The application of melt inclusions (MI) to infer magmatic processes assumes the MI have remained as constant mass, constant volume systems since the time of trapping. Understanding the effects of both compositional and volumetric re‐equilibration is key for the interpretation of MI data. Although the re‐equilibration behavior MI in quartz and olivine has been studied in some detail, the process is less understood for other MI host phases such as plagioclase, a common phase in igneous rocks. A MI can re‐equilibrate when it experiences pressure and temperature (PT) conditions that differ from formation PT conditions. During laboratory heating, irreversible MI expansion may occur. As a result, the internal pressure within the MI decreases, resulting in chemical and structural changes to the MI and host. We present results of heating experiments on plagioclase‐hosted MI designed to induce volumetric re‐equilibration. The experiments consisted of incrementally heating the MI to temperatures above the homogenization temperatures. At ∼40°C above, the temperature at which the daughter minerals melted, irreversible volume expansion lowered the pressure in the MI, and led to exsolution of CO₂ into vapor bubbles. With each additional few degrees of heating, additional episodes of CO₂ exsolution, bubble nucleation and expansion of the vapor bubbles occurred. Re‐equilibration of MI in plagioclase occurred through a combination of ductile and brittle deformation of the host surrounding the MI, whereas previous studies have shown that MI in olivine re‐equilibrate dominantly through ductile deformation associated with movement along dislocations. This behavior is consistent with the differing rheological properties of these phases.

中文翻译：

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实验诱导斜长石夹杂的熔体夹杂物的体积重新平衡

将熔体包裹体（MI）用于推断岩浆过程的假设是，自捕获以来，MI一直保持恒定质量，恒定体积的系统。理解成分和体积再平衡的影响是解释MI数据的关键。尽管已经对石英和橄榄石中MI的再平衡行为进行了详细研究，但对于其他MI宿主相（如斜长石）（火成岩中的常见相），该过程还不太了解。当MI遇到与地层PT条件不同的压力和温度（PT）条件时，MI可以重新平衡。在实验室加热过程中，可能会发生不可逆的MI膨胀。结果，MI内的内部压力降低，导致MI和主体发生化学和结构变化。我们介绍了在斜长石托管的MI上进行加热实验的结果，旨在诱导体积重新平衡。实验包括将MI逐渐加热到均质温度以上的温度。在高于约40°C时，子矿物熔化的温度，不可逆的体积膨胀降低了MI中的压力，并导致CO的释放₂成蒸气泡。对于每个附加几度加热的，CO的附加发作₂出溶，气泡成核和蒸汽泡的膨胀小号发生。斜长石中MI的重新平衡是通过围绕MI的宿主的韧性和脆性变形共同实现的，而先前的研究表明，橄榄石中的MI主要通过与位错运动相关的韧性变形来重新平衡。这种行为与这些相的不同流变特性是一致的。