Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Akira Imai Last modified date:2019.06.24

Professor / Earth System Engineering / Department of Earth Resources Engineering / Faculty of Engineering


Papers
1. Benedict J. Williamson, Matthew Hodgkinson, Akira Imai, Ryohei Takahashi, Robin N. Armstrong, Richard J. Herrington, Testing the Plagioclase Discriminator on the GEOROC Database to Identify Porphyry-Fertile Magmatic Systems in Japan, Resource Geology, 10.1111/rge.12162, 68, 2, 138-143, 2018.04, Despite showing favorable geology, there are no known porphyry-type deposits in Japan. This, therefore, provides an ideal porphyry-“barren” case area on which to test the recently developed plagioclase-based discriminator for porphyry-“fertile” calc-alkaline systems. The discriminator was applied to plagioclase data for Japan in the online GEOROC database for convergent margin settings. Of the 3933 data points available, and considered reliable, 91% fall in the “barren” field, which compares with 73% for equivalent data worldwide. “Fertile” signatures in certain parts of Kyushu and central Honshu should be further investigated, as well as areas where there are magnetite-series magmatic systems with elevated whole-rock Sr/Y but for which there are currently little or no plagioclase data (SW-, N-central-, and NE-Honshu). Why the Japanese arcs appear to show anomalously poor potential for porphyry deposits compared with other arcs worldwide, including Western Luzon, is as yet unclear but possibly relates to tectonic factors or the nature of the magmatic source or because melt PH2O in many of the magmatic systems was too low, as suggested from low average excess Al in plagioclase..
2. Patchawee Nualkhao, Ryohei Takahashi, Akira Imai, Punya Charusiri, Petrochemistry of Granitoids Along the Loei Fold Belt, Northeastern Thailand, Resource Geology, 10.1111/rge.12176, 68, 4, 395-424, 2018.10, Petrochemical characteristics of Permo-Triassic granitoids from five regions (i) Mung Loei, (ii) Phu Thap Fah – Phu Thep, (iii) Phetchabun, (iv) Nakon Sawan – Lobburi, and (v) Rayong – Chantaburi along the Loei Fold Belt (LFB), northeastern Thailand were studied. The LFB is a north–south trending 800 km fold belt that hosts several gold and base-metal deposits. The granitoids consist of monzogranite, granodiorite, monzodiorite, tonalite, quartz-syenite, and quartz-rich granitoids. These are composed of quartz, plagioclase, and K-feldspar with mafic minerals such as hornblende and biotite. Accessory minerals, such as titanite, zircon, magnetite, ilmenite, apatite, garnet, rutile, and allanite are also present. Magnetic susceptibilities in the SI unit of granitoids vary from 6.5 × 10
−3
to 15.2 × 10
−3
in Muang Loei, from 0.1 × 10
−3
to 29.4 × 10
−3
in Phu Thap Fah – Phu Thep, from 2.7 × 10
−3
to 34.6 × 10
−3
in Petchabun, from 2.4 × 10
−3
to 14.1 × 10
−3
in Nakon Sawan – Lobburi, and from 0.03 × 10
−3
to 2.8 × 10
−3
in Rayong – Chantaburi. Concentration of major elements suggests that these intermediate to felsic plutonic rocks have calc-alkaline affinities. Concentration of REE of the granitoids normalized to chondrite displays moderately elevated light REE (LREE) and relatively flat heavy (HREE) patterns, with distinct depletion of Eu. Rb versus Y/Nb and Nb/Y tectonic discrimination diagrams illustrate that the granitoids from Muang Loei, Phu Thap Fah – Phu Thep, Phetchabun, Nakon Sawan – Lobburi, and Rayong – Chantaburi formed in continental volcanic-arc setting. New age data from radiometric K-Ar dating on K-feldspar from granodiorite in Loei and Nakhon Sawan areas yielded 171 ± 3 and 221 ± 5 Ma, respectively. K-Ar dating on hornblende separated from diorite in Lobburi yielded 219 ± 8 Ma. These ages suggest that magmatism of Muang Loei occurred in the Middle Jurassic, and Nakon Sawan – Lobburi occurred in Late Triassic. Both Nb versus Y and Rb versus (Y + Nb) diagrams and age data indicate that Nakon Sawan – Lobburi granitoids intruded in Late Triassic at Nong Bua, Nakon Sawan province and Khao Wong Phra Jun, Lobburi province in volcanic arc setting. Muang Loei granitoids at the Loei province formed later in Middle Jurassic also in volcanic arc setting. The negative δ
34
S
CDT
values of ore minerals from the skarn deposit suggest that the I-type magma has been influenced by light biogenic sulfur from local country rocks. The Au-Cu-Fe-Sb deposits correlate with the magnetite-series granitoids in Phetchabun, Nakon Sawan – Lobburi and Rayong – Chantaburi areas. Metallogeny of the Au and Cu-Au skarn deposits and the epithermal Au deposit is related to adakitic rocks of magnetite-series granitoids from Phetchabun and Nakon Sawan areas. All mineralizations along the LFB are generated in the volcanic arc related to the subduction of Paleo-Tethys. The total Al (
T
Al) content of biotite of granitoids increases in the following order: granitoids associated with Fe and Au deposit < with Cu deposit < barren granitoids. X
Mg
of biotite in granitoids in Muang Loei indicates the crystallization of biotite in magnetite-series granitoids under high oxygen fugacity conditions. On the other hand, low X
Mg
(<0.4) of biotite in magnetite-series granitoids in Phu Thap Fah – Phu Thep and Rayong – Chantaburi indicates a reduced environment and low oxygen fugacity, associated with Au skarn deposit (Phu Thap Fah) and Sb-Au deposit (Bo Thong), respectively. The magnetite-series granitoids at Phu Thap Fah having low magnetic susceptibilities and low X
Mg
of biotite were formed by reduction of initially oxidizing magnetite-series granitic magma by interaction with reducing sedimentary country rocks as suggested by negative δ
34
S
CDT
values..
3. Muhammad Tahir, Akira Imai, Ryohei Takahashi, Shujiro Yano, Ore Genesis and Geochemical Characteristics of Carbonate-Hosted Talc Deposits in Nangarhar Province, Afghanistan, Resource Geology, 10.1111/rge.12174, 68, 4, 352-372, 2018.10, Talc deposits in Nangarhar Province, are hosted by Paleoproterozoic carbonate rocks, metamorphosed to amphibolite facies in the east–west (E–W) trending Spinghar Fault Block. Many deposits in this province have potential economic importance. However, detailed geologic and petrological studies on ore genesis are still lacking. In this study, eight talc deposits and two prospects of the Spinghar Fault Block were investigated. Talc is mainly formed by alteration of the host dolomite marble, magnesite rocks, and tremolitite. Talc ore bodies occur parallel to subparallel to the beddings of the host carbonate rocks. Dolerite occur as dikes and sills and are mostly metamorphosed to amphibolite. Although the amphibolite occurs mostly parallel to subparallel to the beddings of the host carbonate rocks, and talc orebodies, it partly crosscuts the host rocks. Massive layers of tremolitite were observed with most of the talc ore bodies. Quartz veins occur along the gneissosity of gneiss all over the study area. SiO2 and MgO content in talc rocks from all deposits ranged from 49.1 to 65.1 wt% and from 26.1 to 32.9 wt%, respectively. CaO content in talc rocks and magnesite rocks are less than 1 wt%. ƩREE content in talc rocks ranged from 0.1 to 8.9 ppm. Chemical compositions of host carbonate rocks are close to the ideal composition. Concentrations of Al, Ta, Hf, Zr, Th, Cr, Ni, Co, and ƩREE in talc ores and host carbonate rocks were very low and inconsistent with mafic and ultramafic rocks protolith. Therefore, the metamorphosed sedimentary carbonate rocks were likely to be the protolith of the talc ores. The occurrence of parallel to subparallel quartz veins to the gneissosity of gneiss, as well as the presence of hydrous minerals in host carbonate rocks, suggested that hydrothermal fluids were most probably supplied through the gneiss..
4. Thomas Tindell, Koichiro Watanabe, Akira Imai, Ryohei Takahashi, Adrian J. Boyce, Kotaro Yonezu, Anders Schersten, Laurence Page, Takeyuki Ogata, The Kago low-sulfidation gold and silver deposit
A peripheral mineralisation to the Nansatsu high-sulfidation system, southern Kyushu, Japan, Ore Geology Reviews, 10.1016/j.oregeorev.2017.10.027, 102, 951-966, 2018.11, The Kago deposit is a small deposit located at the southern tip of the Satsuma Peninsula of Southern Kyushu, Japan. It lies proximal to the well-known Nansatsu-type mineralisation province dominated by high-sulfidation type epithermal deposits. The deposit was heavily mined in the 18 th Century, largely for its relatively higher gold compared to that of surrounding and regional deposits. The Kago deposit is a typical low-sulfidation deposit, characterised by adularia-quartz veins, composed of electrum, Ag-tetrahedrite, polybasite, chalcopyrite and pyrite. Based on mine records, the grade ranged from 4.1 to 13.3 g/t Au and 2.6–6.6 g/t Ag. Alteration grades from low to high temperature argillic into a propylitic zone at the extremes of the vein exposures. Carbonate is absent. Fluid inclusion microthermometry reveals a typical temperature range of 220–240 °C with salinity of 0.7–2.6 NaCl eq. wt%. Electrum from high-grade ore ranges from 66 to 69 wt% Au. 40Ar/39Ar age dating of adularia bearing colloform/crustiform and brecciated veins, suggests a mineralisation event from 4.23 to 4.0 Ma. δ18O of veined and silicified quartz ranges from +4.0 to +18.4‰. δ18OH2O of fluids in equilibrium with quartz, in the dominant range of measured fluid inclusion temperatures, ranges from −6.5‰ to −0.2‰. δ34S of pyrite has a narrow range from −1.8 to 2.7‰. The deposit lies at the northern extent of the classic Nansatsu high-sulfidation epithermal area, in which a number of silicified bodies punctuate the region in a roughly semi-circular shape. The Kago deposit lies within the principle mineralisation age range of the high-sulfidation deposits, which range from 5.5 to 3.7 Ma. The structural displacement of the Kago deposit from the Nansatsu mineralisation and the differing host rocks has greatly influenced alteration, ore and rock-water interaction of the ore depositing fluids. Here we seek to establish the relationship that this extended mineral province has between the differing styles of mineralisation..
5. Pearlyn C. Manalo, Akira Imai, Leo L. Subang, Mervin C. De los Santos, Kyoka Yanagi, Ryohei Takahashi, Nigel J.F. Blamey, Mineralization of the Northwest quartz-pyrite-gold veins
Implications for multiple mineralization events at lepanto, mankayan mineral district, Northern Luzon, Philippines, Economic Geology, 10.5382/econgeo.2018.4606, 113, 7, 1609-1626, 2018.11, The Northwest quartz-pyrite-gold veins are situated 500 m east of the Lepanto fault in Mankayan, Luzon, Philippines. Most vein mineralization is hosted by the Lepanto metavolcanic basement rocks at an elevation between 700 and 1,050 m. The earliest stage, stage 1, is characterized by sphalerite + chalcopyrite + pyrite ± magnetite veins cutting the host rocks that were altered to chlorite + illite + epidote. Precious metal deposition started in stage 2 as electrum, native gold, and gold-silver tellurides deposited with pyrite, quartz, and carbonate. Deposition of gold and silver tellurides continued in stage 3a with abundant pyrite and tennantite-tetrahedrite solid solution intergrown with chalcopyrite, bornite, and minor sphalerite. The stage 3a veins and host-rock alteration are characterized by abundant muscovite and quartz, while the stage 3b veins and alteration consist of quartz, pyrophyllite, alunite, and dickite. Enargite and luzonite are the dominant sulfide minerals in stage 4, which are either disseminated in silicified host rock or within wide quartz veins. Lesser amounts of quartz and abundant pyrite with inclusions of enargite and luzonite were precipitated in stage 5. Microthermometry on fluid inclusions in quartz of stages 2, 3a, and 4 indicates boiling of the hydrothermal fluids. Bulk gas analysis on fluid inclusions in quartz shows that the stage 2 and 4 fluids had components derived from basaltic and andesitic magma, respectively. Fluids that formed stage 4 quartz were more diluted by meteoric water than the fluids that formed the stage 2 veins. Radiometric 40Ar/39Ar dating on alunite separated from the stage 3b advanced argillic alteration zone yielded 2.2 ± 0.1 Ma. Sulfur isotope compositions of the Northwest quartz-pyrite-gold deposit reveal a bulk δ34S of approximately 5, similar to the calculated value for the adjacent Far Southeast porphyry deposit. Calculated oxygen and hydrogen isotope ratios of the fluids of the Northwest quartz-pyrite-gold deposit stage 3b dickites are similar to those that formed the illite alteration in the Far Southeast porphyry deposit but are higher in δ18O when compared to the fluids that formed the kandites in the Lepanto enargite deposit. The northward cooling of mineralizing fluids previously reported in the Lepanto enargite deposit is not consistent with the mineralogic indications in the Northwest quartz-pyrite-gold deposit. These data indicate multiple mineralization events in the Mankayan district, which is one of the largest mineral districts in the western Pacific..
6. Sofia Marah P. Frias, Akira Imai, Ryohei Takahashi, Ma Ines Rosana Balangue-Tarriela, Carlo Arcilla, Nigel Blamey, Geology, Alteration, and Mineralization of the Kay Tanda Epithermal Gold Deposit, Lobo, Batangas, Philippines, Resource Geology, 10.1111/rge.12205, 2019.01, The Kay Tanda epithermal Au deposit in Lobo, Batangas is one of the Au deposits situated in the Batangas Mineral District in southern Luzon, Philippines. This study aims to document the geological, alteration, and mineralization characteristics and to determine the age of the mineralization, the mechanism of ore deposition, and the hydrothermal fluid characteristics of the Kay Tanda deposit. The geology of Kay Tanda consists of (i) the Talahib Volcanic Sequence, a Middle Miocene dacitic to andesitic volcaniclastic sequence that served as the host rock of the mineralization; (ii) the Balibago Diorite Complex, a cogenetic intrusive complex intruding the Talahib Volcanic Sequence; (iii) the Calatagan Formation, a Late Miocene to Early Pliocene volcanosedimentary formation unconformably overlying the Talahib Volcanic Sequence; (iv) the Dacite Porphyry Intrusives, which intruded the older lithological units; and (v) the Balibago Andesite, a Pliocene postmineralization volcaniclastic unit. K-Ar dating on illite collected from the alteration haloes around quartz veins demonstrated that the age of mineralization is around 5.9 ± 0.2 to 5.5 ± 0.2 Ma (Late Miocene). Two main styles of mineralization are identified in Kay Tanda. The first style is an early-stage extensive epithermal mineralization characterized by stratabound Au-Ag-bearing quartz stockworks hosted at the shallower levels of the Talahib Volcanic Sequence. The second style is a late-stage base metal (Zn, Pb, and Cu) epithermal mineralization with local bonanza-grade Au mineralization hosted in veins and hydrothermal breccias that are intersected at deeper levels of the Talahib Volcanic Sequence and at the shallower levels of the Balibago Intrusive Complex. Paragenetic studies on the mineralization in Kay Tanda defined six stages of mineralization; the first two belong to the first mineralization style, while the last four belong to the second mineralization style. Stage 1 is composed of quartz ± pyrophyllite ± dickite/kaolinite ± diaspore alteration, which is cut by quartz veins. Stage 2 is composed of Au-Ag-bearing quartz stockworks associated with pervasive illite ± quartz ± smectite ± kaolinite alteration. Stage 3 is composed of carbonate veins with minor base metal sulfides. Stage 4 is composed of quartz ± adularia ± calcite veins and hydrothermal breccias, hosting the main base metal and bonanza-grade Au mineralization, and is associated with chlorite-illite-quartz alteration. Stage 5 is composed of epidote-carbonate veins associated with epidote-calcite-chlorite alteration. Stage 6 is composed of anhydrite-gypsum veins with minor base metal mineralization. The alteration assemblage of the deposit evolved from an acidic mineral assemblage caused by the condensation of magmatic volatiles from the Balibago Intrusive Complex into the groundwater to a slightly acidic mineral assemblage caused by the interaction of the host rocks and the circulating hydrothermal waters being heated up by the Dacite Porphyry Intrusives to a near-neutral pH toward the later parts of the mineralization. Fluid inclusion microthermometry indicates that the temperature of the system started to increase during Stage 1 (T = 220–250°C) and remained at high temperatures (T = 250–290°C) toward Stage 6 due to the continuous intrusion of Dacite Porphyry Intrusives at depth. Salinity slightly decreased toward the later stages due to the contribution of more meteoric waters into the hydrothermal system. Boiling is considered the main mechanism of ore deposition based on the occurrence of rhombic adularia, the heterogeneous trapping of fluid inclusions of variable liquid–vapor ratios, the distribution of homogenization temperatures, and the gas ratios obtained from the quantitative fluid inclusion gas analysis of quartz. Ore mineral assemblage and sulfur fugacity determined from the FeS content of sphalerite at temperatures estimated by fluid inclusion microthermometry indicate that the base metal mineralization at Kay Tanda evolved from a high sulfidation to an intermediate sulfidation condition..
7. Nyein N. Sint, Kotaro Yonezu, Thomas Tindell, May T. Aye, Htay Win, Akira Imai, Koichiro Watanabe, Geology and Skarn Cu–Bi–Au Mineralization at Shwe Min Bon Area, Kalaw Township, Southern Shan State, Myanmar, Resource Geology, 10.1111/rge.12187, 69, 1, 85-106, 2019.01, The Shwe Min Bon Cu–Au skarn deposit lies within one of the largest Au–Cu belts in Myanmar. The deposit is situated along the Shan scarp zone, which marks the boundary between the Myanmar central basin to the west and the Shan plateau to the east. The Shwe Min Bon deposit comprises skarn-type metasomatic alteration, and the Cu–Au mineralization occurs along the contact face between the Nwabangyi Dolomite and Shweminbon Formation and the Cretaceous dioritic rocks. The metasomatic process resulted in pro- and retrograde mineral assemblages in exoskarn. Hydrothermal activities in the Shwe Min Bon deposit are classified into prograde, retrograde stage I, and retrograde stage II. The prograde skarn is classified into a proximal garnet skarn with minor clinopyroxene and a distal wollastonite skarn. Chlorite, epidote, and tremolite–actinolite were formed during the retrograde stage I. Cu–Au mineralization mainly occurred in retrograde stage I, which was characterized by moderate temperatures (260–320 °C) and fluid with a moderate salinity (5.0–6.0% NaCl equiv.). Low temperature (180–200 °C) and low salinity (2.0–3.0% NaCl equiv.) were responsible for retrograde stage II. Au mineralization is mainly associated with chalcopyrite and tennantite in retrograde stage I and with tellurobismuthite in retrograde stage II..
8. Muhammad Zain Tuakia, Ryohei Takahashi, Akira Imai, Geological and Geochemical Characteristics of Gold Mineralization in the Salu Bulo Prospect, Sulawesi, Indonesia, Resource Geology, 10.1111/rge.12193, 69, 2, 176-192, 2019.04, 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. CO
2
and N
2
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. δ
18
O
SMOW
values of fluid, +5.8 and +7.6‰, calculated from δ
18
O
SMOW
of quartz from the main stage vein indicate oxygen isotopic exchange with wall rocks during deep circulation. δ
34
S
CDT
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..
9. Takahashi, Ryohei, Tagiri, Ryo, Blamey, Nigel J. F., Imai, Akira, Watanabe, Yasushi, Takeuchi, Akito, Characteristics and Behavior of Hydrothermal Fluids for Gold Mineralization at the Hishikari Deposits, Kyushu, Japan, RESOURCE GEOLOGY, 10.1111/rge.12136, 67, 3, 279-299, 2017.07.
10. Setiawan, I., Takahashi, R., Imai, A., Geology and geochemistry of granitoids associated with REE enrichment at Sibolga and its surroundings, North Sumatra, Indonesia, Resource Geology, 67, 3, 254-278, 2017.07.
11. Padrones, Jenielyn T., Imai, Akira, Takahashi, Ryohei, Geochemical Behavior of Rare Earth Elements in Weathered Granitic Rocks in Northern Palawan, Philippines, RESOURCE GEOLOGY, 10.1111/rge.12123, 67, 3, 231-253, 2017.07.
12. Padrones, Jenielyn T., Tani, Kenichiro, Tsutsumi, Yukiyasu, Imai, Akira, Imprints of Late Mesozoic tectono-magmatic events on Palawan Continental Block in northern Palawan, Philippines, JOURNAL OF ASIAN EARTH SCIENCES, 10.1016/j.jseaes.2017.01.027, 142, 56-76, 2017.07.
13. Tanaka, Kosuke, Okawa, Hirokazu, Hashimoto, Keiichiro, Takahashi, Ryohei;, Imai, Akira, Sugawara, Katsuyasu, Effect of NO2 in exhaust gas from an oxyfuel combustion system on the cap rock of a proposed CO2 injection site, APPLIED GEOCHEMISTRY, 10.1016/j.apgeochem.2016.04.007, 70, 17-26, 2016.07.
14. Maulana, A., Imai, A., Koichiro Watanabe, KOTARO YONEZU, Nakano, T., Page, L., Schersten, A., Boyce, A., van Leewuen, T., Petrochemistry of Late Cenozoic granitic rocks in Sulawesi, Indonesia: Origin and geodynamic setting, Journal of Asian Earth Sciences., 124, 102-125, 2016.10.
15. Saing, S., Takahashi, R., Imai, A., Fluid inclusion and stable isotopes study on the southeastern Martabe deposit: Purnama, Barani and Horas ore bodies, North Sumatra, Indonesia, Resource Geology, 66, 127-148, 2016.04.
16. Harijoko, Agung, Uruma, Ryusuke, Wibowo, Haryo Edi, Setijadji, Lucas Doni, Imai, Akira, KOTARO YONEZU, Koichiro Watanabe, Geochronology and magmatic evolution of the Dieng Volcanic Complex, Central Java, Indonesia and their relationships to geothermal resources, JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 10.1016/j.jvolgeores.2015.12.010, 310, 209-224, 2016.01.
17. Sanematsu, Kenzo, Kon, Yoshiaki, Imai, Akira, Influence of phosphate on mobility and adsorption of REEs during weathering of granites in Thailand, JOURNAL OF ASIAN EARTH SCIENCES, 10.1016/j.jseaes.2015.05.018, 111, 14-30, 2015.11.
18. Gabo, J.A.S., Dimalanta, C.B., Yumul, G.P., Jr., Faustino-Eslava, D.V., Imai, A., Geophysical signatures of a terrane boundary in Northwest Panay, Philippines: Results from the gravity, seismic refraction and electrical resistivity investigations, Terrestrial, Atmospheric, and Oceanic Science, 10.3319/TAO.2015.05.11.03(TC), 26, 6, 663-678, 2015.10.
19. Erdenebayar, Jamsran;, Ogata, Takeyuki, Imai, Akira, Sereenen, Jargalan, Textural and Chemical Evolution of Unidirectional Solidification Textures in Highly Differentiated Granitic Rocks at Kharaatyagaan, Central Mongolia, RESOURCE GEOLOGY, 10.1111/rge.12050, 64, 4, 283-300, 2014.10.
20. Takahashi, R., Shingo, Y., Imai, A., Koichiro Watanabe, Harijoko, A., Warmada, I W., Arifudin, I., Setijadji, L. D., Phuomephone, P., Characteristics of epithermal gold mineralization at the Trenggalek region, East Java, Indonesia, Resource Geology , 64, 149-166, 2014.04.
21. Maulana, Adi, Christy, Andrew G., Ellis, David J., Imai, Akira, Koichiro Watanabe, Geochemistry of eclogite- and blueschist-facies rocks from the Bantimala Complex, South Sulawesi, Indonesia: Protolith origin and tectonic setting, ISLAND ARC, 10.1111/iar.12037, 22, 4, 427-452, 2013.12.
22. Takahashi, Ryohei, Matsueda, Hiroharu, Okrugin, Victor M., Shikazono, Naotatsu, Ono, Shuji, Imai, Akira, Andreeva, Elena D., Koichiro Watanabe, Ore-forming Ages and Sulfur Isotope Study of Hydrothermal Deposits in Kamchatka, Russia, RESOURCE GEOLOGY, 10.1111/rge.12005, 63, 2, 210-223, 2013.07.
23. Dimalanta, Carla B., Yumul, Graciano P., Jr., Imai, Akira, Geodynamic evolution of the Baguio Mineral District: Unlocking the Cenozoic record from clastic rocks, JOURNAL OF ASIAN EARTH SCIENCES, 10.1016/j.jseaes.2012.09.026, 65, 118-130, 2013.03.
24. Imai, A., KOTARO YONEZU, Sanematsu, K., Ikuno, T., Koichiro Watanabe, Pisutha-Arnond, V., Nakapadungrat, S., Boosayasak, J., Rare earth elements in hydrothermally altered granitics rocks in the Ranong and Takua Pa tin field, southern Thailand, Resource Geology , 63, 84-98, 2013.01.
25. Sanematsu, Kenzo, Kon, Yoshiaki, Imai, Akira, Koichiro Watanabe, Watanabe, Yasushi, Geochemical and mineralogical characteristics of ion-adsorption type REE mineralization in Phuket, Thailand, MINERALIUM DEPOSITA, 10.1007/s00126-011-0380-5, 48, 4, 437-451, 2013.04.
26. Concepcion, R. A. B., Dimalanta, C. B., Yumul, G. P., Jr., Faustino-Eslava, D. V., Queano, K. L., Tamayo, R. A., Jr., Imai, A., Petrography, geochemistry, and tectonics of a rifted fragment of Mainland Asia: evidence from the Lasala Formation, Mindoro Island, Philippines, INTERNATIONAL JOURNAL OF EARTH SCIENCES, 10.1007/s00531-011-0643-5, 101, 1, 273-290, 2012.01.
27. Sagapoa, C. V., Imai, A., Ogata, T., KOTARO YONEZU, Koichiro Watanabe, Laterization process of peridotites in Siruka, Choiseul, Solomon Islands, Jour. Southeast Asian Applied Geology,, 3, 76-92, 2011.10.
28. Harijoko, A., Htun,T. M., Saputra, R., Warmada, I W., Setijadji, L. D., Imai, A., Koichiro Watanabe, Mercury and arsenic contamination from small scale gold mining activities at Selogiri area, Central Java, Indonesia, Jour. Southeast Asian Applied Geology, 2, 56-64, 2010.10.
29. Tohma, Yuki, Imai, Akira, Sanematsu, Kenzo, KOTARO YONEZU, Takahashi, Ryohei, Koyama, Masaaki;, Sekine, Ryota, Duncan, Robert, Koichiro Watanabe, Characteristics and Mineralization Age of the Fukusen No. 1 Vein, Hishikari Epithermal Gold Deposits, Southern Kyushu, Japan, RESOURCE GEOLOGY, 10.1111/j.1751-3928.2010.00140.x, 60, 4, 348-358, 2010.10.
30. Tanaka, T., Akira Imai, Egashira, S., Sakomoto, S., Yasunaga, K., Petrological and Geochemical Characteristics of Intrusive Rocks Related to Porphyry Copper Mineralization and the Implications for the Genesis of Deposits in the Namosi area, Viti Levu, Republic of the Fiji Islands, Resource Geology, 10.1111/j.1751-3928.2010.00113.x, 60, 1, 35-51, 2010.01.
31. Huizi PIAO. Kotaro YONEZU, Yohei KAWABATA, Koichiro WATANABE, Akira IMAI and Takushi YOKOYAMA, Recovery of Lithium from Geothermal Water by Manganese Oxide Adsorbent: Approach to the effective Utilization of Geothermal Resources, Proceedings of the 4th International Symposium of Novel Carbon Resource Sciences, 38-41, 2009.12.
32. Kotaro YONEZU, Sachihiro SAKOMOTO, Koichiro WATANABE, Akira IMAI and Takushi YOKOYAMA, Removal of Silicic Acid as Calcium Silicate and Uptake Behavior of Trace Elements, Proceedings of the 4th International Symposium of Novel Carbon Resource Sciences, 27-30, 2009.12.
33. Arifudin IDRUS, Akira IMAI, Andi MAKKAWARU, KAMRULLAH, I Wayan WARMADA, Irzal NUR and Rohaya LANGKOKE, Preliminary Study on Orogenic Deposit Type as a Source of Placer Gold at Bombana, Southeast Sulawesi, Indonesia, Proceedings of International Symposium on Earth Science and Technology, 569-572, 2009.12.
34. Arifudin IDRUS, Akira IMAI, Andi MAKKAWARU, KAMRULLAH, I Wayan WARMADA, Irzal NUR and Rohaya LANGKOKE, Preliminary Study on Orogenic Deposit Type as a Source of Placer Gold at Bombana, Southeast Sulawesi, Indonesia, Proceedings of International Symposium on Earth Science and Technology, 569-572, 2009.12.
35. Yusuke JUYANAGI and Akira IMAI, Fluid Inclusion Thermometry on Quartz Veins and Mineral Assemblages at Baturappe Area and Vicinity, Sulawesi Island, Indonesia, Proceedings of International Symposium on Earth Science and Technology, 409-412, 2009.12.
36. Cecep Y. SUNARIE, Mega F. ROSANA, Koichiro WATANABE and Akira IMAI, Characteristics of Epithermal Gold Mineralization in Tanggeung Area, Cianjur West Java, Indonesia, Proceedings of International Symposium on Earth Science and Technology, 403-408, 2009.12.
37. Yohei KAWABATA, Kotaro YONEZU, Koichiro WATANABE, Akira IMAI and Takushi YOKOYAMA, Removal of Boron by Magnesium Silicate from Synthetic Geothermal Water, Proceedings of International Symposium on Earth Science and Technology, 369-372, 2009.12.
38. Yuki SHINGO, Akira IMAI, Ryohei TAKAHASHI, Koichiro WATANABE, Agung HARIJOKO, I Wayan WARMADA, Arifudin IDRUS, and Phouvang PHOUMEPHONE, Outline of Epithermal Gold Mineralization at Trenggalek Prospects, East Java, Indonesia, Proceedings of International Symposium on Earth Science and Technology, 279-283, 2009.12.
39. Takahiro TANAKA, Akira IMAI and Koichiro WATANABE, Mineralogical Characterization of Ore Minerals at the Victoria Low Sulfidation Epithermal Gold Deposit, Northern Luzon, Philippines, Proceedings of International Symposium on Earth Science and Technology, 275-278, 2009.12.
40. Harrison GEDIKILE, Christopher V. SAGAPOA and Akira IMAI, Mineralization Style of the Charivunga Prospect, Gold Ridge Epithermal Au Deposit, Guadalcanal, Solomon Islands, Proceedings of International Symposium on Earth Science and Technology, 269-274, 2009.12.
41. Thomas TINDELL, Akira IMAI and Ryohei TAKAHASHI, Fluid Inclusion and Geochemical Behaviour of The Kasuga High-Sulphidation Gold Deposit and Basement Veins, Kagoshima, Japan, Proceedings of International Symposium on Earth Science and Technology, 263-268, 2009.12.
42. May T. AYE, Akira IMAI, Subagyo PRAMUMIJOYO, Lucas D. SETIJADJI, Arifudin IDRUS and Johan ARIF, Characteristics of Calc-silicate Unit Related with Skarn Mineralization at Batu Hijau Porphyry Copper-gold Deposit, Sumbawa Island, Indonesia, Proceedings of International Symposium on Earth Science and Technology, 259-262, 2009.12.
43. Kotaro YONEZU, Takushi YOKOYAMA, Akira IMAI and Koichiro WATANABE, Contents of Rare Earth Elements of Quartz Veins in the Hishikari Epithermal Gold Deposit: Preliminary Investigation by Laser Ablation ICP-MS, Proceedings of International Symposium on Earth Science and Technology, 125-128, 2009.12.
44. Ryohei TAKAHASHI, Koichiro WATANABE, Akira IMAI, and Yuuki KOMATA, Applications of Digital Database and Geographical Information System to Earth Resources in Southeast Asia, Proceedings of International Symposium on Earth Science and Technology, 27-32, 2009.12.
45. Ryohei TAKAHASHI, Koichiro WATANABE, Akira IMAI, and Yuuki KOMATA, Applications of Digital Database and Geographical Information System to Earth Resources in Southeast Asia, Proceedings of International Symposium on Earth Science and Technology, 27-32, 2009.12.
46. Akira IMAI, Takashi IKUNO, Kenzo SANEMATSU, Takafumi SUEOKA, Shingo ISHIDA, Koichiro WATANABE, Kong SITHA, Lucas Donny SETIJADJI and Jarupon BOOSAYASAK , Rare Earth Resource Potential in Weathered Crust of Granitic Rocks in Southeast Asian Tin Belt, Proceedings of Earth Science International Conference, 2009.08.
47. Phovang PHOUMEPHONE, Agung HARIJOKO, I Wayan WARMADA, Akira IMAI, Ryohei TAKAHASHI and Yuki SHINGO, Hydrothermal Alteration Associated with Epithermal Gold Mineralization at Dalangturu and Suruh Prospects in Trenggalek Regency, East Java Island, Indonesia, Proceedings of Earth Science International Conference, 2009.08.
48. Phovang PHOUMEPHONE, Agung HARIJOKO, I Wayan WARMADA, Akira IMAI, Ryohei TAKAHASHI and Yuki SHINGO, Hydrothermal Alteration Associated with Epithermal Gold Mineralization at Dalangturu and Suruh Prospects in Trenggalek Regency, East Java Island, Indonesia, Proceedings of Earth Science International Conference, 2009.08.
49. May T. AYE, Subagyo PRAMUMIJOYO, Lucas D. SETIJADJI, Arifudin IDRUS, Akira IMAI and Johan ARIF, Occurrence of Skarn Mineralization in Deep Drill Holes at Batu Hijau Porphyry Copper-gold Deposit, SUmbawa Island, Indonesia, Proceedings of Earth Science International Conference, 2009.08.
50. I Wayan WARMADA, Agung HARIJOKO, Akira IMAI and Koichiro WATANABE, Landslide Triggering Factor in a Hydrothermally-altered Area, Case Study: Kasihan District, Pacitan Regency, East Java, Proceedings of Earth Science International Conference, 2009.08.
51. Irzal NUR, Arifudin IDRUS, Subagyo PRAMUMIJOYO, Agung HARIJOKO, Yusuke JUYANAGI and Akira IMAI, Characteristics of Epithermal Quartz Veins at Baturappe Area, Gowa, South Sulawesi: Implication to Base Metal Exploration , Proceedings of the International Seminar on Geology of the Southern Mountains of Java, 179-186, 2009.08.
52. Phovane PHOUMEPHONE, Agung HARIJOKO, I Wayan WARMADA, Akira IMAI, Ryohei TAKAHASHI and Yuki SHINGO , Hydrothermal Alteration of Epithermal Gold Deposit at Dalangturu and Suruh Areas, Trenggalek Regency, East Java, Indonesia, Proceedings of the International Seminar on Geology of the Southern Mountains of Java, 169-178, 2009.08.
53. May Thwe AYE, Subagyo PRAMUMIJOYO, Lucas Donny SETIJADJI, Arifudin IDURS and Akira IMAI , Porphyry Related Skarn Mineralization with Calc-silicate Rocks in Batu Hijau Deposit, Sumbawa Island, East Indonesia, Proceedings of the 2nd Regional Conference Interdisciplinary Research on Natural Resources and Materials Engineering , 153-160, 2009.08.
54. Kong SITHA, Lucas Donny SETIJADJI, Kenzo SANEMATSU, Takashi IKUNO, Akira IMAI, Arius DIMARA and Koichiro WATANABE , REE in Monzo-granites in Bangka Island, Indonesia , Proceedings of the 2nd Regional Conference Interdisciplinary Research on Natural Resources and Materials Engineering , 145-152, 2009.08.
55. Lucas Donny SETIJADJI, I Wayan WARMADA, Akira IMAI and Kenzo SANEMATSU , Investigation on Rare Earth Elements Mineralization in Indonesia, Proceedings of the 2nd Regional Conference Interdisciplinary Research on Natural Resources and Materials Engineering , 53-58, 2009.08.
56. Akira IMAI, Takashi IKUNO, Kenzo SANEMATSU, Takafumi SUEOKA, Shingo ISHIDA, Koichiro WATANABE, Kong SITHA, Lucas Donny SETIJADJI and Jarupon BOOSAYASAK , Rare Earth Elements in Weathered Crusts of Granitic Rocks in Southeast Asian Tin Belt (Northern Thailand, Southern Thailand (Ranong-Takua Pa-Phuket) and Bangka Island, Indonesia), Proceedings of the 2nd Regional Conference Interdisciplinary Research on Natural Resources and Materials Engineering , 45-52, 2009.08.
57. Chompunoot WIRASERANEE, Kotaro YONEZU, Takushi YOKOYAMA, Akira IMAI, Koichiro WATANABE, Quanchai LEEPAWPANTH and Dawan WIWATTANADATE, Coprecipitation of Au(III) Complex Ions with Mn(II) Hydroxide as Gold Nanoparticles and Its Implication to Selective Recovery from Electronic Wastes , Proceeding of the 3rd International Workshop and Conference on Earth Resources Technology, 224-231, 2009.05.
58. Kotaro YONEZU, Takushi YOKOYAMA, Akira IMAI and Koichiro WATANABE, Characteristics of Rare Earth Elements in Quartz Veins of the Hishikari Epithermal Gold Deposit, Japan: Comparison between Bulk and Local Analyses, Proceeding of the 3rd International Workshop and Conference on Earth Resources Technology, 49-58, 2009.05.
59. Imai, A., Suerte, L. O. and Nishihara, S. , Origin of bornite pods in intrusive rocks at the Kingking porphyry Cu-Au deposit, southeastern Mindanao, Philippines, Resour. Geol., 59, 307-313., 2009.09.
60. Suerte, L. O., Imai, A. and Nishihara, S. , Geochemical characteristics of intrusive rocks, southeastern Mindanao, Philippines: Implication to metallogenesis of porphyry copper-gold deposits, Resour. Geol., 59, 244-262., 2009.09.
61. Imai, A. and Nagai, Y. , Fluid inclusion study and opaque mineral assemblage at the deep and shallow part of the Batu Hijau porphyry Cu-Au deposit, Sumbawa, Indonesia, Resour. Geol., , 59, 231-243., 2009.09.
62. Gabo, J. A. S., Dimalanta, C. B., Asio, M. G. S., Queano, K. L., Yumul, G. P., Jr. and Imai, A. , Geology and geochemistry of the clastic sequences from northwestern Panay (Philippines): Implications for provenance and geotectonic setting, Tectonophysics , 2009.10, [URL].
63. Chumpunoot Wiraseranee, Kotaro Yonezu, Takushi Yokoyama, Dawan Witwattanadate, Quanchai Leepawpanth, Akira Imai, Koichiro Watanabe, Recovery of Precious Metals from Computer Microprocessor by Coprecipitation with Manganese Hydroxide, Proceedings of International Symposium on Earth Science and Technology 2008, 557-564ページ, 2008.12.
64. Takayuki Tanaka, Akira Imai, Saori Egashira, Kentaro Yasunaga, Katsuhiko Maeda, Trace Element Composition of the Intrusive Rocks Related to Porphyry-type Copper Mineralization in Namosi District, Viti Levu, Republic of the Fiji Islands, Proceedings of International Symposium on Earth Science and Technology 2008, 549-556ページ, 2008.12.
65. Saori Egashira, Akira Imai, Takayuki Tanaka, Kentaro Masaki, Kentaro Yasunaga, Katsuhiko Maeda, Fluid Inclusion and Sulfur Isotope Study on Porphyry Copper Deposit at the Waivaka Corridor Area, Namosi District, Viti Levu, Republic of Fiji Islands, Proceedings of International Symposium on Earth Science and Technology 2008, 533-540ページ, 2008.12.
66. Kong Sitha, Lucas Donny Setijadji, Kenzo Sanematsu, Takashi Ikuno, Akira Imai, Arius Dimara, Koichiro Watanabe, Granitic Rocks of Bangka Island (Tin Island), Indonesia and Their Associated Mineralization: A Review and Potential of Unexplored Deposits, Proceedings of International Symposium on Earth Science and Technology 2008, 517-524ページ, 2008.12.
67. Ryohei Takahashi Koichiro Watanabe, Akira Imai, Hiroharu Matsueda, Victor M. Okurugin, Genesis and Formation of Ore Deposits in Kamchatka Peninsula, Far Eastern Russia, Proceedings of International Symposium on Earth Science and Technology 2008, 253-260ページ, 2008.12.
68. Kotaro Yonezu, Tomoaki Shibao, Takushi Yokoyama, Akira Imai, Koichiro Watanabe, Interaction Between Gold(I) Complexes and the Surface of Metal Sulfides (Fe2S and Ag2S), Proceedings of the 2nd International Workshop and Conference on Earth Resources Technology, 131-138ページ, 2008.04.
69. Saori Egashira, Akira Imai, Takayuki Tanaka, Kentaro Masaki, Kentaro Yasunaga, Katsuhiko Maeda, Study on Porphyry-type Copper Mineralization at the Waivaka Corridor Area, Namosi District, Viti Levu, Republic of the Fiji Islands, Proceedings of the 2nd International Workshop and Conference on Earth Resources Technology, 126-130ページ, 2008.04.
70. Takayuki Tanaka, Akira Imai, Saori Egashira, Sachihiro Sakomoto, Kentaro Yasunaga, Petrography and Petrochemical Characteristics of the Intrusive Rocks Related to Porphyry Copper Mineralization in Namosi District, Viti Levu, Republic of the Fiji Island, Proceedings of the 2nd International Workshop and Conference on Earth Resources Technology, 20-24ページ, 2008.04.
71. Akira Imai, Kenzo Sanematsu, Shingo Ishida, Koichiro Watanabe, Jarupong Boosayasak, Enrichment of Rare Earth Elements Associated with Granitic Rocks, Southern Thailand, Proceedings of the 2nd International Workshop and Conference on Earth Resources Technology, 9-13ページ, 2008.04.
72. A. Imai, K. Sanematsu, S. Ishida, K. Watanabe, J. Boosayasak, Rare Earth Elements in Weathered Crust in Sn-bearing Granitic Rocks in Southern Thailand, Proceedings of the International Symposia on Geoscience Resources and Environments of Asian Terranes, Special Issue of Bulletin of Earth Sciences of Thailand, 232-237ページ, 2008.11.
73. Saadi, N. M., Watanabe, K., Imai, A., Saibi, H. , Integrating potential field with remote sensing data for geological investigations in the Eljufra area of Libya, Earth, Planet, Space, 60巻, 539-547ページ, 2008.06.
74. Egashira Saori, Imai Akira, Tanaka Takayuki, Yasunaga Kentaro, Maeda Katsuhiko, Characteristics of the mineralization at the Wainaoulo-Southeast area, Namosi district, Viti Levu, Republic of the Fiji Islands, Proceedings of the International Workshop on Earth Resources Technology, 111-116, 2007.04.
75. Sakomoto Sachihiro, Yonezu Kotaro, Yokoyama Takushi, Okaue Yoshihiro, Imai Akira, Watanabe Koichiro, Adsorption behavior of gold(I)-thiosulfate complex anions onto the surface of manganese dioxide: approach the recovery of gold from geothermal waters, Proceedings of the International Workshop on Earth Resources Technology, 105-110, 2007.04.
76. Suerte Leilanie Osano, Nishihara Sho, Imai Akira, Watanabe Koichiro, Diorites and their roles in the mineralization of southeastern MIndanao, Philippines, Proceedings of the International Workshop on Earth Resources Technology, 81-84, 2007.04.
77. Yonezu Kotaro, Yokoyama Takushi, Motomura Yoshinobu, Imai Akira, Watanabe Koichiro, Study on the determination of trace elements in siliceous deposits formed from hydrothermal water by ICP-MS, Proceedings of the International Workshop on Earth Resources Technology, 77-80, 2007.04.
78. Setijadji Lucas Donny, Imai Akira, Itaya Tetsumaru, Watanabe Koichiro, Geology of metallic deposits in Java island (Indonesia) with a special reference to the island arc magmatism, Proceedings of the International Workshop on Earth Resources Technology, 33-36, 2007.04.
79. Uruma Ryusuke, Kohno Yasuaki, Watanabe Koichiro, Imai Akira, Itaya Tetsumaru, Setijadji Lucas Donny, Harijoko Agung, Migration of subduction degrees in central Java, Indonesia, 4th International Symposium on Gondwana to Asia and 2007 IAGR Annual Convention, no4, 174-175, 2007.11.
80. Tohma Yuki, Watanabe Koichiro, Imai Akira, Sanematsu Kenzo, The Seisen vines, Hishikari epithermal gold deposits, Japan: microscopic observation and fluid inclusions, 4th International Symposium on Gondwana to Asia and 2007 IAGR Annual Convention, no4, 156-157, 2007.11.
81. Tanaka Takayuki, Egashira Saori, Sakomoto Sachihiro, Imai Akira, Yasunaga Kentaro, Maeda Katsuhiko, Petrological study on the intrusive rocks related to porphyry-type copper mineralization in Namosi district, Viti Levu, Republic of the Fiji Islands, 4th International Symposium on Gondwana to Asia and 2007 IAGR Annual Convention, no4, 152-153, 2007.11.
82. Setijadji Lucas donny, Watanabe Koichiro, Imai Akira, Wibowo Haryo Edi, Barianto Didit Hadi, Itaya Tetsumaru, Island arc growth, metallogeny, and volcanic hazard risks of western Sunda arc: clarifying the significance of Gondwana crust, 4th International Symposium on Gondwana to Asia and 2007 IAGR Annual Convention, no4, 139-140, 2007.11.
83. Nagai Yuki, Imai Akira, Deposition model of copper sulfides and ore genesis of the Batu Hijau porphyry Cu-Au deposit, Sumbawa, Indonesia, 4th International Symposium on Gondwana to Asia and 2007 IAGR Annual Convention, no4, 110-111, 2007.11.
84. Fukuda Kazuchika, Imai Akira, Warmada I Wayan, Titisari Anastasia Dewi, Idrus Arifudin, Tun Myo Min, Furqon Reza Al, Saldi Rizza Nurarfi, Study on hydrothermal alteration in Kasihan area, East Java, Indonesia, 4th International Symposium on Gondwana to Asia and 2007 IAGR Annual Convention, no4, 38-39, 2007.11.
85. Egashira Saori, Masaki Kentaro, Imai Akira, Tanaka Takayuki, Yasunaga Kentaro, Maeda Katsuhiko, Porphyry-type copper mineralization at the Waivaka Corridor area, Namosi district, Viti Levu, Republic of the Fiji Islands, 4th International Symposium on Gondwana to Asia and 2007 IAGR Annual Convention, no4, 30-31, 2007.11.
86. Nagai Yuki, Imai Akira, Fluid inclusion study and opaque mineral assemblage in quartz veins at deep and shallow part of the Batu Hijau porphyry Cu-Au deposit, Sumbawa, Indonesia, Proceedings of 5the Internationas Symposium on Earth Science and Technology, 403-410, 2007.12.
87. Tohma Yuki, Imai Akira, Watanabe Koichiro, Sanematsu Kenzo, Characteristics of the Seisen veins, Hishikari gold deposits, Japan, Proceedings of 5the Internationas Symposium on Earth Science and Technology, 395-402, 2007.12.
88. Tanaka Takayuki, Imai Akira, Egashira Saori, Sakomoto Sachihiro, Yasunaga Kentaro, Petrography and chemical composition on the intrusive rocks related to porpghyry-type copper mineralization in Namosi district, Viti Levu, Republic of the Fiji Isalnds, Proceedings of 5the Internationas Symposium on Earth Science and Technology, 385-394, 2007.12.
89. Uruma Ryusuke, Kohno Yasuaki, Watanabe Koichiro, Imai Akira,Itaya Tetsumaru, Setijadji Lucas Donny, Harijoko Agung, Migration of subduction in central Java, Indonesia, Proceedings of 5the Internationas Symposium on Earth Science and Technology, 377-384, 2007.12.
90. Yonezu Kotaro, Okaue Yoshihiro, Yokoyama Takushi, Imai Akira, Watanabe Koichiro, Coprecipitation of Au(I) complex anions by aluminum hydroxide, Proceedings of 5the Internationas Symposium on Earth Science and Technology, 309-316, 2007.12.
91. Egashira Saori, Tanaka Takayuki, Masaki Kentaro, Imai Akira, Yasunaga Kentaro, Maeda Katsuhiko, Characteristics of intrusive rocks associated with copper mineralization at the Waivala Corridor area, Namosi district, Viti Levu, Republic of the Fiji Islands, Proceedings of 5the Internationas Symposium on Earth Science and Technology, 293-298, 2007.12.
92. Sakomoto Sachihiro, Yonezu Kotaro, Okaue Yoshihiro, Yokoyama Takushi, Imai Akira, Watanabe Koichiro, Uptake of boron and gold by calcium silicate hydrate (CSH): Application for effective utilization of geothermal energy at geothermal power plant and the recovery of are metals from geothermal water, Proceedings of 5the Internationas Symposium on Earth Science and Technology, 287-292, 2007.12.
93. Yonezu Kotaro, Yokoyama Takushi, Okaue Oyoshihiro, Imai Akira, Watanabe Koichiro, Concentration of gold(I) thiosullfate complex ions on the surface of alumina gel and their change in chemical state: Preliminary experiment in the elucidation of the formation mechanism of epithermal gold deposits, Resource Geology, 2007.12.
94. Imai, Akira, Ohbuchi Yukiko, Tanaka Takayuki, Morit Seita, Yasunaga Kentaro, Characteristics of porphyry Cu mineralization at Waisoi (Namosi district), Viti Levu, Fiji, Resource Goelogy, 57巻4号374-385頁, 2007.12.
95. Imai, A., Shinomiya, J., Soe, M. T., Setijadji, L. D., Watanabe, K. and Warmada, I W., Porphyry-type mineralization at Selogiri area, Wonogiri regency, central Java, Indonesia, Resource Geology, 57巻2号, 2007.06.
96. Suerte, L. O., Nishihara, S., Imai, A., Watabnabe, K., Yumul, G. P., Jr. and Maglambayan, V. B., The occurrences of ore minerals and fluid inclusion study on the Kingking porphyry copper-gold deposit, eastern Mindanao, Philippines, Resource Geology, 57巻2号, 2007.06.
97. Syafrizal, Imai, A. and Watanabe, K., Origin of ore-forming fluids responsible for gold mineralization of the Pongkor Au-Ag deposit, West Java, Indonesia: Evidences from mineralogic, fluid inclusion microthermometry and stable isotope study of the Ciurug-Cikoret vein, Resource Geology, 57巻2号, 2007.06.
98. Harijoko, A., Ohbuchi, Y., Motomura, Y., Imai, A. and Watanabe, K., Characteristics of the Cibaliung gold deposit: A Miocene low sulfidation type epithermal gold deposit at the western Java, Indonesia, Resource Geology, 57巻2号, 2007.06.
99. Imai, A. Geshi, N., Shimano, T. and Nakada, S., Implication of sulfur isotopic variation to 2000 eruptions of Miyake-jima volcano, Izu arc, Island Arc, 16, 83-92., 2007.03.
100. Setijadji, L. D., Kajino, S., Imai, A. and Watanabe, K., Cenozoic island arc magmatism in Java Island (Sunda Arc, Indonesia): Clues on relationships between geodynamics of volcanic centers and ore mineralization, Resource Geol., 56, 267-292., 2006.01.
101. Ishihara, S., Ohmoto, H., Anhaeusser, C. L., Imai, A., and. Robb, L. J., Discovery of the oldest oxic granitoids in the Kaapvaal Craton and its impolication for the redox evolution of early Earth, Geol. Soc. Amer. Memoir, 198, 67-80., 2006.01.
102. Aramaki, Y., Yokoyama, T., Okaue, Y., Imai, A. and Watanabe, K., A study on the formation of smectite in silica scale formed from geothermal water: The effect of magnesium, Resource Geol., 55, 281-284., 2005.01.
103. Sanematsu, K., Duncan, R., Imai, A. and Watanabe, K., Geochronological constraints using 40Ar/39Ar dating on the mineralization of the Hishikari epithermal gold deposit, Japan, Resource Geol., 55, 249-266., 2005.01.
104. Imai, A. and Ohno, S., Primary ore mineral assemblage and fluid inclusion study of the Batu Hijau porphyry Cu-Au deposit, Sumbawa, Indonesia, Resource Geol., 55, 239-248., 2005.01.
105. Syafrizal, Imai, A., Watanabe, K. and Motomura, Y., Mineralization at the Ciurug vein, Pongkor gold-silver deposit, Indonesia, Resource Geol., 55, 225-238., 2005.01.
106. Imai, A., Evolution of hydrothermal system at the Dizon porphyry Cu-Au deposit, Zambales, Philippines, Resource Geol., 55, 73-90., 2005.01.
107. Minami, T., Imai, A., Bunno, M., Kawakami, K. and Imazu, S., Using sulfur isotope to determine the sources of vermillion in ancient burial mounds in Japan, Geoarcheology, 20, 79-84., 2005.01.
108. Imai, A., Variation of Cl and SO3 contents of microphenocrystic apatite in intermediate to silicic igneous rocks of Cenozoic Japanese Island Arcs: Implications for porphyry Cu metallogenesis in the Western Pacific Island Arcs, Resource Geol.,, 54, 357-372., 2004.01.
109. Imai, A., Occurrence of halogen-rich phlogopite in Late Cenozoic volcanic rocks in the Japanese arcs, Resource Geol, 55, 225-238., 2004.01.
110. Copper exploration and its results of Waisoi deposits in Namosi area, Republic of Fiji Islands.
111. Measurement of sulfur isotope in the cinnabar ore of Guizhou and Funan Provinces in China.
112. Imai, A. and Ozawa, K., Tectonic implication of the hydrated garnet peridotites near Mt. Kinabalu, Sabah, East Malaysia, Jour. Southeast Asian Earth Sci., 6, 431-445., 1991.12.
113. Imai, A., Listanco, E. L. and Fujii, T., Petrologic and sulfur isotopic significance of highly oxidized and sulfur-rich magma of Mt. Pinatubo, Philippines., Geology, 21, 699-702., 1993.08.
114. Imai, A., Sulfide globules associated with a felsite intrusion in the Mount Kinabalu quartz monzonite, Sabah, East Malaysia: Sulfide melt immiscibility in a highly silicic melt., Econ. Geol., 89, 181-185, 1994.01.
115. Kajiwara, Y., Yamakita, S., Ishida, T., Ishiga, H. and Imai, A., Development of a largely anoxic stratified ocean and its temporary massive mixing at the Permian/Triassic boundary supported by the sulfur isotopic record., Palaeogeography, Palaeoclimatology, Palaeoecology,, 111, 367-379, 1994.08.
116. Imai, A., Listanco, E. L. and Fujii, T., Highly oxidized and sulfur-rich magma of Mount Pinatubo: Implication for metallogenesis of porphyry copper mineralization in the western Luzon arc., Newhall, C. G. and Punongbayan, R. S., eds., Fire and Mud: Eruptions and Lahars of Mount Pinatubo, Philippines, 865-874, 1996.12.
117. Ishizuka, O. and Imai, A., "Brown Ore" from the Fukasawa kuroko deposits, northeast Japan: Its characteristics and formation process., Resource Geology, 48, 53-73, 1998.06.
118. Maglambayan, V. B., Ishiyama,D., Mizuta, T., Imai, A. and Ishikawa, Y., Geology, alteration, and formation environment of the disseminated gold-silver telluride Bulawan deposit, Negros Occidental, Philippines., Resource Geology, 48, 87-104, 1998.06.
119. Imai, A., Shimazaki, H. and Nishizawa, T., Hydrogen isotope study of fluid inclusions in vein quartz, Hishikari gold deposits, Japan., Resource Geology, 48, 159-170, 1998.09.
120. Iizasa, K., Fiske, R. S., Ishizuka, O., Yuasa, M., Hashimoto, J., Ishibashi, J., Naka, J., Horii, Y., Fujiwara, Y., Imai, A. and Koyama, S., A Kuroko-type polymetallic sulfide deposit in a submarine silicic caldera., Science, 283, 975-977, 1999.02.
121. Imai, A., Matsueda, H., Yamada, R. and Masuta, K., Polymetallic mineralization at the Shin-Ohtoyo deposit, Harukayama district, Hokkaido, Japan., Resource Geology, 49, 75-88, 1999.06.
122. Spinifex texture of native sulfur: A cooling product of sulfur flow eruptions at Shiretoko-Iwozan volcano, Hokkaido, Japan.
123. Imai, A., Pyrite disease in luzonite from the Lepanto Cu-Au deposit, Mankayan, Philippines: Further example of disease texture and its origin., Resource Geology, 49, 163-168, 1999.09.
124. Imai, A., Genesis of the Mamut porphyry Cu deposit, Sabah, East Malaysia., Resource Geology, 50, 1-23, 2000.03.
125. Hamada, M. and Imai, A., Sulfur isotopic study of the Toyoha deposits, Hokkaido, Japan -Comparison between the earlier-stage and later-stage veins-., Resource Geology, 50, 113-122, 2000.06.
126. Imai, A., Mineral paragenesis, fluid inclusions and sulfur isotope systematics of the Lepanto Far Southeast porphyry Cu-Au deposit, Mankayan, Benguet, Philippines., Resource Geology, 50, 151-168, 2000.09.
127. Ishihara, S. and Imai, A., Geneses of high chlorine and silver-lead-zinc-mineralized granitoids in Tsushima, Japan., Resource Geology, 50, 169-178, 2000.09.
128. Imai, A. and Anan, S., Sulfur isotope study and re-examination of ore mineral assemblage of the Hol Kol and the Tul Mi Chung skarn-type copper-gold deposits of the Suan mining district, Korean Peninsula., Resource Geology, 50, 213-228, 2000.12.
129. Horizontal strain rate in relation to vein formation of the Hishikari gold deposits, southern Kyushu, Japan..
130. Imai, A., Generation and evolution of ore fluids for porphyry Cu-Au mineralization at the Santo Tomas II (Philex) deposit, Philippines., Resource Geology, 51, 71-96, 2001.06.
131. Imai, A., Ishizuka, O., Yamada, R. and Miyamoto, H., Further occurrence of brown ores in Kuroko-type deposits in Japan., Resource Geology, 51, 263-268, 2001.09.
132. Genesis of Na-series rock alteration widespread in the southeastern area of Hachimantai geothermal field: Water-rock interactions driven by descending groundwater and fossil seawater..
133. Imai, A., Metallogenesis of porphyry Cu-Au deposits of the western Luzon arc, Philippines: K-Ar ages, SO3 contents of microphenocrystic apatite and significance of intrusive rocks., Resource Geology, 52, 147-161, 2002.06.
134. Ishihara, S., Robb, L. J., Anhaeusser, C. L. and Imai, A., Granitoid series in terms of magnetic susceptibility: A case study from the Archean Barberton Region, South Africa., Gondwana Research, 5, 581-589, 2002.06.
135. Zeolite-bearing veins pervaded in the Shirahama Formation Upper Pliocene) of the Chikura Group at the southern end of Boso Peninsula, Chiba Prefecture.
136. Sajona, F. G., Izawa, E., Motomura, Y., Imai, A., Sakakibara, H. and Watanabe, K., Victoria carbonate-base metal gold deposit and its significance in the Mankayan mineral district, Luzon, Philippines., Resource Geology, 52, 315-328, 2002.12.
137. Imai, A. and Uto, T., Association of electrum and calcite and its significance to the genesis of the Hishikari gold deposits, southern Kyushu, Japan., Resource Geology, 52, 381-394, 2002.12.