Geomorphological units in Arcos-pains karst region, Minas gerais, Brazil (original) (raw)
Related papers
Geological Field Guide of Montes Claros Karst, Minas Gerais
Estudos geológicos, 2023
The Montes Claros Karst is located on the eastern margin of the Bambuí Basin, one of the covers of the São Francisco Craton affected by the Brasiliano Event, which deformed the limestones of the Lagoa do Jacaré Formation, creating a westward folding system and a pair of fractures F1 (NNE-SSW) and F2 (WNW-ESE). These structures control the circulation of water in the limestone massifs, leading to the development of the Montes Claros karst. The main features of the karst landscape are caves, valleys, dolines and limestone massifs. The caves are the best place to observe the main sedimentary facies of the limestones of the Lagoa do Jacaré Formation, as well as sedimentary and deformational structures. The main controls of the cave conduits are the F1 and F2 fractures. These are the same directions described on a regional and local scale, which shows us that the structural control of the exocarst is the same as that of the endocarst. This geological field guide shows in a didactic way the main facies and sedimentary structures of the limestone of the Lagoa do Jacaré Formation, the deformational structures that favoured the karst formation and the typical karst morphologies in limestone rocks.
Karsts in sandstones and quartzites of Minas Gerais, Brazil
The state of Minas Gerais (Brazil) is characterized by significant karst regions, which develop in both sandstone and quartzite terrains and display complex suites of underground and surface forms. In the Espinhaço Ridge, Central Minas Gerais, several caves of up to a few hundred metres long, occur in the surroundings of the town of Diamantina. Some of these caves, such as Salitre actually consist of swallow-holes. Other horizontal caves are characterized by corrosion forms generated in the phreatic zone. In some places, such as in the Rio Preto area, these phreatic forms are overprinted by ceiling tubes, suggesting a polyphase karst evolution, prior
Karst in sandstones and quartzite of Minas Gerais, Brazil
Cuadernos Laboratoiro Xeoloxico de Laxe
The state of Minas Gerais (Brazil) is characterized by significant karst regions, which develop in both sandstone and quartzite terrains and display complex suites of underground and surface forms. In the Espinhaço Ridge, Central Minas Gerais, several caves of up to a few hundred metres long, occur in the surroundings of the town of Diamantina. Some of these caves, such as Salitre actually consist of swallow-holes. Other horizontal caves are characterized by corrosion forms generated in the phreatic zone. In some places, such as in the Rio Preto area, these phreatic forms are overprinted by ceiling tubes, suggesting a polyphase karst evolution, prior
Polyphased karst systems in sandstones and quartzites of Minas Gerais, Brazil
2005
The state of Minas Gerais (Brazil) exhibits several major karst areas located in sandstone and quartzite terrains, that display a complex suite of underground and surface karstic forms. In the Espinhaço Ridge, central Minas Gerais, several caves, up to a few hundred metres long, occur in the surroundings of the town of Diamantina. Some of these caves, such as Salitre, represent swallow-holes and show dome pits. Other horizontal caves are characterized by corrosion forms generated into the phreatic zone. In some places, such as in the Rio Preto area, these phreatic forms have been overprinted by ceiling tubes, suggesting a polyphase karst evolution, prior to the draining of the cave. Relicts of passages, with circular cross section up to a metre in diametre, can be found amidst the residual tower-like surface landforms, which constitute a typical scenery in the landscape. Their dissection is due to a generalised karstification in the area, resulting in closed canyons, megakarrens and kamenitzas. In southern Minas Gerais, close to the Mantiqueira Ridge, the caves of the state park of Ibitipoca can extent 2 km in length. These caves are associated with a very large hanging geological syncline. Several of these caves contain active streams, that flow for hundreds of metres before disappearing in sand-choked passages. Keyhole cross sections characterize steeply descending passages in these caves, indicating a change from slow phreatic flow towards a faster vadose flow responsible for the vertical incision of the passage. Such change is probably related to base level lowering and/or to turn in the direction of the water flow. Several generations of wall-pockets, from a few centimetres to over a metre long, occur into the caves. These features are good indicators of the initial phase of speleogenesis, generating the initial conduits by their coalescence. This mechanism is also responsible for cut-off meanders. The main river in the area, which flows along the syncline axis, cuts through a rock barrier, generating a tunnel-like passage. This cave drains, through resurgences in its walls, part of the water that flows in other caves located in the flank of the syncline. The non-carbonate karst features observed in the state of Minas Gerais demonstrate the complex organisation of polyphase karst systems due to the linkage of underground and surface forms not previously connected. As in carbonate areas, these systems may play an important hydrological role. Fig. 1: Localisation of the studied areas
Karsts of sandstones and quartzites of Minas Gerais, Brazil
Cuadernos Laboratoiro Xeoloxico de Laxe
The state of Minas Gerais (Brazil) is characterized by significant karst regions, which develop in both sandstone and quartzite terrains and display complex suites of underground and surface forms. In the Espinhaço Ridge, Central Minas Gerais, several caves of up to a few hundred metres long, occur in the surroundings of the town of Diamantina. Some of these caves, such as Salitre actually consist of swallow-holes. Other horizontal caves are characterized by corrosion forms generated in the phreatic zone. In some places, such as in the Rio Preto area, these phreatic forms are overprinted by ceiling tubes, suggesting a polyphase karst evolution, prior
Hundreds of karstic features (n = 266) and gullies (n = 80) are indentified in an area (56.3 km 2 ) of non-carbonate rocks which include pure quartzite (Q), impure quartzite (Qi) and gneiss (G) within the Santana Basin (286 km 2 ), a part of Middle Paraiba do Sul River Valley, southeastern Brazil. Karstic features include caves (n = 32), collapsed dolines (n = 23), solution dolines (n = 209), Sinkholes (n = 02) and resurgences (n = 02). Gullies include active gullies (n = 46) and stabilized gullies (n = 34). Other general features as knickpoints (n = 06) and captured valleys (n = 03) were also indentified. We used GIS to study correlations between the presence of features, precise lithology and relief to indentify possible controls. The results suggest a lithological control on the karstic features with higher frequency of caves, collapsed dolines, sinkholes and resurgences in pure quartzite (Q) and in areas with high relief, but there is no lithological control on solution dolines. Gullies, knickpoints and captured valleys are also not controlled by lithology or relief. The results suggest a fluvial control of gullies and depositional features in valley bottoms caused by headward erosion, after underground captures or knickpoint disruption.
The salitre cave karst in the quartzite rocks of diamantina, Minas Gerais, Brazil
This work presents the main morphological characteristics of the Salitre Cave, located in the municipal district of Diamantina -MG and formed in quartzite rocks of the Espinhaço Supergroup, Sopa-Brumadinho Formation as an example of a well-developed karst system. This system now supported by two to three independent small seasonal rivers and displays well-developed dissolution and breakdown structures, as a result of intense intemperance activity. This karst formed, probably before the beginning of Quaternary taking advantage of a system of fractures, normal and thrust faults caused by Espinhaço and Brasiliano events in the Middle to Late-Cambrian. This work attempts at presenting an integrated view of the investigated area and at emphasizing its importance for the understanding of the processes, which occurred in the in carbonatic, quartzitic and silico-carbonatic rocks of Rio San Francisco and Rio Jequitinhonha Basins among the chain of the Espinhaço Range on east and the river valley of San Francisco on the west.
Karst developed in siliciclastic rocks at Serra do Espinhaço Meridional (Brazil)
This study aims to develop a karst synthesis development in siliciclastic rocks and its spatial distribution at Serra do Espinhaço Meridional (SdEM -Southern Espinhaço Ridge), Minas Gerais (MG), from synthetic survey and mapping of the main areas with presence of more common caves and karst morphologies. The methodological procedure consists in a literature review, consulting to the database , tabulating the data already surveyed and their respective coordinates, fieldwork and karst prospection. Later, the data were organized for graphing and location maps of the main features and discussion of the results. It is highlighted that most of the features studied in SdEM correspond to caves (88%). The location of the features mapped is inserted, primarily, in the eastern and western edges of SdEM and in the central area of this geomorphological unit. Therefore, it appears that although the entire ridge studied has a potential for development of landforms, the carried studies has a horizontal, conceptual, descriptive, and focused on speleology, nature. In the field, were identified features as pits, shelters, sinkholes, kamenitzas, lapiaz, bee nests, among others, whose morphology is equivalent to those identified in carbonate rocks. It is intended, in this way, to encourage scientific studies development on the other karst features and verticalise issues related to geochronology, morphometry and geochemistry factors of karst formation in this area and siliciclastic rocks.
14th UIS Congress, …, 2005
Tributary of the left side of the São Francisco river, the Rio Peruaçu Basin is an important site for archaeological and geomorphological studies in the Central Brazil. From its springs in the sandy detritic layers of the São Francisco-Cochá border, the Peruaçu River flows out to its confluence with the main river, 100 km farther. In its middle watercourse, it has dug a very impressive karstic relief with canyon into the limestone layers. Resulting in these magestic epikarst and endokarst forms the complex evolution begins to be understood. The morphological observation of this great canyon and of the associated forms (caves, sediment deposits, landforms, ...) has placed in a prominent position various complex elements, revealing several phases of the karst evolution. From this, appear two great digging phases stored in 50 m and separated by a complex stage of inundations attributed to the roof collapsing of the great gallery which opened the canyon and the Terra Brava polje too. Consequently i) testimonies of a first drainage stage (Janelão I) are hanging and detached of the current geomorphological context, and ii) adapted forms to inundation phases (Terra Brava) iii) or/and water level lowering (Janelão II) can be identified. The karst system evolution during the Cenozoic is explained in a conceptual model which can be extended to other karst systems of the São Francisco middle stream, showing the regional value of the agents responsible for this evolution.