Continuous Thermal Histories from Inversion of Closure Profiles
Continuous Thermal Histories from Inversion of Closure Profiles
复制标题
DOI：
10.2138/rmg.2005.58.15
复制
发表时间：
2005
影响因子：
--
通讯作者：
T. Harrison;M. Grove;O. Lovera;P. Zeitler
中科院分区：
文献类型：
--
作者：
T. Harrison;M. Grove;O. Lovera;P. Zeitler
#背景大多数地球物理过程赋予地壳一个特征的热特征，这种特征可以以放射性成因矿物的同位素变化的形式保存下来。利用热年代学读取这些事件的记录，可以前所未有地深入了解关键动力学过程的时间和速率，如裂谷作用、逆冲断层作用、构造剥蚀、侵蚀/切割和岩浆作用，否则这些过程可能不会被注意到(McDougall和Harison 1999)。然而，热扰动往往太过微妙，不能用传统的热计时方法来揭示；即，从总体分析中插入离散的温度-时间(T-t)点，使用“标称”关闭温度。相反，最高分辨率的热历史需要利用感兴趣矿物中子产物的浓度分布的知识。在前面的章节中，已经探讨了地壳中的矿物冷却从开放到子产物损失再到封闭系统行为的情况。假设简单形式的单调热历史(Dodson 1973)，则可以使用辐射成因积累和损失之间的平衡来指定整体关闭温度Tc，其由以下公式给出：\BatchMODE\DocumentClass[fleqn，10pt，LegalPaper]{文章}\UsPack{amssymb}\UsPack{amsFonts}\UsPack{amsath}\Pages Style{Empty}\Begin{Document}\[\FRAC{\mathit{E}}{\mathit{rt\_{c}\=\ln\left(\frac{\mathit{ART\_{c}}^{2}\mathit{D}_{0}/\mathit{r}^{2}}{\mathit{E\dt/dt}}\右)\end{文档}(1)其中E为活化能，D是频率因子，R是气体常数，T是绝对温度，A是几何因子(球体=55，圆柱体=27，平板=8.7)，r是有效扩散长度尺度(半径或半宽)，dt/dt是冷却速度。当一些共存的矿物温度计时器的温度和年龄相关联时，可以对温度历史的估计进行内插。这种方法，称为整体闭合方法，已经使用了近30年(Purdy和Jager 1976；Mattinson 1978；Berger等人)。1979年；哈里森等人。1979年)。然而，公式(1)的使用有几个严格的要求。…
### Background Most geophysical processes impart a characteristic thermal signature to the crust that can be preserved in the form of isotopic variations in radiogenic minerals. Reading the record of these events using thermochronology permits unprecedented insights into the timing and rates of key dynamic processes, such as rifting, thrust faulting, tectonic denudation, erosion/incision, and magmatism, that may otherwise go unnoticed (McDougall and Harrison 1999). However, thermal disturbances are often too subtle to be revealed by conventional thermochronometric methods; i.e., interpolation of discrete temperature-time ( T - t ) points from bulk analyses using “nominal” closure temperatures. Rather, the highest resolution thermal histories require harnessing knowledge of the concentration distribution of the daughter product in the mineral of interest. In previous chapters, the case has been explored in which a mineral cooling within the crust transitions from being open to loss of daughter product to closed system behavior. Assuming a monotonic thermal history of simple form (Dodson 1973), it is then possible to use the balance between radiogenic accumulation and loss to assign a bulk closure temperature, T c, which is given by: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[\frac{\mathit{E}}{\mathit{RT\_{c}}}\ =\ ln\left(\frac{\mathit{ART\_{c}}^{2}\mathit{D}_{0}/\mathit{r}^{2}}{\mathit{E\ dT/dt}}\right)\] \end{document}(1) where E is the activation energy, D is the frequency factor, R is the gas constant, T is absolute temperature, A is a geometry factor (sphere = 55, cylinder = 27, and plane sheet = 8.7), r is the effective diffusion length scale (radius or half-width), and dT / dt is cooling rate. When the T c and age of a number of coexisting mineral thermochronometers are correlated, an estimate of the temperature history can be interpolated. This method, termed the bulk closure approach, has been used for nearly 30 years (Purdy and Jager 1976; Mattinson 1978; Berger et al. 1979; Harrison et al. 1979). However, use of Equation (1) carries several stringent requirements. …