Crystal Mush Growth and Collapse on a Steep Wall: The Marginal Border Series of the Skaergaard Intrusion, East Greenland
Crystal Mush Growth and Collapse on a Steep Wall: The Marginal Border Series of the Skaergaard Intrusion, East Greenland
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陡壁上水晶糊的生长和塌陷：东格陵兰斯卡尔加德入侵的边缘边界系列
DOI：
10.1093/petrology/egab100
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发表时间：
2022
影响因子：
3.9
通讯作者：
Holness M
中科院分区：
文献类型：
--
作者：
Holness M
东格陵兰的Skaergaard侵入体固化为一个封闭系统，在岩浆房的顶部、底部和垂直壁处逐渐形成更多的分馏物质。我们认为，通过对暴露的西缘进行实地观察，并结合详细的显微构造和地球化学分析，Skaergaard侵入体垂直壁上的泥质达到了~180 m的最大厚度，并且非常不稳定。由于未保留固结不良的材料，以及在幕式坍塌事件期间，材料不断丢失。几乎完全没有在LZc时代形成的材料的围岩（以下的铁，钛氧化物的大量岩浆的饱和）可能是由崩溃事件，可能与断层的积极延伸格陵兰边缘。MBS的第二次主要坍塌发生在固化的后期阶段，材料的最大损失发生在具有异常厚的糊状物的壁的区域中，从而在地板糊状物的厚度上产生瞬时和局部的增加。这项工作证明了垂直墙的重要性，在提供松散的，分散的材料，形成移动的岩浆浆，可能有助于地板累积或被夹带和喷发在长期使用的系统。
The Skaergaard Intrusion of East Greenland solidified as a closed system, with the development of progressively more fractionated material at the roof, floor and vertical walls of the magma chamber. We argue, using field observations of the exposed western margin together with detailed microstructural and geochemical analysis, that the mush on the vertical walls of the Skaergaard Intrusion reached a maximum thickness of ~180 m, and was highly unstable. Material was lost both continuously, due to non-retention of poorly consolidated material, and during episodic collapse events. The almost complete absence in the wall rocks of material formed in LZc times (following the saturation of the bulk magma in Fe-Ti oxides) was likely to have been caused by a collapse event, perhaps related to faulting of the actively extending Greenlandic margin. A second major collapse of the MBS occurred during the later stages of solidification, with the greatest loss of material occurring in a region of the wall with an unusually thick mush, creating a transient and localised increase in the thickness of the floor mush. This work demonstrates the importance of vertical walls in supplying loose, disaggregated material to form mobile magmatic slurries that may contribute to floor cumulates or be entrained and erupted in long-lived systems.