Secondary discontinuities in basaltic rock masses of the Parana basin, Brazil. generators, mechanisms and structural models

74A equivalent materials under conditions of tangential compression, indicated the possibilities of intensive axial folding followed by relative homogenization. Further structural analyses have indicated the causes of folding as being due to horizontal tectonic compression, in connection with the 'intrusion' of the Arabian plate. 922008 Joints and the neotectonics of the Scotia plate, Antarctica Seheidegger, A E Proc lnternatiomd Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P187-193. Publ Rotterdam: A A Balkema, 1990 Joint orientations were measured in the region of the Scotia Plate. Interpretations of these orientations were then carried out in order to establish the in situ stress orientations. These data were also used to assess the fault plane solutions of earthquakes reported from the area. The significance of the joints as they correspond with present-day neotectonic stress fields is examined. 922009 Mechanics of shear zones and fault belts development by anastomosing patterns of fractures at all scales Archambault, G; Daigneault, R; Rouleau, A; Tavchandjian, O Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P197-204. Publ Rotterdam: A A Balkema, 1990 The controlling factors, variables, mechanical conditions, and existing models on the evolution of brittle and ductile fault and shear belts have been analyzed. The phenomena, which are characterized by progressive interlinking of structural discontinuities in braided networks, are supported by illustrations from field observations and shear zone simulations. The laboratory and field case studies together with statistical methods used for characterization of such discontinuities are presented. 922010 Experimental study of joinfing during cylindrical and noncylindrical folding Rives, T; Petit, J P Proc internationnl Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P205-211. Publ Rotterdam: A A Balkema, 1990 Experiments were carried out using PVC plates coated with a thin film of brittle varnish and then subjected to cylindrical and non-cylindrical bending. The experiments were aimed at understanding the mechanical origin of natural joint patterns linked to folding. As the joints formed in the varnish during bending, their propagation parallel to the fold axis was observed. The geometry of these fractures is compared to that of some natural features. 922011 Fractai fault patterns as a dual DLA problem Sornette, A; Sornette, D; Davy, P Proc International Conference on Methanes of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P229-235. Publ Rotterdam: A A Balkema, 1990 Continental deformations are generally associated with complex patterns of faults developed in the uppermost brittle crust. Scaling analysis using fractals was carried out in order to study continental lithospheric mechanics. Test models were prepared from uncemented sand for the brittle layer and silicone putties of different viscosities for the other layers. Wedge

penetration into the model material was used to simulate development of fault patterns. Analogy with the diffusion limited aggregation tDLA) ~r..:d.-1 of growth is dz~cussed. 922012 Secondary discontinuities in basaltic rock masses of the Parana basin, Brazil. Generators, mechanisms and structural models Souza, N H; Campos, J O Proc International Conference on Alechanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P237-243. Publ Rotterdam: A A Balkema, 1990 Four structural models were studied in order to explain the fault patterns of the basaltic rock masses of the Parana basin. The models were built to reflect the transcurrent reverse faulting, tectonic compressive stresses, confinement stress and the effects of uplift and formation of tensile fractures. Two more models have been studied in order to analyse the formation of secondary discontinuities. The models show significant differences, but they may be considered in the same context. A hypothetical sequence for development of the fault patterns is suggested. 922013 Characterlatlcs of the structural fabric in conditions of rotation - example of North Velebit in Croatia, Yugoslavia Huzak, T; Prelogovic, E Proc International Conj'erence on Mechanics of Jointed and Faulted Rock, Viet~,4, 18-20 April 1990 P245-248. Publ Rotterdam: A A Balkema, 1990 New data that can be used to explain some of the features of fractures and faults which occur in the area have been collected. The effects of uplifting and overthrusting and the stages through which they occurred have been analysed. The changes in stress that followed the formation of the geological structures in the area and their influence on further fracturing have also been examined. 922014 Stress distribution required for fault and joint development Kersten, R W O Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P251-256. Publ Rotterdam: A A Balkema, 1990 The influences of stress distribution and temperature changes on rock mass behaviour have been studied. Using a Mohr diagram for a specific rock/mineral, the maximum stress that can be maintained under various temperature conditions is evaluated. Through this, areas liable to faulting, folding and jointing under tectonic conditions can be identified. 922015 Chalk and petroleum in North-West Europe D'Heur, M Proc International Chalk Symposium, Brighton, 4-7 September 1989 P631-639. Publ London: Thomas Telford, 1990 Chalk was discovered to comprise major hydrocarbon reservoirs in Europe during exploration of the North Sea Ekofisk field. The peculiarities of chalk as a hydrocarbon reservoir are discussed, considering favourable sedimentary facies, lateral initial variation, differential diagenesis, accumulation of oil, and reservoir compaction. Knowledge and understanding of the chalk and its anomalies are vital for optimising petroleum output from these subsea formations.

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