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Variation of Slab Component in Ancient and Modern Merapi Products: A Detailed Look into Slab Derived Fluid Fluctuation over the Living Span of One of the Most Active Volcanoes in Sunda Arc Esti Handini; Toshiaki Hasenaka; Agung Harijoko; Yasushi Mori
Journal of Applied Geology Vol 2, No 1 (2017)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Holocene eruptions of Merapi have produced both medium-K and high-K calc alkaline series which correspond to products older and younger than 1900 years respectively. The change has been attributed to increasing sediment input as the volcano matures. This study presents two Merapi samples which represent Ancient and Modern Merapi. The two samples are analyzed for subduction components including B, Ba, Sr, and Pb using X-ray ﬂuorescence (XRF) spectrometer and prompt gamma ray analysis (PGA). Our ﬁnding shows that Ancient Merapi sample from Plawangan Hill lava is close in afﬁnities with younger than 1900 years high-K magma series. On the other hand, Modern Merapi sample from 2006 eruption juvenile is plotted within medium-K magma series which are observed in eruption products older than 1900 years. Ratios of ﬂuid mobile elements to high ﬁeld strength element (HFSE) (i.e. B/Nb, Ba/Y, Pb/Nb) consistently show that Ancient Merapi sample has higher input of slab derived ﬂuid than Modern Merapi sample. A model using B/Nb and Ba/Nb suggests that Plawangan magma requires 1.5 % of sediment derived ﬂuid, higher than estimated in 2006 eruption magma (1.2 %) and medium-K series magma, and within the range of high-K series magma, to explain its slab component enrichment. This evidence suggests that slab derived component addition to the sub-arc mantle wedge highly ﬂuctuates over short period of evolution of a volcano. One possible explanation is the presence of veined hydrous metasomatized sub-arc mantle as Merapi magma source which allows melting of different mantle area to produce ﬂuctuation of slab components in the course of evolution of Merapi magmas.

Geochemistry of shield stage basalts from Baluran volcano, East Java, Sunda arc Esti Handini; Toshiaki Hasenaka; Nicholas D Barber; Tomoyuki Shibata; Yasushi Mori
Journal of Applied Geology Vol 7, No 2 (2022)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.73697

We report petrography and geochemistry of basaltic lava flows from the shield stage of Baluran, a Quaternary volcanic center in the rear of East Java, Sunda Arc, Indonesia. These basalts contain abundant plagioclase, clinopyroxene, olivine, and minor magnetite. Geochemically, they resemble other medium-K calc alkaline basalts from eastern Java’s volcanoes, but they are less enriched in light ion lithophile elements (LILE) and Pb. The predicted primary basalt of Baluran lavas can be sourced to a more primitive primary melt composition which may also generate medium-K calc-alkaline magmas in the region. The fractionation trajectory of these primary magmas shows the importance of plagioclase, clinopyroxene, olivine, and magnetite phase removal from the melt. Regardless of the diverse composition of the derivatives, the calculated primary basalts from the eastern Java are all in the field of nepheline-normative. This finding suggests variably small degree of melting of clinopyroxene-rich mantle source is at play in the generation of these magmas. Our result further suggests that the clinopyroxene source rock is possibly present as veins in peridotite mantle which have experienced metasomatism by addition of slab-derived fluids at differing proportion.

Susceptibility Zoning of Soil Movement in Tawangmangu District, Karanganyar Regency with Bivariate Statistic Method - Weight of Evidence Dwika Rizki Wirawan; Agung Setianto; Esti Handini
Journal of Applied Geology Vol 7, No 2 (2022)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.78754

Tawangmangu district which is located in Karanganyar Regency, Central Java is a crowded area which is susceptible to disaster. Therefore, susceptibility zoning analysis is needed to support the planning and development of the area. The method used is bivariate statistics - weight of evidence which has never been implemented in its location. There are two types of data, data of potential and soil movement case (divided into train data as 61 points and test data as 40 points); and parameter data of soil movement causes. Parameter data of soil movement is processed to be a WoE (Weight of Evidence) parameter map through the use of train data to know the weight. Later on, it will be validated based on the AUC value. If it’s > 0,60, then the process will proceed. Parameter which has AUC value > 0,60 is type of lithology, slope, hill, elevation, slope direction, distance from the fault, and index of vegetation density. All of those parameters are attached and being final validated by test data. Further, the zonation consists of four; zone of very low soil movement susceptibility, low, medium, and high. The area of the very low soil movement susceptibility zone is 19,68%. Zone of low susceptibility is mostly 24,57%. Zone of medium susceptibility is 25,88%. Meanwhile, the zone of high susceptibility is 29,86%. The result of final validation shows that AUC value from the zoning model made belongs to a good category, which is 0,757.

Magmatic Evolution of Dago Volcano, West Java, Indonesia Adimedha, Tyto Baskara; Harijoko, Agung; Handini, Esti; Sukadana, I Gde; Syaeful, Heri; Ciputra, Roni Cahya; Rosianna, Ilsa; Indrastomo, Frederikus Dian; Pratiwi, Fadiah; Rachael, Yoshi
EKSPLORIUM Vol 44, No 1 (2023): May 2023
Publisher : Badan Riset dan Inovasi Nasional

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/eksplorium.2023.6873

Dago Volcano is a product of Miocene Sunda Arc volcanism located southeast of the capital city of Jakarta. The morphological change from flat lava flow to steeper lava morphology implies a process of magma evolution under Dago Volcano. This research provides an overview of the magma evolution that occurs on this volcano. The methods used include volcanostratigraphic analysis, petrographic analysis, mineral chemistry, and whole-rock geochemistry. The volcanostratigraphy of Dago Volcano is composed of two eruption centers and a flank eruption forming lava and cinder cones products. The mineralogical associations of Dago Volcano products include plagioclase, olivine, and clinopyroxene. The mineral textures of Dago edifices show zoning, sieve, and reaction rims textures. Geochemically, the Dago Volcano product has a magma affinity of med-K calc-alkaline with quite high levels of MgO, Ni, and Cr approaching the characteristics of primitive magma. The magma evolution process of Dago Volcano includes fractional crystallization and magma mixing which originates from the same magma source.

Kerentanan Air Tanah Terhadap Intrusi Air Laut Dengan Menggunakan Metode GALDIT di Sekitar Kota Makassar, Provinsi Sulawesi Selatan Fuady Ahmad Lathif, Iqbal Fuady Ahmad; Wilopo, Wahyu; Handini, Esti
Jurnal Teknologi Sumberdaya Mineral Vol. 6 No. 1 (2025)
Publisher : Program Studi Teknik Pertambangan Fakultas Teknik Universitas Jember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/jeneral.v6i1.53687

Kota Makassar yang berkembang pesat banyak menghadapi tantangan pemenuhan kebutuhan air bersih, terutama dari air tanah yang secara kualitas lebih baik. Di wilayah pesisir, pemanfaatan air tanah yang berlebihan dapat memicu intrusi air laut, yang menyebabkan penurunan kualitas air tanah di beberapa daerah di Kota Makassar. Penelitian ini menggunakan metode GALDIT yang dimodifikasi dengan menambahkan parameter kepadatan penduduk untuk menilai kerentanan air tanah terhadap intrusi air laut. Hasil penelitian menunjukkan bahwa wilayah pesisir Makassar memiliki dua tipe akuifer, yaitu akuifer bebas pada bagian atas yang tersusun dari pasir dan pasir lempungan, serta akuifer semi tertekan di bagian bawah yang tersusun dari batupasir, batupasir lempungan, dan batupasir tufan. Aliran air tanah bergerak dari daerah tinggian di tenggara menuju barat laut, dengan daerah pembuangan di laut Selat Makassar. Terdapat tiga zona kerentanan air tanah: tinggi, sedang, dan rendah. Zona kerentanan tinggi ditemukan di Kecamatan Mariso, Wajo, dan Tallo, yang dipengaruhi oleh genangan air laut akibat reklamasi pantai dan interaksi suplai air sungai dengan air tanah di daerah muara. Analisis menunjukkan bahwa kepadatan penduduk adalah parameter paling signifikan dalam menentukan kerentanan, diikuti oleh muka air tanah, jarak dari garis pantai, konduktivitas hidraulika, tebal akuifer, tipe akuifer, dan dampak status intrusi.

Magmatic Evolution of Dago Volcano, West Java, Indonesia Adimedha, Tyto Baskara; Harijoko, Agung; Handini, Esti; Sukadana, I Gde; Syaeful, Heri; Ciputra, Roni Cahya; Rosianna, Ilsa; Indrastomo, Frederikus Dian; Pratiwi, Fadiah; Rachael, Yoshi
EKSPLORIUM Vol. 44 No. 1 (2023): MAY 2023
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/eksplorium.2023.6873

Dago Volcano is a product of Miocene Sunda Arc volcanism located southeast of the capital city of Jakarta. The morphological change from flat lava flow to steeper lava morphology implies a process of magma evolution under Dago Volcano. This research provides an overview of the magma evolution that occurs on this volcano. The methods used include volcanostratigraphic analysis, petrographic analysis, mineral chemistry, and whole-rock geochemistry. The volcanostratigraphy of Dago Volcano is composed of two eruption centers and a flank eruption forming lava and cinder cones products. The mineralogical associations of Dago Volcano products include plagioclase, olivine, and clinopyroxene. The mineral textures of Dago edifices show zoning, sieve, and reaction rims textures. Geochemically, the Dago Volcano product has a magma affinity of med-K calc-alkaline with quite high levels of MgO, Ni, and Cr approaching the characteristics of primitive magma. The magma evolution process of Dago Volcano includes fractional crystallization and magma mixing which originates from the same magma source.

Characteristics and Genesis of Mount Pengki: A Scoria Cone of Dago Volcano, West Java, Indonesia Adimedha, Tyto Baskara; Ciputra, Roni Cahya; Rosianna, Ilsa; Sukadana, I Gde; Harijoko, Agung; Handini, Esti; Pratiwi, Fadiah; Indrastomo, Frederikus Dian; Syaeful, Heri; Rachael, Yoshi; Sukmawan, I Gusti Made
EKSPLORIUM Vol. 45 No. 2 (2024): NOVEMBER 2024
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/eksplorium.2024.7131

Scoria cones are a typical product of volcanic activity constructed by the bomb and lapilli-sized pyroclasts formed by Strombolian eruption. Mount Pengki is a scoria cone found in Miocene Dago Volcano, West Java. Mount Pengki was a remnant of a Miocene volcano that was exceptionally well preserved and exposed. This scoria cone contains layers of scoria beds and a lava flow unit. The study aims to characterize the exposed scoria bed deposits and investigate the eruptive history and degradation process of Mount Pengki. Field observation, including measured sections and detailed characterizations of the Mount Pengki quarry, allows us to observe its volcanic sequence from its internal structure toward the surface. Morphometric analysis of Mount Pengki can describe the degradation process undergone by the scoria cone. The early phase deposits were characterized by massive to weakly bedded, poorly sorted, clast-supported beds mainly composed of coarse lapilli to bombs/blocks scoria grain. The middle phase deposit typically shows well-stratified, well-sorted, clast-supported scoria beds with coarse ash to coarse lapilli grain size. The late phase deposit is similar to the middle phase deposit, with additional features of coarser-grain, reverse grading, and clast-supported lenticular beds. Eruptive mechanisms involved in the formation of Mount Pengki include ballistic transport of clasts, fallout deposition, and grain avalanching process. The degradation process was likely influenced by prolonged exposure to weathering, cone rim collapse, and regional deformation processes.

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