藏东扎西则-察隅花岗岩带的氧同位素及成岩温度研究  

Oxygen Isotopes and Diagenetic Temperatures of the Grani toids in the Zhaxize Zayu Granite Belt in Eastern Xizang

作　　者：刁志忠[1] 

机构地区：[1]地矿部成都地质矿产研究所

出　　处：《沉积与特提斯地质》1997年第21期131-143,共13页Sedimentary Geology and Tethyan Geology

摘　　要：藏东扎西则－察隅花岗岩带的氧同位素及成岩温度研究刁志忠（地矿部成都地质矿产研究所）拉萨地块是以念青唐古拉山—怒江的一段为圆弧，以拉萨—墨脱—下察隅一线为直径的弧形地块，原为冈瓦纳古陆的一部分。地块内最高点南迦巴瓦峰高７７８２ｍ，以此为界可分为东、西两...The Δ value(δ 18 O quartz- δ 18 O plagioclase )of the granitoids in the Zhaxize Zayu granite belt in eastern Xizang(Tibet)is 1 75‰,approximating to the normal value. There is a gradual increase in δ 18 O quartz ,δ 18 O plagioclase and δ 18 O total values for the granitoids from granodiorite through biotite adamellite and biotite moyite to two mica granite.There are the δ 18 O total values of 8 1‰ to 10 5‰ for crust mantle syntectic granites;8 5‰ to 11‰ for crust mantle syntectic crust derived remelting reworking transitional granites,and 9‰ to 11 5‰ for crust derived remelting reworking granites. The diagenetic temperatures of the granitoids in the study area range between 700 and 400℃ obtained from the determination of the “mineral pair” of δ 18 O quartz δ 18 O plagioclase .The δ 18 O quartzwater and δ 18 O plagioclase values for granodiorite range from less than δ 18 O magmatic water value of 1 7‰ up to the range of δ 18 O magmatic water values of 7‰ to 9 6‰,with elevated diagenetic temperature curves;those for biotite adamellite are mostly within the range of δ 18 O magmatic water values of 7‰ to 9 6‰,with “M” shaped diagenetic tempearature curves;those for biotite moyite vary within and/or around the δ 18 O magmatic water values of 7‰ to 9 6‰,with “V” shaped diagenetic temperature curves,and those for two mica granites are mostly higher than 9 6‰,also with elevated diagenetic temperature curves. In conclusion,the addition of the δ 18 O rich remelted magmatic water or metamorphic water tend to result in the increase in diagenetic temperatures while the incorporation of the δ 18 O depleted metamorphic water or ground water and meteoric water may allow for the decrease in diagenetic temperatures during the diagenesis of the granitoids in this region.

关 键 词：氧同位素 成岩温度 黑云母二长花岗岩 花岗岩类 更长石 斜长石 岩浆水 钾长花岗岩 花岗闪长岩 花岗岩带 

分 类 号：P597[天文地球—地球化学]