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All Journal BULLETIN OF THE MARINE GEOLOGY Jurnal Geologi dan Sumberdaya Mineral (Journal of Geology and Mineral Resources)
Yan Rizal
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Chemistry Earth & Planetary Sciences Energy

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IDENTIFICATION OF SUSPECTED PALEOTSUNAMI DEPOSITS STUDY FROM KARAPYAK BEACH, PANGANDARAN AREA, WEST JAWA, INDONESIA Aswan ⠀; Yan Rizal
BULLETIN OF THE MARINE GEOLOGY Vol 36, No 2 (2021)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.36.2.2021.727

Abstract

Identifying and determining paleotsunami deposits can be a vital tool for establishing the periodicity of earthquakes and their associated tsunami events beyond historical records. However, their deposits can be difficult to establish and to date. In this study, we used the characteristics of the 2006 Pangandaran tsunami deposit as a reference to identify paleotsunami deposits in Karapyak Beach, Pangandaran area, West Java, Indonesia. Similar to the 2006 Pangandaran tsunami deposit, the Karapyak Beach paleotsunami deposit is characterized by light brown loose sand materials overlying a dark brown paleosol layer with erosional contact. A thin layer of tsunami deposit, although varies in thickness, is locally found just above erosional contact. The deposit reveals non-laminated coarse grain size in the lower part that gradually changes into medium to fine sand in the upper part. The base of this lower part is rich with broken mollusc shells and corals. The mid to top of the lower part may contain several still-intact mollusc shells and corals, rock fragments, and anthropogenic products (roof tiles). Those types of fragments are absent in the upper part of this thin tsunami deposit. Grain size analysis shows a mixture of fine and coarse grains in the lower part of the 2006 tsunami deposits, as well as in the suspected paleotsunami deposits, suggesting an uprush of high energy flow during the sedimentation. The fining upward sequence above the mixed grain layers reflects a waning flow in pre-backwash deposition. Foraminifera analysis also shows a mixture of shallow and deep marine foraminifera in both recent tsunami and paleotsunami deposits. Based on the characteristics of the 2006 tsunami deposits, there are at least four paleotsunami deposits identified in Karapyak Beach, Pangandaran area.
Fasies Sedimentasi dan Elemen Arsitektur Formasi Citalang di Desa Sidamukti, Majalengka, Provinsi Jawa Barat Abdul Fauzan Fathan Al-Hakim; Yan Rizal
Jurnal Geologi dan Sumberdaya Mineral Vol. 22 No. 3 (2021): JURNAL GEOLOGI DAN SUMBERDAYA MINERAL
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v22i3.643

Abstract

Daerah Majalengka merupakan satu daerah di Jawa Barat yang sangat menarik untuk dilakukan kajian geologi baik yang berkaitan dengan sedimentologi, tektonik maupun paleontologi. Salah satu objek yang menarik untuk dikaji ulang adalah Formasi Citalang, dimana uraian tentang formasi ini masih banyak terdapat perbedaan tentang satuan batuan penyusunnya, umur dan lingkungan pengendapannya. Disini kajian tentang formasi Citalang ditinjau dari sedimentologinya.Formasi Citalang di daerah penelitian Desa Sidamukti, Kabupaten Majalengka, Provinsi Jawa Barat tersusun atas 6 satuan batuan, yaitu: perselingan batupasir dan konglomerat sisipan tuf, perselingan batupasir dan batulempung, perselingan batupasir dan konglomerat, batupasir sisipan batulanau, perselingan batupasir dan konglomerat dengan sisipan batulanau, serta perselingan batupasir dan batulanau. Dari pengukuran penampang stratigrafi lintasan terpilih didapatkan 10 litofasies yang secara keseluruhan dijumpai dalam masing-masing satuan batuan, berupa: Fine Mud  (Fm), Fine Silt Mud (Fsm), Massive Sandstone (Sm), Horizontal Sandstone (Sh), Low Angle Cross Lamination Sandstone (Sl), Ripple Cross Lamination Sandstone (Sr), Trough Cross Bed Sandstone (St), Gravel Matrix Supported Graded Bedding (Gmg), Gravel Clast Supported Graded Bedding (Gcg), Gravel Clast Supported Massive (Gcm). Elemen arsitektural yang terbentuk pada sistem pengendapan Formasi Citalang adalah  Gravel Bar and Bedforms (GB), Sandy Bedform (SB), dan Sediment Gravity Flow (SG), yang diinterpretasikan terjadi pada lingkungan pengendapan fluvial berupa sungai teranyam.Katakunci: Formasi Citalang, elemen arsitektur, fluvial, litofasies, sungai teranyam.
Co-Authors Abdul Fauzan Fathan Al-Hakim Aswan ⠀