Scholarly record

EROSIONAL RELIEF CONTROLLED BY FISSURES SYSTEMS IN THE PRICOPAN MASSIF, NORTH DOBROGEA (ROMANIA)

Daniela Dimofte

Abstract

The studied area is the North Dobrogea Orogen, Pricopan Massif. Compared to the other massive from the North Dobrogea, the Pricopan massif has a more rugged relief. The Pricopan massif is mostly a granite plutonic body with a lenticular shape, with the long axis (AL) oriented NNW-SSE and the transverse axis (AT). In the southern part, the Pricopan Massif is made up of diagenized sedimentary rocks, named the "Carapelit series". In the ridge area of the granite sector, there are alternations of peaks and saddles, steep slopes, short crossing valleys with steep slopes. In order to explain the variability of the relief in this granite sector, several causes can be invoked: the presence of lithological heterogeneities, the variability of the modal composition of the granite body, the structural variability of the granite or the variability of the characteristics of fissures systems. Field measurements of numerous fissure planes and fault in the Pricopan Massif highlight the presence of three sets of fissures: two vertical sets (longitudinal-SL and transversal-ST) and a horizontal set. Due to these sets, the petrographic bodies, initially compact, were divided into fragments of vary shapes and sizes. Predominant are the plane side fragments, named polyhedral bodies or polyhedral fissures, resulting from the intersection of plane fissure sets. The polyhedral fissures are taking part in a rounding process, gradually decreasing their volume to extinction. The elimination of the polyhedrons from the surface of the petrographic body has as the last effect changes in the topography.

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