Presolar grains are trace components in chondrite matrices. Their abundances and compositions have been systematically studied carbonaceous chondrites but rarely situ other major classes. We conducted a NanoSIMS isotopic search for presolar with O- C-anomalous the matrices of unequilibrated ordinary Semarkona, Meteorite Hills 00526, Northwest Africa 8276. The even most primitive aqueously alter...

Introduction: Because of a poor understanding of the delivery mechanisms of meteoroids from the asteroid belt, early asteroid spectral investigations often assumed that the abundance of various meteorite types among meteorite falls was approximately proportional to the abundance of such assemblages within the asteroid population. Based on that assumption, it was concluded that a large fraction ...

The Rochechouart impact crater in the French Massif Central, has a diameter of 20 25 km [1] and an age of 250 my [2]. The cater is deeply eroded, down to the crater floor. Impact melt outcrops can be found in different parts of the crater [3]. The type of impactor that produced Rochechouart crater is still not clear. The first proposal of an IIA iron asteroid was based on the abundance of some ...

Chondrules may have played a critical role in the earliest stages of planet formation by mediating the accumulation of dust into planetesimals. However, the origin of chondrules and their significance for planetesimal accretion remain enigmatic. Here, we show that chondrules and matrix in the carbonaceous chondrite Allende have complementary (183)W anomalies resulting from the uneven distributi...

Calcium^aluminum-rich inclusions (CAIs) from enstatite chondrites have large 16O excesses, similar to CAIs in carbonaceous and ordinary chondrites, and are also similar in morphology, mineralogy and Al^Mg isotopic systematics. These similarities provide new evidence that most CAIs might have formed in a single, restricted nebular locale and were then distributed unevenly throughout the various ...