The cavernous forms have been developed in a great variety of rocks : gneisses, granitoids, amphibolites and breccias. The weathering is physico-chemical. The weathering material usually contains some clay minerals. The weathering processes
Phreatic sulphide bearing quartz breccias between crystalline basement and Collio formation (Southern Alps, Italy)
In this work a report is given of the geological, petrographic and ore mineralogical features of several sulphide-bearing quartz breccia (SQB) bodies outcropping in a structurally complex sector of the Orobic Alps (Southern Alpine domain) and close
to the uranium-rich mining area of Novazza. Although little studied, these breccia bodies were previously attributed to different genetic processes and/or geological domains (e.g., Crystalline Basement, Basal Conglomerate formation). The features of the SQB
in breccias. Some important inferences relative to regional geology, hydrodynamics and geothermal use of the hot waters are developped at last.-(L'A.).
The study focuses on four categories of data that each represent a coherent set of interrelated archeological and paleoenvironmental issues| a) the australopithecine breccias of the Transvaal and northern Cape| b) the valleys of the lower Vaal River
. The breccias which contain the ore do not result from tectonic nor from paeleokarstic phenomena. They are due to solution of limestone in an evolving hydrothermal system located in open fractures formed after the folding, and more precisely during the stage
to the Calcare di Bari Fm. In agreement with the previous edition of the Geologic Map of Italy few stratigraphic intervals showing a rich content in rudist assemblages and an interval of dolomitic breccias have been used as reference layers and successfully used
The geology of the island is varied, with hard and resistant basalt lavas, breccias and tuffs of intermediate resistance, and highly erodible eolianites. This variability provides an excellent opportunity to examine the influence of rock resistance
the detritic deposits of A. Efthemia and the oldest breccia on the southern talus of the Parnassus cannot be considered as one and the same thing: the former one is older than the latter. Both Mindelian and Wurmian talus fans are related to rhexistasic crisis
lithological guidance of the horizontal levels is demonstrated, considering only the deepest passages to be palaeo-phreatic. The main tectonic structures guide the oldest and inactive parts of the cave, developed mostly within weakly cohesive fault breccias