TY  - JOUR
A1  - Lopez, S.
A1  - Reimers, Dieter
A1  - Gregg, M. D.
A1  - Wisotzki, Lutz
A1  - Wucknitz, Olaf
A1  - Guzman, A.
T1  - Metal abundances in a damped Ly alpha system along two lines of sight at z=0.93
N2  - We study metal abundances in the z = 0.9313 damped Ly alpha system observed along the two lines of sight, A and B, toward the gravitationally lensed double QSO HE 0512-3329. Spatially resolved Space Telescope Imaging Spectrograph spectra constrain the neutral-gas column density to be N(H I) = 1020.5 cm(-2) in both A and B. UV-visual Echelle Spectrograph spectra ( spectral resolution FWHM = 9.8 km s(-1)) show, in contrast, significant line-of-sight differences in the column densities of Mn II and Fe II; these are not due to observational systematics. We find that [Mn/H] = -1.44 and [Fe/H] = -1.52 in damped Ly alpha system A, while [Mn/H] = -0.98 and [Fe/H] > -1.32, and possibly as high as [Fe/H] approximate to -1, in damped Ly alpha system B. A careful assessment of possible systematic errors leads us to conclude that these transverse differences are significant at a 5 sigma level or greater. Although nucleosynthesis effects may also be at play, we favor differential dust depletion as the main mechanism producing the observed abundance gradient. The transverse separation is 5 h(70)(-1) kpc at the redshift of the absorber, which is also likely to be the lensing galaxy. The derived abundances therefore probe two opposite sides of a single galaxy hosting both damped Ly alpha systems. This is the first time firm abundance constraints have been obtained for a single damped system probed by two lines of sight. The significance of this finding for the cosmic evolution of metals is discussed
Y1  - 2005
SN  - 0004-637X
ER  - 
TY  - JOUR
A1  - Guzman, S.
A1  - Petrinovic, I. A.
A1  - Brod, J. A.
A1  - Hongn, Fernando D.
A1  - Seggiaro, R. E.
A1  - Montero, C.
A1  - Carniel, Roberto
A1  - Dantas, E. L.
A1  - Sudo, Masafumi
T1  - Petrology of the Luingo caldera (SE margin of the Puna plateau) a middle Miocene window of the arc-back arc configuration
JF  - Journal of volcanology and geothermal research
N2  - We describe the petrographic characteristics, whole-rock geochemistry and mineral chemistry of rocks from the Pucarilla-Cerro Tipillas Volcanic Complex with emphasis on the rocks belonging to the middle Miocene Luingo caldera, located in the south-eastern portion of the Central Volcanic Zone (CVZ) of the Andes. We modelled the petrogenesis of the Luingo caldera rocks as a mixture of ca. 20% crustal magmas and 80% of mantle magmas by AFC with recharge processes. A comparison of Luingo geochemical data with the composition of Miocene-Pliocene volcanic rocks from the broad area, points to major thickening events during the middle Miocene for the western portion and during the upper Miocene for the eastern portion of the Southern CVZ. In the eastern sector (similar to 66 degrees W) the mantle source appears to change from a spinel-lherzolite type for the middle Miocene to a garnet-lherzolite type for the upper Miocene-Pliocene magmas. The areal distribution of the volcanic products led to the recognition of approximately equivalent areas covered by volcanic rocks both in the eastern and in the western Puna borders. This indicates a broad arc, which was structurally controlled at the proto-Puna/Puna margins, whose geochemical differences are related with variations in crustal thicknesses and heterogeneous mantle sources from west to east.
KW  - Luingo caldera
KW  - Central Andes
KW  - Miocene volcanism
KW  - Southern Central Volcanic Zone
KW  - crustal thickness
Y1  - 2011
U6  - https://doi.org/10.1016/j.jvolgeores.2010.12.008
SN  - 0377-0273
VL  - 200
IS  - 3-4
SP  - 171
EP  - 191
PB  - Elsevier
CY  - Amsterdam
ER  -