Search results for "Karst"
showing 10 items of 150 documents
Simulated European stalagmite record and its relation to a quasi-decadal climate mode
2013
Abstract. A synthetic stalagmite record for the Bunker cave is constructed using a combined climate-stalagmite modeling approach. The power spectrum of the simulated speleothem calcite δ18O record has a pronounced peak at quasi-decadal time scale. Interestingly, mixing processes in the soil and karst above the cave represent a natural low-pass filter of the speleothem climate archive. We identify a quasi-decadal mode characterized by a "tripole pattern" of sea surface temperature affecting stalagmite δ18O values. This pattern, which is well-known in literature as the quasi-decadal mode in the North Atlantic, propagates eastwards and affects western European temperature surrounding the cave.…
Plio-Pleistocene Dust Traps on Paleokarst Surfaces: A Case Study From the Carpathian Basin
2020
Plio-Pleistocene silt/clay-rich deposits and paleo-karst fissure sediments from sites of the northern and southern parts of the Carpathian Basin were investigated. These materials were supposed to be mixed during transport before being captured in karstified fissures. Evidence that the eolian fissure sediments of Plio-Pleistocene age in the older Triassic–Cretaceous limestones are derived from eolian silt and clay includes compositional and textural matches, especially decreasing grain-size trends observed downwards from the paleo-surface of the former landscape. Various environmental factors could be recognized by the statistical evaluation of grain-size distribution curves of fissure fill…
Fossiliferous Holocene tufa of Mende (Lozère, southern France): implication for the Atlantic vegetation of the Causses Basin
2016
International audience; Tufas bearing plant macroremains are uncommon in the Causses Basin (southern France). Here, we report anew fossiliferous tufa deposits at Mende, in Lozère. This palaeontological site is the first Quaternary tufa from thenorthern part of the Causses Basin that yields such an abundance of plant macroremains. The radiocarbon dating showsthat these Holocene deposits are related to the Atlantic period. Geomorphology and mineralogy show that theplant-bearing deposit is a calcareous tufa only composed by calcite, deposited near to an outlet of cool water, linked tothe karstic hydrological system of the Causse de Mende. The flora exposed in this article is dominated by angio…
Quaternary marine and continental unconformity-bounded stratigraphic units of the NW Sicily coastal belt
2017
In the coastal sector of NW Sicily, the regional correlation of relevant unconformities recognised within the Quaternary sedimentary successions allowed the mapping of seven unconformity-bounded stratigraphic units (UBSUs). The regional unconformities are marine or subaerial erosional surfaces, as well as non-depositional surfaces, locally marked by paleosoils. The erosional surfaces were produced from marine abrasion, surface water overland/concentrated flow, river erosion, karst solution, mass movement, or wind erosion. The main lithofacies of the Quaternary UBSUs consist of: (a) marine and coastal bioclastic calcarenites, (b) aeolian sandstones, (c) river deposits, (d) colluvial deposits…
Impacts of soil conditions and light availability on natural regeneration of Norway spruce Picea abies (L.) H. Karst. in low-elevation mountain fores…
2018
Abstract • Key message Natural regeneration ofP. abies(L.) H. Karst. may reach high densities in lower mountain elevations. The highest densities were found in sites with moderate light availability, with low pH, and not near the riverbank. However, age-height classes differed in the predicted magnitude of response, but were consistent in response directions. Mosses and understory species typical of coniferous forests were positively correlated with regeneration density. • Context Norway spruce Picea abies (L.) H. Karst. in Central Europe is at risk under climate change scenarios, particularly in mountain regions. Little is known about the impact of environmental factors on the natural rege…
Middle Jurassic tracks of sauropod dinosaurs in a deep karst cave in France.
2019
14 pages; International audience; Although the deep galleries of natural underground cavities are difficult to access and are sometimes dangerous, they have the potential to preserve trace fossils. Here, we report on the first occurrence of sauropod dinosaur tracks inside a karstic cave. Three trackways are preserved on the roof of the Castelbouc cave 500 m under the surface of the Causse Méjean plateau, southern France. The tracks are Bathonian in age (ca. 168–166 Ma), a crucial but still poorly known time interval in sauropod evolution. The three trackways yield sauropod tracks that are up to 1.25 m long and are therefore amongst the largest known dinosaur footprints worldwide. The trackm…
Le site à ambre et plantes du Cénomanien de Neau (Mayenne, France)
2020
International audience; A new Cenomanian amber- and plant-bearing deposit has been discovered at Neau, in the Mayenne department (France). The Cenomanian fossiliferous lignites are located in karst filling in a substratum of Cambrian limestones. The amber corresponds mainly to tiny millimetric grains, devoid of arthropod inclusions, but rich in microorganisms, especially the sheated bacteria Leptotrichites resinatus , and containing pollen grains ( Classopollis ) and wood fibers (Araucariacae or Cheirolepidiaceae). The lignites provide abundant conifer and ginkgoale cuticle fragments ( Frenelopsis , Eretmophyllum ) and a lot of palynomorphs ( e.g. Gleicheniidites senonicu s, Cyathidites , D…
Twig and Shoot Dieback of Citrus, a New Disease Caused by Colletotrichum Species
2021
(1) Background: This study was aimed at identifying the Colletotrichum species associated with twig and shoot dieback of citrus, a new syndrome occurring in the Mediterranean region and also reported as emerging in California. (2) Methods: Overall, 119 Colletotrichum isolates were characterized. They were recovered from symptomatic trees of sweet orange, mandarin and mandarin-like fruits during a survey of citrus groves in Albania and Sicily (southern Italy). (3) Results: The isolates were grouped into two distinct morphotypes. The grouping of isolates was supported by phylogenetic sequence analysis of two genetic markers, the internal transcribed spacer regions of rDNA (ITS) and β-tubulin …
Seguimiento del fenómeno blanco de la laguna de la Cruz (Cuenca, España)
2020
[EN] In the present study, a five-year follow-up was performed by remote sensing of the calcium carbonate precipitation in La Gitana karstic lake also known as La Cruz (located on the province of Cuenca, Spain). The important role that calcium carbonate precipitation plays in the ecology of the lake is well known for its influence on the vertical migrations of phytoplankton, the concentration of bioavailable phosphorus and, therefore, the eutrophication and quality of the waters. Whiting take place between the months of July and August, and it can be studied at this time through its optical properties, with the main objective of offering updated data on a phenomenon traditionally studied an…
The “Porţile de Fier/Iron Gates” Nature Park (Romania) Some Danube Northern Tributaries Fish Fauna
2014
Abstract The relative larger size of the Berzasca River, respectively the relatively constant environmental conditions, with relatively stenotopic ichthyocenosis, suffered small qualitative and quantitative fish fauna modifications in time, compared to the smaller rivers such as Sirinia, Liubcova/Oreviţa and Mraconia. The Danube “Iron Gates” I Lake influences the lower sectors of the studied rivers in term of fish species exchange. The accidental droughts in the karstic zones of the studied lotic sectors have a negative influence on the spatial continuity of the local fish fauna, and the climate change can increase these influence in the future. All the studied rivers play an important role…