Strong Mutual Correlation Research Articles

Volatile and siderophile trace elements in anorthositic rocks from Fiskenaesset. West Greenland: comparison with lunar and meteoritic analogues

Seventeen trace elements (Ag, Au, Bi, Br, Cd, Cs, Ge, Ir, Ni, Rb, Re, Sb, Se, Te, Tl, U, Zn) were analyzed by radiochemical neutron activation and 13 other elements (Ce, Co, Cr, Eu, Fe, Hf, La, Lu, Na, Sc, Sm, Tb, Yb) by instrumental neutron activation in a total of 12 rocks from the layered anorthositic complex at Fiskenaesset, West Greenland and in the plagioclase-rich unbrecciated eucrite, Serra de Magé. Garnet anorthosite 84428, which has an unusually sodic plagioclase, is spectacularly enriched in Cs, K, Rb. Tl and, to a lesser degree, Te. This appears to be the result of later metasomatism and not a reflection of fractionation trends within the anorthositic complex. For the remaining Fiskenaesset rocks, a factor analysis yields 5 principal factors for linear data for 22 elements and 6 factors for data transformed (log, 3√, √) to give approximately normal distributions. Linear correlations are controlled by high values, whereas the logarithmic transform increases the influence of the lowest values. Enrichment of several elements in chromitite 132022 underlies linear Factor 1. Six of these elements Co, Cr, Fe, Ir, Ni, Zn and possibly Re are probably hosted by chromite. In other zones of the intrusion, different fractionation trends may be more important, since in the transformed analysis these elements divide between Factor 1 (Co, Zn, Ni, Fe) and Factor 4 (Ir, Cr and also Au). Linear Factor 2 reflects the strong mutual correlation between Tl, Rb and An, the anorthite content of plagioclase. Transformed Factor 3 emphasizes the anticorrelation of Na and Sm with An. The positive correlations of Cs, U and Ge (linear Factor 3; transformed Factor 2) are largely due to their concentration in later crystallizates, but enrichment in lower zone gabbros of high An content perhaps indicates concentration in minor or accessory cumulate minerals. Flat chondrite-normalized rare earth element patterns in several anorthosites (except for a small positive Eu anomaly) suggests that the Fiskenaesset magma was relatively unfractionated. Factor 4 (linear) and Factor 5 (transformed) reflects the geochemical coherence of Se and Te. The sympathetic enrichment of Sb and Cd in 3 rocks, resulting in Factor 5 (linear) and Factor 6 (transformed) may be due to the lack of a suitable Zn sulfide host for Cd. In 3 rocks of true anorthosite composition, 8 volatile elements show rather constant abundance when normalized to Cl chondrites (mean 4.2 ± 0.4% Cl), possibly suggesting that volatile-rich material was accreted late in the Earth's formation, perhaps after core segregation. These anorthosites are higher than lunar anorthosite 15415 by a factor of 58 ± 9 in volatile elements. Siderophile and chalcophile elements are much more variable in Cl-normalized abundances in both lunar and terrestrial anorthosites, but surprisingly give somewhat similar Earth/Moon abundance ratios. Volatile elements in terrestrial oceanic basalts and lunar mare basalts are not as uniformly abundant as in anorthosites. but nevertheless yield a similar Earth/Moon ratio of 44 ± 8. Volatile elements in Serra de Magé are more abundant than in lunar anorthosites, but lower than in terrestrial equivalents, averaging (3.6 ± 0.8) × 10 −3 C1.

Acid Loss in the Human Duodenum

Abstract We infused isotonic hydrochloric acid solutions of different p H into the proximal duodena of normal males. From samples aspirated at 15 cm and 30 cm downstream, we studied some relationships between acid load, acid loss, and chemical neutralization of acid in the duodenal lumen. At infusions with solutions of p H 1, p H 2, and p H 3, gain of fluid was recognized; the gain in the lumen increased progressively with increase in infused acid load. Duodenal fluid P CO 2 , levels increased markedly during p H 1 and p H 2 infusions; values up to 700 mm Hg were recorded. Osmolality of duodenal fluid decreased as a result of the neutralizing reaction between acid and bicarbonate during p H 2 and p H 1 infusions. The major changes were observed in the proximal duodenal segment; P CO 2 and osmolality reverted toward normal in the distal segment. Level of P CO 2 and degree of decrease in osmolality were similarly related to the amount of acid lost from the duodenum and exhibited a strong mutual correlation, reflecting their common origin in the chemical neutralization of HCl with endogenous bicarbonate. Almost all acid loss occurred in the proximal duodenal segment. If acid entered the distal segment it evoked a further secretion of fluid; otherwise, net absorption occurred in the segment.