In ordinary chondrites (OCs), phosphates and feldspar are secondary minerals known to be products of parent body metamorphism. Both minerals provide evidence that metasomatic fluids played a role during metamorphism. We studied the petrology and chemistry of phosphates and feldspar in petrologic type 4-6 L chondrites, to examine the role of metasomatic fluids, and to compare metamorphic conditions across all three OC groups. Apatite in L chondrites is Cl-rich, similar to H chondrites, whereas apatite in LL chondrites has lower Cl/F ratios. Merrillite has similar compositions among the three chondrite groups. Feldspar in L chondrites shows a similar equilibration trend to LL chondrites, from a wide range of plagioclase compositions in petrologic type 4 to a homogeneous albitic composition in type 6. This contrasts with H chondrites which have homogeneous albitic plagioclase in petrologic types 4-6. Alkali-and halogen-rich and likely hydrous metasomatic fluids acted during prograde metamorphism on OC parent bodies, resulting in albitization reactions and development of phosphate minerals. Fluid compositions transitioned to a more anhydrous, Cl-rich composition after the asteroid began to cool. Differences in secondary minerals between H and L, LL chondrites can be explained by differences in fluid abundance, duration, or timing of fluid release. Phosphate minerals in the regolith breccia, Kendleton, show lithology-dependent apatite compositions. Bulk Cl/F ratios for OCs inferred from apatite compositions are higher than measured bulk chondrite values, suggesting that bulk F abundances are overestimated and that bulk Cl/F ratios in OCs are similar to CI. IntroductionOrdinary chondrites (OCs) show a sequence of equilibration of both textural and chemical characteristics. These changes are described by petrologic types 3-6 and are generally accepted to represent progressive degrees of metamorphism which occur within 65 million years after accretion (Van Schmus and Wood 1967;Huss et al. 2006). Textural changes include recrystallization of the matrix, crystallization of chondrule mesostasis, blurring of the chondrule-matrix texture, and growth of secondary phases. Olivine and pyroxene show a wide range of compositions in type 3. Due to differences in the MgFe interdiffusion rate for olivine and pyroxene, equilibration in olivine occurs by petrologic type 4 followed by pyroxene which is equilibrated by type 5.The metamorphic environment on OC parent bodies is only poorly constrained and peak temperatures are only roughly defined. Peak temperatures for petrologic type 3 are not thought to exceed 500 ºC, types 4-5 range from 500-800 ºC, and type 6 from 800 ºC to the onset of melting at ~1000 ºC (Scott and Krot 2014). Additionally, although the presence of fluids has been inferred from mineralogical observations, the importance of fluids and their role during metamorphism is still poorly understood. Low petrologic type chondrites show evidence for the action of fluids from the presence of phyllosilicates (Alexander...

The UK prevalence and incidence of clinically significant CPE is currently low, but these MDR bacteria affect most UK regions. Improved IPC measures, vigilance and monitoring are required.

Axial and radial profiles of temperature and velocity of an argon plasma jet in open air, were measured by a calorimetrie probe, at temperatures up to 11 600 0 K and velocities up to 410 mIs. The radial profiles were shown to be Gaussian.Velocities and decelerations of elose-sized microspheres (30 -140~m dia) in the plasma jet were measured by a high-speed streak camera. A maximum partiele deceleration of 8 000 g was observed.Experimental drag coefficients were found to be about 30% greater than standard curve values. This increase was in accord with the computer predictions of the value of the Basset history term in the full equation of motion.

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