2 research outputs found
Relaci贸n de las direcciones de karstificaci贸n y del termalismo con la fracturaci贸n en las Cordilleras B茅ticas.
No full textBased on the interpretation of aerial photographs (scales between 1:10,000 and 1:35,000) an analysis is made of the various karstic fracture systems within the Betic Cordilleras of Southern Spain. The age of the fractured materials is comprised between the Middle Triassic to the Pliocene, with lithologies that. though predominantly carbonatic, also include celestite, and gypsum-bearing evaporites, Besides their directional frequency, the methodologies employed also allowed an estimate of the length relationships among fracture systems. </br> The resulta so obtained, tested against field observations, indicate that two fracture systems (N 130-160 E and N 5-35 E) are predominant, characterized respective1y by a relatively greater length of its componental fractures and by having a bimodal directional frequency, On a regional scale both systems correlate well with important structural lineaments that appear to have been active either as strike-slip or normal faults. Another fracture system striking roughly N 70-100 E presents comparatively less evidence of karstification, in spite of its considerable tectonic and paleogeographic significance (i. e., it parallels the boundary between internal ad external realms of the cordilleras, the socalled C谩diz-Alicante fracture system), The intersection of these systems (especially those striking N 70-100 E and N 130160 E) appears to be a major control of the location of the main thermal springs , as well as of the intense seismic activity of the area. </br> From a methodological standpoint. the results obtained in this study cover a scale level about which no information was previously available, and confirm existing hypotheses -based on satellite imaginery and microtectonic analysis-s- concerning the occurrence of changes in the orientation of the maximum vector of compressive stress. The strike of the karstification lineaments here signaled coincide with those obtained in analogous studies in the portuguese Algarve region, on the other hand, which suggests that the mesozoic and cainozoic karst systems in the south of the Iberian Peninsula may have had a common evolution.<br><br>Se analizan las direcciones de las principales familias de fracturas registradas en diferentes sistemas k谩rsticos de las Cordilleras B茅ticas, a partir de estudios fotogeol贸gicos (escalas 1/10.000-1/35.000). La edad de los materiales analizados comprende desde el Tr铆as medio al Plioceno; su litolog铆a predominante es carbon谩tica, aunque tambi茅n se han considerado materiales evapor铆ticos (celestina y yeso). Adem谩s de su frecuencia direccional, las metodolog铆as empleadas permiten estimar relaciones de longitud entre sistemas de fracturas.</br> Los resultados obtenidos, contrastados con observaciones de campo, se帽alan el predominio de los sistemas de direcci贸n N 130-160 E Y N 5-35 E, caracterizado el primero por la mayor longitud relativa de sus fracturas y, el segundo, por presentar car谩cter bimodal en su frecuencia direccional. Ambos sistemas se corresponden con importantes accidentes que, a escala regional, han funcionado como fallas de salto en direcci贸n y como fallas normales. Menores evidencias de karstificaci贸n presenta el sistema N 70-100 E, de gran significado tect贸nico y paleogeogr谩fico (contacto zonas Internas-Externas, accidente de C谩diz-Alicante). La intersecci贸n entre estos sistemas (principalmente los N 70-100 E y N 130-160 E) condiciona, adem谩s de la intensa sismicidad del 谩rea, la localizaci贸n de las principales surgencias termales. </br> Desde el punto de vista metodol贸gico, los resultados obtenidos cubren un nivel de escala del que se carec铆a de informaci贸n y confirman hip贸tesis previas -establecidas en base a la interpretaci贸n de im谩genes de sat茅lite, as铆 como a partir del an谩lisis microtect贸nico- relativas a cambios en la orientaci贸n del m谩ximo esfuerzo compresivo. Las direcciones de karstificaci贸n aqu铆 se帽aladas coinciden con las obtenidas en estudios an谩logos en el Algarve portugu茅s , lo que sugiere una evoluci贸n com煤n en todos los sistemas k谩rsticos meso-cenozoicos del sur de la Pen铆nsula
