TY - JOUR
T1 - Geo- and cosmochemistry of the twin elements yttrium and holmium
AU - Pack, Andreas
AU - Russell, Sara S.
AU - Shelley, J. Michael G.
AU - van Zuilen, Mark
PY - 2007/9/15
Y1 - 2007/9/15
N2 - We have analyzed the Y/Ho-ratios in bulk chondrites, chondrules and four Ca- and Al-rich inclusions (CAIs) from carbonaceous and unequilibrated ordinary and enstatite chondrites (EC) by laser ablation inductively coupled mass spectrometry (LA-ICPMS). We demonstrate that bulk rock sample preparation by containerless melting is a suitable method for preparation of bulk rock samples for high-precision LA-ICPMS. Bulk chondrites have variable Y/Ho-ratios. Carbonaceous chondrites (CI1, CM2, CV3, and CK4) have a common Y/Ho-ratio (25.94 ± 0.08, 2σ) that is regarded as the solar system Y/Ho-ratio. The Y/Ho-ratio increases from carbonaceous, through ordinary (LL, L, H) to enstatite chondrites (EL6), which show the highest Y/Ho-ratio of 27.25. We discuss the result with respect to the origin of fractionation of Re and Os between chondrite groups. Within analytical error, Y and Ho show a good correlation in OC and CV3 chondrules and define an Y/Ho-ratio of 26.22 ± 0.40 (2σ). Y/Ho-fractionation in Ca- and Al-rich inclusions is related to differences in volatility. The bulk silicate Earth is suggested to have a solar Y/Ho-ratio and links the Earth with carbonaceous chondrites. Y/Ho variations in primitive and differentiated terrestrial igneous rocks are discussed in framework of incompatibility of Y and Ho during partial melting. Applicability of Y/Ho as tracer for or against a sedimentary origin of the putative host rock of the Earth's oldest traces of life from the island of Akilia is briefly discussed.
AB - We have analyzed the Y/Ho-ratios in bulk chondrites, chondrules and four Ca- and Al-rich inclusions (CAIs) from carbonaceous and unequilibrated ordinary and enstatite chondrites (EC) by laser ablation inductively coupled mass spectrometry (LA-ICPMS). We demonstrate that bulk rock sample preparation by containerless melting is a suitable method for preparation of bulk rock samples for high-precision LA-ICPMS. Bulk chondrites have variable Y/Ho-ratios. Carbonaceous chondrites (CI1, CM2, CV3, and CK4) have a common Y/Ho-ratio (25.94 ± 0.08, 2σ) that is regarded as the solar system Y/Ho-ratio. The Y/Ho-ratio increases from carbonaceous, through ordinary (LL, L, H) to enstatite chondrites (EL6), which show the highest Y/Ho-ratio of 27.25. We discuss the result with respect to the origin of fractionation of Re and Os between chondrite groups. Within analytical error, Y and Ho show a good correlation in OC and CV3 chondrules and define an Y/Ho-ratio of 26.22 ± 0.40 (2σ). Y/Ho-fractionation in Ca- and Al-rich inclusions is related to differences in volatility. The bulk silicate Earth is suggested to have a solar Y/Ho-ratio and links the Earth with carbonaceous chondrites. Y/Ho variations in primitive and differentiated terrestrial igneous rocks are discussed in framework of incompatibility of Y and Ho during partial melting. Applicability of Y/Ho as tracer for or against a sedimentary origin of the putative host rock of the Earth's oldest traces of life from the island of Akilia is briefly discussed.
UR - http://www.scopus.com/inward/record.url?scp=34548564362&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2007.07.010
DO - 10.1016/j.gca.2007.07.010
M3 - Article
SN - 0016-7037
VL - 71
SP - 4592
EP - 4608
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 18
ER -