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Previous issue date: 2016-08-23 / Este estudo teve seu foco em dados de superf?cie e sub-superf?cie rasa,
permitindo a caracteriza??o da evolu??o recente do carste epig?nico em quatro
est?gios. Durante o Est?gio 1 as fraturas foram abertas pelo processo de
dissolu??o, as quais formaram caminhos verticais em escala centim?trica ?
m?trica. O conjunto mais abrangente de fraturas concentra a dissolu??o. Ao
longo de camadas horizontais intersectadas pelas fraturas tamb?m se observa
dissolu??o intraestratal e interestratal. Este sistema de canaliza??o forneceu os
caminhos para o fluxo de ?gua, gerando avan?ada lixivia??o. A expans?o
alargamento desses condutos em sub-superf?cie ocasiona no Est?gio 2 a
queda de blocos, gera??o de dolinas e cavernas. Durante o Est?gio 3, a
propaga??o da dissolu??o horizontal e vertical ao longo de fraturas e camadas
causam coalesc?ncia de dolinas e captura de pequenos riachos que evoluem
para vales incisos e canyons, como pode ser observado no Riacho do
Livramento, afluente do rio Apodi-Mossor?, descrito na ?rea III deste estudo.
Processos fluviais dominam a dissolu??o do carste durante o Est?gio 4, onde
os sedimentos aluviais que recobrem a superf?cie c?rstica carbon?tica,
resultando no preenchimento e posterior soterramento de cavernas e dolinas
ao longo do vale. Observou-se assim que a influ?ncia do controle tect?nico e
do acamamento sedimentar ocorre em todas as fases de evolu??o do carste,
resultando nas diversas estruturas e formas de relevo coexistentes
espacialmente e que se sucedem, temporalmente, durante os diversos est?gios
descritos. Os dados aqui apresentados corroboram os resultados obtidos em
outros estudos utilizando dados de GPR, po?os e levantamentos s?smicos,
tanto na Bacia Potiguar como em outras bacias sedimentares que
evidenciaram que tais estruturas podem ser preservadas ap?s o soterramento. / This research analyzes different types of karst landforms and their relationships
with fracture systems, sedimentary bedding, and fluvial processes. We mapped
karst features in Cretaceous carbonates of the Janda?ra Formation in the
Potiguar Basin, Brazil. The study area is a semi-arid region, with low annual
rainfall (600mm) and high evaporation (2000mm). We used high-resolution
digital elevation models acquired by Light Detection and Ranging (LiDAR) and
aerial ortophotographs acquired by unmanned aerial vehicle (UAV). This study
focuses on surface and near surface process and grouped karst evolution into
four stages. Fractures were opened by dissolution, which form vertical fluid
pathways during stage 1 in a centimetric to metric scale. The most pervasive
set of fracture concentrates the dissolution. Coeval intrastratal and interstratal
dissolution occurred along horizontal layers, which bound dissolved fractures.
This conduit system acted as pathways for water flow, which caused advanced
leaching. The enlargement of conduits in subsurface contributed to the collapse
of blocks, generation of sinkholes, and caves expansion in stage 2. During
stage 3, propagation of horizontal and vertical dissolution along fractures and
layers cause coalescence of sinkholes and capture of small streams. Fluvial
processes dominate karst dissolution during stage 4, where alluvial sediments
that caps the carbonate karst surface and fill caves and sinkholes along the
valley. Tectonic and sedimentary bedding control all stages of karst evolution
and resulting structures and landforms formed during these stages coexist.
Comparisons with GPR, borehole and seismic surveys in sedimentary basins
indicate that these structures are preserved after burial.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/22583 |
| Date | 23 August 2016 |
| Creators | Silva, Orildo de Lima e |
| Contributors | 37923579415, http://lattes.cnpq.br/6050302316049061, Silva, Carlos Cesar Nascimento da, 81352921472, http://lattes.cnpq.br/5136096872133075, Xavier Neto, Pedro, 16361121372, http://lattes.cnpq.br/0420885770350995, Bezerra, Francisco Hil?rio Rego |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM GEODIN?MICA E GEOF?SICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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