engleski

Structural analysis of faults and shear joints and reconstruction of Cenozoi paleostress fields on the island of Pag, External Dinarides

This study includes collection, analysis and interpretation of structural data on faults and shear joints observed in Late Cretaceous to Quaternary rocks exposed on the Island of Pag in the External Dinarides. Based on fault kinematic data visualization, processing and analysis it was possible to separate six distinctive fault groups. For each group we calculated stress tensors by means of computer program TectonicsFP and determined related paleostress fields. Separated fault groups and related paleostress fields are interpreted in the following chronological order. Fault groups 5 and 6 are interpreted as the oldest fault structures documented by this study. These groups comprise NW-SE striking reverse faults related to compressional stress regime characterized by the NE-SW directed main compressional stress axis. Activity of these faults is presumed during the Late Eocene – Oligocene, i.e. during the main deformational phase in the External Dinarides. Group 4 comprises ENE-WSW striking dextral faults formed in stress regime characterized by the NW-SE directed compressional and the NE-SW directed tensional stress axis. Group 3 comprises conjugate fault set represented by the NW-SE striking reverse-sinistral and the NE-SW striking reverse-dextral faults. These were formed in stress regime characterized by NW-SE directed compressional and NE-SW directed tensional stress axis, practically the same as for the previous group. Activity of faults groups 4 and 3 is presumed during the Miocene. Group 2 comprises a conjugate fault set represented by the NW-SE striking normal faults. These faults were formed in extensional stress regime characterized by the NE-SW directed tensional stress axis, i.e. orthogonal to the predominant trend of compressional structures in the External Dinarides. Activity of these faults is presumed during the Miocene and Pliocene. Group 1 is the youngest fault group that comprise conjugate fault set composed of the NNW-SSE striking dextral and the NNE-SSW striking sinistral faults. These faults were formed in stress regime characterized by the N-S directed compressional and the E-W directed tensional stress axis and are presumed to be active during the Pliocene and Quaternary.

paleostress analysis; Cenozoic; External Dinarides

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