Water solubility in aluminosilicate melts of haplogranite composition at 2 kbar

Abstract

The compositional dependence of H20 solubility was investigated at 2 kbar and 800 °C in haplogranite melts (system SiO2-NaAISi3Os-KA1Si308 or Qz-Ab-Or). The sixteen investigated compositions contained 25, 35 or 45 wt.% normative Qz and various Ab/(Ab + Or ) ratios (0.15-0.92 ). Starting solid materials were anhydrous bubble-free glasses to which 10 wt.% H20 was added. The H20 contents of the isobarically quenched melts (glasses) were measured by Karl-Fischer titration.The results show that H20 solubility in aluminosilicate melts depends significantly upon anhydrous composition. The highest solubility values are obtained for the most Ab-rich melts. At a constant normative quartz content, the solubility of water decreases from 6.49 _+ 0.20 wt.% H20 for a composition Qz35AbroOro5 (normative composition expressed in wt.%) to 5.50 4-_ 0.15 wt.% H20 for a composition QzasAbloOr55. Along this join, the most significant changes are observed for Ab-rich melts whereas H20 solubility in Or-rich melts remains almost constant.The H20 solubility data imply that H20 is preferentially associated with the Ab component in aluminosilicate melts.Application of the results to natural granitic melts suggests that Na-rich, H20-saturated melts may be significantly less viscous than H20-saturated, K-rich melts.The temperature dependence of H20 solubility, investigated for composition Qz28Ab38Or34 at 2 kbar, is low. Increasing temperature from 750 ° to 1150 °C only causes a decrease in H20 solubility from 6.00 to 5.41 wt.% H20. These data are in agreement with previous data obtained for albite melts.

Effects of F, B2O3 and P2O5 on the solubility of water in haplogranite melts compared to natural silicate melts

“…The analytical precision for H20 is better than _+ 0.15 wt. % H20 (see Holtz et al 1992a). The analysis of the H20 content of some samples was duplicated and the variation is within this analytical precision (see Table 3, 2 kb experiments with samples HPG8-B4 and HPG8-B9).…”

“…This method consists in heating the sample progressively from 20 to 1300C using an induction furnace (detail on heating rates for the glasses is given by Holtz et al 1992a), the liberated H20 is then transported by a dry Ar stream in a titration cell. A detailed Westrich (1987).…”

“…The use of crushed material was preferred to single pieces since spluttering of the glass may occur by explosive liberation of H20 in such H20-poor glasses. Holtz et al (1992a) made tests for one haplogranite glass at 2 kb and 750 ~ (H20 content ~ 6 wt. % H20 ) and showed that the measured H20 content was similar using a single glass piece or roughly crushed material.…”

Petrology of the Syenites in Sancheong, Korea

“…따라서 산청지역의 섬장암은 주변에 분포하는 반 려암 또는 섬록암의 분화(분별)과정에 의해 형성되었 다고 보기 어렵다. 두 번째로 알칼리 교대작용 (Lee and Kim, 1968; and Bowen, 1958;Holtz et al, 1992). 연구지역의 섬장암에서는 많은 양의 K-장석이 나타나는 것도 이 것을 뒷받침하는 것으로 판단된다.…”

Experimental strategies for the investigation of low temperature properties in granitic and pegmatitic melts

“…We have begun an experimental program to help to fill in this picture 1993a,b;Holtz et al, 1992;1993a,b;Knoche et al, 1992;Bagdassarov et al, 1993;Chakraborty et al, 1993 ). This paper is an overview of some preliminary results.…”