Masters of disguise: can achondrite parent bodies hide beneath a chondritic cover?

伪装大师：无球粒陨石母体能否隐藏在球粒陨石覆盖层之下？

• 批准号: 2440647
• 金额: --
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2440647
• 关键词: Masters; disguise; achondrite; parent; bodies

Chondrite meteorites are the most primitive known building blocks of terrestrial planetsas they show elemental abundances as still found in our Sun [1]. Other groups of meteorites knownas achondrites and iron meteorites show various degrees of differentiation resembling the Earth'sbasaltic crust and iron core, respectively. Traditionally, these categories of meteorites have beeninterpreted to derive from more primitive (chondrites) and more differentiated (achondrites, and irons)parent bodies, respectively. However, an alternative interpretation has it that even differentiatedparent bodies can retain an undifferentiated chondritic crust [2]. This theory is consistent withobservation of asteroid 21 Lutetia that has a chondritic surface composition but appears to beinternally differentiated [3]. That scenario could arise in small planetesimals that experience internalheating from short-lived radionuclide decay. Partial melting and internal magmatism would facilitatedifferentiation of the interior while an outer crust remains intact and unprocessed. However, thatregime will likely be restricted to a certain size and formation age of parent bodies. In earlier or largerplanetesimals, more intense heating and internal dynamics might lead to tectonic disruption and/orvolcanic resurfacing of the chondritic lid. A new generation of multi-phase reaction-transport modelsfor magma transport through deforming ductile-brittle rock [4-6] will allow us to put the hypotheticalstability of a chondritic crust on an achondrite parent body to the test!

球粒陨石是已知的最原始的陆地行星的组成部分，因为它们显示出的元素丰度仍然在我们的太阳中发现[1]。其他种类的陨石被称为无球粒陨石和铁陨石，它们表现出不同程度的分化，分别类似于地球的玄武岩地壳和铁芯。传统上，这些类别的陨石被解释为分别来自更原始的（陨石）和更分化的（无球粒陨石和铁）母体。然而，另一种解释是，即使是分异的母体也可以保留未分异的地壳[2]。这一理论与对小行星21 Lutetia的观测一致，该小行星具有南极表面成分，但似乎内部分化[3]。这种情况可能出现在经历短寿命放射性核素衰变内部加热的小行星中。部分熔融和内部岩浆作用将促进内部的分异，而外壳保持完整和未加工。然而，该制度可能会被限制在一定的规模和形成年龄的母体。在更早或更大的小行星中，更强烈的加热和内部动力学可能导致构造破坏和/或火山重新出现南极洲盖。新一代的多相反应-输运模型[4-6]将使我们能够检验无球粒陨石母体上的变质地壳的假设稳定性。