The Kansas University meteorit

Abstract

Abstract-A new 2.8 kg meteorite find fiom the United States, Kansas University, is classified as an L6 (S3) chondrite based on optical microscopy and electron microprobe analysis of mafic minerals. Natural thermoluminescence (TL) and 14C measurements suggest that the Kansas University meteorite has a short terrestrial age compared to other meteorite finds fiom this area and is not paired with the other local meteorite finds, Densmore (1 879), Lawrence, Kansas and Long Island, Kansas. HISTORYAround the turn of the century, a single stone weighing 2.8 kg was recovered by Mr. Handel Tong Martin. Martin was curator of Paleontology at the University of Kansas at the time and acquired the stone while searching for fossils in an unknown location. The stone was given to Mr. William H. Martin, son of Handel Martin, who in turn gave the stone to his son, Mr. William H. Martin, Jr. The stone was brought to the University of Arkansas in December of 1990, where it was identified as a meteorite. The specific location of where the meteorite was found is unknown, but we presume it to be in the Lawrence, Kansas area. The main mass of the stone remains on loan at the University of Arkansas; a small sample weighing 8.0 g and the thin section studied are in the meteorite collection of the University of Arkansas. PETROGRAPHIC DESCRIPTIONThe Kansas University meteorite is roughly cube-shaped with one face covered by an extensively scalloped fusion crust (Fig. 1). There is no apparent fusion crust on the other faces. The meteorite is only moderately weathered, and one corner bears saw marks where a sample of >50 g was probably removed prior to its arrival at the University of Arkansas. Fragments broken from the main mass are fairly lightly colored, with only a few areas of rust stains, and metal grains are prominent on polished surfaces.In thin section, the meteorite shows only scattered instances of weathering. In general, the meteorite displays an interlocking texture of olivine and pyroxene. A few chondrules were noted, but these were indistinct, with blurred edges. On this basis, we classify the Kansas University meteorite as petrologic type 6, following the scheme of Van Schmus and Wood ( 1967).Examination of the thin section suggests that the meteorite is moderately shocked. Undulatory extinction and occasional planar fractures are noted in both olivine and pyroxene grains. A few small opaque shock veins were observed, but no melt pockets were noted in our section. Using the criteria of St6ffler et al. (1991), we suggest that the Kansas University meteorite is shock stage S3. MINERALOGYElectron microprobe analysis of the meteorite was conducted at Johnson Space Center (JSC) using a 15 keV, 30 nA beam. Marjalahti olivine was used as the standard. The olivine has a mean composition of Fa26,0 (N = 10, u = 1.4), and the pyroxene has a mean composition of Fs21,~ (N = 3, u = 0.8) and W01.2 (N = 3, CJ = 0.1). Minor amounts of highCa pyroxene were noted. These data are consistent with the classification of this meteorite as an L chondri...