Latowu ultramafic block in the Southeastern Arm Sulawesi locally hosts elevated concentrations of Fe in addition to Ni. We investigated both host rock and mineralized samples' mineralogy and chemistry to find out mineralogical and chemical characteristics and interpret the iron mineralization process with beneficiation implications. The mineralogical nature of the samples was analyzed using optical microscopy and X-ray diffractometry (XRD) methods. The whole-rock and mineral chemistry analyses were performed using X-ray fluorescence (XRF) spectroscopy and electron probe microanalysis (EPMA) techniques. The analysis showed that the ultramafic rocks had been undergone a strong to complete serpentinization degree where lizardite appears to be the predominant mineral. Magnetite in this research comprised the principal iron-bearing mineral and functioned as discrete fine-grains and subhedral to anhedral crystals. Magnetite occurs as fragments in breccia, alteration rim in spinel, fine-grained disseminations, and micro veins. This research found that the whole-rock chemistry of an ultramafic breccia showed an elevated concentration in Fe2O3 with a grade of 28.44 wt%. Electron probe analysis of magnetite shows a wide variation of Fe ranging from 31.10 wt% to 67.20 wt%. It is interpreted that the formation of magnetite within ultramafic rocks is influenced by the hydration of primary minerals, mainly olivine. Iron is most likely released from olivine or pyroxene crystals during serpentinization, and the higher water content of serpentine promotes its mobility. It is suggested that the magnetic separation method can be potentially used to increase the Fe grade.
To investigate how canopy thickness and canopy saturation affect the amount and kinetic energy of throughfall, we conducted indoor experiments using a 9.8‐m‐tall transplanted Japanese cypress ( Chamaecyparis obtusa ) and a large‐scale rainfall simulator with spray nozzles at a height of 16 m. The amount of throughfall and raindrop sizes and velocities were measured at twenty‐four points under four canopy structures generated by staged branch pruning. Decreasing the canopy thickness resulted in increases of the initial throughfall amount, volume proportion of large throughfall drops, the number of drops with high velocities, and throughfall kinetic energy. Compared to a saturated canopy, a canopy undergoing wetting had lower throughfall amounts and volume proportion of large drops, but higher mean drop velocity. Canopy thickness affected throughfall generation by affecting the processes of canopy saturation and drop generation within the canopy.
In this study, we investigated the detailed processes of hydro-chemical changes in regional groundwater flow systems associated with large earthquakes using stable isotope ratios of dissolved trace elements. A Cl-B-Li ternary diagram, in combination with isotope systematics of δ11B and δ7Li was applied to the groundwater system of Kumamoto, Japan to understand the groundwater disturbances associated with the Kumamoto earthquakes in 2016. Our approach was based on the conservative chemical behavior of these three elements in the groundwater system, and their contrasting concentrations and isotopic signatures of B and Li among seawater, stagnant groundwater, and hydrothermal fluid. A small contribution from the influx of deep hydrothermal fluid into the aquifer was detected in one observation well near the epicenter of the 2016 Kumamoto earthquake, along the Futagawa fault. B-Li isotope systematics are useful isotopic proxies to precisely evaluate hydro-chemical changes in groundwater flow systems, and detect contribution of different sources associated with various tectonic disturbances on a finer scale.
Geochemistry of ultramafic rocks in the Latowu Area of North Kolaka Regency, Southeast Sulawesi has been investigated with the aim at deciphering of mineral characteristics, chemical composition and their potential use as carbon dioxide storage. Mineralogy was characterized by both scanning electron microscopy (SEM) and X-ray diffractometry (XRD); whereas bulk rock and mineral chemistry were analyzed by means of X-ray fluorescence spectrometry (XRF) and Electron probe microanalyzer (EPMA) respectively. Results of analyses show that lizardite is predominant serpentine mineral present, followed by chrysotile and trace amount of magnetite. Remnants of olivine and pyroxene were detected in some samples but they have been pseudomorphicly replaced by serpentine. Serpentinization of Latowu ultramafic rocks has led to decrease in grain size and density. Lizardite is characterized by fine grained particles with higher in iron. The higher Mg and Fe of the rocks indicate a suitability as feed materials for carbon dioxide sequestration. Mineral and chemical properties of ultramafic rocks have significant role in evaluating the feasibility of mineral carbonation.
