Analisis Dinamik Tegasan Purba pada Satuan Batuan Paleogen – Neogen di Daerah Pacitan dan Sekitarnya, Provinsi Jawa Timur Ditinjau dari Studi Sesar Minor dan Kekar Tektonik

C. I. Abdullah¹, N. A. Magetsari¹ & H. S. Purwanto²

¹Departemen Teknik Geologi, FIKTM, ITB, Bandung

²Jurusan Teknik Geologi, UPN “Veteran”, Yogyakarta

There are four trends of geological structures in the region of Pacitan and its closed surrounding, as the result of the tectonic deformation which occured during the Tertiary up to Quaternary. Those trends of geological structures are classified as fault groups in the direction of NW - SE (N310⁰E - N330⁰E), N - S (N350⁰E - N010⁰E), NE - SW (N045⁰E - N050⁰E), and E - W (N080⁰E). The result of the paleostress reconstruction based on the minor faults and shear fractures, point to three axis direction of principle stress: First, Early Miocene Stress with the s₁ direction between 15⁰, N164⁰E - 09⁰, N170⁰E. The respective stress caused the formation of fault in the direction of NW - SE and fold structures. Second, Middle Miocene Stress with the s₁ direction between 16⁰, N192⁰E – 15⁰, N196⁰E , which caused the formation of fault in the direction of NE - SW and N - E. Third, Plio-Pleistocene Stress with the s₁ direction 14⁰, N198⁰E. This latest stress caused the reactivation of the fault groups which occurred previously.

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