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Petrology, geochemistry and paleogeographic reconstruction of the East Sulawesi Ophiolite, Indonesia
Ade Kadarusman Sumio Miyashita Shigenori Maruyama Christopher D. Parkinson Akira Ishikawa 《Tectonophysics》2004,392(1-4):55
The East Sulawesi Ophiolite (ESO) is tectonically dismembered and widely distributed in Central and East Sulawesi. It comprises, from base to top, residual mantle peridotite and mafic–ultramafic cumulate through layered to isotropic gabbro, to sheeted dolerites and basaltic volcanic rocks. Residual peridotite is dominantly spinel lherzolite intercalated with harzburgite and dunite. Ultramafic rocks from different locations display significant differences in rock composition and mineral. However, the clinopyroxene of peridotite displays REE pattern similarities with those of mid-ocean ridge (MOR) origin, rather than those of suprasubduction zone (SSZ) origin. The gabbroic unit consists of massive gabbro, layered gabbro, mafic and ultramafic cumulate and anorthosite. The observed crystallization sequence of gabbroic unit, which is olivine→(spinel)→plagioclase→clinopyroxene→(orthopyroxene)→(hornblende), and the mineral chemistry data indicate that the ESO gabbro has similarities with MOR setting.Major and trace element geochemistry of basalt and dolerite suggests MOR, oceanic plateau and minor SSZ origins. A possible oceanic plateau origin is supported by the following: (i) the 15-km thickness is comparable with the thickness of oceanic plateau rather than normal oceanic lithosphere; (ii) there are no or only minor olivine phenocrysts in the basalt; and (iii) predominance of aphyric texture in the basalts. The REE pattern of ESO basalt exhibits N-MORB-like signatures. However, a negative Nb anomaly in the trace element spider diagram may be attributed to mantle heterogeneity of an OPB source.The geochemical variations and disparities for both peridotite and basalt and the noncogenetic relationship between crust and mantle sections in several locations suggest that the ESO may have been formed at one tectonic setting and was later overprinted by magmatism in different environments through its birth to emplacement. A possible Cretaceous origin of an oceanic plateau component of the ESO is indicated on the basis of calculated paleopositions using plate trajectory analyses together with previously published paleolatitude data. The ESO can be traced back to the proximity of the presently active region of the SW Pacific Superplume. 相似文献
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S.J. Turner P.A. Flindell D. Hendri I. Hardjana P.F. Lauricella R.P. Lindsay B. Marpaung G.P. White 《Journal of Geochemical Exploration》1994,50(1-3)
The Ratatotok district in the Minahasa Regency of North Sulawesi, Indonesia is an area of significant gold mineralisation. Gold has been mined in the district since at least the 1850s, and intensively by the Dutch between 1900 and 1921 with a recorded production of 5,060 kg of gold. Newmont began exploring the district in 1986, and has delineated a major sediment-hosted replacement-style deposit at Mesel, and other smaller deposits in an 8×5 km area. A total drill-indicated resource of over 60 metric tonnes of gold (+2 Moz) is reported for Mesel, and three of the smaller deposits. Approximately 80% of this resource is refractory. Silver grades are usually low (<10 g/t). The Mesel deposit is similar to many Carlin-type deposits in carbonate hostrocks, alteration, geochemical signature and ore mineralogy, but is distinct in tectonic setting. The discovery of replacement-style mineralisation at Mesel, in an impure limestone within a Tertiary island arc environment, demonstrates that deposits with outward characteristics similar to Carlin-type mineralisation are not restricted to a continental setting.Carbonate sediments in the Ratatotok district were deposited in a Late Miocene restricted basin. Later compressional tectonics caused uplift that resulted in karst development in the limestone and erosion of the adjacent volcanic arc with deposition of a thick epiclastic unit. This was followed by intrusion of shallow level pre-mineral andesite into the sequence. Mineralisation at Mesel, and probably elsewhere in the district, is synchronous with the late-stage reactivation of strike-slip faults. Mineralising fluids at Mesel were focussed along steep structures sympathetic to these faults, and trapped below a relatively impermeable andesite cap rock. Hydrothermal fluids caused decalcification of the silty, more permeable carbonate units with the formation of secondary dolomite, deposition of fine arsenian pyrite, silica veinlets and gold. Volume loss due to decalcification and dolomite formation caused collapse brecciation which enhanced fluid flow and further mineralisation. This locally culminated in total decarbonation and deposition of massive silica. Late-stage stibnite occurs in structural zones within the ore deposit, whereas arsenic (as realgar and orpiment) and mercury (as cinnabar) are concentrated on the periphery.Elsewhere in the Ratatotok district, gold mineralisation is restricted to replacement-style mineralisation in permeable zones along limestone-andesite contacts, open-space filling quartz-calcite veins and stockworks, and residual quartz-clay breccias. The residual breccias are developed in-situ, and are interpreted to form by dissolution of the wallrock limestone from around pre-existing mineralisation. This has resulted in widespread eluvial gold occurrences. 相似文献
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《地学前缘(英文版)》2023,14(2):101500
Ultrahigh-temperature (UHT) metamorphism represents an extreme crustal thermal event with peak conditions exceeding 900 °C at 7–13 kbar. In the modern-style plate tectonic system, records of the UHT metamorphism are relatively rare due to the secular cooling of Earth. In the Palu region of Western Sulawesi, we newly discovered a series of HT-UHT metamorphic rocks including amphibolite, granulite, eclogites and gneiss. Of them, two granulite samples (18CS14-2, 18CS14-4) with high garnet content (>50 mol%) are chosen for petrographic observation, phase equilibrium modelling, and zircon U-Pb dating. These rocks are characterized by a relic M1 assemblage of Grt + Ky + Bt + Rt and a M2 assemblage of Grt + Sil + Pl + Spl + Crd ± Qtz + Ilm + melt. Phase equilibrium modelling based on effective bulk compositions yields UHT conditions of 7.2–8.5 kbar/940–1080 °C (18CS14-2) and 7.0–7.3 kbar/1000–1040 °C (18CS14-4). U-Pb analysis reveals two generations of metamorphic zircon with evolving REE content that is intimately related to garnet growth and decomposition. Zircon age of 36–5.3 Ma is ascribed to syn- to post-M1 metamorphism, whereas the young zircon age of 5.1–3.8 Ma is linked to syn- and post-M2 stage. The UHT metamorphism was probably the consequence of the upwelling of asthenospheric mantle triggered by post-collisional delamination of lithosphere in the Miocene-Pliocene (ca. 5 Ma). It could represent the youngest known UHT metamorphism on Earth. 相似文献
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A generation of fine Dutch tectonic geologists had already recognized decades ago that the Indonesian Archipelago possesses a dual character, namely as the place of intersection of two of the largest mountain systems and as an intracontinental zone between the Asiatic and Australian continents. They also realized that the Indonesian island arcs represent a mountain belt in statu nascendi, exhibiting a systematic relationship of active tectonic and magmatic features to the deep submarine trenches. 相似文献
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印尼苏拉威西岛红土型镍矿的高效快速勘查模式 总被引:3,自引:0,他引:3
金属镍是我国紧缺资源之一,印度尼西亚拥有丰富的红土型镍矿,但是由于国外开采,在矿业政策、技术条件、气候条件上面临很多挑战,实施高效、快速、低成本勘探是解决这些问题的根本途径.文章以印尼苏拉威西岛的一个红土型镍矿勘查区为例,应用高精度磁法勘探,通过分析勘查区磁性特征圈定勘探靶区;对实验室和X-荧光仪分析的样品数据进行一元回归分析,将手持X-荧光分析仪成功应用于镍矿体的现场圈定,从而建立了红土型镍矿的高效、快速、低成本的勘查模式. 相似文献
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Alpine‐type orogenic garnet‐bearing peridotites, associated with quartzo‐feldspathic gneisses of a 140–115 Ma high‐pressure/ultra‐high‐pressure metamorphic (HP‐UHPM) terrane, occur in two regions of the Indonesian island of Sulawesi. Both exposures are located within NW–SE‐trending strike–slip fault zones. Garnet lherzolite occurs as <10 m wide fault slices juxtaposed against Miocene granite in the left‐lateral Palu‐Koro (P‐K) fault valley, and as 10–30 m wide, fault‐bounded outcrops juxtaposed against gabbros and peridotites of the East Sulawesi ophiolite within the right‐lateral Ampana fault in the Bongka river (BR) valley. Six evolutionary stages of recrystallization can be recognized in the peridotites from both localities. Stage I, the precursor spinel lherzolite assemblage, is characterized by Ol+Cpx+Opx±Prg‐Amp ± Spl±Rt±Phl, as inclusions within garnet cores. Stage II, the main garnet lherzolite assemblage, consists of coarse‐grained Ol+Opx+Cpx+Grt; whereas finer‐grained, neoblastic Ol+Opx+Grt+Cpx±Spl±Prg‐Amp±Phl constitutes stage III. Stages IV and V are manifest as kelyphites of fibrous Opx+Cpx+Spl in inner coronas, and Opx+Spl+Prg‐Amp±Ep in outer coronas around garnet, respectively. The final (greenschist facies) retrogressive stage VI is accompanied by recrystallization of Serp+Chl±Mag±Tr±Ni sulphides±Tlc±Cal. P–T conditions of the hydrated precursor spinel lherzolite stage I were probably about 750 °C at 15–20 kbar. P–T determinations of the peak stage IIc (from core compositions) display considerable variation for samples derived from different outcrops, with clustering at 26–38 kbar, 1025–1210 °C (P‐K & BR); 19–21 kbar, 1070–1090 °C (P‐K), and 40–48 kbar, 1205–1290 °C (BR). Stage IIr (derived from rim compositions) generally records decompression of around 4–12 kbar accompanied by cooling of 50–240 °C from the IIc peak stage. Stage III, which post‐dates a phase of ductile deformation, yielded 22±2 kbar at 750±25 °C (P‐K) and 16±2 kbar at 730±40 °C (BR). The granulite–amphibolite–greenschist decompression sequence reflects uplift to upper crustal levels from conditions of 647–862 °C at P=15 kbar (stage IV), through 580–635 °C at P=10–12 kbar (stage V) to 350–400 °C at P=4–7 kbar (stage VI), respectively, and is identical to the sequence recorded in associated granulite, gneiss and eclogite. Sulawesi garnet peridotites are interpreted to represent minor components of the extensive HP‐UHP (peak P >28 kbar, peak T of c. 760 °C) metamorphic basement terrane, which was recrystallized and uplifted in a N‐dipping continental collision zone at the southern Sundaland margin in the mid‐Cretaceous. The low‐T , low‐P and metasomatized spinel lherzolite precursor to the garnet lherzolite probably represents mantle wedge rocks that were dragged down parallel to the slab–wedge interface in a subduction/collision zone by induced corner flow. Ductile tectonic incorporation into the underthrust continental crust from various depths along the interface probably occurred during the exhumation stage, and the garnet peridotites were subsequently uplifted within the HP‐UHPM nappe, suffering a similar decompression history to that experienced by the regional schists and gneisses. Final exhumation from upper crustal levels was clearly facilitated by entrainment in Neogene granitic plutons, and/or Oligocene trans‐tension in deep‐seated strike–slip fault zones. 相似文献
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An extraordinarily large-scale landslide with a volume of about 200 million m3, a width of about 1,600 m, and a height of about 750 m occurred on 2004 March 26, 13:45 local time, on a steep caldera wall
on the northwest flank of Mt. Bawakaraeng (2,830 m) at the headwater of the Jeneberang River in South Sulawesi, Indonesia.
The debris avalanche extended about 7 km from the headwater and buried the river valley, causing devastating damage. There
are a great many calderas in the world, notably Japan. If a large-scale sector collapse were to occur in a heavily populated
area, it would be a devastating disaster for the people living in the area. The aim of this paper is to outline such a landslide
and explain its mechanism of occurrence. We evaluated the stability of the original slope before the landslide using the limit
equilibrium method and the finite-element-based shear strength reduction method (SSRFEM) with the strength reduction factor.
The limit equilibrium method showed that a rise in the groundwater level caused the landslide. Although the critical slip
surface predicted by the SSRFEM was shallower than that of the actual slip surface, the end positions of the actual and predicted
slip surfaces were almost the same. Moreover, the end position of the critical slip surface before the landslide—the headwater
of the Jeneberang River—was a knick point at which the slope inclination became steeper. SSRFEM analysis may be useful for
evaluating the slope stability of large-scale landslides, because the critical slip surface predicted by it was close to the
actual surface, even though we assumed homogenous conditions without information on the degree of weathering or ground properties.
As the knick point formed at the end of the critical slip surface and is equivalent to the end of the actual slip surface,
we assume such topographic features to be a primary geomorphologic cause of the landslide. 相似文献
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板块俯冲起始是板块构造理论的核心内容, 但却研究最为薄弱。印度尼西亚北苏拉威西岛弧是始新世期间开始发育的一个印度洋洋内弧, 其记录了多期次(包括印度洋、马鲁古海和西里伯斯海)的且处于不同演化阶段的俯冲作用及相应的俯冲起始过程, 因此该岛弧是研究板块俯冲起始的天然实验室。本文通过回顾板块俯冲起始研究进展, 结合北苏拉威西岛弧内已有的野外调查、锆石U-Pb定年、岩石地球化学特征等, 以厘清区域内岛弧岩浆的岩石类型、形成时代、空间分布和岩浆活动节律, 制约岛弧岩浆的构造背景和岩浆源区性质等, 并着重关注该岛弧内可能与板块俯冲起始相关的地质和岩石记录, 如弧前玄武岩、玻安岩、俯冲带(SSZ)型蛇绿岩、变质底板等。在此基础上, 综合限定北苏拉威西岛弧记录的印度洋洋壳俯冲历史, 探讨其俯冲起始的时间与地球动力学机制。本文仅抛砖引玉, 期待更多学者参与到北苏拉威西岛弧板块俯冲起始的研究中来。
相似文献14.
The Salu Bulo prospect is one of the gold prospects in the Awak Mas project in the central part of the western province, Sulawesi, Indonesia. The gold mineralization is hosted by the meta‐sedimentary rocks intercalated with the meta‐volcanic and volcaniclastic rocks of the Latimojong Metamorphic Complex. The ores are approximately three meters thick, consisting of veins, stockwork, and breccias. The veins can be classified into three stages, namely, early, main, and late stages, and gold mineralization is related to the main stage. The mineral assemblage of the matrix of breccia and the veins are both composed of quartz, carbonate (mainly ankerite), and albite. High‐grade gold ores in the Salu Bulo prospect are accompanied by intense alteration, such as carbonatization, albitization, silicification, and sulfidation along the main stage veins and breccia. Alteration mineral assemblage includes ankerite ± calcite, quartz, albite, and pyrite along with minor sericite. Pyrite is the most abundant sulfide mineral that is spatially related to native gold and electrum (<2–42 μm in size). It is more abundant as dissemination in the altered host rocks than those in veins. This suggests that water–rock interaction played a role to precipitate pyrite and Au in the Salu Bulo prospect. The Au contents of intensely altered host rocks and ores have positive correlations with Ag, Ni, Mo, and Na. Fluid inclusions in the veins of the main stage and the matrix of breccia are mainly two‐phase liquid‐rich inclusions with minor two‐phase, vapor‐rich, and single‐phase liquid or vapor inclusions. CO2 and N2 gases are detected in the fluid inclusions by Laser Raman microspectrometry. Fluid boiling probably occurred when the fluid was trapped at approximately 120–190 m below the paleo water table. δ18OSMOW values of fluid, +5.8 and +7.6‰, calculated from δ18OSMOW of quartz from the main stage vein indicate oxygen isotopic exchange with wall rocks during deep circulation. δ34SCDT of pyrite narrowly ranges from ?2.0 to +3.4‰, suggesting a single source of sulfur. Gold mineralization in the Salu Bulo prospect occurred in an epithermal condition, after the metamorphism of the host rocks. It formed at a relatively shallow depth from fluids with low to moderate salinity (3.0–8.5 wt% NaCl equiv.). The temperature and pressure of ore formation range from 190 to 210°C and 1.2 to 1.9 MPa, respectively. 相似文献
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Geochemistry and petrology of selected coal samples from Sumatra, Kalimantan, Sulawesi, and Papua, Indonesia 总被引:3,自引:1,他引:3
Harvey E. Belkin Susan J. Tewalt James C. Hower J.D. Stucker J.M.K. O'Keefe 《International Journal of Coal Geology》2009,77(3-4):260-268
Indonesia has become the world's largest exporter of thermal coal and is a major supplier to the Asian coal market, particularly as the People's Republic of China is now (2007) and perhaps may remain a net importer of coal. Indonesia has had a long history of coal production, mainly in Sumatra and Kalimantan, but only in the last two decades have government and commercial forces resulted in a remarkable coal boom. A recent assessment of Indonesian coal-bed methane (CBM) potential has motivated active CBM exploration. Most of the coal is Paleogene and Neogene, low to moderate rank and has low ash yield and sulfur (generally < 10 and < 1 wt.%, respectively). Active tectonic and igneous activity has resulted in significant rank increase in some coal basins. Eight coal samples are described that represent the major export and/or resource potential of Sumatra, Kalimantan, Sulawesi, and Papua. Detailed geochemistry, including proximate and ultimate analysis, sulfur forms, and major, minor, and trace element determinations are presented. Organic petrology and vitrinite reflectance data reflect various precursor flora assemblages and rank variations, including sample composites from active igneous and tectonic areas. A comparison of Hazardous Air Pollutants (HAPs) elements abundance with world and US averages show that the Indonesian coals have low combustion pollution potential. 相似文献
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We present petrologic, geochemical and U–Pb sensitive high resolution ion microprobe (SHRIMP) data from previously undocumented dacite intrusions from the SE Arm of Sulawesi. The dacites occur in a strand of a major fault (the Kolaka Fault) that crosses the SE Arm of Sulawesi and northern Bone Bay. U–Pb SHRIMP dating shows the “Kolaka Dacite” yields zircon grains and overgrowths that range between ca. 4 and 7 Ma, indicating active magmatism in SE Sulawesi at this time. The youngest age population (4.4 ± 0.2 Ma) from this range is interpreted to be the maximum crystallization age for the dacite. The Kolaka Dacite is undeformed, and so potentially intruded during or after movement within a strand of the Kolaka Fault. The dacites may have otherwise been emplaced passively along existing foliation planes in the country rock schist. Additional U–Pb data were collected from inherited zircons, yielding ages between 8 Ma and 1854 Ma. We consider that these inherited zircons are xenocrysts, derived from either (1) a partially melted protolith and/or (2) xenocrysts assimilated during ascent of the magma. In either case, the inherited zircons record the age of the basement rocks beneath this part of SE Sulawesi. These inherited zircon cores show that the SE arm of Sulawesi is underlain by Proterozoic or younger material, validating earlier ideas that the crust here was derived from Gondwana. 相似文献
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M. M. Sari T. Inoue Y. Matsumoto K. Yokota 《International Journal of Environmental Science and Technology》2017,14(3):463-472
Poboya is a major small-scale gold-mining area in Central Sulawesi, Indonesia, that has been operating since 2009. About 200–500 kg of mercury is released each day as a result of gold-mining activities over a total area of 7000 ha. We examined mercury contamination by using two types of sample, namely food and human hair. Samples were obtained in Poboya and in the city of Palu, 11 km away. Samples of 22 foods were obtained from traditional markets in Poboya and Palu. Total mercury concentrations ranged from 0.003 to 0.31 µg/g in foods from Poboya and from 0.001 to 0.13 µg/g in those from Palu. The highest total mercury concentration in Poboya was found in unripe banana, which is frequently consumed by the local people. In Poboya, the weekly mercury intakes from foods were calculated at 180.3 µg/person from vegetables, 1.7 µg/person from processed foods, 51.4 µg/person from seafood, and 17.2 µg/person from meat and eggs. In Palu, the weekly mercury intakes were 2.9 µg/person from vegetables, 3.1 µg/person from processed foods, 60.8 µg/person from seafood, and 19 µg/person from meat and eggs. These findings delineated Poboya as an area polluted by mercury contamination. Intake of mercury-contaminated food influenced the results obtained in human hair. Hair concentrations of total mercury in Poboya ranged from 0.3 to 19.6 µg/g. 相似文献
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《Chemie der Erde / Geochemistry》2015,75(1):73-87
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. 相似文献
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Sadao Sasajima Susumu Nishimura Kimio Hirooka Yoichiro Otofuji Theo Van Leeuwen Fred Hehuwat 《Tectonophysics》1980,64(1-2)
Paleomagnetic studies in conjunction with fission-track dating on the western arc of Sulawesi yield important evidence bearing on the tectonic history of the area. During the Paleogene to Early Miocene time interval the paleomagnetic pole for southwestern Sulawesi was situated at 36.5°E 44.8°N. This pole position is significantly different from that in the time interval Middle Miocene to Recent, which is consistent with the north pole of the axial geocentric dipole. This fact suggests that subsequent to the Paleogene to Early Miocene period, possibly 19–13 m.y. B.P., a major tectonic event occurred which caused about 40 degrees of anticlockwise rotation of the area. It is suggested by the present work that the postulated collision followed by welding of eastern Sulawesi with western Sulawesi during the Pliocene (Katili, 1978) may be the tectonic event mentioned above. In addition, our data does not support the hypothesis that western Sulawesi has been derived from the dispersal of Gondwanaland. 相似文献