Percepción del Contraste Bilabial-Labiodental en Las Consonantes Aproximantes del Castellano de Chile [Perception of the bilabial-labiodental contrast in the approximant consonants of the Chilean Spanish]

Perception of the bilabial-labiodental contrast in the approximant consonants of the Chilean Spanish.– Until recently, the consensus was that labiodental realizations of Spanish /b/ did not exist, and that consequently this variation in place of articulation could be safely disregarded. However, new evidence emerged showing that labiodental variants of /b/ do exist in relatively high numbers, at least in some dialects such as in Chilean Spanish. This study set out to determine whether Chilean Spanish listeners are able to perceive the differ-ences between bilabial and labiodental approximant variants of Spanish /b/ (i.e., [β̞] versus [ʋ]). In order to test this, natural and synthetic stimuli were presented to 31 native listeners in identification and discrimination tasks. Results showed that, while the identification task with natural stimuli provided mixed evidence of sensitivity to the con-trast, the identification and discrimination tasks with synthetic stimuli provided no evidence of listeners perceiving the phonetic contrast categorically. In sum, listeners do no seem able to perceive the acoustic differences between the two segments, and thus it is unlikely that this phonetic contrast could be employed to encode sociolinguistic information

Metamorphism and PGE-Au content of chromitite from the Ipanema mafic/ultramafic Complex, Minas Gerais, Brazil

The Santa Cruz massif, which forms part of the Ipanema mafic/ultramafic Complex, Minas Gerais, Brazil, has an exposed upward sequence of metadunite, metaharzburgite (including three separate chromitite layers), metapyroxenite, metagabbro, and metaanorthosite. Primary igneous chromite grains in the main chromitite layer are poikiloblastic and tectonically fragmented, and have a narrow (10-20 mum) margin of chromian spinel. Cataclased chromite fragments are extensively replaced and mantled by chromian spinel; they have a composite margin comprised of an inner zone of more aluminous spinel and an euhedral outer zone of more Cr-rich spinel, representing granulite and amphibolite facies metamorphic events, respectively. The contents of platinum-group elements (PGE) and Au in chromite separates are relatively high (Os 45, Ir 23, Ru 136, Rh 19, Pt 98, Pd 63, and Au 83 ppb), and significantly enriched (similar to 4x) over whole rock values. Platinum-group minerals are not observed and micrometre-sized inclusions of sulfide minerals (chalcopyrite and pentlandite) in relict chromite are rare. However, comparison of mineral proportions in the separated chromite and whole rock shows that the precious metals are hosted predominantly in the relict igneous chromite grains, rather than the secondary chromian spinel and primary and secondary Mg-rich silicates. The major element composition and average chondrite-normalized PGE pattern of the separated chromite correspond to S-poor stratiform chromitite. We suggest that the precious metals accumulated with chromite during crystallization of a S-poor magma, and were not remobilized in the relict chromite during the subsequent high grade metamorphism