• 作者： 俞震甫
• 作者服務機構： 中央研究院地球科學研究所
• 中文摘要： 超高壓變質作用是指變質時壓力條件超過石英－柯石英平衡界線之變質作用。目前在世界上含有微鑽石及柯石英包裹體之地殼源超高壓岩石出露於五個大陸碰撞造山帶中，證實了地殼岩石可因大陸碰撞而隱沒至超過一百公里的地函深度。由實驗礦物／岩石學亦確立了與超高壓變質條件特別相關的一些礦物（群）。這些礦物（群）能保存於地表的溫壓條件，主要肇因於超高壓岩體的快速上升，以及上升時環境缺乏液相和持續的冷凍效應。由於在某些造山帶中，超高壓礦物（群）發現的地點相當侷限，因此實不易據以界定超高壓岩體的區域規模。此外，目前的資料亦顯示超高壓變質作用發生時，環境中水的活性應相當低，且變質液相中亦含有相當量的氬氣，造成超高壓礦物在形成時均含“超氬”而不利於氬氣定年。根據定年工作及變質溫壓的估計，超高壓變質岩體由地函探度上升至下地殼深度的速度應大於7-14釐米∕年；唯因缺乏一些關鍵性的控制條件，對超高壓岩體上升的地體構造機制模式，目前尚無定論。
• 英文摘要： The ultrahigh一Pressure（UHP）metamorPhism was defined as the metamorPhism oeeurring underPressure eonditions higher than the quartz－eoesite equilibrium eurve．Based on the diseovery of mierodiamondand eoesite inelusions，UHp metamorPhie roeks of crustal origin have been rePorted from five continent－collision orogenie belts around the world．This shows that crustal roeks can be subdueted to mantle dePths（＞100 km）during eontinental collision．Several minerals∕mineral assemblages charaeteristieally relevantto UHP conditions have also been established through exPerimental studies．A fast exhumation rate，theabsenee of a fluid Phase and the continuous refrigeration effeet during exhumation are required to PreserveUHP minerals at the Earth's surfaee．However，the restrieted oeeurrenee of UHP minerals makes it diffieultto confidently establish a regional seale for some UHP terranes．It was demonstrated that water activityin fluid Phase during UHP metamorPhism was low．“Excess Ar”was also shown to be commonlyincorPorated within UHP minerals，causing diffieulties in Ar geoehronology．Age dating of UHP rockscombined with Petrologic Pressure一temPerature studies revealed that the exhumation rate of UHP roeksfrom mantle dePths to the lower crustal level was higher than7一14 mm∕yr．The geodynamie model forthe exhumation mechanism（s）of these UHP terranes，however，remains eontroversial due to the laek ofkey constraints．
• 中文關鍵字： mineral inclusion; tectonic exhurnation; ultrahigh-pressure metamorphism
• 英文關鍵字： --