Petrography And Mineral Chemistry Of A New Lunar Meteorite M16005

M16005 is a new lunar meteorite.The thin section sample shows that M16005 is a regolith breccia containing a few lithic clasts?about 15%of the total section area?,abundant glasses and mineral fragments.Several glassy spherules,as the typical components of regolith,and partial fusion crust were observed in the section.The matrix consists of very fine-grained,cryptocrystalline?⁵?m?and/or vitric particles with sporadic small vesicles.Optical and microprobe examinations reveal that it is a well consolidated,polymict regolith breccia.The Fe/Mn ratios of pyroxene and olivine in M16005 lie approximately along the lunar line,although the range of values is very large?44-79 for pyroxene and 72-127 for olivine?.In addition,some main lines of evidence support a lunar origin,such as high anorthite content in plagioclase,characteristic lunar minerals?armalcolite?,and textural,mineralogical,and chemical similarities to the Apollo samples.Mineral fragments are dominated by pyroxene(En_7-69Wo_4-36),with lesser amounts of plagioclase(An_91-96Or_<0.4)and olivine(Fa_17-95).Minor ilmenite,chromite,silica,Ni-Fe metal,troilite are also present.Several pyroxene fragments possess exsolution lamellae up to 8?m wide.However,some grains exhibit compositional zoning from En₆₄Wo₁₁?core?to En₃₀Wo₂₅?rim?.We also found some late-stage materials,like symplectitic intergrowths of fayalite(Fo_10-13)+augite(En_12-17Wo_37-42)+silica after former pyroxferroite.M16005 contains various types of lithic clasts?anorthositea,troctolite,coarser-grained clasts and crystalline impact melt breccias?.Most clasts are sub-angular,feldspathic,and the majority has a subophitic texture,whereas others are granular,microporphyritic and poikiloblastic.Some Mg-s lithologies observed in M16005,may give us new insights into the formation of Feldspathic Highlands Terrane,as well as the evolution of Moon.Most of the glasses analyzed are basaltic and picritic,and fall along a mixing line of very low Ti and/or low Ti mare basalts components.The largest glassy vein?about 11%in area?containing¹0%of clastic materials?<1 mm?crosscut the sample.Petrographic and mineral chemical characteristics showing multiple sources for the M16005 clasts suggest that it is a mixed mare and highland regolith brecciabasaltic meteorite,and possible near the the Procellarum KREEP Terrane.