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.New Frontiers in Integrated Solid Earth Sciences Phần 9

Việc công nhận một mối quan hệ di truyền giữa các miệng núi lửa và động lực khu vực, transtension trái phương được tăng cường bởi các phân tích chi tiết của lịch sử tectono magma của Caldera Negra Muerta. | 334 A. Tibaldi et al. dynamics and associated ignimbrite volcanism are genetically linked to the activity of NW-SE-striking zones of left-lateral transtension. In fact most calderas in the southern central Andes are associated with NW-SE-striking transcurrent fault systems such as the Lipez Calama-Olacapato-El Toro Archibarca and Culampaja Salfity 1985 which define four major transverse volcanic zones. The recognition of a genetic relationship between caldera dynamics and regional left-lateral transtension is strengthened by the detailed analysis of the tectono-magmatic history of the Negra Muerta Caldera which has recently been the subject of other studies Petrinovic et al. 2005 Ramelow et al. 2006 . Riller et al. 2001 explain the formation of this partially eroded and asymmetric caldera in terms of an evolution in two successive increments driven by leftlateral strike shear and fault-normal extension on the prominent Calama Olacapato-El Toro fault zone. Analogue Modelling In the last decade analogue modelling in scaled experiments has been used to test the control exerted by strike-slip faulting on volcanic activity. van Wyk de Vries and Merle 1998 used analogue modelling to evaluate the effect of volcanic loading in strike-slip zones as well as the effect of regional strike-slip faults on the structure of volcanic edifices. Their analogue models indicate that volcanoes in strike-slip zones develop extensional pull-apart structures. A feedback mechanism can arise in which loading-related extension enables increased magma ascent eruptions and hence increased loading. The authors suggest that the Tondano caldera North Sulawesi may be the result of feedback between volcano loading and faulting. Other major volcano-tectonic depressions such as Toba Ranau Sumatra and Atitlan Guatemala might have a similar origin. Holohan et al. 2007 made scaled analogue models to study the interactions between structures associated with regional-tectonic strike-slip deformation and .