Chemical compositions and cassfication of Grove Mountains(GRV)98003 and other Chinese iron meteorites

Concentrations of Cr, Co, Ni, Cu, Ga, Ge, As, Sb, W, Re, Ir, Pt and Au of two ungrouped iron meteorites, Grove Mountains （GRV） 98003 from Antarctica and Ujimqin, were measured using instrumental neutron activation analysis. According to the bulk chemistry, GRV 98003 is classified as a member of ⅠAB group, and Ujimqin as a unique one of ⅠAB iron meteorite complex. The elemental abundance pattern and correlation between elements （e. g. Ni-Au, Co-Au, As-Au, W- Au, Cu-Au, Sb-Au） of GRV 98003 are similar with those of NAW 468 （ⅠAB）, but significantly depleted in refractory siderophile elements （ Re, It） and moderate volatile elements （Ca, Ge） relative to the latter. In addition, we reclassify Nantan （ⅢCD） as a member of ⅠAB main group （MG） and Yongning （ⅠA） as a unique iron meteorite related with IAB iron meteorite complex.

Ion Probe Study of Silicate Inclusions from Colomera （IIE） Iron Meteorite： the Rare Earth Element Perspective

Coupled with a petrographical study, I carried out an ion probe study of rare earth element microdistributions in mineral phases of silicate inclusions from the Colomera ⅡE iron meteorite. Most mineral grains have homogeneous REEs, but show considerable inter-grain variations by a factor of 2 to 100. The whole rock REE abundances for Colomera, estimated by combining REE data with modal abundances, are relatively LREE-enriched with REEs of -10'CI, which suggest that Colomera silicates were highly differentiated and might represent a low degree partial melt (-10%) of a chondritic source. REE geochemistry of Colomera silicate inclusions points to an origin that involves differentiation, dynamic mixing, remelting, reduction, recrystallization, and subsequent rapid cooling near the surface of a planetary body.

The chemical compositions of Antarctic iron meteorites and their classification

The concentrations of 13 elements in the metal of 52 Antarctic irons have been reported and these irons have been classified based on the structures and their Ga,Ge, Ni, Ir and other trace elemental contents. The 52 iron meteorites assigned to chemical group consist of 16 of ⅠAB,12 of ⅡAB, 1 of ⅡE,3 of ⅢAB, 1 of ⅢCD, 1Of ⅣA and 18 of ungrouped irons. The ⅠAB, ⅢCD and ⅡE iron meteorite groups areconsidered to be of nonmagmatic origin. Nonmagmatic ⅠAB, ⅢCD and ⅡE ironsformed as individual pools of a chondritic body. The other groups, ⅡAB, ⅢAB andⅣA show the evidences of having originated by fractional crystallization of a metallicmagma.The slopes on element-Ni trends in the magmatic are generally higher than inthe nonmagmatic groups. Most interestings are the high abundance Of ungrouped andⅠAB (47.2% and 27.8%,respectively) and low abundance of ⅢAB (5.8%).Antarctic irons of the group abundances can be distinguished from non-Antarctic irons,which provide the information about previously unsampled parent planets, mass,shockand collision,as well as nebula regions.

首次在嫦娥五号月壤中鉴定出铁陨石碎片类型

Lunar soil preserves numerous fragments of meteorites impacting on the Moon,providing a unique opportunity to investigate the distribution of the types of projectiles over billions of years.Here we report the first discovery of an iron meteorite fragment from the Chang’e-5 lunar soil,which consists mainly of martensite(quenched from taenite),kamacite,and schreibersite,with a trace of pentlandite.The meteorite fragment is Ni-and P-rich,S-poor,and based on its mineral chemistry and bulk composition,can be classified into the IID-group,a rare and carbonaceous group of iron meteorite originating in the outer Solar System.This meteorite fragment experienced only limited partial melting followed by fast cooling,suggestive of efficient preservation of intact remnants of iron meteorites impacting on the porous lunar regolith.Alternatively,it is a relic of a low-velocity impact of submillimeter-sized metal grains originated from an IID-like iron meteorite.Our observations demonstrate that it is feasible to achieve the type distribution of meteorites impacting on the Moon via systematically analyzing a large number of metal grains separated from lunar soils,thus shedding light on the dynamic evolution of the Solar System.