TY - JOUR

T1 - Trace element diffusion in rhyolitic melts

T2 - Comparison between synchrotron radiation X-ray fluorescene microanalysis (μ-SRXRF) and secondary ion mass spectrometry (SIMS)

AU - Hahn, Matthias

AU - Behrens, Harald

AU - Tegge-Schüring, Astrid

AU - Koepke, Jürgen

AU - Horn, Ingo

AU - Rickers, Karen

AU - Falkenberg, Gerald

AU - Wiedenbeck, Michael

PY - 2005/4/29

Y1 - 2005/4/29

N2 - Two microbeam techniques, synchrotron radiation X-ray fluorescence micro-analysis (μ-SRXRF) and secondary ion mass spectrometry (SIMS) are compared for analyzing diffusion profiles of trace elements in two hydrous rhyolitic glasses (1.87 and 5.00wt% H2O). In order to verify the results, laser ablation coupled to inductively coupled plasma optical emission (LA-ICP-OES) has been used on one sample. Samples were produced by diffusion couple experiments performed in an internally heated gas pressure vessel at 1200°C and 500 MPa. One half of each couple was doped with 24 trace elements representing different geochemical groups: low field strength elements (Rb, Sr, Ba), transition metals (Cr, Co, Ni, Cu, Zn), rare earth elements (La, Ce, Nd, Sm, Eu, Gd, Er, Yb) + Y, high field strength elements (V, Zr, Nb, Hf, Ta) and main group elements (Ge, Sn). Several profiles were measured with both p-SRXRF and SIMS on both samples. In principle, concentrations of all elements can be extracted simultaneously from a single SRXRF spectrum. However, some trace elements could not be reliably quantified with our analytical system: Ta and Pb (used for detector collimator material), Ti, V (low energy of Kα, Co (Kα-peak overlapping with Fe K β-peak) and Cr, Ni, Cu, Zn (overlapping with 1-lines of REEs). In contrast, SIMS analyses measure each element sequentially. Hence, not all elements of the large total set of trace elements could be analyzed in a single run. Some elements requiring a high mass resolution (NaSi interfering with V, CaO interfering with Ni) or having low yields (Sn) were not profiled. Multi ple diffusivities derived from V-SRXRF and SIMS profiles are in very good agreement for most elements. In general, the trace element diffusivity decreases with increasing valence state, e.g. in sample D22 containing 1.87 wt% H 2O from log D = -10.80 for the monovalent Rb to log D=-13.34 for the tetravalent Zr (Din m2/s). By increasing the water content in sample D18 to 5.00 wt%, diffusion coefficients increase approximately by one order of magnitude for all elements studied.

AB - Two microbeam techniques, synchrotron radiation X-ray fluorescence micro-analysis (μ-SRXRF) and secondary ion mass spectrometry (SIMS) are compared for analyzing diffusion profiles of trace elements in two hydrous rhyolitic glasses (1.87 and 5.00wt% H2O). In order to verify the results, laser ablation coupled to inductively coupled plasma optical emission (LA-ICP-OES) has been used on one sample. Samples were produced by diffusion couple experiments performed in an internally heated gas pressure vessel at 1200°C and 500 MPa. One half of each couple was doped with 24 trace elements representing different geochemical groups: low field strength elements (Rb, Sr, Ba), transition metals (Cr, Co, Ni, Cu, Zn), rare earth elements (La, Ce, Nd, Sm, Eu, Gd, Er, Yb) + Y, high field strength elements (V, Zr, Nb, Hf, Ta) and main group elements (Ge, Sn). Several profiles were measured with both p-SRXRF and SIMS on both samples. In principle, concentrations of all elements can be extracted simultaneously from a single SRXRF spectrum. However, some trace elements could not be reliably quantified with our analytical system: Ta and Pb (used for detector collimator material), Ti, V (low energy of Kα, Co (Kα-peak overlapping with Fe K β-peak) and Cr, Ni, Cu, Zn (overlapping with 1-lines of REEs). In contrast, SIMS analyses measure each element sequentially. Hence, not all elements of the large total set of trace elements could be analyzed in a single run. Some elements requiring a high mass resolution (NaSi interfering with V, CaO interfering with Ni) or having low yields (Sn) were not profiled. Multi ple diffusivities derived from V-SRXRF and SIMS profiles are in very good agreement for most elements. In general, the trace element diffusivity decreases with increasing valence state, e.g. in sample D22 containing 1.87 wt% H 2O from log D = -10.80 for the monovalent Rb to log D=-13.34 for the tetravalent Zr (Din m2/s). By increasing the water content in sample D18 to 5.00 wt%, diffusion coefficients increase approximately by one order of magnitude for all elements studied.

KW - Rhyolite

KW - SIMS

KW - Synchroton radiation X-ray fluorescence microanalysis

KW - Trace element diffusion

UR - http://www.scopus.com/inward/record.url?scp=18444381750&partnerID=8YFLogxK

U2 - 10.1127/0935-1221/2005/0017-0233

DO - 10.1127/0935-1221/2005/0017-0233

M3 - Article

AN - SCOPUS:18444381750

VL - 17

SP - 233

EP - 242

JO - European journal of mineralogy

JF - European journal of mineralogy

SN - 0935-1221

IS - 2

ER -