Carbonaceous micrometeorites from Antarctica
Carbonaceous micrometeorites from Antarctica
复制标题
DOI：
10.1111/j.1945-5100.1998.tb01665.x
复制
发表时间：
1998-07
影响因子：
2.2
通讯作者：
C. Engrand;M. Maurette
中科院分区：
文献类型：
--
作者：
C. Engrand;M. Maurette
摘要：在清洁的条件下，从10600吨南极融化的冰水中回收了超过100000个50-500 μm尺寸范围内的大型行星际尘埃颗粒，这些尘埃颗粒既有未融化的，也有部分融化/脱水的微陨石和宇宙球粒。格陵兰和南极冰盖的通量测量表明，微陨石向地球表面提供的外星物质比陨石多2000倍。南极微陨石的矿物学和化学研究表明，它们只与相对罕见的CM和CR碳质球粒陨石群有关，大多数是由高度不平衡的无水和含水矿物组合组成的南极碳质物体。然而，这两个太阳系天体家族之间也有显著的差异，包括较高的C/O比和微陨石物质中非常明显的球粒耗尽;因此，它们是“无球粒陨石”。因此，微陨石的母流星体是太阳系天体中占主导地位的一个新群体，它们可能形成于外太阳系，并通过最合适的运载工具-彗星-传送到内太阳系。本文的主要目的之一是讨论微陨石研究的应用，以前已经提交给外太空生物学家，但处理合成的早期地球上的前生物分子，最近，与太阳系的早期历史。
Abstract— Over 100 000 large interplanetary dust particles in the 50–500 μm size range have been recovered in clean conditions from ∼600 tons of Antarctic melt ice water as both unmelted and partially melted/dehydrated micrometeorites and cosmic spherules. Flux measurements in both the Greenland and Antarctica ice sheets indicate that the micrometeorites deliver to the Earth's surface ∼2000× more extraterrestrial material than brought by meteorites. Mineralogical and chemical studies of Antarctic micrometeorites indicate that they are only related to the relatively rare CM and CR carbonaceous chondrite groups, being mostly chondritic carbonaceous objects composed of highly unequilibrated assemblages of anhydrous and hydrous minerals. However, there are also marked differences between these two families of solar system objects, including higher C/O ratios and a very marked depletion of chondrules in micrometeorite matter; hence, they are “chondrites‐without‐chondrules.” Thus, the parent meteoroids of micrometeorites represent a dominant and new population of solar system objects, probably formed in the outer solar system and delivered to the inner solar system by the most appropriate vehicles, comets. One of the major purposes of this paper is to discuss applications of micrometeorite studies that have been previously presented to exobiologists but deal with the synthesis of prebiotic molecules on the early Earth, and more recently, with the early history of the solar system.