Karakteristik batubara merupakan salah satu aspek pertimbangan dalam mengembangkan suatu industri... more Karakteristik batubara merupakan salah satu aspek pertimbangan dalam mengembangkan suatu industri pertambangan batubara. Karakteristik batubara seperti peringkat, kualitas dan tipe dikontrol dan dipengaruhi oleh lingkungan tempat diendapkannya batubara tersebut. Dengan mengetahui lingkungan pengendapan batubara, secara tidak langsung dapat diperkirakan pula karakteristik batubara tersebut. Percontoh batubara yang diuji berasal dari lapisan batubara Formasi Muara Enim Cekungan Sumatera Selatan, Kecamatan Merapi Barat, Kabupaten Lahat. Penelitian dilakukan menggunakan metode analisis petrografi organik untuk mengetahui komposisi maseral dan mineral penyusunnya serta metode analisis stratigrafi untuk mengetahui fasies batuan penyusun serta memperkuat pemikiran dalam penentuan lingkungan pengendapan batubara daerah penelitian. Interpretasi lingkungan pengendapan batubara dilakukan berdasarkan hubungan nilai tissue preservation index (TPI) dan gelification index (GI) dan hasil perbanding...
The aim of this study is to identify of petrology characteristic based on geochemical analysis in... more The aim of this study is to identify of petrology characteristic based on geochemical analysis in order to know the granitoid rock type. Administratively, the study area is in the City and District of Singkawang, West Kalimantan Province, at coordinate 108°48'30†- 109°1'30†E and 0°40'30†- 0°54'30†N and, situated ± 145 km to the north of Pontianak City. The outcrop of granitoid along Bajau Cape coast and its surrounding, had been analyzed petrographically and geochemically using AAS method. Based on analysis of five samples show that the ratio mole of Al2O3/(CaO+Na2O +K2O) > 1 ranged between 1.12 and 1.7, while the rest of three samples are moderately aluminous, with a ratio value between 0.5 and 1.0. The ratio between K2O and (K2O+Na2O+CaO) ranges 0.07 to 0.55 (moderate) that forms alkali feldspar normative ranges from 3.8 to 15.89 wt%. This ratio shows that granite alkali feldspar is classified to be calc-alkaline series. Petrographically, this r...
Sea floor sediment surrounding Lemukutan Island, West Kalimantan is distributed on rather steep s... more Sea floor sediment surrounding Lemukutan Island, West Kalimantan is distributed on rather steep sea bottom morphology. The steep bottom seems a continuation of rugged morphology of the island, especially at the northeast and southeast parts. This paper discusses the relation between sediment grain sizes and the steepness of sea bottom morphology. Grain size analyses of sediment shows various sediment types such as slightly gravelly muddy sand, gravel mostly composed of coral and lithic, and gravelly sand. Results show that steepness of sea bottom slope control deposited sediment types, coarse fraction sediments tend to settle on the area of high slope angle as at the northeastern and southeastern of the island. On the other hand, high energy marine environment, such as at the sea in front of north headland of Lemukutan Island, tends to accumulate coarse sediments. High percentages of organism shells in marine sediments obviously are deposited at those two domains. Keywords: sea bott...
Marine sand mining activities in Lontar Village have been started legally since 2003 and temporar... more Marine sand mining activities in Lontar Village have been started legally since 2003 and temporarily halted in 2013. The locals blamed the activities for severe environmental destruction in almost every corner of the village such as low productivity ofaquaculture, coastal erosion, and habitat loss. This paper has an objective to provide preliminary data and analyses for environmental impact assessment of marine sand mining in Serang (Lontar Village). Field investigations were carried out in June 2014 to collect primary data such as bathymetrical data and water quality parameters in the region to understand the environmental conditions after 10 years of marine sand mining activities as well as the characteristicsof local oceanography. Extensive interview with the locals were also conducted to collect information about the socioeconomic conditions of the village. Field findings showed that LontarVillage have experienced critical environmental problems such as coastal erosion, high turbidiy and loss of marine lives. Moreover, we also found that the abandoned aquaculture fields have also been converted as sand mining quarries. Recommendations to reduce further environmental damage in Lontar Village are proposed considering both socio-economy and physical aspects.
Bangka Island is one of the islands in Indonesia which is traversed by Southeast Asia granitoid b... more Bangka Island is one of the islands in Indonesia which is traversed by Southeast Asia granitoid belt. This belt stretches from Burma (Myanmar) to Bangka Belitung. This granitoid has potential as a source rock of mineral that carrying tin and rare earth element. At present, mapping of granitoid rocks to the waters area is rarely published, so acoustic basement mapping is necessary to do in order to determine the distribution of granitoids in Toboali waters. The research method used is a single channel seismic with an energy source of 300 joules. The sound source uses a single plate boomer, so it has a high enough resolution but the penetration is not deep enough. Acoustic basement in Toboali waters varies in depth from 15 75 ms or getting deeper south. When viewed from the continuity of the acoustic basement, it is estimated that the granitoid is 7 km from the nearest coastline.
Morphologically, Singkawang and adjacent area consist of zones beaches, undulating hills, and ste... more Morphologically, Singkawang and adjacent area consist of zones beaches, undulating hills, and steep hills. Granitic rocks and alluvium as a based rock of Singkawang coasts. Generally, Singkawang coasts was developed for coastal farms, fishery pond, and beach resorts, where most of these area have been eroded. Geological and physical oceanography condition are the aspects that build the characteristics of Singkawang coast. Human activities also play an important role in managing the equilibrium and dynamics of this coastal region. This research is to determine the dynamics and coastline changes of Singkawang coasts based on the characteristics of the coastal element and sediment. The high erosion was occurred at Semalagi–Cape Bajau. The Cape Bajau - Cape Banjar is relatively stable due to headlands of this coast is characterized by igneous rocks which resistant to the erosion. The Cape Banjar – South Coasts is very intensive erosion coast. Modern shorelines of the Singkawang coas...
Study of elemental composition in sediment has been proven useful in interpreting the depositiona... more Study of elemental composition in sediment has been proven useful in interpreting the depositional environmental changes. Multi Sensor Core Logger (MSCL) is a non-destructive analysis that measures several parameters in sediment core including magnetic susceptibility and elemental composition. Magnetic susceptibility and elemental analysis were measured in four selected marine sediment cores from western part of Bangka Strait (MBB-67. MBB-119, MBB-120 and MBB-173) by using magnetic susceptibility and X-ray Fluorescence (XRF) sensors attached to the MSCL. The data was collected within 2 cm interval. Scatter plots of Y/Zr and Zr/Ti show singular trend demonstrated by sediments from MBB-173 and two groups that composed of MBB-67 (Group 1) and MBB-119 + MBB-120 (Group 2). MBB-67 that is located adjacent to Klabat Granite shows upward changes in mineralogy, slight increase of grain size and negligible change in Y concentration. Cores MBB-119 and MBB-120 are inferred to be deposited durin...
Ten unconsolidated sediment samples from Menumbing shallow marine area, Bangka Island, Indonesia ... more Ten unconsolidated sediment samples from Menumbing shallow marine area, Bangka Island, Indonesia were addressed to density separation in order to reveal heavy mineral composition. Prior to density separation, bulk sediment samples were analyzed by XRD, XRF, and ICP-MS to describe mineralogy and elementary composition as well as rare earth element concentration. The objective of this research is to explicate heavy mineral composition as important factor for Rare Earth Element concentration. From XRD result, sediment are dominated by quartz with appearance peak of halite, plagioclase, and clay mineral (illite, smectite, and kaolinite), while elementary composition reveals Zr concentration range from 250-530 ppm (average 380 ppm), Th values from 7-32 ppm (average 18 ppm), and concentration of Y from 14-28 ppm (average 19 ppm). Density separation splits light and heavy mineral (ρ = 2.9 g/cm). Heavy minerals in Menumbing sediment are distributed in > 75 μm fraction with abundance of i...
Bintan Island is one of the areas traversed by the Southeast Asian granitoid belt which is known ... more Bintan Island is one of the areas traversed by the Southeast Asian granitoid belt which is known to have the potential for heavy mineral placer deposits. Due to the dwindling presence of heavy mineral placer deposits in land areas, it is necessary to look for the potential presence of heavy mineral placer deposits in water areas. Searching for placer heavy mineral deposits accomodation in these waters requires subsurface mapping.The method used in this subsurface mapping is a single channel seismic method with a total of 179 lines in the direction of northeast – southwest and west – east. The results of this seismic recording are then interpreted the boundaries of the seismic facies unit and distributed using the kriging method. Furthermore, the thickness calculates by using the assumption velocity 1600 m/s.Based on the facies unit boundaries that have been interpreted, the quaternary sediments that formed in the study area are divided into 2 types of units, namely: Unit 2 which is ...
Gita member is part of Talang Akar Formation is known as hydrocarbon reservoir at Asri Basin, eas... more Gita member is part of Talang Akar Formation is known as hydrocarbon reservoir at Asri Basin, eastern part of South Sumatra. This formation consists of several depositional systems such as braided channel, meandering channel, fluvial-deltaic, and estuarine system. A channel system was an interesting system developed in the Asri Basin, however, to get the channel distribution in Asri Basin is quite challenging because the thickness of the channels caused its appearance is generally close or under seismic resolution, the existence of coal below our target also affects the impression of “S” sand on seismic data. In this study, spectral decomposition and RGB Blending have been successful to identify “S” sand. RGB Blending map is extracted from 15 Hz as low frequency, 45 Hz as middle frequency, and 75 Hz as high frequency. Our interpretation was applied at RGB Blending map and reveal the “S” sand is classified as a meandering channel depositional system with the main direction of the cha...
The late Pleistocene-Holocene stratigraphic architecture of the Bawean Island and surrounding wat... more The late Pleistocene-Holocene stratigraphic architecture of the Bawean Island and surrounding waters, southeast Java Sea has been analyzed by using sparker seismic profiles. Geological interpretation of these seismic profiles revealed the widespread distribution of paleochannels with different shape and size in the present-day Java Sea. Two channel types can be distinguished based on its morphology: U-shaped channels in the western part and V-shaped channels in the eastern part. The stratigraphic successions were grouped into two major seismic units separated by different seismic boundaries. Characters of marine and fluvial deposits were determined based on seismic boundaries and internal reflectors. Three seismic facies can be identified within late Pleistocene – Holocene incised channel fills associated with SB2. The internal structure of incised-channels consist of chaotic reflector at the bottom, covered by parallel–sub parallel and almost reflection-free indicating the homogeno...
Bangka Island and surrounding areas (including coast and seabed sediments) is known as main tin p... more Bangka Island and surrounding areas (including coast and seabed sediments) is known as main tin producer (cassiterite) in the world as these part of the Southeast Asia Granitic belt, but in fact, other than as a producer of tin, Bangka Belitung is also as heavy mineral placer (as accessories mineral) and REE potential producer which one based on the geological conditions.The potential of accessories minerals on sediment coast, other than cassiterite that occurs around Betumpak Cape, i.e: magnetite (7.86 %), ilmenite (4.9%), zircon (2.51%) and apatite (1.07%) respectively with content. While the content of monazite by using a hand drill has the potential content of up to 67.8 g/m3, while the content of monazite hypothetical resources off the coast of Bangka approximately 471,087,689 m3. As for the content of monazite hypothetical resources off the coast of South Bangka are approximately 23,995,820 m3.At Toboali coast, South Bangka the presence of REE in sediments are above the Earth&...
The bathymetry, petrology, marine magnetic, and seismic-SBP data have identified the northwest-so... more The bathymetry, petrology, marine magnetic, and seismic-SBP data have identified the northwest-southeast direction submarine ridge that shows hydrothermal activity. This activity occurred through Mount Baruna Komba, Abang Komba, and Ibu Komba. The volcanic rocks are andesite basaltic lava flows, tuff, and pumice. The andesite basaltic lava shows porphyritic, intergranular, intersertal to glomeroporphyritic textures. The rock composes anhedral minerals of k-feldspar, plagioclase, and pyroxene. These minerals present in small-sized, short prismatic dispersed in very fine groundmass minerals or glasses. Most of the volcanic rocks have experienced various degrees of alteration. The k-feldspar and plagioclase are most dominantly transformed into sericite, clay mineral, carbonate, epidote and oxide mineral, opaque mineral, and secondary plagioclase through the albitization process, while pyroxene replaced by chlorite. Other minerals are biotite and quartz, and base metals are present Cu, ...
Batuan granit mempunyai arti penting terutama akan kandungan mineral ekonomisnya. Di Indonesia ba... more Batuan granit mempunyai arti penting terutama akan kandungan mineral ekonomisnya. Di Indonesia bagian barat, batuan granit lebih terkenal dengan asosiasi mineralisasi kasiterit (timah). Tidak semua batuan granit mempunyai kandungan mineral kasiterit. Batugranit biotit berhubungan dengan mineralisasi kasiterit, sedangkan batugranit hornblende tidak ada hubungannya dengan mineralisasi kasiterit.
Intensitas kehadiran mineral zirkon dasar laut di lokasi penelitian dijumpai di perairan barat da... more Intensitas kehadiran mineral zirkon dasar laut di lokasi penelitian dijumpai di perairan barat daya Pulau Kabung (SKWL-56), yang terakumulasi pada sedimen pasir lanauan di kedalaman laut 23 m. Berdasarkan hasil analisis mineragrafi butir, mineral ini memberi penampakan variasi warna antara merah muda, putih, dan kuning kecoklatan; bentuk prismatik memanjang dengan penampakan translusen hingga transparan. Berdasarkan penampang profil distribusi zirkon, terlihat kecenderungan penyebaran zirkon dasar laut mengalami penurunan dari sekitar Pulau Kabung ke arah Pulau Lemukutan, dan dari Pulau Kabung ke arah daratan Kalimantan. Kehadiran mineral zirkon dasar laut di lokasi penelitian dengan memperhatikan intensitas penampakan, penyebaran, bentuk kristal, dan asosiasi kehadiran mineral lain menunjukkan bahwa zirkon yang ada merupakan endapan letakan hasil transportasi yang dicirikan dengan berubahnya bentuk kristal dan pada beberapa percontoh yang diamati terlihat adanya sisa penggerusan sebagai hasil aktivitas transportasi, selain itu juga ditandai dengan berubahnya derajat ketransparanan akibat pengaruh penetrasi dalam rekahan di dalam mineral, sehingga hadir beberapa material pengotor selama proses pengendapan.
Intensitas pancaran unsur radioaktif berdasarkan data aktivitas batuan dan aktivitas pancaran ß s... more Intensitas pancaran unsur radioaktif berdasarkan data aktivitas batuan dan aktivitas pancaran ß serbuk di Pantai Sedau dilakukan menggunakan metode analisis Spektrometer Gamma dan alat cacah ß terhadap sembilan contoh sedimen dan batuan. Intensitas radioaktif batuan memperlihatkan kisaran U238 dari 0,1202 ± 0,008 Bq/25gr hingga 0,4348 ± 0,005 Bq/25gr; Th232 0,0768 ± 0,005 Bq/25gr hingga 0,4812 ± 0,015 Bq/25gr; sedangkan intensitas gross gammanya berkisar dari 1,0503 ± 0,029 Bq/25gr hingga 5,6433 ± 0,273 Bq/25gr. Semua contoh yang memiliki intensitas unsur radioaktif untuk aktivitas batuan tinggi berasal dari batuan yang sama (monzogranit), yaitu di lokasi SKP08-04. Hasil yang sama pada pancaran ß serbuknya yang memperlihatkan aktivitas ß gross tertinggi juga terjadi di lokasi SKP08-04 pada batuan monzogranit dengan intensitas paparan 0,370 ± 0,025 Bq/25gr. Berdasarkan pengamatan petrografi, monzogranit di SKP08-04 memperlihatkan pelimpahan feldspar dengan kondisi yang relatif bel...
Karakteristik batubara merupakan salah satu aspek pertimbangan dalam mengembangkan suatu industri... more Karakteristik batubara merupakan salah satu aspek pertimbangan dalam mengembangkan suatu industri pertambangan batubara. Karakteristik batubara seperti peringkat, kualitas dan tipe dikontrol dan dipengaruhi oleh lingkungan tempat diendapkannya batubara tersebut. Dengan mengetahui lingkungan pengendapan batubara, secara tidak langsung dapat diperkirakan pula karakteristik batubara tersebut. Percontoh batubara yang diuji berasal dari lapisan batubara Formasi Muara Enim Cekungan Sumatera Selatan, Kecamatan Merapi Barat, Kabupaten Lahat. Penelitian dilakukan menggunakan metode analisis petrografi organik untuk mengetahui komposisi maseral dan mineral penyusunnya serta metode analisis stratigrafi untuk mengetahui fasies batuan penyusun serta memperkuat pemikiran dalam penentuan lingkungan pengendapan batubara daerah penelitian. Interpretasi lingkungan pengendapan batubara dilakukan berdasarkan hubungan nilai tissue preservation index (TPI) dan gelification index (GI) dan hasil perbanding...
The aim of this study is to identify of petrology characteristic based on geochemical analysis in... more The aim of this study is to identify of petrology characteristic based on geochemical analysis in order to know the granitoid rock type. Administratively, the study area is in the City and District of Singkawang, West Kalimantan Province, at coordinate 108°48'30†- 109°1'30†E and 0°40'30†- 0°54'30†N and, situated ± 145 km to the north of Pontianak City. The outcrop of granitoid along Bajau Cape coast and its surrounding, had been analyzed petrographically and geochemically using AAS method. Based on analysis of five samples show that the ratio mole of Al2O3/(CaO+Na2O +K2O) > 1 ranged between 1.12 and 1.7, while the rest of three samples are moderately aluminous, with a ratio value between 0.5 and 1.0. The ratio between K2O and (K2O+Na2O+CaO) ranges 0.07 to 0.55 (moderate) that forms alkali feldspar normative ranges from 3.8 to 15.89 wt%. This ratio shows that granite alkali feldspar is classified to be calc-alkaline series. Petrographically, this r...
Sea floor sediment surrounding Lemukutan Island, West Kalimantan is distributed on rather steep s... more Sea floor sediment surrounding Lemukutan Island, West Kalimantan is distributed on rather steep sea bottom morphology. The steep bottom seems a continuation of rugged morphology of the island, especially at the northeast and southeast parts. This paper discusses the relation between sediment grain sizes and the steepness of sea bottom morphology. Grain size analyses of sediment shows various sediment types such as slightly gravelly muddy sand, gravel mostly composed of coral and lithic, and gravelly sand. Results show that steepness of sea bottom slope control deposited sediment types, coarse fraction sediments tend to settle on the area of high slope angle as at the northeastern and southeastern of the island. On the other hand, high energy marine environment, such as at the sea in front of north headland of Lemukutan Island, tends to accumulate coarse sediments. High percentages of organism shells in marine sediments obviously are deposited at those two domains. Keywords: sea bott...
Marine sand mining activities in Lontar Village have been started legally since 2003 and temporar... more Marine sand mining activities in Lontar Village have been started legally since 2003 and temporarily halted in 2013. The locals blamed the activities for severe environmental destruction in almost every corner of the village such as low productivity ofaquaculture, coastal erosion, and habitat loss. This paper has an objective to provide preliminary data and analyses for environmental impact assessment of marine sand mining in Serang (Lontar Village). Field investigations were carried out in June 2014 to collect primary data such as bathymetrical data and water quality parameters in the region to understand the environmental conditions after 10 years of marine sand mining activities as well as the characteristicsof local oceanography. Extensive interview with the locals were also conducted to collect information about the socioeconomic conditions of the village. Field findings showed that LontarVillage have experienced critical environmental problems such as coastal erosion, high turbidiy and loss of marine lives. Moreover, we also found that the abandoned aquaculture fields have also been converted as sand mining quarries. Recommendations to reduce further environmental damage in Lontar Village are proposed considering both socio-economy and physical aspects.
Bangka Island is one of the islands in Indonesia which is traversed by Southeast Asia granitoid b... more Bangka Island is one of the islands in Indonesia which is traversed by Southeast Asia granitoid belt. This belt stretches from Burma (Myanmar) to Bangka Belitung. This granitoid has potential as a source rock of mineral that carrying tin and rare earth element. At present, mapping of granitoid rocks to the waters area is rarely published, so acoustic basement mapping is necessary to do in order to determine the distribution of granitoids in Toboali waters. The research method used is a single channel seismic with an energy source of 300 joules. The sound source uses a single plate boomer, so it has a high enough resolution but the penetration is not deep enough. Acoustic basement in Toboali waters varies in depth from 15 75 ms or getting deeper south. When viewed from the continuity of the acoustic basement, it is estimated that the granitoid is 7 km from the nearest coastline.
Morphologically, Singkawang and adjacent area consist of zones beaches, undulating hills, and ste... more Morphologically, Singkawang and adjacent area consist of zones beaches, undulating hills, and steep hills. Granitic rocks and alluvium as a based rock of Singkawang coasts. Generally, Singkawang coasts was developed for coastal farms, fishery pond, and beach resorts, where most of these area have been eroded. Geological and physical oceanography condition are the aspects that build the characteristics of Singkawang coast. Human activities also play an important role in managing the equilibrium and dynamics of this coastal region. This research is to determine the dynamics and coastline changes of Singkawang coasts based on the characteristics of the coastal element and sediment. The high erosion was occurred at Semalagi–Cape Bajau. The Cape Bajau - Cape Banjar is relatively stable due to headlands of this coast is characterized by igneous rocks which resistant to the erosion. The Cape Banjar – South Coasts is very intensive erosion coast. Modern shorelines of the Singkawang coas...
Study of elemental composition in sediment has been proven useful in interpreting the depositiona... more Study of elemental composition in sediment has been proven useful in interpreting the depositional environmental changes. Multi Sensor Core Logger (MSCL) is a non-destructive analysis that measures several parameters in sediment core including magnetic susceptibility and elemental composition. Magnetic susceptibility and elemental analysis were measured in four selected marine sediment cores from western part of Bangka Strait (MBB-67. MBB-119, MBB-120 and MBB-173) by using magnetic susceptibility and X-ray Fluorescence (XRF) sensors attached to the MSCL. The data was collected within 2 cm interval. Scatter plots of Y/Zr and Zr/Ti show singular trend demonstrated by sediments from MBB-173 and two groups that composed of MBB-67 (Group 1) and MBB-119 + MBB-120 (Group 2). MBB-67 that is located adjacent to Klabat Granite shows upward changes in mineralogy, slight increase of grain size and negligible change in Y concentration. Cores MBB-119 and MBB-120 are inferred to be deposited durin...
Ten unconsolidated sediment samples from Menumbing shallow marine area, Bangka Island, Indonesia ... more Ten unconsolidated sediment samples from Menumbing shallow marine area, Bangka Island, Indonesia were addressed to density separation in order to reveal heavy mineral composition. Prior to density separation, bulk sediment samples were analyzed by XRD, XRF, and ICP-MS to describe mineralogy and elementary composition as well as rare earth element concentration. The objective of this research is to explicate heavy mineral composition as important factor for Rare Earth Element concentration. From XRD result, sediment are dominated by quartz with appearance peak of halite, plagioclase, and clay mineral (illite, smectite, and kaolinite), while elementary composition reveals Zr concentration range from 250-530 ppm (average 380 ppm), Th values from 7-32 ppm (average 18 ppm), and concentration of Y from 14-28 ppm (average 19 ppm). Density separation splits light and heavy mineral (ρ = 2.9 g/cm). Heavy minerals in Menumbing sediment are distributed in > 75 μm fraction with abundance of i...
Bintan Island is one of the areas traversed by the Southeast Asian granitoid belt which is known ... more Bintan Island is one of the areas traversed by the Southeast Asian granitoid belt which is known to have the potential for heavy mineral placer deposits. Due to the dwindling presence of heavy mineral placer deposits in land areas, it is necessary to look for the potential presence of heavy mineral placer deposits in water areas. Searching for placer heavy mineral deposits accomodation in these waters requires subsurface mapping.The method used in this subsurface mapping is a single channel seismic method with a total of 179 lines in the direction of northeast – southwest and west – east. The results of this seismic recording are then interpreted the boundaries of the seismic facies unit and distributed using the kriging method. Furthermore, the thickness calculates by using the assumption velocity 1600 m/s.Based on the facies unit boundaries that have been interpreted, the quaternary sediments that formed in the study area are divided into 2 types of units, namely: Unit 2 which is ...
Gita member is part of Talang Akar Formation is known as hydrocarbon reservoir at Asri Basin, eas... more Gita member is part of Talang Akar Formation is known as hydrocarbon reservoir at Asri Basin, eastern part of South Sumatra. This formation consists of several depositional systems such as braided channel, meandering channel, fluvial-deltaic, and estuarine system. A channel system was an interesting system developed in the Asri Basin, however, to get the channel distribution in Asri Basin is quite challenging because the thickness of the channels caused its appearance is generally close or under seismic resolution, the existence of coal below our target also affects the impression of “S” sand on seismic data. In this study, spectral decomposition and RGB Blending have been successful to identify “S” sand. RGB Blending map is extracted from 15 Hz as low frequency, 45 Hz as middle frequency, and 75 Hz as high frequency. Our interpretation was applied at RGB Blending map and reveal the “S” sand is classified as a meandering channel depositional system with the main direction of the cha...
The late Pleistocene-Holocene stratigraphic architecture of the Bawean Island and surrounding wat... more The late Pleistocene-Holocene stratigraphic architecture of the Bawean Island and surrounding waters, southeast Java Sea has been analyzed by using sparker seismic profiles. Geological interpretation of these seismic profiles revealed the widespread distribution of paleochannels with different shape and size in the present-day Java Sea. Two channel types can be distinguished based on its morphology: U-shaped channels in the western part and V-shaped channels in the eastern part. The stratigraphic successions were grouped into two major seismic units separated by different seismic boundaries. Characters of marine and fluvial deposits were determined based on seismic boundaries and internal reflectors. Three seismic facies can be identified within late Pleistocene – Holocene incised channel fills associated with SB2. The internal structure of incised-channels consist of chaotic reflector at the bottom, covered by parallel–sub parallel and almost reflection-free indicating the homogeno...
Bangka Island and surrounding areas (including coast and seabed sediments) is known as main tin p... more Bangka Island and surrounding areas (including coast and seabed sediments) is known as main tin producer (cassiterite) in the world as these part of the Southeast Asia Granitic belt, but in fact, other than as a producer of tin, Bangka Belitung is also as heavy mineral placer (as accessories mineral) and REE potential producer which one based on the geological conditions.The potential of accessories minerals on sediment coast, other than cassiterite that occurs around Betumpak Cape, i.e: magnetite (7.86 %), ilmenite (4.9%), zircon (2.51%) and apatite (1.07%) respectively with content. While the content of monazite by using a hand drill has the potential content of up to 67.8 g/m3, while the content of monazite hypothetical resources off the coast of Bangka approximately 471,087,689 m3. As for the content of monazite hypothetical resources off the coast of South Bangka are approximately 23,995,820 m3.At Toboali coast, South Bangka the presence of REE in sediments are above the Earth&...
The bathymetry, petrology, marine magnetic, and seismic-SBP data have identified the northwest-so... more The bathymetry, petrology, marine magnetic, and seismic-SBP data have identified the northwest-southeast direction submarine ridge that shows hydrothermal activity. This activity occurred through Mount Baruna Komba, Abang Komba, and Ibu Komba. The volcanic rocks are andesite basaltic lava flows, tuff, and pumice. The andesite basaltic lava shows porphyritic, intergranular, intersertal to glomeroporphyritic textures. The rock composes anhedral minerals of k-feldspar, plagioclase, and pyroxene. These minerals present in small-sized, short prismatic dispersed in very fine groundmass minerals or glasses. Most of the volcanic rocks have experienced various degrees of alteration. The k-feldspar and plagioclase are most dominantly transformed into sericite, clay mineral, carbonate, epidote and oxide mineral, opaque mineral, and secondary plagioclase through the albitization process, while pyroxene replaced by chlorite. Other minerals are biotite and quartz, and base metals are present Cu, ...
Batuan granit mempunyai arti penting terutama akan kandungan mineral ekonomisnya. Di Indonesia ba... more Batuan granit mempunyai arti penting terutama akan kandungan mineral ekonomisnya. Di Indonesia bagian barat, batuan granit lebih terkenal dengan asosiasi mineralisasi kasiterit (timah). Tidak semua batuan granit mempunyai kandungan mineral kasiterit. Batugranit biotit berhubungan dengan mineralisasi kasiterit, sedangkan batugranit hornblende tidak ada hubungannya dengan mineralisasi kasiterit.
Intensitas kehadiran mineral zirkon dasar laut di lokasi penelitian dijumpai di perairan barat da... more Intensitas kehadiran mineral zirkon dasar laut di lokasi penelitian dijumpai di perairan barat daya Pulau Kabung (SKWL-56), yang terakumulasi pada sedimen pasir lanauan di kedalaman laut 23 m. Berdasarkan hasil analisis mineragrafi butir, mineral ini memberi penampakan variasi warna antara merah muda, putih, dan kuning kecoklatan; bentuk prismatik memanjang dengan penampakan translusen hingga transparan. Berdasarkan penampang profil distribusi zirkon, terlihat kecenderungan penyebaran zirkon dasar laut mengalami penurunan dari sekitar Pulau Kabung ke arah Pulau Lemukutan, dan dari Pulau Kabung ke arah daratan Kalimantan. Kehadiran mineral zirkon dasar laut di lokasi penelitian dengan memperhatikan intensitas penampakan, penyebaran, bentuk kristal, dan asosiasi kehadiran mineral lain menunjukkan bahwa zirkon yang ada merupakan endapan letakan hasil transportasi yang dicirikan dengan berubahnya bentuk kristal dan pada beberapa percontoh yang diamati terlihat adanya sisa penggerusan sebagai hasil aktivitas transportasi, selain itu juga ditandai dengan berubahnya derajat ketransparanan akibat pengaruh penetrasi dalam rekahan di dalam mineral, sehingga hadir beberapa material pengotor selama proses pengendapan.
Intensitas pancaran unsur radioaktif berdasarkan data aktivitas batuan dan aktivitas pancaran ß s... more Intensitas pancaran unsur radioaktif berdasarkan data aktivitas batuan dan aktivitas pancaran ß serbuk di Pantai Sedau dilakukan menggunakan metode analisis Spektrometer Gamma dan alat cacah ß terhadap sembilan contoh sedimen dan batuan. Intensitas radioaktif batuan memperlihatkan kisaran U238 dari 0,1202 ± 0,008 Bq/25gr hingga 0,4348 ± 0,005 Bq/25gr; Th232 0,0768 ± 0,005 Bq/25gr hingga 0,4812 ± 0,015 Bq/25gr; sedangkan intensitas gross gammanya berkisar dari 1,0503 ± 0,029 Bq/25gr hingga 5,6433 ± 0,273 Bq/25gr. Semua contoh yang memiliki intensitas unsur radioaktif untuk aktivitas batuan tinggi berasal dari batuan yang sama (monzogranit), yaitu di lokasi SKP08-04. Hasil yang sama pada pancaran ß serbuknya yang memperlihatkan aktivitas ß gross tertinggi juga terjadi di lokasi SKP08-04 pada batuan monzogranit dengan intensitas paparan 0,370 ± 0,025 Bq/25gr. Berdasarkan pengamatan petrografi, monzogranit di SKP08-04 memperlihatkan pelimpahan feldspar dengan kondisi yang relatif bel...
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