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All Journal IJOG : Indonesian Journal on Geoscience Jurnal Geologi dan Sumberdaya Mineral (Journal of Geology and Mineral Resources) Agrin : Jurnal Penelitian Pertanian
G. Hartono
2Geological Engineering, STTNas, Jln. Babarsari, Sleman, Yogyakarta
Agriculture, Biological Sciences & Forestry Earth & Planetary Sciences Education Energy Engineering Environmental Science

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Waduk Parangjoho dan Songputri: Alternatif Sumber Erupsi Formasi Semilir di daerah Eromoko, Kabupaten Wonogiri, Jawa Tengah Bronto, Sutikno; Mulyaningsih, Sri; Hartono, G.; Astuti, B.
Indonesian Journal on Geoscience Vol 4, No 2 (2009)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1126.755 KB) | DOI: 10.17014/ijog.v4i2.71

Abstract

http://dx.doi.org/10.17014/ijog.vol4no2.20091The Semilir Formation was typically originated from products of a very explosive volcanic activity, i.e. breccias, lapillistones, and tuffs containing abundant pumice. It has a light grey to white colour and high silica andesite to dacite in composition, mainly rich in volcanic glass and quartz. Sedimentary structures of these volcanic rocks are massive, grading, planar bedding, and cross-bedding to antidunes, with grain size varies from ash (≤ 2 mm) to lapilli (2 – 64 mm) to bomb and block (> 64 mm). The formation is widely distributed from the west side (Pleret and Piyungan areas, Bantul Regency, Special Province of Yogyakarta) until Eromoko area in the east (Wonogiri Regency, Jawa Tengah Province). Stratigraphically, the Semilir Formation underlies the Nglanggeran Formation, and overlies the Mandalika Formation in the eastern part and Kebo-Butak Formation in the western part. Geomorphological- and lithological analyses of the Semilir Formation in areas of Parangjoho and Song- putri Dams, Eromoko Sub-regency, Wonogiri Regency indicate that the two depressions were alternatively volcanic sources of the Semilir Formation in the Eromoko area. This is proved by the presence of co-ignimbrite breccias(co-ignimbrite lag fall deposits), that descriptively they are polymict breccias. This rock is characterized by a mixing of pumice and various hard rock fragments that primarily are juvenile materials (volcanic blocks, bombs), accessory-, and accidental rock fragments set in pumice-rich volcanic ash and lapilli sizes. The accessory materials came from older volcanic rocks, whereas the accidental ones were originated from basement rocks. During a caldera forming event or a destruction period of an older composite volcanic cone(s), all older rocks resting above the magma chamber were ejected to the surface by a very high magmatic pressure. Since they were heavier than the juvenile material, most accessory and accidental rock fragments were left (lag fall) in caldera rim behind the ash and pumice flow. In the dam areas of Parangjoho and Songputri, the lag fall fragments consisting of andesite, pyroxene andesite, dacite, and pumice, being 10 – 150 cm in diameter are set in pumice-rich lapilli tuffs. Some of the rock fragments are volcanic blocks and bombs, while the older rocks are angular to very angular shape, having prismatic jointing or jigsaw-crack structures. The eruptions in the Parangjoho and Songputri craters were controlled by north-south trending fractures, and they resemble to the Katmaian caldera explosion type.  
Gunung Api purba Watuadeg: Sumber erupsi dan posisi stratigrafi Bronto, Sutikno; MulyaningSih, Sri; Hartono, G.; Astuti, B.
Indonesian Journal on Geoscience Vol 3, No 3 (2008)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (856.976 KB) | DOI: 10.17014/ijog.v3i3.53

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http://dx.doi.org/10.17014/ijog.vol3no3.20081Pillow lava flows of pyroxene basalt containing 50 wt.% SiO are exposed at Opak River, west of Watuadeg Village, Sleman - Yogyakarta. The length of flow structures is between 2 – 10 m, with diameter of 0.5 – 1.0 m and it has a glassy skin at the surface body. Flow directions vary from N70E in the northern side, through N 120E in the middle to N 150E in the southern side. About 150 m away from the river to the west, there is a small hill about 15 m high, that has a similar composition with the pillow lavas. Both lava flows and the small hill are composed of pyroxene basalt, dark grey in color, hypocrystalline vitrophyre to porphyritic texture, with fine-grained phenocrysts of pyroxene (10 %) and plagioclase (25 %) set in glassy groundmass. These data indicate that the small hill was the eruption source of the basaltic pillow lavas. The lavas are overlain by pumice-rich volcaniclastic rocks, composed of tuff, lapillistones and pumice breccias, that are known as the Semilir Formation. Near the contact with lavas, the volcaniclastic rocks contain some fragments of pyroxene basalt, similar composition with the pillow lavas. This fact, together with analyses of petrology, volcanology, and radiometric dating show that the basaltic pillow lavas are unconformably overlain by the Semilir Formation.  
The Evolution of Gajahmungkur Paleovolcano, Wonogiri, Central Java, as A Reference to Revize the Terminology of “Old Andesite Formation” Syafri, Ildrem; Sudradjat, A.; Sulaksana, Nana; Hartono, G.
Indonesian Journal on Geoscience Vol 5, No 4 (2010)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1060.567 KB) | DOI: 10.17014/ijog.v5i4.109

Abstract

DOI: 10.17014/ijog.v5i4.109Gajahmungkur is a Tertiary paleovolcano located in Wonogiri Regency, Central Java. The volcanic product of this volcano are widely distributed and composed of important elements of the stratigraphic sequence in the Southern Mountain area. The volcanic products so far have been simply classified as “Old Andesite Formation” which apparently is not in line with the stratigraphic code and the Indonesian Stratigraphic Code. The description of paleovolcano therefore might contribute to the revision of the “Old Andesite Formation”. The evolution of Gajahmungkur paleovolcano commenced with the formation of a submarine volcano, and then at the second phase a composite volcano emerged above sea level forming a volcano island. The third phase was the self destruction resulting in a formation of a caldera. Pumiceous components dominated the products. At the fourth phase, the activities began to decline producing more basaltic rocks. The statistical analysis of the interrelation between various physical properties of the clastic rocks leads to the identification of volcanic facies and the location of the paleovolcano vent.
Evolution of Rajabasa Volcano in Kalianda Area and Its Vicinity, South Lampung Regency Bronto, Sutikno; Asmoro, P.; Hartono, G.; Sulistiyono, Sulistiyono
Indonesian Journal on Geoscience Vol 7, No 1 (2012)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2816.767 KB) | DOI: 10.17014/ijog.v7i1.132

Abstract

DOI: 10.17014/ijog.v7i1.132Rajabasa Volcano (± 1281 m) and Lampung Tuff, located in the South Lampung Regency, is the main point in order to understand the evolution of Quaternary volcanism in the area. A remote sensing analysis and field geologic work are the methods of the study. The volcanism began with the construction period of the Pre-Rajabasa composite cone which was followed by the destruction period of the cone to form the Pre-Rajabasa Caldera having ca. 25 km in diameter. The present Rajabasa Volcano, along with cones of flank eruptions and monogenesis, has appeared in the Pre-Rajabasa Caldera depression. Those volcanic activities are considered as the second construction period. During the first and the second construction periods, basaltic to andesitic lava flows, pyroclastic breccias, and tuffs were erupted. The Rajabasa eruption points moved in WNW - ESE direction, which were possibly controlled by a subsurface weak zone. The Pre-Rajabasa Caldera erupted voluminous Lampung Tuffs having rhyolite in composition, and they are considered as a combination of pyroclastic falls, flows, and surges, or pyroclastic density currents.
GUNUNG API PURBA DI DAERAH BAKAUHENI - PULAU SANGIANG,SELAT SUNDA, KABUPATEN LAMPUNG SELATAN Bronto, S.; Asmoro, P.; Hartono, G.; Sulistiyono, S
Jurnal Geologi dan Sumberdaya Mineral Vol 22, No 1 (2012): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (451.136 KB)

Abstract

Along the Merak - Bakauheni route, Sunda Strait, there are some island composing by Tertiary volcanic rocks. Relating to the plan of construction of Sunda Strait Bridge, several Tertiary and Quaternary volcanic islands at Merak – Bakauheni ferry route are examined as paleovolcanoes in order to evaluate their potential hazards. Methods that used in this study are remote sensing analyses of satellite image and topographic maps, and field geologic investigation. As results, three paleovolcanoes are recognized, namely Harimaubalak, Kandangbalak and Sangiang. To understand the history of their volcanic activities radiometric analyses are required. Those three paleovolcanoes are located in a line having NW – SE direction, considered as a weak zone because the pattern similarity with the active Sumatran fault system. To anticipate the possibilities of opening new vents or reactivated eruptions from the weak zone it is suggested to make further studies on seismicity, tectonic analyses, and the present of sub surface hot sources.Key words : bakauheni, harimaubalak, paleovolcano, sangiang, sunda strait, lampung
ANALISIS BIAYA PRODUKSI KENTANG DI KELURAHAN KEJAJAR KECAMATAN KEJAJAR KABUPATEN WONOSOBO Hartono, G.; Prihtanti, Tinjung Mary
Agrin Vol 12, No 1 (2008): Agrin
Publisher : Jenderal Soedirman University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20884/1.agrin.2008.12.1.74

Abstract

Tujuan penelitian ini untuk mengetahui pengaruh jumlah produksi, upah tenaga kerja, harga benihkentang, harga urea, harga pupuk kandang, dan harga obat pemberantas hama penyakit terhadap biaya produksiusaha tani kentang. Metode penelitian yang dipakai adalah metode penelitian deskriptif, sementara datadikumpulkan dengan menggunakan metode survei. Sebanyak 40 responden diambil secara acak sederhana dari110 petani kentang monokultur di Kelurahan Kejajar, Kacamatan Kejajar, Kabupaten Wonosobo. Hasilpenelitian menunjukkan bahwa secara keseluruhan terdapat pengaruh nyata dari variabel independen yangmeliputi: harga benih kentang, harga urea, harga pupuk kandang, harga obat pemberantas hama penyakit, upahtenaga kerja, dan jumlah produksi, terhadap biaya produksi usaha tani kentang yang dianalisis dengan modelfungsi biaya Cobb-Douglas dan masing-masing koefisien regresinya secara berturut adalah: 0,87000; 0,04393;0,09935; -0,91600; -3,47900 dan 0,63400.Kata kunci: fungsi biaya Cobb-Douglas, harga input, kentang. ABSTRACTThe objectives of this research were to know the affects of price of urea, manure, pesticide, labour wageand production level on the potato production cost. Descriptive method was used in this research, while data wascollected using survey method. Fourty respondents were randomly selected among the 110 population of potatofarmers at Kejajar village, sub district of Kejajar, regency of Wonosobo. The results of this research showed thatthere had a significantly affect between of price of seed, urea, manure and pesticide, labour wage and productionlevel on potato production cost, using the Cobb-Douglas cost function model, and with regression coefficients of0.87000; 0.04393; 0.09935; -0.91600; -3.47900 and 0.63400, respectively.Key words: Cobb Douglas cost function, input price, potato.
Co-Authors A. Sudradjat B. Astuti Ildrem Syafri Mulyaningsih, Sri Nana Sulaksana P. Asmoro S Sulistiyono, S S. Bronto, S. Sulistiyono Sulistiyono Sutikno Bronto Tinjung Mary Prihtanti