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A sedimentological study after the flash floods that hit North Luwu on July 13, 2020, has been carried out on three affected rivers, namely the Masamba River, the Radda River, and the Binuang River. The study aims to determine the sedimentological impact of the 2020 flash flood disaster, including sedimentation rate, annual bedload sediment volume, and total sediments, which will be used as a reference for future mitigation consideration. The study is based on fieldwork for data collection and laboratory analysis. The results of field measurements and laboratory analysis are then processed by calculating the sedimentation rate at the annual discharge, the bedload sediment volume, and the total estimated sediment accumulated by the flash flood. Sedimentation rate analysis was performed using the Ackers-White formula, and flood delineation was processed using HEC-RAS software. The climatological data from the climatology station at Andi Djemma Airport were used to calculate the river discharge. It is estimated that the volume of bedload sediment in the Binuang River is 16,194,168 m3/year, that of the Masamba River is 7,852,061 m3/year, and that of the Radda River is 4,003,011 m3/year. The volume of sediment brought by flash flood sedimentation in the Radda River is 9,141,608.39 m3, while that in the Masamba River is 55,131,761.29 m3, and that in the Binuang River is 136,838,603.61 m3. The total estimated sedimentation generated by the flash flood on the three rivers on July 13, 2020, is 222,476,966 m3. Based on the study, zonation for vulnerability levels is designed for a future mitigation scheme. The zonation can be classified into three zones: 1) the highly affected zone; 2) the moderately affected zone; and 3) the least affected zone, with special purposes in each zone. It is strongly recommended that future disaster settlement and infrastructure reconstruction policies be based on this zone to reduce disaster risk. Doi: 10.28991/CEJ-2023-09-04-011 Full Text: PDF

Indonesia is one of the largest Ni ore producers in the world and is also expected to be an important potential source of some critical metals (e.g., Co, Sc, rare-earth elements, and platinum-group elements). However, few studies have examined Ni laterite deposits in this country. In this study, we investigate Ni enrichment and the potential accumulation of critical metals in four laterite profiles with varying degrees of serpentinization and weathering intensity in the Soroako and Pomalaa mining areas of Sulawesi, Indonesia. We integrate geochemical evaluation with a mass-balance approach and mineralogical anal ysis to better constrain the geochemical factors influencing the mobilization of Ni during lateritization. Nickel contents in the saprolite horizon of the profiles that are strongly weathered and developed over serpentinized peridotite are higher than those that are weakly weathered and developed over unserpentinized harzburgite. The bulk Ni contents of saprolite horizons are related to Ni contents of Ni-bearing Mg-phyllosilicates, which suggests that Ni remobilization is the main control on Ni enrichment in the profiles. Mass balance calculations reveal that the amounts of gained Fe and Ni in the pro files are positively correlated. This relationship indicates that the redistribution of Ni is likely controlled by the aging of Ni-bearing goethite (dissolution/ recrystallization) involving ligand-promoted dissolution by organic matter and/or reductive dissolution by microbial activity near the surface. Critical metals show enrichment in specific horizons. Enrichments in Co and rare earth elements are strongly influenced by the formation of Mn-oxyhydroxides in the oxide zone of the profiles. In contrast, Sc, Pt, and Pd show residual enrichment patterns, with grades influenced mainly by their initial contents in bedrock. The profiles show a positive correlation between Sc and Fe, as reported for other Ni laterite deposits. Among the critical metals, Sc, Pt, and Pd contents in the studied profiles are comparable with values reported from other Ni laterite deposits worldwide.

Economic growth is a very interesting phenomenon and needs to be taken seriously and become a benchmark to see how successful the country's economic development is, and used as a tool to design and determine future development policies. Indonesia's economic growth changes every year. This change is due to many things that affect it. This study aims to analyze the effect of inflation, poverty, and imports on economic growth from 1990 to 2019. The method used in this study is the error correction model (ECM). In this study, the results obtained that partially poverty and inflation have a significant negative effect, while imports are significantly positive for economic growth in both the short and long term. Simultaneously, all the variables in the model have a significant effect on economic growth.

Water as a natural resource is the most important part for humans to continue their life. One example of the vital role of water resources for human activities is to fulfill food through agriculture and plantations. The availability of water needs for agricultural productivity is certainly an important study to maintain supply capacity and avoid crises in agricultural and plantation foodstuffs. As mandated by the Water Resources Law, the utilization of water resources is aimed at sustainably utilizing water resources by prioritizing the fulfillment of the basic needs of the community fairly. For the sake of the continuity of human life, water resources must be managed properly by paying attention to and protecting the environment. Almost not all the agricultural and plantation areas in the Planting area have irrigation channels that utilize surface water. Consequently, agricultural production does not reach maximum results, because its water needs are very dependent on rainwater. On the other hand, even though there is an irrigation network, there are areas where the availability of water is not sufficient, so that farming activities of farmers cannot get maximum results. This limitation causes farmers to depend on surface water supply, especially during the rainy season so that problems such as prolonged drought can have fatal consequences. One of the efforts to improve agricultural irrigation is to create a groundwater irrigation network by taking water from bore wells.

Incremental accretion of continental fragments from East Gondwana to Eurasia resulted in the growth of Asia and rise of the Tibetan Plateau, yet its detailed evolution remains uncertain. Argoland, a continental fragment that rifted from NW Australia during the Late Jurassic, played a key role in the initial opening of the Indian Ocean and the evolution of eastern Tethys. However, its present identity remains elusive, with East Java-West Sulawesi currently assumed to be the most likely option. To constrain the missing Argoland and its role in India-Asia convergence, we report new detrital zircon data from Sulawesi, Indonesia, and West Burma, Myanmar, and synthesize literature results from relevant regions in Southeast Asia, which (>15,000) reveal age profiles of West Sulawesi, the central Sulawesi metamorphic belt, and southeast Borneo comparable to that of Bird's Head, New Guinea, whereas age patterns of West Burma and East/West Java are similar to those of NW Australia. Notably, the most dominant age populations in NW Australia are rarely detected in Sulawesi and Borneo. These observations, combined with previous geological records and recent paleomagnetic data, suggest that West Burma is the mysterious Argoland, opposing the currently favored East Java-West Sulawesi model, with East Java and West Sulawesi probably having originated from NW Australia and Bird's Head, respectively. We estimate an average northward motion of ∼6–8 cm/yr for West Burma, which split from NW Australia to approach the equator during ca. 155–95 Ma, shedding new light on the reconstruction and breakup of northern East Gondwana, progressive building of Southeast Asia, and India-Asia convergence.

This research aims to explain collaboration for active learning of vocational students through apprenticeships in West Java province, This program is to support Indonesia government program to revitalize vocational education in accordance with Presidential Instruction to improve human development index in Indonesia. This research involves 520 students taking apprenticeship in grade 11 from several vocational school in West Java Province. The participating schools were purposely selected by the first professional certification institution who conducted the field research through questionnaire answered. The results with from statistics descriptive of five indicators, which are student collaboration for active learning in apprenticeship showed that working together, obeying general rule, good speaking, respect and professionalism with positive ethics is more 35% (n = 520). It is very clear that collaboration is carried out by students from different schools. On the other hand, the role of the instructor is very helpful in apprenticeship. Possible explanation is that the finding of student collaboration using questionnaire answered for active learning in context vocational education and training has limitations to this research. It is indicated that further research be useful to be conducted by other researchers.

Cenozoic magmatism occurs throughout West Sulawesi, Indonesia, yet its detailed evolution remains enigmatic due mainly to the scarcity of precise dating. Here, we report new whole-rock geochemical and zircon U-Pb-Hf isotopic data of plutonic/volcanic rocks and river sediments from West Sulawesi to constrain the petrogenesis and magmatic tempo. The magmatic rocks are intermediate to felsic (SiO2 = 58.1–68.0 wt%), high-K calc-alkaline to shoshonitic (K2O = 2.2–6.0 wt%), metaluminous to weakly peraluminous, and I-type in composition. Trace element concentrations and ratios (e.g., Nb/U = 1.7–4.3 and Ti/Zr < 28), along with negative zircon εHf(t) values (–17.0 to –0.4) and old crustal model ages (TDMC = 2.1–1.1 Ga), indicate a dominant magma source region from the underlying continental crystalline basement. U-Pb dating on zircons from ten magmatic rocks yielded weighted mean 206Pb/238U ages of 7.2–6.1 Ma, best representing the crystallization ages of host magmas, further consistent with the prominent age peaks (7.3–6.3 Ma) defined by detrital zircons from four sedimentary samples. Our new data, combined with available results, allow the identification of a noticeable climax of magmatism (flare-up) at ca. 7–6 Ma, forming a continuous magmatic belt throughout West Sulawesi. Given the absence of contemporaneous subduction and the coincidence of incipient opening of the South Banda Basin during ca. 7.15–6.5 Ma, the Late Miocene magmatic flare-up in West Sulawesi and coeval regional extension in eastern Indonesia are attributed to a resumed episode of Banda slab rollback.

The development of scientific subjects in geography at the secondary school level has an impact on knowledge about geology, including rocks and their formation processes, the origin of the earth, to how to plan urban planning in a geographic information system. Geography books generally refer to the international earth science curriculum, making it very difficult for high school students to understand it. The main problem revealed by teachers and students who are interested in OSN in the field of earth is that the material being contested is quite complex. The basic problems of geology, spatial planning and disaster become national and even global issues. Through the Community Service Program activities, the Faculty of Engineering in this case is represented by a team of lecturers from the Geological Engineering Study Program offering Student Centered Learning methods to facilitate understanding of the National Science Olympiad material in the field of Earth Sciences. Besides that, it can also motivate and competitiveness to take part in competitions, especially for students of SMA Negeri 8 Gowa. The purpose of community service activities is to: a) Provide basic geological knowledge as part of earth science; b) Providing knowledge of Indonesian geology; c) Provide material tested in the national earth science olympiad; d) Provide the practice of identifying minerals and rocks, geological structures, fossils, and topographic map readings.

Kondisi Indonesia yang rawan bencana menyebabkan besarnya dampak yang dialami baik karena jatuhnya korban jiwa, kerugian materil antara lain rusaknya/hancurnya infrastruktur dan fasilitas vital lainnya. Mengingat dampak tersebut, maka pengetahuan dan pemahaman masyarakat mengenai bencana alam dan bagaimana upaya yang harus dilakukan bila terjadi bencana alam perlu dilakukan edukasi sejak dini. Peristiwa bencana alam geologi memerlukan manajemen resiko penanggulangan bencana baik sebelum, pada saat bencana maupun pasca bencana. Mitigasi adalah serangkaian kegiatan yang dilakukan untuk mengurangi resiko bencana dan termasuk dalam tahap awal manajemen bencana alam. Tentu saja kegiatan memberikan informasi bencana geologi dan mitigasinya menjadi salah satu tanggung jawab kami sebagai ahli geologi dalam lingkup akademisi untuk memberikan pengetahuan dan pemahaman kepada masyarakat yang awam, salah satu sasarannya adalah anak usia dini atau siswa sekolah dasar. Luaran dari kegiatan ini adalah peningkatan kapasitas masyarakat khususnya siswa sekolah dasar untuk memahami sejak dini pentingnya mitigasi bencana dalam upaya mengurangi atau meminimalisir kerugian akibat bencana geologi. Kegiatan ini dilaksanakan dengan metode ceramah dan simulasi beberapa kejadian bencana geologi, pengenalan tas siaga bencana termasuk pengenalan mengenai K3 (Keselamatan dan Kesehatan Kerja) baik di rumah, jalan dan di sekolah.

Landslide disaster risk assessment model has been proposed for Soppeng Regency which is located in the central part of South Sulawesi Province. Some areas in this regency are classified as landslide prone area based on its geological condition. This study is aimed to assess the landslide vulnerability level and produce a landslide vulnerability map by using mapping method as a basis to model the risk reduction assessment. The component of disaster risk assessment consists of threats, vulnerabilities, and capacities. These components are used to obtain the level of disaster risk in an area by calculating the potential for exposed lives, loss of property and environmental damage. The result shows that Soppeng Regency region has some areas that are prone to landslides with low-high levels. The Vulnerability Assessment is classified as medium level whereas the result of landslide disaster capacity assessment is also shown as medium level. Based on these analyses, it was concluded that Soppeng Regency had a high landslide threat index, with a medium exposed population index and a medium capacity index. The study of landslide disaster risk assessment in Soppeng Regency has shown that Soppeng Regency has been classified as landslide prone area with the medium risk level, especially in mountainous and river bank area. It is recommended that disaster risk assessment model should be used as one of the references for providing disaster risk mitigation plan in disaster risk reduction program.

This study describes the field relationships, petrography and geochemistry of various metamorphic and magmatic rocks from the Barru Block, South Sulawesi, Indonesia, and reports Rb-Sr isochron ages for clastic metasedimentary rocks. The Barru Block is composed of a tectonic stack of various lithological units, including cherts, radiolarian mudstone, breccias, shales, phyllites, mica schist, gneisses, amphibolite and ultramafic rocks. Dacitic rocks intrude the metamorphic and ultramafic sequences. Greenschist- to amphibolite-facies metasedimentary rocks represent detritus from nearby continental blocks that have been redistributed by turbidity currents. Quartzofeldspathic gneisses are derived from andesitic and dacitic protoliths, whereas amphibolites have basaltic precursors. The clastic metasedimentary rocks show enrichment in LILE and HFSE, particularly Nb, but depletion in Sr. The amphibolites display trace element patterns typical of N-MORB rocks, whereas compositional characteristics of gneisses and dacites suggest that they originated in an arc-related environment. Geothermobarometric calculations and mineral assemblages of greenschist facies-rocks suggest metamorphic equilibration at 250–300 °C and a maximum pressure of 5 kbar. Temperature estimates for amphibolites are 640 ± 20 °C at a pressure of 1.3–3 kbar, whereas the temperature estimates for quartzofeldspathic gneisses range from ca. 630–660 °C for peak conditions to 430–520 °C for the retrograde stage. Internal Rb-Sr mineral isochrons for three medium-pressure mica schists indicate metamorphic ages of ca. 70.7 ± 2.4 Ma, 107.3 ± 0.7 Ma and 110 ± 2.4 Ma, respectively. This age range confirms the importance of Early Cretaceous (Albian) metamorphism within the region, but also indicates a previously unknown Late Cretaceous (Maastrichtian) metamorphic or deformational event at ca. 70 Ma. The Barru rocks show a range of tectonic environments as diverse as that of the adjacent Bantimala Block, but overall, the Barru rock association is more felsic in composition. Although the two blocks accreted approximately at the same time (Early Cretaceous), differences in protoliths, geochemistry and metamorphic P–T conditions imply that they were not geographically close together at that time, but were subsequently juxtaposed tectonically.

Multi-stage magmatic events associated with large tungsten-tin polymetallic deposits in the Nanling Range have been the subject of extensive research spanning many years. In this paper we report the results of a systematic study of the petrology, whole-rock geochemistry, zircon U-Pb chronology, and trace element geochemistry of granite bodies exposed in the Xianghualing ore field. They show that the granites in the study area are characterized by high SiO2 (63.83%–75.29%), Al2O3 (13.12%–18.87%), Rb (565–3260 ppm), Nd (67.3–113.5 ppm) and Ta (23.2–129.0 ppm) and by low MgO (0.02%–0.22%), TiO2 (0%–0.02%), Sr (5.3–80.5 ppm) and Ba (7.9–66.4 ppm). The rocks are highly differentiated A-type peraluminous granite, which originated in an extensional within-plate tectonic setting. Based on U-Pb dating and trace element analysis, the following multi-stage magma-hydrothermal events were identified: (1) Paleozoic (~347 Ma) and Triassic (~206 Ma) magmatic stages (initial enrichment epochs of ore-forming elements), (2) Jurassic (~161 Ma) magmatic-hydrothermal stage (mineralization epoch), and (3) Cretaceous hydrothermal overprinting stage (with peaks in the Early Cretaceous ~120 Ma and Late Cretaceous ~80 Ma). From an economic point of view, the Late Cretaceous appears to have great potential for tungsten-tin mineralization. Zircon trace element geochemistry indicates that the ore-forming fluids related to tin mineralization in the Cretaceous originated from the crust and underwent highly differentiated evolutionary processes under relatively reducing conditions. This paper emphasizes the Cretaceous tungsten-tin metallogenic events in the Nanling Range and provides an essential basis and new ideas for further tin-tungsten exploration.

One of the sources of building materials in the Ternate area is Batu Angus. In the present study, the determination of the usage quality of Batu Angus as a construction material in accordance with the standards was carried out through several tests. The analysis carried out in this research was in the form of petrographic analysis as well as physical property and mechanical property analysis. Based on the physical properties testing, the effective density of Batu Angus was 2.53-2.81 gr/cm3 and the absorption value was 1.42-2.00 %. Based on the analysis of its mechanical properties, the compressive strength of Batu Angus was 533.74-574.65 kg/cm2 and wear resistance was 28.64-52.11%. The main mineral compositions of Batu Angus include plagioclase, pyroxene and groundmass. The rock encompassed micro porphyry aphanitic, inequigranular, hyalopilitic, and vesicular textures. Based on the engineering value, texture and mineralogical characteristics, Batu Angus can be used as per the SNI 03-0394-1989 standard as light building materials foundation, curbstone, pavements, as well as decorative stone in construction activities.

Pre-Cenozoic blueschist- and eclogite-facies rocks occur widely scattered in the central Indonesian region, possibly representing lateral equivalents of the same subduction zone. High-pressure/low-temperature (HP/LT) metamorphism is thought to have occurred during the Early Cretaceous, which however is only constrained by K–Ar ages. This study is part of a systematic re-investigation of the regional geochronological record of various metamorphic rocks from this belt and focuses on the Luk Ulo Complex in central Java. Rubidium–Sr multipoint isochrons of one eclogite, two epidote-glaucophane schists and one epidote amphibolite yielded Early Cretaceous (Aptian) ages of 119–117 Ma (± 0.6–0.8 Ma). These ages are similar to previously reported K–Ar results, indicating that the existing data had not significantly been compromised by extraneous Ar contamination. Relatively low peak metamorphic temperatures (ca. 400 °C) during the HP/LT stage suggest that the Rb–Sr isotopic system was not significantly affected by diffusive loss during cooling. The Rb–Sr ages most likely constrain the time of mica growth or recrystallization during high-pressure metamorphism. The matching ages of high-pressure and lower pressure rocks are attributed to inheritance, but mixing of rocks that originally had formed at the same time at different depths of the subduction complex cannot completely be ruled out yet. Rubidium–Sr white mica ages of eclogite- and blueschist-facies rocks from central Java are younger than those of similar rocks from the Western Sulawesi tectonic province (130–120 Ma), revealing a previously unknown age difference that had been hidden by the poorer precision of the K–Ar dataset. At this point, it remains unclear whether this age difference is related to processes operating within the same or in different subduction zones. The zircon populations of clastic metasedimentary rocks from the Luk Ulo Complex are dominated by a prominent Jurassic to Carboniferous population (ca. 320–180 Ma) with a distinct Permo-Triassic peak (ca. 270–200 Ma). Another less pronounced Paleozoic age signal shows up at 450–380 Ma. Proterozoic and Archean zircon grains are very rare. At least some data points at the lower end of the age spectrum (ca.135–117 Ma) most likely are related to in-situ metamorphic processes. The youngest zircon grains of unambiguous detrital origin show up at ca. 160 Ma, indicating a Late Jurassic maximum depositional age. Additional detrital zircon data for the Barru Complex (Western Sulawesi) further substantiate previous findings documenting a complex age spectrum with contributions of Mesozoic (Triassic), Paleozoic (Permian, Carboniferous, Devonian to Ordovician), Meso- to Paleoproterozoic subpopulations and rare Archean zircons. The youngest zircons indicate a maximum depositional age of ca. 255–250 Ma. New and existing U–Pb zircon data indicate that the pre-metamorphic basin histories recorded in the Luk Ulo and Barru complexes are linked to different source terrains and depositional systems.

The timeframe of eclogite- and blueschist-facies metamophism in the central Indonesian region is poorly defined. Relative to its geographic extent, the regional coverage of isotopic age data is insufficient for an unambiguous interpretation of the geologic evolution of the Central Indonesian Accretionary Collision Complex. This study reports new geochronological constraints for high-pressure/low-temperature (HP/LT) rocks from the Bantimala Complex, SW Sulawesi, which further substantiate the importance of Cretaceous HP/LT metamorphism for the larger region. Multipoint Rb–Sr mineral isochrons of eclogites and glaucophane-rich rocks display a narrow range of white mica ages (130–120 Ma), interpreted to postdate peak-HP conditions, which is considerably smaller and more precise than the previously published K–Ar age spectrum (137–113 Ma). The close similarity with K–Ar ages suggests that these analyses were only slightly contaminated, if at all, with an extraneous Ar component, which did not significantly compromise the geological relevance of the existing dataset. An important result of this study is the emerging evidence for regional age differences between HP/LT rocks from SW Sulawesi (130–120 Ma) and Java (ca. 118 Ma). The existence of different subduction zones cannot be excluded but P–T and age differences between these occurrences can be reconciled with a model suggesting formation in the same subduction complex. Zircon is very rare in the studied HP/LT rock suite, but two glaucophane-rich rocks were suitable for U–Pb zircon dating and indicate Late Triassic–Early Jurassic protolith ages (ca. 205–185 Ma). The zircon population of a retrogressed eclogite records a more complex history including evidence for igneous crystallization, metamorphic recrystallization or growth, inheritance and variable degrees of Pb-loss. Metamorphic zircon rims mostly yielded U–Pb ages in the 135–110 Ma range that broadly confirm metamorphic ages determined by K–Ar and Rb–Sr white mica geochronology. Zircons that are significantly older (2.55–1.4 Ga and 400–260 Ma) than the protolith age are interpreted to represent detrital grains from subducted sediments that had been incorporated in mafic melts directly derived from a contaminated mantle source. The presence of continentally-derived detrital zircons that have presumably been included during melt formation in the mantle have not yet been described for any eclogite- and/or blueschist-facies rock of basaltic or gabbroic parentage.

DOI:10.17014/ijog.6.2.153-174 Exhumation and tectonomagmatic processes of the granitoid from Sulawesi were discussed using petrochemistry (e.g. petrographic and major element compositions) and geothermobarometry data (mineral chemistry data). Detailed petrographic observations were conducted to determine the mineral composition, texture, and structure of the granitoid rocks, whereas the whole rock composition were determined using XRF method, and the mineral chemistry was analyzed using Electron Microprobe Analyzer (EPMA). The granitoids are classified as calc-alkaline, metaluminous I-type. Pressures of 0.91 to 1.2 kbar and emplacement depths of 3.2 to 4.3 km at temperatures of 677 - 729°C were estimated for Mamasa Pluton. Whereas Masamba Pluton was emplaced at pressures of 2.3 to 2.8 kbar, temperatures of 756 - 774°C, and emplacement depths of 8.2 to 10 km. Moreover, Lalos-Toli and Sony Plutons were emplaced at temperatures of 731 to 736°C and 601 to 609°C, respectively. The pressures varying from 3.1 to 3.3 kbar and 3.2 to 3.4 kbar, equate to an emplacement depth of 11.3 and 11.6 km, respectively. Gorontalo Pluton emplaced at temperatures of 662 - 668°C with the pressure range from 2.6 to 2.7 kbar, is equivalent to 9.3 km deep. Varied oxidation state (ranging from -14 to 19) is inferred from the mineral assemblages, showing a strong association with highly oxidized I-type series granitic rocks. The exhumation rate estimation shows that Mamasa and Masamba Plutons were exhumed respectively at a rate of 0.37 and 1.6 mm/year, whereas Lalos-Toli and Sony Plutons at 1.4 and 2.7 mm/year, respectively. Gorontalo Pluton located in the Northern Sulawesi Province was exhumed at 0.42 mm/year. The rapid exhumation rate of Sony Pluton is attributed to the active vertical movement of Palu-Koro Fault Zone which has been active since Pliocene. It shows that faulting may play an important role in differential exhumation of intrusive bodies in the orogenic belt.

Late Cenozoic granitoids are widespread in a 1600km long belt forming the Western and Northern Sulawesi tectono-magmatic provinces. They can be divided into three rock series: shoshonitic (HK), high-K felsic calc-alkaline (CAK), and normal calc-alkaline to tholeiitic (CA-TH). Representative samples collected from eleven plutons, which were subjected to petrography, major element, trace element, Sr, Nd, Pb isotope and whole-rock δ18O analyses, are all I-type and metaluminous to weakly peraluminous. The occurrence of the two K-rich series is restricted to Western Sulawesi, where they formed in an extensional, post-subduction tectonic setting with astenospheric upwelling providing thermal perturbation and adiabatic decompression. Two parental magma sources are proposed: enriched mantle or lower crustal equivalent for HK magmas, and Triassic igneous rocks in a Gondwana-derived fragment thrust beneath the cental and northern parts of Western Sulawesi for CAK magmas. The latter interpretation is based on striking similarities in radiogenic isotope and trace element signatures. CA-TH granitoids are found mostly in Northern Sulawesi. Partial melting of lower-middle crust amphibolites in an active subduction environment is the proposed origin of these rocks. Fractional crystallization and crustal contamination have played a significant role in magma petrogenesis, particularly in the case of the HK and CAK series. Contamination by organic carbon-bearing sedimentary rocks of the HK and CAK granitoids in the central part of Western Sulawesi is suggested by their ilmenite-series (reduced) character. The CAK granitoids further to the north and CA-TH granitoids in Northern Sulawesi are typical magnetite-series (oxidized). This may explain differences in mineralization styles in the two regions.

Bijih besi di daerah Pakke ditemukan berupa bongkah-bongkah bijih besi magnetit dan hematit yang berasosiasi dengan intrusi granodiorit dan pegmatit granodiorit (Utoyo, 2008). Penelitian ini bertujuan untuk mengetahui kondisi geologi, jenis batuan dan mineral pembawa bijih besi, serta karakteristik endapan bijih besi daerah penelitian. Tahapan pengambilan data berupa Pengamatan Singkapan. Pengambilan sampel litologi, menggunakan metode Rock Sampling. Metode analisis yang digunakan untuk menentukan karakatersitik endapan bijih besi yaitu analisis petrografi untuk mengetahui jenis litologi, analisis mineragrafi untuk mengetahui mineral pembawa bijih dan analisis XRD ( X-Ray Diffraction ) untuk mengetahui mineral alterasi dan mineral bijih. Berdasarkan tipe alterasi dan mineralisasi diketahui bahwa tipe endapan bijih besi pada daerah penelitian yaitu endapan skarn. Dimana endapan skarn ini terbentuk proses metamorfisme kontak yang bertemperatur tinggi. Magma yang kaya akan silika menginstrusi batuan sedimen yang kaya akan karbonat seperti batugamping. Jenis batuan pada daerah penelitian yaitu batuan beku berupa basal yang diindikasikan sebagai source rock dan batuan karbonat berupa wackstone yang diindikasikan sebagai host rock atau batuan penyimpan bijih besi dimana mineral pembawa bijih besi yaitu magnetit, hematit dan goetit.

The Walanae Formation is the youngest sedimentary rock that formed a mountainous area along the Walanae River Valley. It is very interesting and challenging to prove that Walanae Depression developed from the Late Miocene to the Late Pliocene. This area gradually became a marine environment and how the climatic conditions at that time were particularly on the Salo Mario section. Soppeng Regency. Measuring section on Salo Mario obtained 32 layers, consists of interbedded claystone, sandstone, and conglomerate on the upper part of the outcrop. Samples from the layers are then made into smear slides and dried using a UV lamp, and the preparations were analyzed under a microscope at a magnification of 1000x. The result of laboratory observations, nannofossil is only found in 11 layers consisting of coccolith and Discoaster. The nannofossils found are namely Discoaster asymmetricus Gartner, Discoaster berggrenii Bukry, Discoaster bollii Martini and Bramlette, Discoaster brouweri Tan Sin Hok, Discoaster calcaris Gartner, Discoaster deflandrei Bramlette and Riedel, Discoaster neohamatus Bukry and Bramlette, Discoaster pentaradiatus Tan Sin Hok, Discoaster pseudovariabilis Martini and Worsley, Discoaster surculus Martini and Bramlette, Discoaster tamalis Kamptner, Discoaster triradiatus Tan Sin Hok, and Discoaster variabilis Martini and Bramlette. The occurence of the Discoster indicates the warming of the lower photic zone caused by the weakening of upwelling.

This research is aimed to recognize the chemical composition, type, and main mineral morphology that are consisted in Batu Angus. The analytical methods used are X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR), and Scanning Electronic Microscopic (SEM). The result of the research showed that the chemical composition of Angus stone consists of silicone mineral and iron. The kind of silicone mineral is identified as mineral quartz, cristobalite, and tridymite while the iron mineral is identified as maghemite. The silicone mineral morphology has tetragonal, cubic, orthorhombic, hexagonal, and trigonal geometry shapes.

Bantimala Mélange Complex is about 75 Km to the North of Makassar, the capital city of South Sulawesi Province. The presence of High-pressure Metamorphic Rocks, and Ultrahigh Pressure in the Bantimala Mélange Complex, has been known and studied by a number of geologists. Eclogite and Blue Schist are Ultrahigh, and High-pressure metamorphic rocks in the Bantimala Mélange Complex which have important significance in explaining the Cretaceous tectonics in this area. Furthermore, Bantimala Eclogite is the only Ultrahigh-pressure metamorphic rock known to be exposed in Sulawesi. The results of thin section analysis of Eclogite show the presence of Omphacite Minerals, and Coesite as an index mineral for Ultrahigh pressure metamorphic rocks. While in Blue Schist with Glaucophane Minerals are found which are partially replaced by Chlorite which indicates the presence of Poly-metamorphism as a result of retrogradation from Ultrahigh pressure to High pressure and to Medium pressure metamorphic rocks. Radiometric age dating using the Ar40/Ar39 method shows an age spectrum of 100 Ma-114 Ma (Early Cretaceous). The 114 Ma, age is interpreted as the age of Eclogite’s Ultrahigh pressure metamorphic rocks formation with respect to the peak of subduction tectonics. Whereas the age of 100 Ma before now is interpreted as the age of exhumation or collision as the end of the Cretaceous tectonic subduction in the South Arm of Sulawesi or in the East or Southeast of Sundaland.

This paper presents petrographic, geochemical and geochronological data for intrusions that area spatially related to gold and copper mineralization in the Poboya and Sassak areas in western Sulawesi. These data coupled with previous studies are then used to discuss the implications for the mineralization processes and magma sources. In the Poboya area, gold-bearing quartz veins are related to high-K calc-alkaline granitoids that display a reduced nature, whereas in Sassak area porphyry Cu-Au mineralization is associated with monzonitic intrusions intruded by gabbroic and syeno-dioritic intrusions. Granitoids from Poboya have a metaluminous to mildly peraluminous character (mol. Al2O3/mol. CaO + Na2O + K2O = 1.0–1.04) and include both I-type and S-type varieties. The Poboya and Sassak intrusions have Rb-Sr isotopic ages of 3.94 ± 0.03 Ma, 2.97 ± 0.05 Ma and 10.7 Ma ± 0.11 Ma, respectively, which are interpreted to closely approximate the time of emplacement into their country rocks. Zircon U-Pb dating of gabbro and diorite from the Sassak area yielded crystallization ages of 10.8 ± 0.16 Ma and 10.6 ± 0.19 Ma, respectively. New Sr isotopic data (87Sr/86Sr ratios >0.709) are consistent with previous data obtained from the central and northern parts of western Sulawesi, Gondwana-derived Mesozoic granitoids and enriched-mantle or lower crustal equivalents are the most likely magma sources for the Poboya and Sassak igneous rock suites, respectively. The Poboya deposit is interpreted to represent the distal part of a reduced intrusion-related gold system.

Serpentinized ultramafic rocks occur in two separate basement complexes in the South Arm of Sulawesi, the Bantimala and Barru Blocks. We present petrographic, mineral chemical and geochemical data for these rocks, and interpret them in terms of petrogenesis and tectonic setting. The rocks of both blocks show strong serpentinization of original anhydrous silicates. The Bantimala ultramafics consist mainly of peridotite (harzburgite and dunite) and clinopyroxenite, with lenses of podiform chromitite. Metamorphism is evidenced by the occurrence of amphibolite-facies tremolite schist. In contrast, the Barru ultramafics consist of harzburgite peridotite and podiform chromitite, which also show an amphibolite-facies overprint that in this case may be related to intrusion by a large dacite/granodiorite body. Whole-rock trace element analyses and spinel compositions show that the Barru harzburgite is depleted relative to primitive mantle, and has had some melt extracted. In contrast, the Bantimala dunite, harzburgite and clinopyroxenite are cumulates. Both are derived from a supra-subduction zone environment, and were obducted during the closure of small back-arc basins. If there has been no rotation of the blocks, then the Bantimala ultramafics were emplaced from an ENE direction, while the Barru ultramafics were emplaced from the WNW. The ultramafic suites from these two blocks are juxtaposed with metamorphic assemblages, which were later intruded by younger volcanics, particularly in the Barru Block.

This study aims to determine the tariff of Jakarta LRT based on the analysis of ability to pay and willingness to pay for taxi users. The ability to pay value analysis approach uses travel cost method and determination of willingness to pay value using discrete choice analysis. From the analysis results can be seen that the value of the ability to pay is Rp. 63.316 and the willingness to pay value is Rp. 11.500. This indicates that the willingness to pay taxi users is less than the ability to pay.

Penelitian tentang petrografi dan alterasi batuan diabase sebagai batuan samping (wall-rock) di daerah Pationgi Kecamatan Patimpeng Kabupaten Bone Sulawesi Selatan telah dilakukan. Secara administratif, daerah penelitian terletak di Daerah Pationgi Kecamatan Patimpeng Provinsi Sulawesi Selatan, yang terletak pada koordinat 04o54’00" – 04°56’00" Lintang Selatan (LS) dan 120°10'00" - 120°12’00" Bujur Timur (BT). Penelitian ini bertujuan untuk mengetahui karakteristik batuan diabas secara petrografi yang menjadi batuan samping atau wall-rock dan mengetahui mineral-mineral alterasi alterasi serta untuk menentukan kisaran temperatur dan kedalaman proses mineralisasi. Metode penelitian yang digunakan yaitu dengan melakukan pemetaan geologi permukaan yang meliputi kegiatan orientasi lapangan dan pengambilan data-data geologi seperti geomorfologi, stratigrafi dan struktur geologi serta pengambilan detail sampel batuan samping yang telah mengalami alterasi. Analisis laboratorium sampel batuan dilakukan dengan menggunakan metode pengamatan detail petrografi mengunakan mikroskop polarisasi. Batuan diabas yang bertindak sebagai wall rock pada daerah penelitian menunjukkan kondisi yang lapuk sedang, disusun oleh mineral utama berupa piroksin dan plagioklas yang memperlihatkan tekstur diabasik. Hasil pengamatan petrografi menunjukkan proses alterasi di daerah penelitian ditunjukkan oleh adanya kehadiran mineral lempung-klorit-kuarsa-serisit dan mineral karbonat. Himpunan mineral-mineral hasil alterasi ini mengindikasikan bahwa zona alterasi yang berkembang pada daerah ini yaitu Zona Argilik. Berdasarkan kehadiran mineral-mineral alterasi tersebut, proses mineralisasi pada daerah penelitian diinterpretasikan terbentuk pada kisaran suhu 100 0C – 150 0C pada kedalaman 0 – 50 meter dibawah permukaan.

The Sangkaropi district in central-West Sulawesi is one of the few known volcanic hosted massive sulfide (VHMS) districts in Indonesia. It comprises several clusters of mostly small mineral occurrences, including Sangkaropi, Billolo and Rumanga. The mineralization is hosted by felsic volcanics that occur in bimodal association with basalt. Styles of mineralization include syngenetic banded massive and fragmented sulfides and epigenetic veins, stockwork and disseminations. The deposits are classified as zinciferous bimodal-felsic (Kuroko type) VHMS. We present for the first time preliminary results for whole rock and trace element analysis and U-Pb age dating for the bimodal volcanic hosts, together with sulfur isotope data for the mineralization and associated barite alteration. Combined with previous data, this new information suggests the mineralization in the Sangkaropi district took place around 34 Ma (boundary Eocene-Oligocene) in a continental margin arc setting, when the stress regime changed from near-neutral to extensional and volcanism changed from being andesite-dominated to bi-modal. The sulfur isotope data suggest that the mineralizing fluids had both significant magmatic and seawater components.

All Several macro earthquakes have occurred at the Matano fault so it is interesting to study how the energy attenuation in the coda wave. Coda wave is a signal that follows a secondary wave on a seismogram recording. Some macro earthquakes can be monitored well by BMKG through LUWI Station at a distance of 200-300 km from the epicenter. The coda Q-factor is analysed using coda waves at range 2-4 Hz and 4-8 Hz frequencies of lapse times at 20 seconds in vertical component. Variation of coda Q-factor is influenced by the rock medium in the Matano Fault. This Matano Fault is very unique because it is a collision of continental and oceanic rocks that extend from western to eastern part. The study area is divided into three zones, namely the western, central, and eastern zones. The objective of this study is to identify vulnerabilities at low or high level in each zones by the Coda Q-factor that will classify hazardous earthquakes. The value of coda Q-factor is obtained 126.27 in the west, 162.80 in the middle, and 181.96 in the eastern part of the fault. The western part is the most vulnerable area because low coda Q-factor is associated with sediments layer. It is formed by metamorphic rocks close to the active Fault of Palu Koro. The highest coda Q-factor is located at the eastern part of the fault which hazardous zone and has the potential to cause a large earthquake. The eastern zone has a composition of ultrabasic rocks with high rock stress. In general, the average value of Q-factor in the Matano Fault is 157.01, where the value indicates that the characteristics of the Matano Fault are seismic active zones.

We present the first data on bulk-rock major and trace element compositions for a suite of eclogite- and blueschist-facies rocks from the Bantimala Complex, Indonesia, with the aim of better constraining the protolith origins and nature of the subducted crust. The eclogites can be classified into two groups: glaucophane-rich eclogite and glaucophane- free eclogite, whereas the blueschists are divided into albite-epidote glaucophanite and quartz-glaucophane schists. SiO2 contents of the eclogites are 43.3-49.6 wt%, with Na2O + K2O contents 3.7-4.7 wt%. The blueschists show a wider range of compositions, with SiO2 = 40.7-63.8 wt% and Na2O + K2O = 2.7-4.5 wt%. Trace element data suggest that the eclogite protoliths include both enriched and normal mid-oceanic ridge basalt (E-MORB and N-MORB) and also gabbroic cumulates. The blueschists show more varia- tion in protoliths, which include N-MORB, Oceanic Island Basalt (OIB) and Island Arc Basalt (IAB). Plots of element concentrations against the immobile Zr show considerable mobility of large ion lithophiles but not of high field-strength elements during high- pressure metamorphism, and indicate that the high SiO2 content of some blueschists is probably due to metasomatism by a LILE-rich siliceous aqueous fluid. Strong correlations between K, Rb, Ba and Cs suggests that enrichment of these elements occurred by a single process. All the protoliths were subducted, metamorphosed to blueschist/eclogite-facies and subsequently exhumed. It is noteworthy that the samples deduced to have come from thicker-crust environments (OIB, IAB) were subducted to shallower depths (blueschist- facies) than MORB-derived samples, all except one of which reached eclogite-facies con- ditions. The geochemical data of this study demonstrate the variety of ocean floor types that were subducted under the southeast margin of Sundaland in the late Jurassic period.