佩洛夫斯基特后边界的厚度和克拉佩隆坡度
Krystle Catalli1, Sang-Heon Shim, Vitali Prakapenka
1Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Nature
|December 17, 2009
概括
地球地幔中的矿后 (pPv) 阶段边界比以前认为的要厚,这可能解释地震观测和稳定地幔结构. 这项研究研究了在极端条件下它的厚度.
科学领域:
- 地质物理学 地质物理学
- 矿物物理 矿物物理
- 高压科学科学 高压科学
背景情况:
- 地幔阶段边界,比如矿 (Pv) 到后矿 (pPv) 的过渡,显著影响地震波传播和地幔对流.
- 对于ppv边界的一个大的正克莱佩隆斜率理论上会破坏热异常的稳定,这与地震数据相矛盾.
研究的目的:
- 在相关地幔组合中实验确定PPV边界厚度.
- 调和PPV边界的克拉佩隆斜率的理论含义与对D'不连续性的地震观测.
主要方法:
- 在现场测量使用激光加热的钻石细胞.
- 在高压下 (高达145 GPa) 和高温下 (高达3000 K) 进行的实验.
- 对 (Mg{0.91) Fe{2+{0.09)) SiO{3) 和 (Mg{0.9) Fe{3+{0.1)) Al{0.1) Si{0.9) O{3) 组成的分析.
主要成果:
- 测量的Clapeyron斜率与D'的不连续性保持一致.
- 发现ppv边界厚度明显大 (400-600 +/- 100公里) 于D''间断度 (<30公里).
- 由于Al含量和温度梯度,在火石化合物中预测了更厚的ppv边界.
结论:
- pPv边界的实质性厚度可以稳定最下层地幔中的组成异质性和热异常.
- 呈现明显D'不连续性的区域可能具有不同的组成 (例如,较高的Mg/Si或较低的Al).
- 对于理解地幔动态和地震特征而言,ppv过渡的厚度至关重要.
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