大地幔融化事件与大陆生长之间的联系在同位素中被发现
D G Pearson1, S W Parman, G M Nowell
1Northern Centre for Isotopic and Elemental Tracing, Department of Earth Sciences, Durham University, South Road, Durham DH1 4QE, UK. d.g.pearson@durham.ac.uk
Nature
|September 14, 2007
概括
地球的大陆地的增长是脉冲性的,而不是连续的. 使用同位素的新研究揭示了地幔枯竭事件与地形成峰值相吻合,支持我们星球地的脉冲增长模型.
科学领域:
- 地质化学 地质化学
- 地质时间学 (Geochronology)
- 行星科学 行星科学
背景情况:
- 地球大陆地的形成时间和机制仍在争论中.
- 地年龄分布显示高峰,表明脉冲增长或保存偏差.
- -187/-187 (187Re-187Os) 衰变系统跟踪地幔的消耗.
研究的目的:
- 为了调查地幔枯竭事件的时间.
- 为了将地幔分化与大陆地形成联系起来.
- 测试脉冲与连续模型的地生长.
主要方法:
- 使用激光除来分析合金颗粒.
- 量化同位素组成,以确定耗尽年龄.
- 从上层地幔样本中统计分析了枯竭年龄.
主要成果:
- 地幔枯竭年龄是集群的,分布不均.
- 已识别的枯竭年龄峰值大约在12亿年,19亿年和27亿年.
- 这些地幔枯竭事件与大陆地产生峰值相关.
结论:
- 提供了合,全球和脉冲地幔-地差异化的证据.
- 支持通过偶发的大规模地幔融化的大陆生长模型.
- 突出了187Re-187Os系统在理解地和地的演变中的作用.
相关概念视频
Osmosis
158.3K
Approximately 60% to 95% of the weight of living organisms is attributed to water. Therefore, maintaining appropriate water balance within cells is of paramount importance. Osmosis is the movement of water across a semipermeable membrane, such as a cell’s plasma membrane. In living organisms, water plays a crucial role as a solvent—a molecule that dissolves other molecules.
158.3K
Global Climate Change
24.4K
Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
24.4K
Speciation Rates
18.8K
Overview
18.8K
Phase Transitions: Melting and Freezing
11.7K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
11.7K
Isothermal Processes
3.8K
A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to maintain thermal equilibrium. Processes involving phase changes like water evaporation into steam or freezing water into ice at a constant temperature are examples of Isothermal Processes.
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
3.8K
Ostwald’s Dilution Law
168
Consider a binary electrolyte AB with a concentration ‘c’ that reversibly dissociates into its constituent ions. The degree of this dissociation is represented by ⍺. This means that the equilibrium concentration of each ionic species can be expressed as ⍺c. As well as this, the fraction of the electrolyte that remains undissociated at equilibrium is given by (1−⍺). The corresponding equilibrium concentration for this undissociated portion is then calculated...
168


