Anorthosite are characteristic for early stages of development of the Earth. Conditions of their formation reflect specificity of processes, which formed Early Precambrian continental crust. Large deposits of iron, titanium and phosphorus are connected to them, their perspective on rare and precious metals are shown last years.
We have investigated a fluid regime and conditions of formation of anorthosite from the East-Asian belt using inclusions in minerals. It is shown, that the origin of anorthosite magma and the beginning of plagioclase crystallization occurs on depth about 30 km at Ð=9-11 MPa and Ò≥1300ºÑ. Further evolution of the deep magma chamber is connected either with crystallization “in citu”, or with moving of plagioclase cumulus to a middle-crust chamber. Final crystallization of plagioclase “porridge” occurs on depth of 10-18 km at 3-6 MPa and 1200-1300ºÑ with a fluid phase of essential CO2 composition. Sub-isobaric cooling of the chamber, accompanied by separation and crystallization of residual melts, and formation of ore-bearing anorthosite-pegmatite occur at temperature lower than 1200ºÑ. At this stage, along the decontamination of CO2, decontamination of water, phosphorus and halogens has begun.
Sulphidic and early-magmatic apatite-ilmenite-magnetite mineralization in anorthosite can be formed at fluid of essentially CO2 composition. Formation of veins and pegmatite bodies of late-magmatic apatite-ilmenite-magnetite mineralization is possible only at final stages of crystallization of anorthosite accompanied by fluid of CO2-H2O and H2O-salt composition.