CECAV
URI permanente desta comunidadehttps://bdc.icmbio.gov.br/handle/cecav/1
Centro Nacional de Pesquisa e Conservação de Cavernas
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Resultados da Pesquisa
Item Late Quaternary episodes of clastic sediment deposition in the Tarimba Cave, Central Brazil(2021-04-10) Caldeira, Dandara; Uagoda, Rogério; Nogueira, Adivane Morais; Garnier, Jeremie; Sawakuchi, André Oliveira; Hussain, YawarThe study presents three sedimentary profiles from Tarimba cave in central Brazil. The data allow constraining the late Quaternary sedimentary evolution of cave systems in the region. A multi-techniques approach was used to characterize sediment texture (grain size and circularity index), mineralogical composition (X-Ray Diffraction), chemical composition (ICP-OES) and deposition ages (Optically Stimulated Luminescence and radiocarbon). Eight sedimentary facies were identified, including a facies formed by autochthonous sediments (Guano) and seven facies formed by allochthonous siliciclastic sediments. The siliciclastic facies range from clayey to gravelly deposits that correspond to high-density gravity flows (Diamicton) and water laid traction process of varied deposition energy (Channel, Backswamp, and Slackwater). The studied deposits reflect an intense cave filing from the Middle to Late Pleistocene in the last 200 Ka. Subsequent depositional events formed three sedimentation phases: the first before 200 Ka corresponding to a larger granulometric interval, clay to gravel, identified through erosive surfaces; the second, after 197 Ka, is composed of sandy sediments and oscillations in the water flow energy. The third phase between 87 and 52 Ka (which covered the other stages) was responsible for the last fluvial deposition.Item Detection of Cover Collapse Doline and Other Epikarst Features by Multiple Geophysical Techniques, Case Study of Tarimba Cave, Brazil(2020) Hussain, Yawar; Uagoda, Rogerio; Borges, Welitom; Prado, Renato; Hamza, Omar; Cárdenas-Soto, Martín; Havenith, Hans-Balder; Dou, JieReliable characterization of the karst system is essential for risk assessment where many associated hazards (e.g. cover-collapse dolines and groundwater pollution) can affect the natural and built environments threatening public safety. The use of multiple geophysical approaches may offer an improved way to investigate such cover-collapse sinkhole and aid the geohazard risk assessment. In this paper, covered karst, which has two types of shallow caves (vadose and fluvial) located in Tarimba (Goias, Brazil), was investigated using various geophysical methods to evaluate their efficiency in the delineation of the geometry of sediments filled sinkhole. Three methods were used including Electrical Resistivity Tomography (ERT), Seismic Refraction Survey (SRS), Seismic Refraction Tomography (SRT) and Very Low Frequency Electromagnetic (VLF-EM) method. The study developed several resultant (2D) sections of the measured physical properties, including P-wave velocity and electrical resistivity, as well as the induced current (because of local bodies). For the analysis and processing of the data obtained from these methods, the following approaches were adopted: ERT inversion using a least-square scheme, Karous-Hjelt filter for VLF-EM data, and time-distance curves and Vp cross-sections for the SRS. The refraction data analysis showed three-layered stratigraphy topsoil, claystone, and carbonate bedrock, respectively. The findings obtained from ERT (three-layered stratigraphy and sediment-filled doline) as well as VLF-EM (fractured or filled caves as a positive anomaly) were found to be consistent with the actual field conditions. However, the SRS and SRT methods did not reach the depth of the cave because of shorter profile lengths. The study provides a reasonable basis for the development of an integrated geophysical approach for site characterization of the karst system, particularly the perched tank and collapse doline.- Late Quaternary episodes of clastic sediment deposition in the Tarimba Cave, Central Brazil(2021-04-10) Caldeira, Dandara; Uagoda, Rogério; Morais Nogueira, Adivane; Garnier, Jeremie; Sawakuchi, André Oliveira; Hussain, YawarThe study presents three sedimentary profiles from Tarimba cave in central Brazil. The data allow constraining the late Quaternary sedimentary evolution of cave systems in the region. A multi-techniques approach was used to characterize sediment texture (grain size and circularity index), mineralogical composition (X-Ray Diffraction), chemical composition (ICP-OES) and deposition ages (Optically Stimulated Luminescence and radiocarbon). Eight sedimentary facies were identified, including a facies formed by autochthonous sediments (Guano) and seven facies formed by allochthonous siliciclastic sediments. The siliciclastic facies range from clayey to gravelly deposits that correspond to high-density gravity flows (Diamicton) and water laid traction process of varied deposition energy (Channel, Backswamp, and Slackwater). The studied deposits reflect an intense cave filing from the Middle to Late Pleistocene in the last 200 Ka. Subsequent depositional events formed three sedimentation phases: the first before 200 Ka corresponding to a larger granulometric interval, clay to gravel, identified through erosive surfaces; the second, after 197 Ka, is composed of sandy sediments and oscillations in the water flow energy. The third phase between 87 and 52 Ka (which covered the other stages) was responsible for the last fluvial deposition.