Experimental studies of annealing of etched fission tracks in fluorapatite
Experimental studies of annealing of etched fission tracks in fluorapatite
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DOI：
10.1016/0016-7037(91)90320-5
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发表时间：
1991-05
影响因子：
5
通讯作者：
K. Crowley;M. Cameron;R. Schaefer
中科院分区：
文献类型：
--
作者：
K. Crowley;M. Cameron;R. Schaefer
氟磷灰石中可刻蚀裂变径迹损伤的退火处理（Ca 4.96 Fe 0.01 Na 0.02 Sr 0.01 REE 0.01）5.01-（P 2.98 Si 0.02）3.00 O 12（F 1.00 Cl 0.02）1.02和Sr氟磷灰石（Ca 4.68 Na 0.04 Sr 0.02 REE 0.03）4.97（P2.98Si0.03）3.01O12F1.03在40 ~ 360° C温度范围内进行了1、10、100和1000 h的实验室加热实验。对于大约105个加热实验中的每一个，退火的特征在于测量平行于c轴取向的矿物部分中的受限轨迹的长度以及轨迹的方位角与c轴之间的锐角。退火的特征在于蚀刻轨迹长度随着温度或加热时间的增加而单调减小。轨迹缩短在衰落的所有阶段都是各向异性的：平行于c的轨迹最能抵抗缩短，垂直于c的轨迹至少能抵抗缩短，而中间角度的轨迹具有中间的退火抵抗力。平均径迹长度与平行或垂直于c的径迹长度之间的关系近似为线性。本文给出的氟磷灰石和Sr氟磷灰石的数据以及绿色等人的退火数据的归一化平均径迹长度（r）随温度（T）或加热时间（t）的增加而减小。（1986）从Durango磷灰石，最好用方程g（r; α，β）= C 0+[C 1 ln t+ C 2][（1 T）-C 3]描述，其中g（r; α，β）是r的幂变换，α，β，C 0，C 1，C 2和C 3是参数。在阿克里尼乌斯图上，该模型方程的衰减等值线（常数r的等值线）绘制为一系列直线，这些直线相交于称为“交叉点”的单个点。对于此处给出的氟磷灰石和锶氟磷灰石数据，交叉点出现在523° C≤ T≤ 957° C，10− 5≤ t≤ 10− 2 s的区间内。这一点被解释为代表磷灰石中径迹稳定性的极限。活化能，这是成比例的衰落的轮廓的斜率，增加从约20千卡/摩尔在退火的开始到约66千卡/摩尔在衰落的最后阶段。这种增加表明，轨道变得更耐逐步退火缩短。氟磷灰石和锶氟磷灰石模型方程的交叉点和活化能在5%的水平上没有显着差异。我们的结论是，到第一顺序，这两个样品的退火电阻，其特征在于由蚀刻轨道的归一化平均长度是相同的。从这些数据集开发的模型方程可能提供合理的一阶预测轨道退火在地质时间尺度。特别是，他们预测在环境温度下，在1 my至1 by的时间尺度上，缩短约10%至15%，这与磷灰石中的自发径迹比诱导径迹短10%至20%的观察结果一致。然而，在这些模型可用于解释常规测量的长度分布之前，需要进行额外的测试。
Annealing of etchable fission-track damage in fluorapatite (Ca 4.96 Fe 0.01 Na 0.02 Sr 0.01 REE 0.01) 5.01-(P 2.98 Si 0.02) 3.00 O 12 (F 1.00 Cl 0.02) 1.02 and Sr fluorapatite (Ca 4.68 Na 0.04 Sr 0.02 REE 0.03) 4.97 (P 2.98 Si 0.03) 3.01 O 12 F 1.03 was investigated in laboratory heating experiments at 1, 10, 100, and 1000 h at temperatures ranging from 40 to 360° C. For each of the approximately 105 heating experiments, annealing was characterized by measuring the lengths of confined tracks in mineral sections oriented parallel to the c axis and the acute angles between azimuths of the tracks and the c axis. Annealing is characterized by the monotonic decrease in etched track length with increasing temperature or heating time. Track shortening is anisotropic at all stages of fading: tracks parallel to c are most resistant to shortening, tracks perpendicular to c are at least resistant to shortening, and tracks at intermediate angles have intermediate annealing resistances. The relationship between mean track length and track length parallel or perpendicular to c is approximately linear. The decrease in normalized mean track length (r) with increasing temperature (T) or heating time (t) for the fluorapatite and Sr fluorapatite data presented here, as well as the annealing data of Green et al.(1986) from Durango apatite, is best described by the equation g (r; α, β)= C 0+[C 1 ln t+ C 2][(1 T)− C 3], where g (r; α, β) is a power transform of r, and α, β, C 0, C 1, C 2, and C 3 are parameters. On the Arrhenius diagram, the fading contours (contours of constant r) for this model equation plot as a series of straight lines that intersect at a single point termed the “crossover point.” For the fluorapatite and Sr-fluorapatite data presented here, the crossover points occur within the interval 523° C≤ T≤ 957° C, 10− 5≤ t≤ 10− 2 s. This point is interpreted to represent the limit of stability of tracks in apatite. Activation energies, which are proportional to the slopes of the fading contours, increase from about 20 kcal/mol at the onset of annealing to about 66 kcal/mol at the final stages of fading. This increase indicates that tracks become more resistant to shortening with progressive annealing. The crossover points and activation energies for the fluorapatite and Sr-fluorapatite model equations are not significantly different at the 5% level. We conclude that, to the first order, the annealing resistance of these two samples as characterized by normalized mean length of etched tracks is identical. The model equations developed from these data sets probably provide reasonable first-order predictions of track annealing at geological time scales. In particular, they predict between about 10 and 15% shortening at ambient temperatures over time scales of 1 my to 1 by, which is consistent with the observation that spontaneous tracks in apatite are between 10 and 20% shorter than induced tracks. However, additional testing is required before these models can be used to interpret measured length distributions on a routine basis.