The karst rock relief clearly reveals the ways in which the karst surface and caves have been shaped and how they have developed. The oldest traces are the rock features of old karst caves, which ...were formed under climate conditions entirely different from the current ones, i.e., in the Pleistocene, and which have been dry for a longer period of time. Today, the wind is the prevailing factor in shaping the rock on the surface and in the karst of the White Desert near Farafra in particular, where we can witness the development of an entire range of wind rock features which helps us sort and classify them logically. However, in the wadis near the Qara Oasis a unique rock relief is forming, in which traces of water flow and dissolution of the rock under the sandy deposits are utterly predominant. The rainfall volume is low, however, the heavy rainfall events lasting short periods of time are enough to shape the less resistant rock. The rock features dominating the walls are co-shaped by dissolution and aeolian erosion. Crust forms on those parts of the rock surface that come in contact with water. The bare surfaces, on the other hand, are carved out by the wind. In the places where the crust has flaked off, the wind carves out cups.
It is recognized that karst processes are actively involved in the current global carbon cycle based on twenty years research, and the carbon sink occurred in karst processes is possibly an important ...part of “missing sink” in global carbon cycle. In this paper, an overview is given on karst carbon cycle research, and influence factors, formed carbon pools (background carbon sink) and sink increase potentials of current karst carbon cycle are analyzed. Carbonate weathering could contribute to the imbalance item (BIM) and land use change item (ELUC) in the global carbon cycle model, owing to its uptake of both atmospheric CO2 (carbon sink effect) and CO2 produced by soil respiration (carbon source reduction effect). Karst carbon sink includes inorganic carbon sink resulted from hydrogeochemical process and organic carbon sink generated by aquatic photosynthetic DIC conversion, forming relatively stable river (reservoir) water body or sediment carbon sink. The sizes of both sinks are controlled by terrestrial ecosystems and aquatic ecosystems, respectively. Desertification rehabilitation and carbon sequestration by aquatic plants are two effective ways to increase the carbon sink in karst area. It is estimated that the rate of carbon sink is at least 381 000 t CO2/a with vegetation restoration and afforestation in southwest China karst area, while the annual organic carbon sink generated by aquatic photosynthesis is about 84 200 t C in the Pearl River Basin. The development of a soil CO2 based model for assessment of regional dissolution intensity will help to improve the estimation accuracy of carbon sink increase and potential, thus provide a more clear and efficient karst sink increase scheme and pathway to achieve the goals of “double carbon”. With the deep investigation on karst carbon cycle, mechanism and carbon sink effect, and the improvement of watershed carbon sink measurement methods and regional sink increase evaluation approaches. Karst carbon sink is expected to be included in the list of atmospheric CO2 sources/sinks of the global carbon budget in the near future.
One of the unique examples of the development of subsoil karren into a stone forest on the varied geological bedrock of the Lunan surface is revealed to us. Originally of subsoil formation and later ...denuded, the rounded hills that dissect the karst surface have transformed into a clustered stone forest whose central part usually consists of a larger dissected rock mass with individual stone pillars and teeth at the edge. The geologic profile contains beds of dense, homogeneous and compact fine-grained limestones that alternate with beds of mostly coarse-grained and just as compact dolomitised limestones. These bed properties are also reflected in the exterior of the rock as a diverse relief. The average calcium carbonate content in both types of rocks combined is 97.3%. The rock is thickly bedded to massive; beds are mainly positioned subhorizontally. The contacts between the beds of limestone and dolomitised limestone are sharp and clearly visible, especially in the bottom part of the geologic profile, whereas in the central part, they are often blurred and one type of rock grades continuously into the other. In the areas containing limestone, individual bedding planes are especially visible. As can be inferred, the slightly more porous dolomitised rock, made up of larger particles, disintegrates faster in a more permanently waterlogged acid subsoil environment, where the moisture penetrates it deeper. However, as it takes longer to dissolve, it protrudes from the surface of the dolomitic limestone rock when exposed to moisture from occasional rain. The composition and fracturing of the diverse rock strata decisively influences the shape of the pillars and their rock relief. Larger subsoil rock forms (channels, notches, half-bells) have developed on all rock strata. The diversity of the rock is also reflected by the notches that have formed under the soil along the more rapidly soluble partly dolomite rock strata. Denuded subsoil-shaped pillars are reshaped by rainwater and trickling water. Smaller rock forms carved by rainwater have formed mostly only on evenly composed, fine- grained limestone rock. The tops on such rock are more distinctly conical and blade-like and wider on more slowly soluble rock.
Due to various factors influencing diverse rocks, karst phenomena take unique shapes that are most often reflected in the rock relief. Through a series of different developmental factors, new factors ...first gradually transform the traces of old formations and over time, if they are distinct enough, they can replace them with completely new ones. In places old forms are reflected in the formation of a new rock relief only indirectly. The rock relief of karst phenomena, in this case karren, also develops under the influence of a single factor. Developmentally, rock forms, due to dissection of the surface and lasting of development, often in several layers merge into one another. A development model enables us to discover the overall development of the formation of the selected part of the rocky karst surface. The individual rock forms which have merged into the rock relief represent just one stage of development. Good knowledge of the overall development enables us to discern the development so far and predict future development. A number of development models can be discerned. One of the basic models reveals the manner of the rain-induced formation and development of horizontal and gently sloping carbonate rock strata into karren and stone forests, especially after the disintegration of the upper (thinner) rock strata and the denudation and shaping of the bottom strata. It reveals many characteristics of rock formation, from the sheet flow to the formation of rain flutes, their merging into rain channels and the development of funnel-like notches; that is, developmental transition of rock forms and rock relief in the overall development from the flat surface to its dissection into peaks.
So far reported unstable correlations between environmental settings and doline geometry require a revision of doline delineating methods and morphometric analyses that follows from such input data. ...We examine the reliability of the most accessible data sources for doline delineation, namely basic topographic maps at a scale of 1:5,000 and ortho-rectified aerial photographs (digital orthophotos) of 0.5 m resolution. Their reliability has been quantified in the Dinaric karst (Krk Island, NE Adriatic Sea). The adequacy of most commonly used morphometric parameters (viz. elongation and circularity) and their variations applied in previous studies are mathematically verified and practically tested. The simulation of an individual method behaviour performed on polygons with increasing circularity and elongation demonstrated their ranges of validity. The efficiency of a particular method was verified by the application to the real dataset of dolines. The optimal variation of an individual parameter (circularity = Pcc/Pd; elongation = of the best fitting ellipse) is identified and suggested for use in order to provide uniform results and increase the comparability of future morphometric analyses. Asymmetry (the distance between the centroid of doline ground plan and the centroid of the largest inscribed circle) as an additional parameter for describing doline ground plans has been developed and is proposed for further use.
The extremely interesting karst of the Capo San Vito area in western Sicily displays the majority of the distinct characteristics of the three-dimensional landscape: karst surfaces, caves, unique ...water trickling systems, and maritime development (Ruggieri, 2009, 2015). By the sea as well as higher in the hinterland, the surface is mostly karren-like. This part of the planned study of the formation of the entire rock surface of this karst presents the results of studying the slope karren above Custonaci. They reveal the development of karren from subsoil karren and the characteristic formation of the karst surface in this area and on this rock.
Minamidaito Island is a karstified coral island located on the Philippine plate. Karstification periods occurred during the end of the Pliocene, in major part of the Pleistocene, and in the Holocene. ...The first period of karstification can be observed in the lower Daito dolomitized limestone (5 Ma and 4 Ma); the karstification seems to have occurred as a result of sea level change caused by the cooler conditions of the paleoclimatic environment. Geological studies were performed to study reef carbonates in detail. Among them, biointrasparite limestone of framestone and bafflestone types with transitions to grainstone and dolomitized biointrasparry limestone of framestone and bafflestone types dominate. Calcimetric analyses established that in certain locations the distribution of limestone and dolomite differs from the distribution previously described. Rock relief reveals the unique formation of coastal karren, the development of the surface in the interior of the island, and the most characteristic periods of cave development. Key words: Minamidaito Island, lithlogy, coral dolomitized limestone, rock relief, coastal karren, karstification, vegetation.
The study of the formation and development of karst phenomena and their rock relief using laboratory plaster modeling has again proven useful and informative. We continued the study of subsoil karren ...that forms under tight, poorly permeable contact with soil and of rain flutes formed by water at various temperatures. We determined the pattern of the reshaping of plaster tubes that are wider at the flow inlet than at the outlet end. The results are a significant contribution to explaining the formation of high ceiling niches and pockets in karst caves. The third experiment was carried out in phreatic conditions where water in a flume was forced to flow between layers of different composition. During the experiment, we observed the typical development of channels between pure plaster layers (uniform limestone beds), between plaster layers with added Portland cement reinforced fragments (breccia beds), siporex (slowly dissolving beds) and between three different layer types. Key words: laboratory modeling, karst, rock relief, subsoil karren, rain flutes, caves.
Jame brez stropa so bile stare jame, ki so zaradi znižanja kraškega površja razkrite. Posebno pozornost so nam na to pomembno, tudi površinsko kraško obliko osredotočila zemeljska dela pri gradnji ...avtocest na Krasu. Unroofed caves are old caves which have appeared due to the lowering of karst relief. Groundwork for motorway construction on Kras has brought our attention to this important surface form of karst relief.
A comparison of karren formation on various rocks under diverse environmental conditions makes an important contribution to our understanding of the formation and development of karst. In this ...regard, the present study brings a number of new insights through description of the karst development on marbles at the foothills of the Altai Mountains. We studied karst phenomena in the field and in the laboratory where structural-textural properties, mineral composition and quantity of carbonate components were determined. Rivers dissected karst surface and additionally uncovered carbonate rocks. The marble layers are faulted, folded and sheared, consequently containing numerous densely spaced net of discontinuities, which are often parallel. Brittle deformations significantly increased the rocks’ porosity, consequently making it more sensitive to water absorption and freezing thaw effect. Distinct continental climate, with extreme daily and seasonal temperature variations, conditions the pronounced peeling off of the marbles along discontinuities. The diversity of disintegration is conditioned by the massive or oriented structure, cleavage, texture, and type and grain size of the marbles’ mineral constituents. Interaction and alternation of chemical dissolution and mechanical disintegration play the major role on the karren formation and its preservation. The formed karren is mostly destroyed due to peeling off and disintegration of the marbles.
PDF