Analisis struktur dan evolusi tektono-stratigrafi Jawa Timur Utara Cekungan Jawa Timur
D aerah penelitian termasuk Cekungan Jawa Timur yang merupakan cekunganTersier dengan sejarah geodinamika yang aktif. Meski demikian, pembagianstratigrafinya masih dalam litostratigrafi, terutama di daratan Jawa Timur. Salahsatu cara memahami perkembangan cekungan secara regional yakni menggunakanpendekatan tektonostratigrafi, yang merupakan metode analisis stratigrafi denganmemperhitungkan pengaruh kegiatan tektonik terhadap asal suksesi stratigrafi.Penelitian ini bertujuan mempelajari perkembangan struktur dan stratigrafi daerahpenelitian, yang kemudian digunakan untuk pemodelan konseptual geologimengenai evolusi tektonostratigrafi daerah penelitian.Analisis tektonostratigrafi pada penelitian ini menggunakan dataset seismik, yangterbagi menjadi 5 lintasan seismik regional (arbitrary line) dan 4 well top disekitar wilayah Jawa Timur utara. Penelitian didasarkan pada konseptektonostratigrafi dan stratigrafi seismik untuk menentukan paket reflektorseismik yang selanjutnya digunakan untuk menginterpretasi horison dan strukturgeologi pada daerah penelitian. Unit tektonostratigrafi didasarkan kesesuaian topformasi dengan sikuen pengendapan tertentu yang telah dikenali di kolomstratigrafi umum Cekungan Jawa Timur.Hasil interpretasi data seismik dan well top menunjukkan stratigrafi seismikdaerah penelitian secara tektonostratigrafi tersusun atas 7 satuan, yaitu UnitPre-Rift, Unit Syn-Rift, Unit Post-Rift 1, Unit Post-Rift 2, Unit Syn-Contraction 1,Syn-Contraction 2 dan Unit Post-Deformasi. Struktur geologi yang berkembangpada daerah penelitian terbagi menjadi 2 sistem struktural, yakni sistem sesar naikterkait perlipatan di selatan yang termasuk Zona Kendeng dan sistem sesarmendatar di utara termasuk dalam Zona Rembang. Evolusi tektonostratigrafidaerah penelitian diawali oleh tektonik ekstensi unit Pre-Rift pada Paleosen-EosenAwal, diikuti sedimentasi Unit Syn-Rift dan Post-Rift selama Eosen Tengah –Miosen Tengah. Tektonik kompresi pada Miosen Tengah mengakomodasisedimentasi Unit Syn-Contraction dan dilanjutkan dengan pengendapan UnitPost-Deformasi sejak Pleistosen – Resen.
T he study areas is part of the East Java Basin which is a Tertiary basin withactive geodynamics history. However, regional stratigraphy in this area is stillusing lithostratigraphy approach, especially on the East Java onshore. The way toovercome the stage of sedimentary basins formation is by usingtectonostratigraphic approach. This approach is a method for stratigraphicanalysis with particular attention to the influence of tectonic processes upon theorigin of stratigraphic successions. The primary aim of this study is discusses thestage of structural and stratigraphy formation which can be accepted in therenewal of the tectonostratigraphy evolution of the study area.The tectonostratigraphic analysis in this study used dataset seismic, which weredivided into 5 arbitrary line and 4 well top data over the North East Java region.The research is based on the concept of tectonostratigraphy and seismicstratigraphy to determine the seismic reflector package and interpret the seismichorizon and geological structure in the study area. The tectonostratigraphic unitlies in the suitability of the top formation with depositional sequences that havebeen identified in the general stratigraphic column of the East Java Basin.The results of the interpretation of seismic and well top data show thattectonostratigraphy seismic stratigraphy of the study area can be divided into 7units, i.e.., Pre-Rift, Syn-Rift, Post-Rift 1, Post-Rift 2, Syn-Contraction 1,Syn-Contraction 2 and Post-Deformation Unit. The geological structure thatdeveloped in the study area is divided into 2 structural systems, i.e.., thrustfault-related folding systems in the south of the research area, part of KendengZone and the wrench fault system in the north, part of Rembang Zone. Theevolution of tectonostratigraphy in the study area was preceded by tectonicextension of the Pre-Rift Unit in the Early Paleocene, followed by sedimentationof the Syn-Rift and Post-Rift Units during Middle Eocene - Middle Miocene.Compression tectonics in the Middle Miocene accommodated the sedimentation ofthe Syn-Contraction unit and continued with the deposition of thePost-Deformation Unit since the Pleistocene - Recent..