Liquid immiscibility is a critical mechanism to diversify magma compositions. The physical separation of exsolved melt droplets is an essential process in generating new magmas. However, little attention has been paid to this physical process. In this study, we present a new model for segregation of immiscible melt droplets in which exsolution, settling, and coalescence are all considered. The separation of immiscible droplets is similar to that of crystals in magma when the discrete melt exsolves as large (millimeter‐size) droplets and/or when the magma cools slowly. However, when immiscible melt droplets are small (micrometer‐size) and/or magma cools rapidly, coalescence can significantly enhance their separation. The low interfacial tension between coexisting silicate melts leads to the exsolution of extremely small melt droplets. Furthermore, the high viscosity of silica‐rich melt suppresses the coalescence of droplets. Consequently, the separation of highly viscous silica‐rich melt droplets is slow but could have occurred in a slowly cooling magma such as the Skaergaard intrusion. By contrast, the coalescence rate of melt droplets with low viscosity is high. Iron‐rich melt droplets, which have low viscosities, could have been separated from hydrous andesitic melts to form magnetite‐apatite ore deposits at El Laco and Marcona. Furthermore, the viscosities of sulfide and carbonatitic melts are low. Therefore, immiscibility between sulfide and silicate melts may lead to the formation of magmatic sulfide deposits, and immiscibility between carbonatitic and silicate melts can support periodical eruptions of carbonatitic lava.

中文翻译：

---

不混溶液滴的沉降：微观和露头观测之间缺少联系的理论模型

液体不溶混性是使岩浆成分多样化的关键机制。溶解的熔滴的物理分离是产生新岩浆的必不可少的过程。但是，对此物理过程的关注很少。在这项研究中，我们提出了一种新模型，用于分离不溶混的熔滴，其中考虑了溶解，沉降和聚结。当不连续的熔体溶解成大的（毫米大小）液滴时，和/或当岩浆缓慢冷却时，不混溶的液滴的分离与岩浆中的晶体相似。但是，当不混溶的熔滴很小（微米级）和/或岩浆迅速冷却时，聚结会大大增强其分离。共存的硅酸盐熔体之间的低界面张力导致极小的熔体液滴的析出。此外，富含二氧化硅的熔体的高粘度抑制了液滴的聚结。因此，高粘度富含二氧化硅的熔滴的分离很慢，但可能发生在缓慢冷却的岩浆中，例如Skaergaard侵入体。相反，低粘度的熔滴的聚结率高。低粘度的富铁熔滴可能会与含水安山岩熔体分离，从而在El Laco和Marcona形成磁铁矿-磷灰石矿床。此外，硫化物和碳酸盐熔体的粘度低。因此，硫化物和硅酸盐熔体之间的不混溶性可能导致岩浆硫化物沉积物的形成，而碳酸盐岩和硅酸盐熔体之间的不溶性可以支持碳熔岩的周期性喷发。