科研之友
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摘要
Regional and local strike-slip systems in Chile are complex and pose interesting questions, such as the interaction between strike-slip and reverse faults, how they evolve, and the relationship between shortening, rotation and uplift. Within this context, we developed a new analytical method based on analogue and numerical modelling applied to 3D, pure and transtensional-transpressional strike-slip systems. Analogue modelling results indicate that in restraining stepovers of strike-slip fault systems, where antiformal pop-up structures are usually formed, pre-existent basement structures with a high angle to the main strike-slip fault will generate a higher rotation of blocks. However, when these structures are oriented at a high angle with respect to the main stress convergence vector, the rotation will be less and therefore a higher tendency to uplift will be produced. These results were applied to NW- and SE-striking basement faults oblique to N-S mega-thrust faults in central Chile (32～-35～S), for which we propose a simultaneous development based on the analogue model results. Moreover, we propose that strike-slip movement occurred on thrust faults in central Chile. Furthermore, we performed a numerical restoration of an analogue experiment which modeled a pure strike-slip system, and concluded that the restoration is very sensitive to shortening data as well as to rotational data. These results are extremely important for future numerical and regional analysis of strike-slip systems. Los sistemas de rumbo regionales y locales en Chile son complejos y plantean interesantes preguntas, tales como la interacci車n entre fallas de rumbo y fallas inversas, c車mo evolucionan ellas, y la relaci車n entre acortamiento, rotaci車n y alzamiento. En este contexto, desarrollamos un nuevo m谷todo anal赤tico basado en modelamiento anal車gico y num谷rico de sistemas de rumbo de cizalle puro y sistemas transpresionales-trantensionales en 3D. Los resultados del modelamiento anal車gico indican que en los %26apos;restraining stepovers%26apos; de sistemas de rumbo, donde se forman normalmente anticlinales pop-up, estructuras de basamento preexistentes con un alto 芍ngulo respecto a la falla de rumbo principal generar芍n una mayor rotaci車n de bloques. Sin embargo, cuando estas estructuras est芍n orientadas a altos 芍ngulos con respecto al vector de esfuerzo principal, la rotaci車n ser芍 menor y, por lo tanto, producir芍n una mayor tendencia al alzamiento. Estos resultados fueron aplicados a estructuras de rumbo NW y SE en el basamento oblicuas a megasistemas inversos norte-sur en Chile Central (32～-35～
