International Geologiical Congress - Oslo 2008

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CGG-01 General contributions to glaciology and glacial geology

 

Glacial Quaternary geology of las Gonzales basin, páramo los conejos, Venezuelan andes

 

Maximiliano Bezada, Universidad Pedagógica Experimental Libertador (Venezuela)
Orlando Gonzalez, Universidad Pedagógica Experimental Libertador (Venezuela)
Juan Carrera, Universidad Pedagógica Experimental Libertador (Venezuela)
Ciro Santiago, Universidad Pedagógica Experimental Libertador (Venezuela)
Dorfe Diaz, Instituto Nacional de Geología y Minería (Venezuela)
Ander De Abrisqueta, Instituto Nacional de Geología y Minería (Venezuela)
Pablo Hernandez, Instituto Nacional de Geología y Minería (Venezuela)
 

 

The area of Páramo los Conejos in the Venezuelan Andes is an important glaciated zone on the area, although its geology is almost unknown. The altitude of the studied area is between 2600 and 4300 meters above sea level, where we found important erotional and sedimentary evidence which, according to the pedological features, indicate at least two Quaternary glaciations in the valley of Las Gonzalez river, which are represented in an attachment sequence of two level of moraines that can be traced for more than seven kilometers, representing one of the most large glaciated valleys in the region. In the bottom of the valley, there is a sequence of recessional moraines and rock outcrop which daps the stream to create glacial lakes; most of them, actually completely fill it out with organic and fine sediments. In order to reconstruct the deglaciation history of the area, two lakes and three lake plains were sampled with a percussion core.

The stratigraphy of the core registered several events of advance and readvance of the glaciers which with the radiocarbon dating in progress will permit to reconstruct the Quaternary history of the area. The analysis of the outcrop reveals that half of the geology of this glaciated area is completely different of the other, where the glaciated area was never found over a basement of sedimentary rock as it is this case where the glacier affected outcrop of sandstone, mudstone and limestone of cretaceous age rest unconformity over porphydoblastic gneiss. On the other hand, the upper part of the basin is characterized by the outcrop of the Precambrian banded gneiss typical of the other glaciated area in the Venezuelan Andes. These differences in the geology outcrop along the valley are reflected in the grain composition of the Quaternary sediments and in the morphometric of the sand fraction observed in the scanning electron microscopy.

 

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