for the whole karstbase:
Showing 46 to 59 of 59
Identifying Late Miocene episodes of connection and isolation in the Mediterranean-Paratethyan realm using Sr isotopes, 2006, Flecker R, Ellam Rm,
After decades of research, the timing and nature of Late Miocene connections between the Mediterranean, Paratethys and the global ocean are still speculative. The hydrologic flux implications of exchange or isolation are central to all hypotheses for generating the major lithological changes that represent the Messinian Salinity Crisis. Moreover, differences in the hydrologic fluxes envisaged are the primary distinction between models. Despite this, these fluxes remain largely unconstrained. This paper describes the basis for using Sr isotope data innovatively combined with salinity data through hydrologic budget modelling to determine the timing and nature of Mediterranean hydrologic connectivity. We examine the hypotheses for three Late Miocene events to illustrate how this approach allows us to test implied hydrologic scenarios and exclude incompatible models. 1) Pre-evaporite restriction of the Mediterranean; 2) the initiation of salt precipitation; 3) connection between the Sea of Marmara and both Paratethys and the Mediterranean during the Messinian. This process suggests that the Atlantic-Mediterranean exchange was significantly reduced up to three million years before evaporite precipitation. It also indicates that end-member hypotheses for initiating salt precipitation in the Mediterranean (desiccation and connected basin models) are inconsistent with Sr isotope data. A contrasting model where evaporite formation was triggered by Atlantic transgression into a strongly evaporation-dominated Mediterranean is shown to be more compatible with available datasets. The application to Sea of Marmara samples indicates that salinity changes in the basin were not caused by changes to the amount of inflow from either Paratethys or the Mediterranean. Other possible as yet untested applications important for constraining different aspects of the Messinian Salinity Crisis are highlighted

Changing perspectives in the concept of 'Lago-Mare' in Mediterranean Late Miocene evolution, 2006, Orszagsperber Fabienne,
The Cenozoic Alpine orogeny caused the partition of Tethys into several basins. During the Late Neogene, the Mediterranean attained its final configuration, whereas, eastwards, the Paratethys, isolated from the World Ocean, disintegrated progressively into a series of smaller basins. As a result, an endemic fauna developed in these basins, mainly composed of brackish to freshwater faunas, indicating an environment affected by changes in water salinity. These small basins of the Paratethys were named 'Sea-Lakes' by Andrusov [Andrusov, D., 1890. Les Dreissenidae fossiles et actuelles d'Eurasie. Geol. min. 25, 1-683 (in Russian)]. Subsequently this name was translated into 'Lac-Mer' [Gignoux, M., 1936. Geologie stratigraphique, 2[deg]edition, Masson, Paris].In the Mediterranean isolated from the Atlantic at the end of the Miocene (Messinian), thick evaporites deposited, consisting of a marine Lower Evaporite unit and an Upper Evaporite unit, mainly of continental origin. Ruggieri [Ruggieri, G., 1962. La serie marine pliocenica e quaternaria della Val Marecchia. Atti Acad. Sci. Lett. Arti. Palermo, 19, 1-169.] used the term 'Lago-Mare', to characterize the brackish to fresh water environment which occurred within the Mediterranean at the end of the Messinian.During recent decades, numerous scientific investigations concerning the history of the Messinian within the Mediterranean were devoted to the understanding of conditions prevailing after the deposition of the marine evaporites. Brackish to freshwater faunas are found in several outcrops and boreholes in the Mediterranean, both in the uppermost beds of gypsum and inter-bedded within the clastic sediments of the Upper Evaporite Unit, immediately preceeding the flooding by the marine Pliocene waters. These faunas, because of their similarities with the fauna described in the Paratethys, were named 'Paratethyan', or 'Caspi-brackish' fauna, this leading some authors to imply a migration of these fauna from Paratethys to the Mediterranean. However, others refute this hypothesis.New data induced some researchers to consider that exchanges existed between the Mediterranean and the Eastern Paratethys and also between the Mediterranean and the Atlantic Ocean at the Miocene-Pliocene transition. These investigations now take advantage of the accurate time scales established by authors (biostratigraphy, cyclostratigraphy, magnetostratigraphy), allowing good stratigraphic correlations between the Mediterranean and the Paratethys, and precisions on the geodynamic evolution of this area.Furthermore, sediments at the base of the Zanclean (MPl1), locally containing brackish to fresh water faunas conducted authors to attribute this formation to an infra- or pre-Pliocene and also to a Lago-Mare 'event'.Thus, the 'Lago-Mare' concept drifted from its original meaning, and is evolving because of progresses in the understanding of the Mediterranean geodynamics and the adjacent areas during the Miocene-Pliocene transition

The Messinian salinity crisis in the Mediterranean basin: A reassessment of the data and an integrated scenario, 2006, Rouchy Jean Marie, Caruso Antonio,
After a long period of controversial debate about the interpretation of the Messinian salinity crisis (MSC), a near consensus existed since the ODP Leg 42A for a model keeping the major lines of the deep basin-shallow water model initially proposed by Hsu et al. (1973). The knowledge of the crisis was improved since the 1995s by the availability of a very accurate astronomically calibrated timescale. The debate about its interpretation was then reactivated by several new scenarios that questioned most the major aspects of the previous classical models. The updated re-examination of the most salient features along with consideration of the hydrological requirements for evaporite deposition allow us to assess the viability of the new models. We propose an integrated scenario that revives the key points of the previous model with new statements about the chronology, depositional settings, hydrological mechanisms, consequences and correlations with the global changes. A model implying two main stages of evaporite deposition that affected successively the whole basin with a slight diachronism matches better the whole dataset. The distribution of the evaporites and their depositional timing were constrained by the high degree of paleogeographical differentiation and by the threshold effects that governed the water exchanges. It is assumed that the central Sicilian basin was a deep basin located in a marginal position with regard to the deepest central basins. The restriction of the Mediterranean was predominantly under a tectonic control, but the complex development of the evaporitic crisis implied the interplay of both glacio-eustatic changes and fluctuations of the circum-Mediterranean climate.The first evaporitic stage (lower evaporites) that includes the deposition of the thick homogeneous halite unit with K-Mg salt interbeds in the deepest basins is correlated with the major evaporative drawdown and higher aridity, and occurred during the glacial period recorded in the ocean sediments between 6.3 and 5.6 Ma. The deposition of the potash in Sicily is tentatively linked to the two major glacial peaks TG 20 and TG 22, while the end of this first stage is linked to the peak TG 12. The second stage (upper evaporites) correlates with the interval of warming and global sea level rise recorded in the ocean since 5.6-5.5 Ma onwards. During this second stage, freshwater contribution increased and culminated by the latest Messinian dilution, i.e. the Lago-Mare event, as the result of the worsened tectonically driven closure of the Atlantic gateways combined to an evolution towards wetter climate conditions at least on the mountainous peripheral areas. In fact, reduced inputs of seawater continued to enter at least episodically the basin through the MSC explaining the sporadic presence of marine organisms. These inputs reached their lowest value and practically ceased during the latest Messinian dilution, just before the abrupt restoration of stable open marine conditions at the beginning of the Zanclean.A polyphased erosional surface affected the Mediterranean margins during the MSC with several critical episodes. The major episode related to the greatest water level fall, more than 1000 m, occurred during the deposition of the lower evaporites, from the onset of the evaporite deposition till the end of the first stage. Erosional processes remained active during the second evaporitic stage especially whenever the basin dried-up and a last important event marked by the karstification of the evaporites developed during the latest Messinian dilution just before the Early Zanclean reflooding that filled the erosional morphology

Structurally controlled hydrothermal dolomite reservoir facies: An overview, 2006, Davies G. R. , Smith Jr. L. B.

Structurally controlled hydrothermal dolomite (HTD) reservoir facies and associated productive leached limestones are major hydrocarbon producers in North America and are receiving increased exploration attention globally. They include multiple trends in the Ordovician (locally, Silurian and Devonian) of the Michigan, Appalachian, and other basins of eastern Canada and the United States, and in the Devonian and Mississippian of the Western Canada sedimentary basin. They also occur in Jurassic hosts along rifted Atlantic margins, in the Jurassic–Cretaceous of the Arabian Gulf region and elsewhere. Hydrothermal dolomitization is defined as dolomitization occurring under burial conditions, commonly at shallow depths, by fluids (typically very saline) with temperature and pressure (T and P) higher than the ambient T and P of the host formation. The latter commonly is limestone. Proof of a hydrothermal origin for HTD reservoir facies requires integration of burial-thermal history plots, fluidinclusion temperature data, and constraints on timing of emplacement. Hydrothermal dolomite reservoir facies are part of a spectrum of hydrothermal mineral deposits that include sedimentary-exhalative lead-zinc ore bodies and HTD-hostedMississippi Valley–type sulfide deposits. All three hydrothermal deposits show a strong structural control by extensional and/or strike-slip (wrench) faults, with fluid flowtypically focused at transtensional and dilational structural sites and in the hanging wall. Transtensional sags above negative flower structures on wrench faults are favored drilling sites for HTD reservoir facies. Saddle dolomite in both replacive and void-fillingmodes is characteristic of HTD facies. For many reservoirs, matrix-replacive dolomite and saddle dolomite appear to have formed near-contemporaneously and from the same fluid and temperature conditions. The original host facies exerts a major influence on the lateral extent of dolomitization, resultant textures, pore type, and pore volume. Breccias zebra fabrics, shear microfractures, and other rock characteristics record short-term shear stress and pore-fluid-pressure transients, particularly proximal to active faults. High-temperature hydrothermal pulses may alter kerogen in host limestones, a process designated ‘‘forced maturation.’’ basement highs, underlying sandstone (and/ or carbonate?) aquifers (probably overpressured), and overlying and internal shale seals and aquitards also may constrain or influence HTD emplacement. Although many questions and uncertainties remain, particularly in terms of Mg and brine source and mass balance, recognition and active exploration of the HTD play continues to expand. Increasing use of three-dimensional seismic imagery and seismic anomaly mapping, combined with horizontal drilling oblique to linear trends defined by structural sags, helps to reduce risk 


Aroca (domaine marin ctier, Pays basque, France) : un karst continental ennoy par les transgressions maritimes quaternaires, 2007, Vanara Nathalie , Perre Alain, Pernet Marc, Latapie Serge, Jaillet Stphane, Martine Olivier
AROCA (LITTORAL, BASQUE COUNTRY, FRANCE): A CONTINENTAL KARST DROWNED BY QUATERNARY MARITIME TRANSGRESSIONS. The rocky formations in shallow areas of the Atlantic coast are hardly known. Studies are rare because of the difficulties of direct observation (diving in always agitated, troubled water, depth between 20 and 40 m). Our first step was to make a detailed topography of a submarine plateau named Aroca, 4 km off Socoa harbour (bay of Saint-Jean-de-Luz). This plateau was already known for having a large variety of forms within a small surface (150 x 100 m). We gave names to most remarquable formations and defined five main characteristic zones: - in the exokarstic domain 1/ a top surface with channels, 2/ a dismantled surface with pinnacles; - in the endokarstic domain 3/ caves, galleries, arches; - at the limits 4/ three inclined plans, west, north and east, 5/ a cliff to the south. A typology of forms shows a predominance of ablation reliefs: aplanation, over-deepened channels, covered rooms and galleries, arches, residual pinnacles. Deposit accumulations regroup chaotic breakdown blocks, pebble accumulations and sand covers. Statement of explanations requires recognition of the nature and age of the outcrops and succession of erosional agents during the Pleistocene. Rocks are dated from Ypresien (limestones) to Bartonian (marls). Continental erosion during sea regressions is responsible of caracteristic landforms and deposits; for example wall banks, allochthonous pebbles The currently active marine erosion during sea transgressions is due to storms, tide, dissolution, biochemical action (lithophages) and gravity. We propose a paleogeographic reconstitution. After an essentially calcareous sedimentation in Eocene and an essentially marly sedimentation in Oligocene, the sea recedes during Miocene. From then, the platform, henceforward above the water, is subject to meteoric erosion. In Pliocene, evolution of the massif is isovolumic (under a marly cover and with a low hydraulic gradient). During the lower and middle Pleistocene, the erosion of the marly cover goes on. During the upper Pleistocene, the wurmian (18000 BP) marine regression allows entrenchment of the hydrographic system thanks to an increase of hydraulic gradients (classic functional karst). From 15000 years onwards, a general transgression of sea level happens by successive steps. During the Boreal, a break in transgression allows the formation of a paleo-shore at 20 to 30 m, inducing a peneplanation phase in the tidal or infratidal zone. From 7500 BP onwards, a a rapid transgression from 23 to 8, then a slower one from 8 to the present level stops karstification on the massif. At present, only marine abrasion is active and tends to obliterate the previously built landforms.

Stalagmite evidence for the precise timing of North Atlantic cold events during the early last glacial, 2007, Drysdale Rn, Zanchetta G, Hellstrom Jc, Fallick Ae, Mcdonald J, Cartwright I,
Evidence of millennial-scale cold events following the last interglacial are well preserved in North Atlantic marine cores, Greenland ice, and pollen records from Europe. However, their timing was previously undetermined by radiometric dating. We report the first precise radiometric ages for two such events, C23 (105.1 {} 0.9 ka to 102.6 {} 0.8 ka) and C24 (112.0 {} 0.8 ka and 108.8 {} 1.0 ka), based on stable carbon and oxygen isotope measurements on a stalagmite from Italy (CC28). In addition to providing new information on the duration of these events in southern Europe, the age data provide invaluable tuning points for the Melisey I (C24) and Montaigu (C23) pollen zones identified in western Europe. The former event is of particular significance because it represents the end of the Eemian interglacial forest phase in western Europe. The new age data will also allow fine tuning of the timing and duration of Greenland stadial 24 (equivalent to C23) in the North Greenland Ice Core Project ice core and, via a common gasage chronology, tuning of the Vostok and EPICA (European Project for Ice Coring in Antarctica) ice cores

Variable calcite deposition rates as proxy for paleo-precipitation determination as derived from speleothems in Central Florida, U.S.A., 2008, Van Beynen P. E. , Soto L. , And Polk J.
Deposition rates derived from speleothems have been shown to be a useful paleoclimatic proxy. Past studies have shown that the most common climatic parameter measured by variable deposition rates is precipitation, where increased precipitation leads to increased calcite deposition. This was the premise of our study, where three Floridian stalagmites deposition rates were measured and compared to paleohydrologic indicators taken from the sample or from other regional records. Deposition rates were measured by determining the volume of calcite precipitated between TIMS U-series dates (mm3 yr21), thereby accounting for morphological changes on the stalagmite over its depositional history. Most prior research relied on a simple linear interpolation between known ages to calculate rate (mm yr21). Results show three distinct periods of increased deposition for our stalagmites centered on 2.0, 1.25 and 0.5 ka BP. A comparison with Mg/Ca and Sr/Ca ratios and calcite deposition tentatively shows elevated elemental ratios during the three aforementioned periods. Elevated trace element ratios have been shown to be correlated with increased residence time of percolation waters in the overlying bedrock above caves and consequently decreased rainfall. To corroborate this finding, paleo-precipitation records from Little Salt Spring, Florida and Lake Miragoane, Haiti, were examined for coeval arid periods with our stalagmites. Both records do possess similar dry periods and provide added support that the region experienced periods of abrupt aridity over the last two millennia. The combined effect of a change in the mean position of the Intertropical Convergence Zone and the easterly winds associated with the North Atlantic High appear to be the major causes for these times of aridity.

VEGETATION OF THE DOLINES IN MECSEK MOUNTAINS (SOUTH HUNGARY) IN RELATION TO THE LOCAL PLANT COMMUNITIES, 2009, Csiky Jnos Erd?s, Lszl, Morschhauser Tams, Trk Pter & Krmczi Lszl
This paper deals with the forest vegetation of the lower part of the dolines in Mecsek Mts. (South Hungary). In order to char-acterize this vegetation type, samples were compared to the 6 plant communities occurring in the neighbourhood of the dolines. Considering the vegetation texture and species com-position, the vegetation of the dolines resembles mainly the extrazonal beechwoods (Helleboro odori-fagetum) and local ravine forests (Scutellario altissimae-Aceretum) that preserve several mountain, subatlantic relict species in this area. Our study revealed that the plant communities characteristic of the karst surface of Western Mecsek are arranged along a moisture and nutrient gradient. In this system, the habitat conditions of the dolines are similar to those of the beech forests and the lo-cal ravine forests, fresh and relatively rich in nutrients. In the karst, dominated by oak-hornbeam and beech forests, effects of the thermal inversion are the most spectacular where beech forests follow turkey oak-sessile oak forests and oak-hornbeam forests on the lower part of the doline slopes. The described vegetation type of these depressions is developed by edafic fac-tors; its identification as a separate association is not supported by the analyses.

Wavelet analysis of Late Holocene stalagmite records from Ortigosa Caves in Northern Spain, 2009, Muoz A. , Sen A. K. , Sancho C. , And Genty D.
We have deduced short-term climatic changes from millennial to annual scales from the study of laminae thickness and radiocarbon analysis of Holocene stalagmite records from two caves in Ortigosa de Cameros (Iberian Range, northern Spain). Speleothems are made up of dark compact laminae (DCL) and white porous laminae (WPL) of seasonal origin. Couplets seasonality is deduced from monitoring calcite laminae growth, drip water rates, and soil organic matter flushed into the caves. The thickness variations of the couplets are analyzed using a continuous wavelet transform and the various periodicities at interannual, decadal, multidecadal, and centennial scales are revealed from the wavelet power spectrum. The periodicities at decadal, multidecadal and centennial scales, with periods around 9.7, 10.4, 14, 16, 22, 43, 73, 83 and 180 years, are mainly related to solar activity. Among the interannual periodicities, oscillations around the 2.4-yr-period may be linked to the Quasi-Biennial Oscillation (QBO), whereas periods ranging from 4 to 7 years may be associated with the El Nin o-Southern Oscillation (ENSO) and/or the North Atlantic Oscillation (NAO).

Middle-Late Quaternary paleoclimate of northern margins of the Saharan-Arabian Desert: reconstruction from speleothems of Negev Desert, Israel, 2010, Vaks Anton, Barmatthews Miryam, Matthews Alan, Ayalon Avner, Frumkin Amos

Speleothems in arid and hyper-arid areas of Negev Desert, Israel, are used in paleoclimate reconstruction of northern margins of Saharan-Arabian Desert, focused on the following objectives: 1) precise U–Th dating of the timing of speleothem growth as an indicator of periods of humid climate, i.e. positive effective precipitation; 2) the origin of rainfall using the speleothem δ18O and changes in spatial pattern of speleothem deposition and speleothem thickness along a north–south transect; 3) changes of vegetation cover based on speleothem δ13C variations.

During the last 350 ka major humid periods, referred to herein as Negev Humid Periods (NHP), occurred in the central and southern Negev Desert at 350–310 ka (NHP-4), 310–290 ka (NHP-3), 220–190 ka (NHP-2), and 142–109 ka (NHP-1). NHP-4, NHP-2 and NHP-1 are interglacial events, whereas NHP-3 is associated with a glacial period. During NHP-1, 2 and 3 the thickness and volume of the speleothems decrease from the north to the south, and in the most southern part of the region only a very thin flowstone layer formed during NHP-1, with no speleothem deposition occurring during NHP-2 and 3. These data imply that the Eastern Mediterranean Sea was the major source of the rainfall in northern and central Negev. More negative speleothem δ18O values, relative to central parts of Israel (Soreq Cave) are attributed to Rayleigh distillation because of the increasing distance from the Mediterranean Sea. Speleothem deposition during the NHP-4 in the southern Negev was more intensive than in most of the central Negev, suggesting the prominence of the tropical rain source.

Decrease in speleothem δ13C during NHP events indicates growth of the vegetation cover. Nevertheless, the ranges of δ13C values show that the vegetation remained semi-desert C4 type throughout the NHPs, with an additional significant carbon fraction coming from the host rock and the atmosphere. These observations, together with small thickness of the speleothem layers, favor that NHP events consisted of clusters of very short humid episodes interspersed with long droughts.

NHP events were contemporaneous with climate periods with monsoon index of ≥51 (cal/cm2 × day) and with the formation of sapropel layers in the Mediterranean Sea. Such simultaneous intensification of the monsoon and Atlantic-Mediterranean cyclones is probably related to the weakening of the high pressure cell above sub-tropical Atlantic Ocean, which enabled more rainfall to penetrate into the Saharan-Arabian Desert from the north and south. The contemporaneous occurrence of the NHP events and the increased monsoon rainfall could have opened migration corridors, creating climatic “windows of opportunity” for dispersals of hominids and animals out of the African continent.


THE FIRST DATING OF CAVE ICE FROM THE TATRA MOUNTAINS, POLAND AND ITS IMPLICATION TO PALAEOCLIMATE RECONSTRUCTIONS, 2010, Hercman H. , Gą, Siorowski M. , Gradziń, Ski M. Kiciń, Ska D.

Lodowa Cave in Ciemniak, which belongs to the dynamic ice cave type, contains the biggest perennial block of cave-ice in the Tatra Mountains. The ice represents congelation type, since it originates from freezing of water which infiltrates the cave. Two generations of ice have been recognized in this cave. They are divided by the distinct unconformity. The ice building both generations is layered. Two moths which were found in the younger generations were sampled and dated by 14C method yielding 195 ± 30 and 125 ± 30 years. Bearing in mind the position in the section and the fact that the cave ice has waned since the 20s of the last century, the age is 1720-1820 AD and 1660-1790 AD respectively. It proves that the ice was formed during the Little Ice Age. Hence, the erosion boundary which underlies this generation records the degradation of ice before the Little Ice Age most probably during the Medieval Warm Period. The ice volume in the cave was substantially smaller before the Little Ice Age than it is today, despite the clear tendency to melting, which has been recognized since 20s of the last century. The older generation of ice is supposed to have its origins in a cold stage between the Atlantic period and the Medieval Warm Period.


OBSERVATIONS OF PLIOCENE KARSTS FOSSILIZED BY QUATERNARY EOLIAN SILTS IN THE MATMATA MOUNTAINS (SOUTH-EAST TUNISIA), 2012, Sghari, Abdeljalil

The submeridional Dahar chain in southeastern Tunisia is over 200 km long. It is separated from the Mediterranean Sea by the Jeffara plain with some tens of kilometers in width. This landscape continues to the South into Libya, but to the North, the chain ends with the Matmata mountains which form a plateau slightly inclined to the west and some 10 km wide. The eastern scarp shows a mainly calcareous geological stratigraphy from Upper Permian to the Senonian. The Dahar-Matmata structure belongs to the Sahara platform and shows a hiatus during the whole Tertiary, since it was emerged since Upper Cretaceous. The Tunisian Atlas nearby shows a completely different paleogeographic evolution, with a complete Tertiary series and a later Plio-Quaternary structuration. These two paleogeographic domains of Southern Tunisia, the Sahara Atlas and the NE border of the Sahara platform, were influenced by the Messinian crisis (5.9 Ma to 5.3 Ma). This was expressed by the collapse of the Mediterranean Sea level, profoundly modifying the fluvial dynamics with an inversion of the erosional system, from normal erosion to regressive erosion. It results a deepening of canyons in the downstream part and a deepening of the watercourses in the upstream part. The geological structures in the Messinian have been deeply affected by these large eustatic changes, with an incision of cluses in the Atlas and the deposition of a thick clayeysandy series that we could recently link to deltaic systems and Gilbert deltas. The re-establishment of seaways between the Atlantic and the Mediterranean, and the subsequent infill in the Lower Pliocene (Zanclean transgression), with an important inpact in Southern Tunisia, had multiple consequences in that region. The newly adjusted sealevel, together with a more humid climate that was confirmed by faunal and floral extension oof tropical plants in Northern Africa, stimulated an important karstification of the limestone areas. In the Dahar chain, caves, dolines, karstic depressions or karstic dry valleys emerged, the most spectacular ones being found in the Matmata Mountains. The karstic depressions are the forms that represent best this Pliocene karstification that surely was interrupted in an early stage, because localized endokarstic forms had not enough time to develop. So the karstification seems to have been active in Matmata from 5.4 to 4.0 million years, i.e. two times as long than the duration of the Messinian crisis. The interruption of karstification is due to an increase in temperature and dryness, which even gets more intense during the Pliocene, pulverizing the soils. Already at the beginning of the desertification, a calcareous crust forms by rapid cristallization of dirt. It is immediately transported from the karstic zones to the Jeffara plain. This transfer fo dissolved calcite was the origin of the resistant calcitic crust well known in the Jeffara plain. We now identified the same crust in a karstic depression in the Matmata Mountains, opening the way to new geomorphologic and tectonic interpretations, and a review of the eolian silts formerly attributed to the Upper Pleistocene. Later, during Upper Pliocene-Gelasian, we observe a general tectonic uplift of the Dahar chain and the Matmata Mountains as well as the subsidence of the Jeffara plain at the Medenine fault (NW-SE), prolonging the large Gafsa fault towards the East. The karstic paleoforms were thus uplifted more than 500 m, but nevertheless remain open on the Jeffara plain, as seen by large depressions. As a consequence, the karstic depressions of Matmata played the role of traps for eolian silts blown from the Jeffara plain during the extreme desertification in the Upper Pliocene-Gelasian. The morphological reconstruction since the Messinian shows a succession of important events during the Pliocene that profoundly influenced the Quaternary. All indications permit to reject the hypothesis that the Matmata silts came from the West (Eastern Erg).

 


OBSERVATIONS OF PLIOCENE KARSTS FOSSILIZED BY QUATERNARY EOLIAN SILTS IN THE MATMATA MOUNTAINS (SOUTH-EAST TUNISIA), 2012, Sghari, Abdeljalil

The submeridional Dahar chain in southeastern Tunisia is over 200 km long. It is separated from the Mediterranean Sea by the Jeffara plain with some tens of kilometers in width. This landscape continues to the South into Libya, but to the North, the chain ends with the Matmata mountains which form a plateau slightly inclined to the west and some 10 km wide. The eastern scarp shows a mainly calcareous geological stratigraphy from Upper Permian to the Senonian. The Dahar-Matmata structure belongs to the Sahara platform and shows a hiatus during the whole Tertiary, since it was emerged since Upper Cretaceous. The Tunisian Atlas nearby shows a completely different paleogeographic evolution, with a complete Tertiary series and a later Plio-Quaternary structuration. These two paleogeographic domains of Southern Tunisia, the Sahara Atlas and the NE border of the Sahara platform, were influenced by the Messinian crisis (5.9 Ma to 5.3 Ma). This was expressed by the collapse of the Mediterranean Sea level, profoundly modifying the fluvial dynamics with an inversion of the erosional system, from normal erosion to regressive erosion. It results a deepening of canyons in the downstream part and a deepening of the watercourses in the upstream part. The geological structures in the Messinian have been deeply affected by these large eustatic changes, with an incision of cluses in the Atlas and the deposition of a thick clayeysandy series that we could recently link to deltaic systems and Gilbert deltas. The re-establishment of seaways between the Atlantic and the Mediterranean, and the subsequent infill in the Lower Pliocene (Zanclean transgression), with an important inpact in Southern Tunisia, had multiple consequences in that region. The newly adjusted sealevel, together with a more humid climate that was confirmed by faunal and floral extension oof tropical plants in Northern Africa, stimulated an important karstification of the limestone areas. In the Dahar chain, caves, dolines, karstic depressions or karstic dry valleys emerged, the most spectacular ones being found in the Matmata Mountains. The karstic depressions are the forms that represent best this Pliocene karstification that surely was interrupted in an early stage, because localized endokarstic forms had not enough time to develop. So the karstification seems to have been active in Matmata from 5.4 to 4.0 million years, i.e. two times as long than the duration of the Messinian crisis. The interruption of karstification is due to an increase in temperature and dryness, which even gets more intense during the Pliocene, pulverizing the soils. Already at the beginning of the desertification, a calcareous crust forms by rapid cristallization of dirt. It is immediately transported from the karstic zones to the Jeffara plain. This transfer fo dissolved calcite was the origin of the resistant calcitic crust well known in the Jeffara plain. We now identified the same crust in a karstic depression in the Matmata Mountains, opening the way to new geomorphologic and tectonic interpretations, and a review of the eolian silts formerly attributed to the Upper Pleistocene. Later, during Upper Pliocene-Gelasian, we observe a general tectonic uplift of the Dahar chain and the Matmata Mountains as well as the subsidence of the Jeffara plain at the Medenine fault (NW-SE), prolonging the large Gafsa fault towards the East. The karstic paleoforms were thus uplifted more than 500 m, but nevertheless remain open on the Jeffara plain, as seen by large depressions. As a consequence, the karstic depressions of Matmata played the role of traps for eolian silts blown from the Jeffara plain during the extreme desertification in the Upper Pliocene-Gelasian. The morphological reconstruction since the Messinian shows a succession of important events during the Pliocene that profoundly influenced the Quaternary. All indications permit to reject the hypothesis that the Matmata silts came from the West (Eastern Erg).


Origin of the interstitial isopod Microcharon (Crustacea, Microparasellidae) from the western Languedoc and the northern Pyrenees (France) with the description of two new species, 2013, Nicole Coineau, Claude Boutin, Malvina Artheau

The interstitial groundwater genus Microcharon (Crustacea, Isopoda, Microparasellidae) is highly diversified in southern France. A new species,Microcharon boulanouari n. sp. is described from the Aude River, whereas specimens from the Lachein River in the central Pyrenees are reassigned to another species, M. ariegensis new to Science. Microcharon boulanouarin. sp. is closely related to the species of the group rouchi and may belong to the phylogenetic western Mediterranean lineage. The two-step model of colonization and evolution provides an understanding of the origin and age of this stygobite. Microcharon boulanouari n. sp. is derived from marine ancestors that lived in the interstitial littoral shallow bottoms of the Atlantic embayment which covered southwestern France at the very beginning of the early Eocene period. Both the regression of this gulf at the start of the Eocene and the Pyrenees uplift may have played a major role in the evolutionary history through vicariance of Microcharon boulanouari n. sp. and of the northern Pyrenean species of the grouprouchi.


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