The largest karst cave discovered in a tunnel during motorway construction in Slovenia’s Classical Karst (Kras)   总被引：1，自引：0，他引：1  

Martin Knez  Tadej Slabe  Stanka Šebela  Franci Gabrovšek 《Environmental Geology》2008,54(4):711-718

Karst researchers of the Karst Research Institute ZRC SAZU are regularly consulted during the planning of Slovenia’s motorways and invited to observe and monitor construction in the karst areas. More than 350 caves have been discovered in the course of building 60 km of new motorways over the past decade. Access to the most important caves is preserved by concrete tubes closed with metal covers at the roadside. The largest cave system in a tunnel, named LC-S647, is almost entirely preserved. The protection of this cave will serve as a good example for the preservation of natural heritage in the future. Construction work for the motorway uncovered a high degree of karstification. In particular, the discovery of this cave in the Kastelec tunnel LC-S647 showed the existence of a major cave system in the geological and speleological past. A number of unconnected passages have also been found. Caves discovered during highway construction have brought new knowledge about the cavernosity and the geological history of this part of the karst.  相似文献   

A New Genus and Species of Rhynchonellid (Brachiopoda, Recent) from Submarine Caves in the Mediterranean Sea   总被引：1，自引：0，他引：1  

Alan  Logan Helmut  Zibrowius 《Marine Ecology》1994,15(1):77-88

Abstract. A new rhynchonellid brachiopod genus Tethyrhynchia , with type species Tethyrhynchia mediterranea n. sp., is described from specimens discovered in dark zones of submarine caves along the Mediterranean coast of France between Marseille and La Ciotat, and also at Zembra Island, off the Gulf of Tunis, Tunisia. Other brachiopods occurring with this diminutive rhynchonellid are also small and include the megathyridids Argyrotheca cistellula and Megathiris detruncata . This is the first recorded occurrence of a rhynchonellid from the Mediterranean Sea. The new form is apparently neotenous, in that the lophophore in adults never develops beyond the trocholophous stage. A new type of rhynchonellid crus, crescentic in profile and here named the lunifer type, is described. The new genus is assigned to the new family Tethyrhynchiidae , and comparisons are made with other extant rhynchonellid genera.  相似文献   

Taxonomic composition and seasonality of diatoms in three Dinaric karstic lakes in Croatia     

Nenad Jasprica  Dubravka Hafner 《Limnologica》2005,35(4):304-319

The composition and temporal distribution of planktonic diatoms were studied in three small shallow karstic lakes – Modro Oko, Desne, and Kuti – throughout the seasons in 1994, 1995, 1997, and 1998. Physico-chemical parameters did not differ among the three lakes, except for NO₃ concentrations. Altogether, 137 diatom taxa within 41 genera were found in all three lakes combined. The highest number of taxa belonged to the genera Surirella (13), Navicula (12), andCymbella (9). Most taxa were tychoplanktonic, with true panktonic taxa contributing only 14% of the total. Despite their physical-chemical similarity, the lakes showed differences in the structure and dynamics of their diatom communities. Blooms occurred at different times in each of the lakes, and community similarity (Jaccard index) among all three was low (17.6–29.1%). The highest mean values of surface diatom abundance in Modro Oko (2199 cells L⁻¹), Desne (7900 cells L⁻¹), and Kuti (20690 cells L⁻¹) were not significantly different. Margalef's species richness index did not differ either among the lakes or seasonally. Only five diatom taxa in quantitative samples, and 22 taxa in net-samples, were common to all lakes. The most frequent diatoms were Cyclotella striata (56–93%), Fragilaria ulna (50–67%), and Asterionella formosa (27–83%). The most abundant taxa in Modro Oko, Desne, and Kuti were, respectively, Cymbella sp. 1 (402 cells L⁻¹), Cyclotella striata (3000 cells L⁻¹) and Asterionella formosa (20690 cells L⁻¹). Eighteen taxa were recorded for the first time in Croatia: Amphora commutata, Caloneis amphisbaena var. subsalina, C. silicula var. peisonis, Campylodiscus echeneis, Coscinodiscus lacustris, Denticula elegans, Gyrosigma acuminatum var. lacustre, G. distortum var. parkeri, G. fasciola, Navicula menisculus var. menisculus, N. pusilla, N. helensis, Stauroneis parvula var. prominula, Staurosira construens f. subsalina, Stephanodiscus sp. 1, Surirella gracilis, S. ovalis, and S. striatula. The genus Stephanodiscus was recorded for the first time in Croatia.  相似文献   

Rapid entrenchment of stream profiles in the salt caves of Mount Sedom,Israel     

Amos Frumkin  Derek C. Ford 《地球表面变化过程与地形》1995,20(2):139-152

Rock salt is approximately 1000 times more soluble than limestone and thus displays high rates of geomorphic evolution. Cave stream channel profiles and downcutting rates were studied in the Mount Sedom salt diapir, Dead Sea rift valley, Israel. Although the area is very arid (mean annual rainfall ≈ 50 mm), the diapir contains extensive karst systems of Holocene age. In the standard cave profile a vertical shaft at the upstream end diverts water from a surface channel in anhydrite or clastic cap rocks into the subsurface route in the salt. Mass balance calculations in a sample cave passage yielded downcutting rates of 0–2 mm s^?1 during peak flood conditions, or about eight orders of magnitude higher than reported rates in any limestone cave streams. However, in the arid climate of Mount Sedom floods have a low recurrence interval with the consequence that long-term mean downcutting rates are lower: an average rate of 8·8 mm a^?1 was measured for the period 1986–1991 in the same sample passage. Quite independently, long-term mean rates of 6·2mm a^?1 are deduced from ¹⁴C ages of driftwood found in upper levels of 12 cave passages. These are at least three orders of magnitude higher than rates established for limestone caves. Salt cave passages develop in two main stages: (1) an early stage characterized by high downcutting rates into the rock salt bed, and steep passage gradients; (2) a mature stage characterized by lower downcutting rates, with establishment of a subhorizontal stream bed armoured with alluvial detritus. In this mature stage downcutting rates are controlled by the uplift rate of the Mount Sedom diapir and changes of the level of the Dead Sea. Passages may also aggrade. These fast-developing salt stream channels may serve as full-scale models for slower developing systems such as limestone canyons.  相似文献   

Middle-Late Pleistocene polycyclic evolution of a stable coastal area (southern Apulia, Italy)     

Giuseppe Mastronuzzi  Yves Quinif  Paolo Sans  Gianluca Selleri 《Geomorphology》2007,86(3-4):393-408

The Otranto–Leuca coastal tract is marked by the presence of numerous sea caves placed close to present sea level. They are located generally at the back of a shore platform covered by a sequence of breccia deposits, marine sediments and speleothems. At Grotta di Masseria dell'Orte, marine cemented sands rest on a narrow shore platform at about 6.2 m above mean sea level and are covered by speleothems older than 185 ka. At Grotta del Diavolo, which is mostly filled by breccia deposits, three beach levels have been detected at about 3.0, 3.5 and 5.9 m above msl. They are either covered by or overlie speleothems that yield an U/Th age of 340, 78 ka and between 170.3 and 146.5, respectively. Geomorphological evidence and radiometric ages indicate that the area after a period of uplift has been tectonically stable since the last part of the Middle Pleistocene so that marine landforms close to the present shoreline underwent a polycyclic evolution. The sedimentary fills of sea caves formed during Middle-Late Pleistocene glacial stages, when arid or semiarid conditions promoted the removal of regolith and the development of thick breccia deposits. During Marine Isotope Stages (MIS) 9.3, 5.5 and 5.1, cave sediments were partially eroded whereas beach layers and related speleothems developed. These are, in fact, the only marine isotope stages marked by a sea level position which in this Mediterranean region was either close to, or slightly higher than, the present one.  相似文献   

2D magnetic resonance tomography applied to karstic conduit imaging   总被引：1，自引：1，他引：1  

J.-F. Girard  M. Boucher  A. Legchenko  J.-M. Baltassat 《Journal of Applied Geophysics》2007,63(3-4):103-116

Karstic conduits play a crucial role for water supply in many parts of the world. However, the imaging of such targets is generally a difficult task for most geophysical methods. Magnetic Resonance Sounding (MRS) is a geophysical method designed for imaging of water bearing structures. Initially, MRS was developed for characterizing horizontally stratified aquifers. However, when applying a 1D MRS measuring setup to the imaging of 2D–3D targets, the size of which may be much smaller than the loop, the accuracy and the lateral resolution may not be sufficient. We have studied the possibility of simultaneously processing several MRS aligned along a profile to perform a Magnetic Resonance Tomography (MRT). This work emphasizes the gain of resolution for 2D–3D imagery of MRT versus the interpolation of 1D inversion results of MRS along the same profile. Numerical modelling results show that the MRT response is sensitive to the size and location of the 2D target in the subsurface. Sensitivity studies reveal that by using the coincident transmitting/receiving (TX/RX) setup and shifting the loop around the anomaly area, the depth, section and position of a single karstic conduit with a size smaller than the MRS loop size can be resolved. The accuracy of the results depends on the noise level and signal level, the latter parameter being linked to the depth and volume of the karstic conduit and the water content in the limestone matrix. It was shown that when applying MRT to the localization of 2D anomalies such as karstic conduits, the inclination of the geomagnetic field, the orientation of the MRT profile and the angle of crossover of the conduit by the MRT profile must be taken into account. Otherwise additional errors in interpretation should be expected. A 2D inversion scheme was developed and tested. Both numerical and experimental results confirm the efficiency of the developed approach.  相似文献   

A Late Pleistocene palaeoclimate record based on mineral magnetic properties of the entrance facies sediments of Kulna Cave, Czech Republic     

P. Sroubek  J. F. Diehl  J. Kadlec  K. Valoch 《Geophysical Journal International》2001,147(2):247-262

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对鄂尔多斯盆地周边岩溶水系统的几点认识   总被引：1，自引：0，他引：1  

刘方 《陕西地质》2001,19(2):72-74

鄂尔多斯盆地地周边分布的古生界碳酸盐岩赋存有丰富的岩溶地下水，受背景地质条件的控制，不同地段地层岩性，岩溶发育程度，岩溶水的补给和赋存富集规律均有差异，并形成了多个岩溶水系统。  相似文献   

Occurrence of hypogenic caves in a karst region: Examples from central Italy   总被引：1，自引：0，他引：1  

S. Galdenzi  M. Menichetti 《Environmental Geology》1995,26(1):39-47

The caves of the Umbria and Marche regions in central Italy are made up of three-dimensional maze systems that display different general morphologies due to the various geological and structural contexts. At the same time, the internal morphologies of the passages, galleries, and shafts present some similarity, with solutional galleries characterized by cupolas and blind pits, anastamotic passages, roof pendants, and phreatic passages situated at different levels. Some of these caves are still active, as is the case for Frassassi Gorge, Parrano Gorge, and Acquasanta Terme, with galleries that reach the phreatic zone, where there is a rising of highly mineralized water, rich in hydrosulfydric acid, and with erosion of limestone walls and the formation of gypsum. Elsewhere there are fossil caves, such as Monte Cucco and Pozzi della Piana, where large speleothems of gypsum are present 500 m or more above the regional water table. In all of these important karst systems it is possible to recognize basal input points through fracture and intergranular porosity networks at the base of the oxidizing zone in the core of the anticline, where mineralized water rises up from the Triassic evaporitic layers in small hydrogeological circuits. Different underground morphologies can derive from the presence of a water table related to an external stream or from the confined setting of the carbonate rocks, underlying low permeable sedimentary cover, where artesian conditions can occur.  相似文献   

彭县塘坝子—葛仙山景点石灰岩溶洞景观及旅游资源开发前景     

张彦儒 《四川地质学报》1993,(1)

塘坝子-葛仙山景点,地处举世瞩目的龙门山推覆-滑覆构造带上,已成为拟建中的“龙门山地质公园”的重要组成部分。其独特的石灰岩岩溶地貌和溶洞景观,是成都旅游区和彭县景区内宝贵的旅游景观配套资源,除旅游开发价值较高外,亦是离成都市区较近较理想的人防各战疏散基地,因而具有一定的资源综合开发潜力。对该景点的尽早开发,还可缓解邻区旅游热点的人满之患。  相似文献