在对流地幔中保存贵气
Helge M Gonnermann1, Sujoy Mukhopadhyay
1Department of Earth Science, Rice University, Houston, Texas 77005, USA. helge@rice.edu
Nature
|May 30, 2009
概括
通过降温板块回收高贵气体,稀释了地幔度,解释了高-3/-4比率和-40预算,而不需要脱气的下层地幔储库.
科学领域:
- 地质化学 地质化学
- 地质物理学 地质物理学
- 地球科学 地球科学 地球科学
背景情况:
- 海洋岛基岩中的高 (3) He/(4) He比率表明没有脱气的下层地幔水库.
- 地球的阿尔贡-40预算意味着一个大,无气化地幔储存库.
- 岩石沉降到下层地幔中与广泛的贵重气体排气相矛盾.
研究的目的:
- 为了使高贵气度与地幔加工的证据相协调.
- 为了解释高的 (3) He/(4) He比率和地球 (40) Ar预算的起源.
主要方法:
- 在地球地幔中模拟贵重气体的回收和混合.
- 分析板块沉降对地幔外气化速度的影响.
- 将模型预测与地球物理和地球化学观测进行比较.
主要成果:
- noble-gas-depleted slabs的回收利用稀释了地幔中的贵重气体度.
- 这种稀释降低了地幔脱气速度,在下层地幔中保留了贵气.
- 该模型解释了高的 (3) He/(4) He比率和没有孤立储库的 (40) Ar预算.
结论:
- 一个简单的板块回收和混合模型解释了地幔中的高贵气体签名.
- 不需要隐藏的储或长期的下层地幔隔离来保存原始的贵气.
- 上层和下层地幔之间的加工速度差异解释了 (3) / (4) 比率的变化.
相关概念视频
Noble Gases
The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name “noble” because they were assumed to be nonreactive since they have filled valence shells. In 1962, Dr. Neil Bartlett at the University of British Columbia proved this assumption to be false.
The Equilibrium Constant
Consider the oxidation of sulfur dioxide:
Adiabatic Processes for an Ideal Gas
When an ideal gas is compressed adiabatically, that is, without adding heat, work is done on it, and its temperature increases. In an adiabatic expansion, the gas does work, and its temperature drops. Adiabatic compressions actually occur in the cylinders of a car, where the compressions of the gas-air mixture take place so quickly that there is no time for the mixture to exchange heat with its environment. Nevertheless, because work is done on the mixture during the compression, its...
The Joule and Joule–Thomson Experiments
Consider an adiabatic system composed of two chambers, A and B, designed such that no heat flows into or out of the system. Initially, chamber A is filled with a gas at a fixed temperature T1, pressure p1, and volume V1, while chamber B is evacuated. The gas is then gradually forced through a rigid, porous barrier to chamber B, ultimately reaching temperature T2, pressure p2, and volume V2. A piston on the right side maintains a constant pressure (p2), which is lower than p1. The significant...
Perfect Gases and the First Law
A perfect gas obeys the equation of state pV = nRT. The internal energy of a perfect gas remains unaffected by volume alterations. Therefore, the internal energy of a perfect gas is solely dependent on temperature.Consider an ideal gas enclosed in a cylinder situated within a substantial constant-temperature bath. In an isothermal process, where the temperature remains constant, the change in internal energy equates to zero. Thus, according to the first law of thermodynamics, heat absorbed (q)...
Gas Solubility
Gas solubility in liquids forms liquid-gas solutions, such as soft drinks, where carbon dioxide is dissolved in water, and the ocean, where the solubility of oxygen and carbon dioxide supports marine life. The ability of oceans to dissolve gases impacts weather conditions in the troposphere.However, gas-liquid interactions vary. For instance, hydrogen chloride gas is highly soluble in water, while oxygen's solubility is much lower. Because these solutions are non-ideal, Raoult’s law, which...


