Tetsuya YOKOYAMA
Professor

Department of Earth and Planetary Sciences,
Tokyo Institute of Technology
2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551, Japan
Phone: +81-3-5734-3539
Email: tetsuya.yoko(at)eps.sci.titech.ac.jp

RESEARCH INTERESTS AND EXPERIENCES
Cosmochemistry

2001-present

Nucleosynthetic isotope anomalies in meteorites and their components for heavy elements
including Cr, Sr, Mo, Te, Nd, Sm, Er, Yb, and Os.

Radiometric dating of planetary materials using 87Rb-87Sr, 147,146Sm-143,142Nd, 187Re-187Os, and235,238

U-207,206Pb systematics.



The evolution of U-Pb isotope systematics in Martian mantle and crust.



Behavior of highly siderophile elements during core formation.

Geochemical analyses of small amounts (<100 mg) of extraterrestrial samples for the analyticalcompetition related to the sample- return mission.

Geochemistry

1993-present

Uranium-series disequilibrium in volcanic rock samples from island arc and intra-plate settings.

Timescale of magma processes beneath active volcanoes.

Rare gas and carbon isotope compositions in hot spring gases.

Analytical Chemistry

1992-present

Development of high precision isotope analyses for trans-iron elements (e.g., Sr, Mo, Te, Nd,
Sm, Er, Yb, Os, Pb, Ra, Th, and U) with thermal ionization mass spectrometry (TIMS).

Determination of trace element abundances in terrestrial and extraterrestrial materials withinductively coupled plasma mass spectrometry (ICP-MS).



Determination of trace element abundances in ancient coins with instrumental neutron
activation analysis (INAA).



Determination of major element abundances in terrestrial materials and ancient coins with
X-ray fluorescence spectroscopy (XRF).

Development of chemical separation techniques with ion-exchange chromatography fortrans-iron elements from terrestrial and extraterrestrial materials.



Development of new sample digestion techniques for terrestrial and extraterrestrial materials.

DEGREES
Ph.D. in Earth and Planetary Science

March 1999

Graduate School of Natural Science and Technology, Okayama University, Japan
M.Sc. in Chemistry

March 1995

Graduate School of Science, Department of Chemistry, University of Tokyo, Japan
B.Sc. in Chemistry

March 1993

School of Science, Department of Chemistry, University of Tokyo, JapanEMPLOYMENTProfessor

2017-present

Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Japan
Associate Professor

2007-2017

Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Japan
Research Associate

2005-2007

Department of Geology, University of Maryland, USA
COE-21 Postdoctoral Fellowship2003-2005

Institute for the Study of the Earth's Interior, Okayama University, Japan
JSPS Research Fellowship for Young Scientists (PD)

2001-2003

Institute for the Study of the Earth's Interior, Okayama University, Japan
COE Researcher

1998-2001

Institute for the Study of the Earth's Interior, Okayama University, Japan
Technical Assistant

1998-1998

Institute for the Study of the Earth's Interior, Okayama University, Japan

HONORS
Educational prize for young faculty in school of Science

2015

Tokyo Institute of Technology
Award for young scientist in school of Science

2009Tokyo Institute of Technology
The Geochemical Society of Japan Award for Young Researcher
The Geochemical Society of Japan

2004

PUBLICATION LIST (Peer-reviewed papers)
1.

2.
3.
4.
5.
6.

7.

8.
9.
10.
11.
12.
13.
14.
15.

Nakamura, H., Sano, A., Kagami, S., Yokoyama, T., Ishikawa, A., Komiya, T., Iwamori, H.
Compositional heterogeneity of Archean mantle estimated from Sr and Nd isotopic systematics
of basaltic rocks from North Pole, Australia, and the Isua Supracrustal Belt, Greenland.
Precambrian ResearchTaniuchi, H., Kuritani, T., Yokoyama, T., Nakamura, E., Nakagawa, M. A new concept for
the genesis of felsic magma: the separation of slab-derived supercritical liquid. Sci. Rep. 10,
1-9, 2020.
Kuritani, T., Nakagawa, M., Nishimoto, J., Yokoyama, T., Miyamoto, T. Magma plumbing
system for Millennium Eruption at Changbaishan volcano, China: Constraints from whole-rock
U-Th disequilibrium. Lithos 366-367, 105564, 2020.
Yokoyama, T., Fukai, R., Nakahara, M. Separation of heavy lanthanoids by flash column
chromatography for precise determination of Er and Yb isotope compositions in rock samples.
Geostandard. Geoanal. Res. 44, 265-285, 2020. doi: 10.1111/ggr.12317
Moriwaki, R., Usui, T., Tobita., M., Yokoyama, T. Geochemically heterogeneous Martian
mantle inferred from Pb isotope systematics of depleted shergottites. Geochimica et
Cosmochimica Acta 274, 157-171, 2020. doi: 10.1016/j.gca.2020.01.014
Okabayashi, S., Yokoyama, T., Hirata, T., Terakado, K., Galimov, E.M. Iron isotopic signature
in Luna 16, 20, 24 soils: Effect of space weathering and Fe isotopic composition of very
low-Ti basalt. Geochimica et Cosmochimica Acta 269, 1-14, 2020. doi:
10.1016/j.gca.2019.10.020
Asaah, A.N.E., Yokoyama, T., Aka, F.T., Kuritani,T., Iwamori, H., Usui, T., Gountie, M.D.,
Tamen, J., Hassegawa, T., Fozing, T.E.M., Nche, A.L. Major/trace elements and Sr–Nd–Pb
isotope systematics of lavas from Lakes Barombi Mbo and Barombi Koto in the Kumba
graben, Cameroon Volcanic Line: Constraints on petrogenesis. Journal of African Earth
Science. 161, 103675 (14 pp), 2020. doi: 10.1016/j.jafrearsci.2019.103675
Yokoyama, T., Nagai, Y., Fukai, R., Hirata, T. Origin and evolution of distinct Mo isotopic
variabilities within carbonaceous and non-carbonaceous reservoirs. Astrophys. J. 883, 62(23pp), 2019. DOI: 10.3847/1538-4357/ab39e7
Kagami, S., Haba, M.K., Yokoyama, T., Usui, T., Greenwood, R.C. Geochemistry and Sm-Nd
chronology of a Stannern trend eucrite, Northwest Africa 7188. Meteoritics & Planetary
Science, 54, 2710-2728, 2019. DOI: 10.1111/maps.13382
Fukai, R., Yokoyama, T. Assessment of the secondary instrumental fractionation in TIMS:
Implication for high precision Nd isotope analysis of geological samples. Geochem. J. 53,
333-337, 2019. doi: 10.2343/geochemj.2.0569
Nakanishi, N., Yokoyama, T., Ishikawa, A. Refinement of the micro-distillation technique forisotopic analysis with pg-level Os in geologic samples. Geostandard. Geoanal. Res. 43,
231-243, 2019. DOI: 10.1111/ggr.12262
Fukai, R., Yokoyama, T. Nucleosynthetic Sr–Nd isotope correlation in chondrites: Evidence fornebular thermal processing and dust transportation in the early Solar System. Astrophys. J. 879,
79 (12pp), 2019. doi: 10.3847/1538-4357/ab0e0d
Okabayashi, S., Yokoyama, T., Nakanishi, N., Iwamori, H. Fractionation of highly siderophileelements in metal grains from unequilibrated ordinary chondrites: Implication for the origin ofchondritic metals. Geochimica et Cosmochimica Acta, 244, 197-215, 2019.
Kuritani, T., Yamaguchi, A., Fukumitsu, S., Nakagawa, M., Matsumoto, A., Yokoyama, T.
Magma plumbing system at Izu-Oshima volcano, Japan: constraints from petrological,
geochemical and principal component analyses. Frontiers in Earth Science, 6, 178, 2018.
Aka, F.T., Hasegawa, T., Nche, L.A., Asaah, A.N.E., Mimba, M.E., Teitchou, I., Ngwa, C.,
Miyabuchi, Y., Kobayashi, T., Kankeu, B., Yokoyama, T., Tanyileke, G., Ohba, T., Hell, J.V.,
Kusakabe, M. Upper Triassic mafic dykes of Lake Nyos, Cameroon (West Africa) I: K-Ar age
evidence within the context of Cameroon Line magmatism, and the tectonic significance.

16.
17.
18.
19.
20.

21.

22.
23.
24.
25.
26.
27.
28.
29.

30.
31.

Journal of African Earth Sciences, 141, 49-59, 2018.
Nakanishi, N., Yokoyama, T., Okabayashi, S., Usui, T., Iwamori, H. Re–Os isotope
systematics and fractionation of siderophile elements in metal phases from CBa chondrites.
Meteoritics & Planetary Science 53, 1051-1065, 2018.
Myojo, K., Yokoyama, T., Okabayashi, S., Wakaki, S., Sugiura, N., Iwamori, H. The origin
and evolution of nucleosynthetic Sr isotope variability in calcium and aluminum-richrefractory inclusions. The Astrophysical Journal 853, 48 (9pp), 2018.
Moriwaki, R., Usui, T., Simon, J.I., Jones, J.H., Yokoyama, T., Tobita, M. Lead isotope
systematics of the olivine-phyric shergottite Tissint: New geochemical signatures of the
shergottite source mantle. Earth and Planetary Science Letters 474, 180-189, 2017.
Fukai, R., Yokoyama, T. Neodymium isotope heterogeneity for ordinary and carbonaceouschondrites and the origin of non-chondritic 142Nd composition of the Earth. Earth andPlanetary Science Letters 474, 206-214, 2017.
Kuritani, T., Sakuyama, T., Kamada, N., Yokoyama, T., Nakagawa, M. Fluid-fluxed melting ofmantle vs. decompression melting of hydrous mantle plume as the cause of intraplatemagmatism over a stagnant slab: implications from Fukue Volcano Group, SW Japan. Lithos,282-283, 98-110, 2017.
Fukami, Y., Tobita, M., Yokoyama, T., Moriwaki, R., Usui, T. Precise isotope analysis for
sub-nanogram lead by total evaporation thermal ionization mass spectrometry (TE-TIMS)
coupled with 204Pb–207Pb double spike method. Journal of Analytical Atomic Spectrometry. 32,
848-857, 2017.
Tsujimoto, T., Yokoyama, T., Bekki, K. Chemical evolution of 244Pu in the solar vicinity and its
implication for the properties of r-process production. Astrophys. J. Lett., 835, L3 (5pp), 2017.
Fukai, R., Yokoyama, T., Kagami, S. Evaluation of the long-term fluctuation in isotope ratios
measured by TIMS with static, dynamic, and multistatic methods: A case study for Nd isotope
measurements. International Journal of Mass Spectrometry, 414, 1-7, 2017.
Yokoyama, T., Nagai, Y., Hinohara, Y., Mori, T. Investigating the influence of nonspectral
matrix effects for determination of 22 trace elements in rock samples by ICP-QMS.
Geostandards and Geoanalytical Research, DOI: 10.1111/ggr.12147, 41, 221-242, 2017.
Tobita, M., Usui, T., Yokoyama, T. New Constraints on the Shergottite Petrogenesis byAnalysis of Pb Isotopic Compositional Space: Implication for Mantle Heterogeneity andCrustal Assimilation on Mars. Geochemical Journal, 51, 81-94, 2017.
Fukami, Y., Yokoyama, T. Tellurium isotope compositions in acid leach fractions ofcarbonaceous chondrites. Geochemical Journal, 51, 17-29, 2017.
Kuritani, T., Tanaka, M., Yokoyama, T., Nakagawa, M., Matsumoto, A. Intensive hydration of
the wedge mantle at the Kuril arc–NE Japan arc junction: implications from mafic lavas from
Usu Volcano, northern Japan. Journal of Petrology, 57, 1223-1240, 2016.
Kagami, S., Yokoyama, T. Chemical separation of Nd from geological samples forchronological studies using 146Sm–142Nd and 147Sm–143Nd systematics. Analytica Chimica Acta,
937, 151-159, 2016.
Yokoyama, T., Walker, R.J. Nucleosynthetic isotope variation of siderophile and chalcophileelements in the Solar System. Reviews in Mineralogy and Geochemistry. vol. 81. in Highly
siderophile and strongly chalcophile elements in high temperature geochemistry andcosmochemistry, 81, 107-160, 2016.
Nagai, Y., Yokoyama, T. Molybdenum isotope analysis by negative thermal ionization mass
spectrometry (N-TIMS): Effects of oxygen isotopic compositions. Journal of Analytical
Atomic Spectrometry., 31, 948-960, 2016.
Asaah, A.N.E., Yokoyama, T., Aka, F.T., Usui, T., Kuritani,T., Wirmvem, M.J., Iwamori, H.,
Asaah, F.N.J., Ohba, T., Tanyileke, G., Hell, J.V. A. Geochemistry of Lavas from Maar-bearing

32.
33.
34.

35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.

Volcanoes in the Oku Volcanic Group of the Cameroon Volcanic Line. Chemical Geology, 406,
55-69, 2015.
Yokoyama, T., Fukami, Y., Okui, W., Ito, N., Yamazaki, H. Nucleosynthetic strontium isotope
anomalies in carbonaceous chondrites. Earth Planet. Sci. Lett., 416, 46-55, 2015.
Tanaka, R., Yokoyama, T., Kitagawa, H., Tesfaye, D.B., Nakamura, E. Evaluation of theapplicability of acid leaching for the 238U-230Th internal isochron method. Chemical Geology,
396, 255-264, 2015.
Asaah, A.N.E., Yokoyama, T., Aka, F.T., Usui, T., Wirmvem, M.J., Tchamabe, B.C., Ohba, T.,
Tanyileke, G., Hell, J.V. A comparative review of petrogenetic processes beneath the
Cameroon Volcanic Line: Geochemical constraints. Geoscience Frontiers, 6, 557-570, 2015,
DOI: 10.1016/j.gsf.2014.04.012,
Yamazaki, E., Nakai, S, Sahoo, Y.V., Yokoyama, T., Mifune, H., Saito, T., Chen, J., Takagi, N.,
Hokanishi, N., Yasuda, A. Feasibility studies of Sn isotope composition for provenancing
ancient bronzes. Journal of Archaeological Science, 52, 458-467, 2014.
Nakamura, H., Fujita, Y., Nakai, S., Yokoyama, T., Iwamori, H. Rare earth elements andSr-Nd-Pb isotopic analyses of the Arima hot spring waters, Southwest Japan: Implications fororigin of the Arima-type brine. J. Geol. Geosci., 3, 1000161, 2014.
Nagai, Y., Yokoyama, T. Chemical Separation of Mo and W from Terrestrial andExtraterrestrial Samples via Anion Exchange Chromatography. Anal. Chem., 86, 4856-4863,
2014. DOI: 10.1021/ac404223t,
Fukami, Y., Yokoyama, T. Precise tellurium isotope analysis by negative thermal ionization
mass spectrometry (N-TIMS) J. Anal. St. Spectrom. 29, 520-528, 2014.
Uno M., Iwamori, H., Nakamura, H., Yokoyama, T., Ishikawa, T., Tanimizu, M. Elemental
transport upon hydration of basic schists during regional metamorphism: geochemical
evidence from the Sanbagawa metamorphic belt, Japan. Geochem. J., 48, 29-49, 2014.
Feineman, M., Moriguti, T., Yokoyama, T., Terui, S., Nakamura, E. Sediment-enriched adakitic
magmas from the Daisen volcanic field, Southwest Japan. Geochem. Geophys. Geosystem. 14,
3009-3031, 2013.
Yamazaki, E., Nakai, S., Yokoyama, T., Ishihara, S., Tang, H. Tin Isotope Analysis of
Cassiterites from Southeastern and Eastern Asia. Geochem. J. 47, 21-35, 2013.
Maruyama, S., Ikoma, M., Genda, H. Hirose, K., Yokoyama, T., Santosh, M. The naked planet
Earth: Most essential pre-requisite for the origin and evolution of life. Geoscience Frontiers., 4,141-165, 2013.
Aka, F.T., Yokoyama, T. Current status of the debate about the age of Lake Nyos dam(Cameroon) and its bearing on potential flood hazards. Natural Hazards, 65, 875-885, 2013.
Moynier, F., Day, J.M.D., Okui, W., Yokoyama, T., Bouvier, A., Walker, R.J., Podosek, F.A.
Planetary-scale strontium isotopic heterogeneity and the age of volatile depletion of early solar
system materials. Astrophys. J. 758, 45 (7pp), 2012.
Okabayashi, S., Yokoyama, T.D., Kon, Y., Yamamoto, S., Yokoyama, T., Hirata, T. Evaluationof Laser Ablation in Liquid (LAL) technique as a new sampling technique for elemental andisotopic analysis using ICP-mass spectrometry. J. Anal. Atom. Spectrom., 26, 1393-1400, 2011.
Yokoyama, T., Alexander, C.M.O'D., Walker, R.J. Assessment of nebular versus parent bodyprocesses on presolar components present in chondrites: Evidence from osmium isotopes.
Earth Planet. Sci. Lett., 305, 115-123, 2011.
Kuritani, T., Yokoyama, T., Kitagawa, H., Kobayashi, K., Nakamura, E., Geochemical
evolution of historical lavas from Askja Volcano, Iceland: Implications for mechanisms andtimescales of magmatic differentiation. Geochim. Cosmochim. Acta, 75, 570-587, 2011.
Chekol, T.A., Kobayashi, K., Yokoyama, T., Sakaguchi, C., Nakamura, E. Timescales ofmagma differentiation from basalt to andesite beneath Hekla Volcano, Iceland: Constraints

49.
50.
51.
52.
53.

54.
55.
56.
57.

58.
59.
60.
61.
62.

63.
64.

from U-series disequilibria in lavas from the last quarter-millennium flows. Geochim.
Cosmochim. Acta, 75, 256-283, 2011
Yokoyama, T., Alexander, C.M.O'D., Walker, R.J. Osmium isotope anomalies in chondrites:
Results for acid residues and related leachates. Earth Planet. Sci. Lett., 291 48-59, 2010.
Qin, L., Alexander, C.M.O'D., Carlson, R.W., Horan, M.F., Yokoyama, T. Contributors tochromium isotope variation of meteorites. Geochim. Cosmochim Acta, 74, 1122-1145, 2010.
Yokoyama, T., Walker, D., Walker, R.J. Low osmium solubility in silicate at high pressuresand temperatures. Earth Planet. Sci. Lett., 279, 165-173, 2009.
Kuritani T., Yokoyama, T., Nakamura, E. Generation of rear-arc magmas induced by influxof slab-derived supercritical liquids: Implications from alkali basalt lavas from Rishiri volcano,
Kurile Arc. J. Petrol., 49, 1319-1342, 2008.
Aka, F.T., Yokoyama, T., Kusakabe, M. Nakamura, E., Tanyileke, G., Ateba, B., Ngako, V.,
Nnange, J., Hell, J. U-series dating of Lake Nyos maar basalts, Cameroon (West Africa):
Implications for potential hazards on the Lake Nyos dam. J. Volcanol. Geotherm. Res., 176,
212-224, 2008.
Yokoyama, T., Vinai, R.K., Alexander, C.M.O'D., Lewis, R.S., Carlson, R.W., Shirey, S.B.,
Thiemens, M.H., Walker, R.J. Osmium isotope evidence for uniform distribution of s- andr-process components in the early solar system. Earth Planet. Sci. Lett., 259, 567-580, 2007.
Kuritani T., Yokoyama, T., Nakamura, E. Rates of thermal and chemical evolution of acooling magma chamber: a chronological and theoretical study on basaltic and andesitic lavas
from Rishiri Volcano, Japan. J. Petrol., 48, 1295-1319, 2007.
Yokoyama, T., Aka, F.T., Kusakabe, M., Nakamura, E. Plume-lithosphere interaction beneath
Mt. Cameroon volcano, West Africa: Constraints from 238U-230Th-226Ra and Sr-Nd-Pb isotope
systematics. Geochim. Cosmochim. Acta, 71, 1835-1854, 2007.
Yokoyama, T., Kuritani, T., Kobayashi, K., Nakamura, E. Geochemical evolution of ashallow magma plumbing system during the last 500 years, Miyakejima volcano, Japan:
Constraints from 238U-230Th-226Ra systematics. Geochim. Cosmochim. Acta, 70, 2885-2901,
2006.
Kuritani T., Usui, T., Yokoyama, T., Nakamura E. Accurate isotopic and concentration
analyses of small amounts of Pb using isotope dilution coupled with the double spike
technique. Geostandards and Geoanalytical Res., 30, 209-220, 2006.
Yokoyama, T., Nakamura, E. Precise analysis of the 228Ra/226Ra isotope ratio for short-lived
U-series disequilibria in natural samples by total evaporation thermal ionization mass
spectrometry (TE-TIMS). J. Anal. Atom. Spectrom., 19, 717-727, 2004.
Yokoyama, T., Kobayashi, K., Kuritani, T., Nakamura, E. Mantle metasomatism and rapid
ascent of slab components beneath island arcs: Evidence from 238U-230Th-226Ra disequilibria of
Miyakejima volcano, Izu arc, Japan. J. Geophys. Res. doi:10.1029/2002JB002103, 2003.
Kuritani, T., Yokoyama, T., Kobayashi, K., Nakamura, E. Shift and rotation of composition
trends by magma mixing: 1983 eruption at Miyake-jima volcano, Japan. J. Petrol., 44,
1895-1916, 2003.
Nakamura, E., Makishima, A., Moriguti, T., Kobayashi, K., Sakaguchi, C., Yokoyama, T.,
Tanaka, R., Kuritani, T., Takei, H. Comprehensive geochemical analyses of small amounts(<100mg) of extraterrestrial samples for the analytical competition related to the samplereturn mission, MUSES-C. Inst. Space Astronaut. Sci. Rep. SP. No.16, 49-101, 2003.
Yokoyama, T., Nakamura, E., Kobayashi, K., Kuritani, T. Timing and trigger of arc volcanism
controlled by fluid flushing from subducting slab. Proc. Japan Acad., 78, Ser. B, 190-195,
2002.
Yokoyama, T., Nakamura, E. Precise determination of ferrous iron in silicate rocks. Geochim.
Cosmochim. Acta, 66, 1085-1093, 2002.

65. Yokoyama, T., Makishima, A., Nakamura, E. Precise analysis of 234U/238U ratio using UO2+ ion
with thermal ionization mass spectrometry for natural samples. Chem. Geol., 181, 1-12, 2001.
66. Takei, H., Yokoyama, T., Makishima, A., Nakamura, E. Formation and suppression of AlF3
during HF digestion of rock samples in Teflon bomb for precise trace element analyses by
ICP-MS and ID-TIMS. Proc. Japan Acad.,77, Ser. B, 13-17, 2001.
67. Yokoyama, T., Makishima, A., Nakamura, E. Evaluation of the coprecipitation of incompatible
trace elements with fluoride during silicate rock dissolution by acid digestion. Chem. Geol.,
157, 175-187, 1999.
68. Yokoyama, T., Makishima, A., Nakamura, E. Separation of thorium and uranium fromsilicate rock samples using two commercial extraction chromatographic resins. Anal. Chem.,
71, 135-141, 1999.
69. Yokoyama, T., Nakai, S., Wakita, H. Helium and carbon isotopic compositions of hot springgases in the Tibetan Plateau. J. Volcanol. Geotherm. Res., 88, 99-107, 1999.