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40K可以进行分支衰变成40 Ar和40 Ca。在正常情况下 ,这对40 K 40 Ar或3 9Ar 40 Ar年龄与40 K 40 Ca年龄在误差范围内应该一致。测定了国家钾标样的含量、国家钾长石 (W 0 3116 )和球团矿 (W 72 0 0 )的钾钙含量、国内K Ar法标准矿物黑云母 (ZBH 2 5 )和角闪石 (ZBJ)的钾钙含量以及Tachiti标样的 (40 Ca/42 Ca)比值和含量 ,结果实测值与标称值在误差范围内一致。对大别山碧溪岭超高压变质榴辉岩的多硅白云母、绿辉石和石榴子石进行了 (40 Ca/42 Ca)和 (40 K/42 Ca)的测定。由15组数据构成的等时线斜率S =0 .12 0 8± 0 .0 4 2 3,相应的K Ca年龄为 2 2 8± 75Ma。然而多硅白云母和绿辉石的3 9Ar 40 Ar等时线年龄分别为 80 7.1± 32 .6Ma和 4 5 6 .7± 2 7.2Ma ,在误差范围内明显地高于40 K 40 Ca等时线年龄 ,这给出了前者存在过剩氩的直接证椐。此外 ,K Ca等时线的初始值 (40 Ca/42 Ca) i 为 15 1.4 2 4± 0 .0 13,相应的 ξCa为 +2 7。由于地幔岩的 ξCa≈ 0 ,所以前者表明榴辉岩的原岩具有典型的大陆地壳性质 ,这为大别山超高压变质岩体是由大陆物质俯冲至上地幔的深度 ,然后折返至大陆的形成过程提出了又一个判据
40K can undergo branch decay to 40 Ar and 40 Ca. Under normal conditions, this should be consistent over the error range for 40 K 40 Ar or 3 9Ar 40 Ar ages and 40 K 40 Ca ages. The content of potassium in the national standard, the potassium and calcium contents of the national potash feldspar (W 0 3116) and pellet (W 72 0 0), the standard mineral biotite K Z (K 2) and the amphibole (ZBJ) as well as the ratio and content of (40 Ca / 42 Ca) in Tachiti samples. The results show that the measured values agree with the nominal values within the error range. (40 Ca / 42 Ca) and (40 K / 42 Ca) were measured for picene, omphacite and garnet in the Bixiling UHP metamorphic eclogites in the Dabie Mountains. The isochronal slope S = 0.12 0 8 ± 0 .0 4 2 3 composed of 15 sets of data and the corresponding K Ca age is 2 2 8 ± 75 Ma. However, the 3 9Ar 40 Ar isochron ages of palygorskite and omphacite were 80 7.1 ± 32.6Ma and 466.7 ± 2 7.2Ma, respectively, which were significantly higher than 40 K 40 Ca, etc. in the error range Time-line age, which gives a direct indication of the existence of excess argon in the former. In addition, the initial value of the K Ca isochron (40 Ca / 42 Ca) i is 15 1.4 2 4 ± 0 .0 13 and the corresponding ξ Ca is +2 7. Due to the ξCa≈0 of the mantle rock, the former indicates that the protolith of the eclogite has typical continental crustal properties. This suggests that the Dabie ultrahigh-pressure metamorphic rocks are formed by the subduction of the continental material to the depth of the upper mantle and then reentry to the mainland Another criterion