Electron microprobe and LA-ICP-MS analyses of ... - Arkisto.gsf.fi

More documents

Recommendations

Info

Lehtonen et al.Electron microprobe and LA-ICP-MS analyses of mantle xenocrysts…1 CONTENTS OF THE REPORTThis report contains electron microprobe (EPMA) and LA-ICP-MS analyses of garnet xenocrystsfrom Lentiira-Kuhmo and Kuusamo area kimberlites in NE Finland (Figure 1). The analyticaldatabase has been used in Lehtonen and O'Brien (in press); this paper should be referred if thedatabase is used somewhere else. The analyses are given in Microsoft Excel 2003 format (Appendix1). EPMA analyses are given for 6107 and LA-ICP-MS analyses for 107 garnetxenocrysts.2 SAMPLESXenocryst samples from Lentiira-Kuhmo area are from Seitaperä (Dyke 16) and Rantala kimberlitesand from heavy mineral concentrates taken from till samples. The Kuusamo samples representxenocrysts from four southern Kuusamo kimberlites Kalettomanpuro, Kattaisenvaara,Käsmä 45 and Käsmä 47, and one northern Kuusamo kimberlite. Rantala and Lentiira sampleswere made available to this study by Kopane Diamond Developments Plc, southern Kuusamosamples by Sunrise Diamonds Plc and northern Kuusamo samples by Mantle Diamonds Ltd. andKopane Diamond Developments.In the case of hard-rock kimberlite samples, xenocryst grains (0.25-2.0 mm) were liberated bylightly crushing the kimberlite material followed by heavy medium separation and hand picking.The processing of till samples is described in Lehtonen et al. (2005). Hundreds of garnetxenocrysts were recovered from the kimberlite and till concentrates and mounted for analysis. Inthis study only unsorted garnet concentrates were used in order to gain unbiased populations foreach of the kimberlites.3 ANALYTICAL TECHNIQUESGarnet major element compositions were determined by a Cameca Camebax SX50 and SX100electron microprobes (EMP) at GTK, applying an acceleration voltage of 25 kV, probe current of48 nA and beam diameter of 1 µm. Selected garnet xenocrysts from Lentiira-Kuhmo were analyzedfor trace elements by LA-ICP-MS at the University of Cape Town using the methodologyand equipment described in Grégoire et al. (2003). Typical theoretical detection limits are in therange of 10-20 ppb for REE, Zr and Y, and 2 ppm for Ti and Ni. Trace Ni data by EMP were obtainedon pyrope grains employing 500 nA probe current, 600s counting times on peak plusbackground positions and were reduced by the CSIRO TRACE program for the SX50 (Robinson& Graham, 1992). Cross-checking of the trace methods shows that Ni analyses in pyrope byEMP can achieve similar precision to those of LA ICP-MS down to the level of ca. 10 ppm.
Lehtonen et al.Electron microprobe and LA-ICP-MS analyses of mantle xenocrysts…4 REFERENCESGrégoire, M., Bell, D.R., le Roex, A.P., 2003. Garnet lherzolites from the Kaapvaal Craton(South Africa): Trace element evidence for a metasomatic history. Journal of Petrology 44 (4),629-657.Lehtonen, M.L., Marmo, J.S., Nissinen, A.J., Johanson, B.S., Pakkanen, L.K., 2005. Glacial dispersalstudies using indicator minerals and till geochemistry around two eastern Finland kimberlites.Journal of Geochemical Exploration 87 (1), 19-43.Lehtonen, M., O'Brien, H., in press. Mantle transect of the Karelian Craton from margin to corebased on P-T data from garnet and clinopyroxene xenocrysts in kimberlites. Bulletin of the GeologicalSociety of Finland.Robinson, B.W., Graham, J., 1992. Advances in Electron Microprobe Trace Element Analysis.Journal of Computer-Assisted Microscopy 4, 263–265.
Page 1 and 2: Espoo UnitM41.2/2008/52 23.10.2009E
Page 6 and 7: Lehtonen et al.Electron microprobe
Page 8 and 9: Location Index# SiO2 TiO2 Al2O3 Cr2
Page 14 and 15: EPMA DATA wt%EPMA trace-DATA ppmLoc
Page 53 and 54:
EPMA DATA wt%EPMA trace-DATA ppmLoc
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
show all

Electron microprobe and LA-ICP-MS analyses of ... - Arkisto.gsf.fi

Create successful ePaper yourself

Delete template?

Save as template?