地球化学
地毬化學
지구화학
GEOCHIMICA
2001年
2期
163-168
,共6页
李一良%傅斌%郑永飞%赵彦冰
李一良%傅斌%鄭永飛%趙彥冰
리일량%부빈%정영비%조언빙
榴辉岩%麻粒岩%氧同位素%扩散交换%大别山
榴輝巖%痳粒巖%氧同位素%擴散交換%大彆山
류휘암%마립암%양동위소%확산교환%대별산
报道了大别造山带西南部湖北红安榴辉岩和罗田麻粒岩的氧同位素组成,并讨论了氧扩散作用对矿物氧同位素平衡的影响。结果得到,红安榴辉岩的全岩δ18O值为6.4‰~7.3‰,罗田黄土岭麻粒岩的全岩δ18O值为7.6‰~7.8‰,罗田惠兰山麻粒岩的全岩δ18O值为3.9‰。这些榴辉岩和麻粒岩全岩的氧同位素组成保持了峰期变质条件下的平衡分馏特征,得到的氧同位素温度对于红安榴辉岩为425~620℃,对于罗田麻粒岩为740~945℃。根据快速颗粒边界扩散模型计算的矿物对氧同位素温度不仅与大多数实测氧同位素温度一致,而且与岩石学测温结果相吻合。因此,这些岩石与东大别榴辉岩一样在形成后经历了快速冷却过程,退变质反应过程中没有外来流体加入。
報道瞭大彆造山帶西南部湖北紅安榴輝巖和囉田痳粒巖的氧同位素組成,併討論瞭氧擴散作用對礦物氧同位素平衡的影響。結果得到,紅安榴輝巖的全巖δ18O值為6.4‰~7.3‰,囉田黃土嶺痳粒巖的全巖δ18O值為7.6‰~7.8‰,囉田惠蘭山痳粒巖的全巖δ18O值為3.9‰。這些榴輝巖和痳粒巖全巖的氧同位素組成保持瞭峰期變質條件下的平衡分餾特徵,得到的氧同位素溫度對于紅安榴輝巖為425~620℃,對于囉田痳粒巖為740~945℃。根據快速顆粒邊界擴散模型計算的礦物對氧同位素溫度不僅與大多數實測氧同位素溫度一緻,而且與巖石學測溫結果相吻閤。因此,這些巖石與東大彆榴輝巖一樣在形成後經歷瞭快速冷卻過程,退變質反應過程中沒有外來流體加入。
보도료대별조산대서남부호북홍안류휘암화라전마립암적양동위소조성,병토론료양확산작용대광물양동위소평형적영향。결과득도,홍안류휘암적전암δ18O치위6.4‰~7.3‰,라전황토령마립암적전암δ18O치위7.6‰~7.8‰,라전혜란산마립암적전암δ18O치위3.9‰。저사류휘암화마립암전암적양동위소조성보지료봉기변질조건하적평형분류특정,득도적양동위소온도대우홍안류휘암위425~620℃,대우라전마립암위740~945℃。근거쾌속과립변계확산모형계산적광물대양동위소온도불부여대다수실측양동위소온도일치,이차여암석학측온결과상문합。인차,저사암석여동대별류휘암일양재형성후경력료쾌속냉각과정,퇴변질반응과정중몰유외래류체가입。
The oxygen isotope composition of single minerals from eclogite at Hong'an and granulite at Luotian in the
Southwest Dabie Mountains of Hubei Province were measured, respectively. The results were discussed in view of
the effect of oxygen diffusion on oxygen isotope equilibrium between minerals. The Gaoqiao eclogite at Hong'an has
whole-rock 818O values of 6.4‰ to 7.3%, Huangtuling felsic granulite at Luotian has whole-rock 818O values of
7.6% to 7.8%, and Huilanshan mafic granulite at Luotian has whole-rock δ18O values of 3.9%. Oxygen isotope
equilibrium fractionations have been preserved between the minerals at peak metamorphic conditions, yielding
oxygen isotope temperatures of 425℃ to 620℃ for the eclogite and 740℃ to 945℃ for the granulites. The fast
boundary diffusion model was applied to the minerals and corresponding oxygen isotope temperatures were
calculated, which are not only in agreement with most of the oxygen isotope temperatures measured for the
mineral-pairs, but also concordant with petrological temperatures. Therefore, both eclogite and granulite in
Southwest Dabie Mountains experienced a fast cooling process like the eclogites in East Dabie Mountains subsequent
to their formation, and there was no the significant introduction of exotic fluid to the high-pressure rocks in the
process of retrograde metamorphism.