期刊
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
卷 159, 期 1, 页码 93-112出版社
SPRINGER
DOI: 10.1007/s00410-009-0418-1
关键词
Garnet; Closure temperature; Sm-Nd; Diffusion; Peraluminous granite; Geochronology
Garnet is a vital mineral for determining constrained P-T-t paths as it can give both the P-T and t information directly. However, estimates of the closure temperature of the Sm-Nd system in garnet vary considerably leading to significant uncertainties in the timing of peak conditions. In this study, five igneous garnets from an early Proterozoic 2414 +/- A 6 Ma garnet-cordierite bearing s-type granite-which was subjected to high-T reworking have been dated to examine their diffusional behaviour in the Sm-Nd system. Garnets 8, 7, 6 and 2.5 mm in diameter were compositionally profiled and then dated, producing two-point Sm-Nd isochron ages of 2412 +/- A 10, 2377 +/- A 5, 2370 +/- A 5 and 2365 +/- A 8 and 2313 +/- A 11 Ma, respectively. A direct correlation exists between grain size and amount of resetting highlighting the effect of grain size on closure temperature. Major element EMPA and LA-ICPMS REE traverses reveal homogenous major element profiles and relict igneous REE profiles. The retention of REE zoning and homogenisation of major element zoning suggest that diffusion rates of REEs are considerably slower than that of the major cations. The retention of REE zoning and the lack of resetting in the largest grains suggest that Sm-Nd closure temperature in garnet is a function of grain size, thermal history and REE zoning in garnet.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据