| Muling is located in the Mishan-Fushun fault zone, eastern branch of thenorthern section of Tanlu fault zone. The Cenozoic basalts occurred in northeastChina usually contain large amounts of mantle xenoliths, Muling is one of the mostimportant part of it. In this paper, we use classical traditional mineralogical methods,EMPA, Raman spectra and LA-ICP-MS to research the mineralogical, spectra andgeochemistry characteristics of the clinopyroxene megacrysts found in Cenozoicbasalts in this region. Also, we use different mineral thermobarometers to calculatethe equilibrium temperature and pressure of the clinopyroxene megacrysts.The results of the experiments show that clinopyroxene megacrysts in this regionhave no compositional zonation structure, major elements have a high content of Mg#,Cr (except for some samples) is slightly low, the correlation between the majorelements is good, similar to the clinopyroxene megacrysts found in other place in eastChina, indicating that the clinopyroxene megacrysts were formed in the same magma.The clinopyroxene megacrysts is aluminum augite afer analyzing. We get aconclusion that the megacrysts were formed in a stable environment between1257～1409℃，17×108～31×108Pa by using different empirical formulas, in deep uppermantle at about63～99km below the earth. Clinopyroxene megacrysts Ramanspectrum shows the main bands as:1010cm-1,672cm-1,560cm-1, determined bydifferent kinds of molecular vibration type. The trace elements contents are between17.40～45.37ppm according to LA-ICP-MS, rich in MREE, the connection betweenthe trace elements is good, but different with other places in China, this needs furtherresearch. Different Cr contents lead to different color, the green samples have arelatively high Cr contents. The clinopyroxenes in this region formed in alkali basaltwith high temperature and pressure, they’re important in mineralogy andgeochemistry, but they have a long way to go as a new kind of gemstones. |
PDF Full Text Request