地质速率计——矿物氧扩散的应用

doi:10.11867/j.issn.1001-8166.1997.05.0428

地球科学进展 ›› 1997, Vol. 12 ›› Issue (5): 428 -433. doi: 10.11867/j.issn.1001-8166.1997.05.0428

地质速率计——矿物氧扩散的应用

傅斌，郑永飞，魏春生

中国科学技术大学地球与空间科学系合肥 230026

收稿日期:1996-10-03 修回日期:1996-12-16 出版日期:1997-10-01
通讯作者: 傅斌,男,1968年8月出生,博士研究生,同位素地球化学专业。

APPLICATION OF OXYGEN DIFFUSION IN MINERALS TO GEOSPEEDOMETRY

FU Bin,ZHENG Yongfei,WEI Chunsheng

Department of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026

Received:1996-10-03 Revised:1996-12-16 Online:1997-10-01 Published:1997-10-01

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概述了同位素封闭体系内的矿物氧扩散和同位素交换机制及其在地质速率计上的应用。火成岩从高温冷却或变质岩从高峰变质温度冷却过程中，由于冷却速率不同，扩散作用导致的矿物晶体内部及晶粒间氧同位素再平衡也有所不同。通过实测岩石中各组成矿物氧同位素比值、模式含量和颗粒半径，据矿物氧扩散和同位素交换模型（Gileti模型和Eiler模型），可以估算出岩石的冷却速率。实例研究进一步阐明了扩散对氧同位素组成的影响及其在确定冷却速率上的应用。

关键词: 地质速率计, 矿物氧扩散, 氧同位素交换, 理论模型, 冷却速率

Oxygen diffusion in minerals and accompanied isotopic exchange inclosed systems are discussed with special application to geospeedometry. The extent of either intractrystalline or intercrystalline isotopic re equilibration by oxygen diffusion in minerals is ascribed to different cooling rates at which igneous rocks were cold from high crystallization temperature or metamorphic rocks from peak metamorphic temperature. According to the models of oxygen diffusion and isotopic exchange in minerals(i.e., Giletti model and Eiler model), the cooling rate of rocks can be calculated from the measured δ 18 O values, modal abundences and grain sizes of major rock forming minerals. Case studies are presented to elucidate the effect of oxygen diffusion on isotopic composition in minerals and its application to determination of cooling rate.

Key words: Geospeedometry, Oxygen diffusion, Isotope exchange, Theoretical models, Cooling rate, Rock-forming minerals.

中图分类号:

P597

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