A melt inclusion is a small parcel or "blobs" of melt that is entrapped by crystals growing in magma and eventually forming igneous rocks. In many respects it is analogous to a fluid inclusion.
Characteristics
Melt inclusions are generally small - most are less than 80 micrometres across. They may contain a number of different constituents, including glass, small crystals and a separate vapour-rich bubble. They occur in the crystals that can be found in igneous rocks, such as for example quartz, feldspar, olivine, pyroxene, nepheline, magnetite, perovskite and apatite. Melt inclusions can be found in both volcanic and plutonic rocks. In addition, melt inclusions can contain immiscible melt phases. Their study is an exceptional way to find direct evidences for presence of two or more melts at entrapment.
Analysis
Although they are small, melt inclusions can provide an abundance of useful information. Using microscopic observations and a range of chemicalmicroanalysis techniques geochemists and igneous petrologists can obtain a range of unique information from melt inclusions. The most common uses of melt inclusions is studying the composition and compositional evolution of magmas existed in the history of specific magma systems. This is because inclusions can act like "fossils" - trapping and preserving these melts before they are modified by later processes. In addition, because they are trapped at high pressures and temperatures many melt inclusions also provide important information about the entrapping conditions and their volatile content that driveexplosivevolcanic eruptions.
History
, in 1858, was the first to document microscopic melt inclusions in crystals. The study of melt inclusions has been driven more recently by the development of sophisticatedchemical analysis techniques. Scientists from the former Soviet Union lead the study of melt inclusions in the decades after World War II, and developed methods for heating melt inclusions under a microscope, so changes could be directly observed.
