Fluid-rock interaction during subsolidus microtextural development of alkali granite as exemplified by the Saertielieke pluton,Ulungur of the northern Xinjiang,China
会议名称：《中国科学院地质与地球物理研究所2002学术年会》
会议日期：2002年
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
关 键 词：Oxygen isotope Perthitic alkali feldspar Secondary arfvedsonite Deformation of quartz Alkali granite
摘 要：Three lithological GroupsⅠ(medium-grained,with magmatogenic arfvedsonite),Ⅱ(medium-grained,with secondary arfvedsonite) andⅢ(fine-grained,with magmatogenic arfvedsonite) are identified in the Saertielieke alkali granite pluton,Ulungur of the northern Xinjiang,China.A weak negative correlation between the O values of alkali feldspar and quartz separates from each group,and the distinctly lower O values of alkali feldspar separates from GroupsⅠandⅡthan those from GroupⅢare interpreted in terms of superimposed closed-system and open-system isotope exchange.A small amount of locally exsolved magmatic fluid is involved in the development of the perthitic texture in alkali feldspar at～400℃that results in a volume increase and,hence,causes quartz *** microtextural changes promote the closed-system oxygen isotope exchange between quartz and alkali feldspar that causes a dispersion in the quartz O ***,the distinctly lower O values of alkali feldspar and secondary arfvedsonite coupled with their microtextural characteristics indicate that meteoric-derived water plays an important role in the further development of alkali feldspar exsolution texture at T400℃and directly causes secondary arfvedsonite *** estimated relative exchange rates k/k/k of～10/100/1 for GroupsⅠandⅢ,and～10/100/100 for GroupⅡsuggest that alkali feldspar,quartz,and secondary arfvedsonite have exchanged with meteoric-derived water mainly via dissolution-reprecipitation,whereas magmatogenic arfvedsonite has exchanged via diffusion.