Masahiko Honda - Academia.edu (original) (raw)

Papers by Masahiko Honda

Lithos, 2019

He-NeAr compositions were determined in diamonds from the Argyle lamproite, Western Australia, to... more He-NeAr compositions were determined in diamonds from the Argyle lamproite, Western Australia, to assess whether subducted material affects the noble gas budget and composition of stable old sub-continental lithospheric mantle (SCLM). Twenty diamonds (both peridotitic and eclogitic) were characterized for their carbon isotopic compositions and N abundance and aggregation from which 10 eclogitic growth zones and 5 peridotitic growth zones were analysed for their He-NeAr compositions. The eclogitic diamonds have δ 13 C values of-4.7 to-16.6‰ indicating a subduction signature, whereas the peridotitic diamonds have mantle-like compositions of-4.0 to-7.8‰. Mantle residence temperatures based on N-in-diamond thermometry showed that the eclogitic diamonds were mainly formed at 1260-1270°C or above 1300°C near the base of the lithosphere, whereas the peridotitic diamonds generally formed at lower temperatures (mostly 1135-1230°C). A noble gas subduction signature is present to various extents in the eclogitic diamonds and is inferred from a hyperbolic mixing relationship between R/Ra and 4 He and δ 13 C values concentrations with a predominance of low R/Ra values (<0.5; R/Ra = 3 He/ 4 Hesample / 3 He/ 4 Heair). In addition, low 40 Ar/ 4 He and 40 Ar/ 36 Ar ratios, high nucleogenic 21 Ne/ 4 He and low 3 He/ 22 Ne ratios are characteristic of subducted material and were found in the eclogitic diamonds. The peridotitic diamonds show generally higher R/Ra values (median 1.1 ± 1.1) and lower 4 He/ 40 Ar ratios compared to eclogitic diamonds (median 0.1 ± 0.8 R/Ra; with 7/10 samples having an average of 0.13 ± 0.14 R/Ra). The studied peridotitic diamond growth zones showed a negative correlation between R/Ra and 4 He concentrations over 2 orders of magnitude and limited variation in 3 He, that can be largely explained by radiogenic 4 He ingrowth. At low 4 He concentrations the R/Ra value is

Chemical Geology, 2019

The physical characteristics and impermeability of diamonds allow them to retain radiogenic 4 He ... more The physical characteristics and impermeability of diamonds allow them to retain radiogenic 4 He produced in-situ from radioactive decay of U, Th and Sm. This study investigates the U-Th/He systematics of fibrous diamonds and provides a first step in quantification of the uncertainties associated with determining the in-situ produced radiogenic 4 He concentration. Factors determining the total amount of measured helium in a diamond are the initial trapped 4 He, the in-situ produced radiogenic 4 He, α-implantation, α-ejection, diffusion, and cosmogenic 3 He production. Alpha implantation is negligible, and diffusion is slow, but the cosmogenic 3 He component can be significant for alluvial diamonds as the recovery depth is unknown. Therefore, samples were grouped based on similar major and trace element compositions to determine possible genetically related

Journal of the American Society for Mass Spectrometry, Jan 15, 2016

Performance of the Helix MC Plus noble gas mass spectrometer installed at the Australian National... more Performance of the Helix MC Plus noble gas mass spectrometer installed at the Australian National University (ANU) is reported. Results for sensitivity, mass discrimination and their linearity against partial pressure of noble gases, and mass resolution of the mass spectrometer are presented, and the results are compared with those of conventional noble gas mass spectrometers. The application of the five detectors on the Helix MC Plus in measuring various noble gas isotopes in multi-collector modes and the integration of the software drivers of peripheral hardware devices into the controlling program Qtegra of the mass spectrometer are discussed. High mass resolution (>1800) and mass resolving power (>8000) make this mass spectrometer unique in noble gas cosmo-geochemistry. It provides the capability to measure isobaric interference-free noble gas isotopes in multi-collector mode, significantly improves the accuracy to determine isotopic ratios, and greatly increases the effic...

Geochimica Et Cosmochimica Acta, 1993

Memoirs of National Institute of Polar Research Special Issue, Dec 1, 1983

Introduction: Total fusion experiments have been conducted on single lunar olivine grains, from s... more Introduction: Total fusion experiments have been conducted on single lunar olivine grains, from soil 10084, to extract solar noble gases. This pilot study was undertaken firstly, to test the analytical setup and secondly, to confirm the level of data quality of the analysis. Previous work on individual lunar grains by other authors used different mineral separates, mainly ilmenites, or different extraction methods, such as stepwise pyrolytic technique or laser vaporization (eg. [1-3]). We have compared our results to these to verify the reliability of our approach. Our ultimate aim is to correlate the fairly well established solar He and Ne ratios with oxygen isotope analyses on the same grains. This approach might offer an opportunity to unravel the various oxygen signatures found in lunar soil [4, 5]. In this study a new dataset of solar He and Ne from single lunar olivine grains is presented and compared to other results on lunar soil and the more recent findings of the Genesis mission [6]. Methods: The olivine fraction of 10084 was chosen for this trial analysis on solar noble gases. 24 large grains (>100µm) were handpicked from the mineral split and transferred into individual pits in a copper sample tray. Since the grains were not weighed, their weights were estimated geometrically. The sample tray was then heated over night at 50°C to remove possible absorbed atmospheric gases. Analytical method. The measurements were performed on the VG5400 noble gas mass spectrometer in Canberra. For this experiment a diode laser was attached to the gas extraction system. The 810nm wavelength laser beam (10A) was used to conduct total fusion of the sample, releasing noble gases. This procedure allowed relatively short analytical time with low blank levels. HESJ (3 He/ 4 He = 2.9x10-5) and Heavy Gas Pipette (with atmospheric Ne) were used as standards to determine the sensitivity and discrimination for the helium and neon measurements, respectively. The blank levels for 4 He and 20 Ne were 1.27x10-9 ±7.21x10-11 and 2.68x10-12 ±3.05x10-12 ccSTP respec

Motivated by exciting, but puzzling, noble gas results in terrestrial diamonds (e.g. high 3 He/ 4... more Motivated by exciting, but puzzling, noble gas results in terrestrial diamonds (e.g. high 3 He/ 4 He ratios close to the solar value from industrial class diamonds [Ozima et al., 1983] and low 40 ArP 6 Ar [ = 189] from an Arkansas, U.S.A., diamond [Melton and Giardini, 1980]), we undertook the study of noble gases in diamonds from different locations. Although this is ongoing research, we can report preliminary results, some of which require confirmation. We have measured 15 diamond samples: Premier type I; Finsch type II; De Beers pool type I and II; Zaire; Arkansas; Australian (two samples); Brazilian (three); and industrial class diamonds, probably of South African origin (four). One industrial class diamond was successively heated for 30 minutes at 1200, 1700, 2000 and 2050°C. The fractional releases of 4 He were 0.007, 0.027, 0.964, and 0.002, respectively. All the He was confirmed to be released along with the 2000°C graphitization of the sample. All other samples were graphitized at 2000°C for noble gas analysis. The 3 HefHe ratios are characterized by a large spread (10 4), ranging from values below atmospheric to values in excess of the planetary (but not the solar) ratio. The highest

Journal of Geophysical Research, 1987

We have measured noble gases in 17 diamond samples, mostly inclusion free, from diverse, known lo... more We have measured noble gases in 17 diamond samples, mostly inclusion free, from diverse, known locations. The 'He/'He ratios are characterized by a large spread (10'), ranging from values below atmospheric to close to the solar ratio. Hlghest ratios were seen for an Australian colorless diamond composite and an Arkansas diamond. These samples also have imprecise but intriguing neon isotopic ratios, which are close to the solar value. An origin for the solarlike He and Ne in the diamond samples is unlikely to be accounted for by the presence of nucleogenic or spallogenic components. For single diamond stones a positive correlation is found between 'He/'He and 1 'C/ 12 C, possibly indicating that heavy carbon is accompanied by primordial helium. However, the He result for the Australian colorless diamond composite with low o 1 'C value requires another explanation, possibly sedimentary carbon contaminated with cosmic dust. The wide variation in 'He/' 0 *Ar ratios observed from diamond samples suggests a complex history for the source regions and the diamond crystallization processes. Results for two Australian diamond composites (colorless and colored), which came from the same kimberlite pipe, are especially notable: the colorless stones contain no radiogenic components but solarlike He and Ne isotopic ratios, whereas the colored stones are enriched in radiogenic and fissiogenic components. Seemingly the Australian diamonds crystallized in a heterogeneous environment in the mantle source region. A pair of Arkansas diamonds, believed to be from a single pipe, exhibits sim1lar anomalies. Analytical Procedures Samples Most of the diamond samples have been examined for texture and screened for inclusions by one of us (E.R.); exceptions are the industrial class and Zaire diamonds (hereafter IDn and ZAI, respectively). Samples ID1, 2, 3, and 4 were obtained commercially from a diamond dealer. ID1 is a composite of 12 small individual stones with few solid inclusions. ID2, 3, and 4 are single stones. They have significant inclusions, and their crystal form is very irregular. Five gem-quality South African individual stones were donated by De Beers Consolidated Mines, Ltd. A type I diamond was collected from the Premier pipe which is known to be of Pr'ecambrian age (1.25 b.y.) (PR1). Both type I and II diamonds were collected from the Finsch pipe (Fil and 2) and from among the De Beers, Wessel ton, Dutoitspan, and Bulfontein pipes (DEl and 2). These last five pipes are known to be of Cretaceous age (J. B. Hawthorne, De Beers, private communication, 1985). All the samples 12,507 12,508 Honda et al.: Solarlike Helium and Neon Isotopes in Diamonds ~Sapphire Viewing window Ni-slug Diamond wrapped in Ta foil Mo funnel I 0 'i' ~ 8-Cooling water Side view of basket heater Sample system 10 em

Geochimica et Cosmochimica Acta, 1988

We report Ar and Xe data from stepwise heating analysis of five neutron-irradiated whole rock LL ... more We report Ar and Xe data from stepwise heating analysis of five neutron-irradiated whole rock LL chondrites (Soko Banja, Alta Ameen, Tuxtuac, Guidder and Olivenza). None of these meteorites yields a well-defined 40Ar-39Ar apparent age plateau comprised of more than two release fractions, although in some cases intermediate-temperature apparent ages may provide significant lower limits to the age of initial Ar retention. Possibly excepting Guidder, these samples yield well-defined high-temperature correlations between '29Xe/'MXe and '**Xe/""Xe, and thus determinations of '291/'271 and '29Xe/'30Xe at the time of isotopic closure for Xe. Nominal '291-'29Xe formation ages range from 2.7 Ma before to 8.2 Ma after Bjurbole. Considered in isolation, the present I-Xe results can be viewed in a coherent chronological framework, although possible isotopic heterogeneity of I cannot be excluded. I-Xe systematics do not correlate with metamorphic grade for the LL chondrites, however, nor with chronologies based on other methods ("Ar-39Ar, initial 87Sr/86Sr, metallographic or fission track retention cooling rates). The LL chondrites are, in this respect, like the other ordinary chondrites (H and L groups). Barring serious unrecognized flaws in essentially all the relevant chronometric methodologies, the primary conclusion is that the thermal history of the ordinary chondrites, including the LL chondrites. is very complicated. _

Earth and Planetary Science Letters, 1996

The well established geology and geochemistry of Hawaiian volcanism allows a detailed evaluation ... more The well established geology and geochemistry of Hawaiian volcanism allows a detailed evaluation of the relationships between geochemically distinct tracers, such as the noble gases and the lithophile elements Sr, Nd and Pb. Four volcanic evolutionary stages show characteristic Sr-Nd-Pb isotopic progressions: early and late stages include depleted melts, whereas the intermediate shields tend to be less depleted, including source components similar to bulk earth values. In contrast, 3He/4He ratios gradually decrease from high values during the early stage to MORB-like values for the late stage. This lack of correlation between the lithophile and noble gas records may be accounted for by: (1) a unique ‘Loihi-like’ mantle component for Hawaii, or (2) a systematic offset between the two records. Whereas many studies have preferred the first scenario, we opt for the latter, and suggest that both systems are coupled in the deep mantle, but become decoupled when a gas-rich melt phase separates from the plume.We suggest that incipient CO2-dominated melts, carrying the noble gases, could separate in the plume flexure, and may buoyantly migrate ahead of the plume, carrying the bulk of its lithophile inventory. These melts permeate the lithosphere, which, upon sufficient heating by the plume, could generate the initial stage alkali basalts and tholeiites. The subsequent formation of the shield stage tholeiites occurs when the main plume, carrying the less depleted lithophile signature, has risen to shallower levels, and commences to melt on a large scale. The melts of this stage show lower 3He/4He ratios owing to asthenospheric entrainment by the plume, which has previously lost a major part of its volatile inventory, allowing for dilution of the isotopic signature by MORB-type noble gases. If this model is correct, the less depleted (Sr, Nd and Pb) and less degassed (noble gases) components are from one and the same source, and may provide the best estimate for the isotopic composition of the deep mantle.

Earth and Planetary Science Letters, 2014

Submarine magmatic glasses from the Manus, Woodlark, North Fiji and Lau backarc basins in the Sou... more Submarine magmatic glasses from the Manus, Woodlark, North Fiji and Lau backarc basins in the Southwest Pacific, as well as a sample from Volcano A on the volcanic front of the Tonga Arc adjacent to the Lau Basin, were investigated to characterise the Cl, Br and I elemental budgets in subduction systems. In particular we seek to determine the extent of variability in the Br/Cl and I/Cl ratios of backarc basin basalts (BABB) and evaluate if these ratios could improve constraints on the source of subducted volatile components in backarc basins worldwide. The selected glasses represent variably evolved melts of boninite, basalt, basaltic-andesite, dacite and rhyolite composition and were selected from spreading centres and seamounts located at varying distances from the associated arcs. In general the strongest subduction signatures (e.g. Ba/Nb of 100-370) occur in the samples closest to the arcs and lower more MORB-like Ba/Nb of <16 are found in the more distal samples. The glasses investigated have extremely variable halogen concentrations (e.g. 3-4200 ppm Cl), with the highest concentrations in enriched glasses with the most evolved compositions. As observed in previous studies, the K/Cl, Br/Cl and I/Cl ratios of glasses from individual settings do not vary as a function of MgO and are considered representative of the magma sources because these ratios are not easily altered by partial melting or fractional crystallisation. Systematic variations in these ratios between basins can therefore be related to mixing of halogens from different sources including: i) the mantle wedge which has MORBlike Br/Cl and I/Cl; ii) a subduction-derived slab fluid with estimated salinity of ~4-10 wt % salts and variable I/Cl; and iii) brines characterised by salinities of 55 ± 15 wt % salts and Br/Cl slightly higher than seawater, that are sometimes assimilated in crustal magma chambers. The slab fluids enriching the Woodlark Basin, North Fiji Basin and the Fonualei Spreading Centre of the Lau Basin have MORB-like I/Cl and Br/Cl overlapping the lower end of the MORB range, indicating a probable source from dehydration of altered ocean crust (AOC). In contrast, slab fluids with I/Cl ratios of up to 10 times the MORB value were detected in BABB from Manus Basin, the Valu Fa Ridge and the Tonga Arc, and in these cases the elevated I/Cl ratios are most easily explained by the involvement of fluids released by breakdown of I-rich serpentinites. The data show slab fluids vary in composition across the Tonga Arc and from north to south in the Lau Basin. However, the compositional range of subducted halogens overlaps that of MORB indicating subduction could be a major source of halogens in the Earth's mantle.

Precambrian Research, 1985

Honda, M., Sylvester, P.J., Podosek, F.A. and Schulz, K.J., 1985. 4°Ar/39Ar geochronology of mafi... more Honda, M., Sylvester, P.J., Podosek, F.A. and Schulz, K.J., 1985. 4°Ar/39Ar geochronology of mafic rocks from the granite--rhyolite terrane of southeastern Missouri. Precambrian Res., 27: 301--306.

Marine Geology, 1987

... Gardner, JV, Dean, WE and Blakely, RJ, 1984. Shimata seamount: an example of recent mid-plate... more ... Gardner, JV, Dean, WE and Blakely, RJ, 1984. Shimata seamount: an example of recent mid-plate volcanism. Geol. ... Union 65 (1984), p. 1078. Gardner et al., 1984J.V Gardner, WE Dean and RJ Blakely, Shimata seamount: an example of recent mid-plate volcanism, Geol. Soc. ...

Two models for generation of heterogeneous He, Ne and Ar isotopic ratios in Icelandic basalts are... more Two models for generation of heterogeneous He, Ne and Ar isotopic ratios in Icelandic basalts are evaluated using a mixing model and the observed noble gas elemental ratios in Icelandic basalts,Ocean island Basalt (OIBs) and Mid-Ocean Ridge Basalt (MORBs). Additional information is contained in the original extended abstract.