A set up of an atmosphere-controlled furnace with stirring device, and effect of stirring on the crystallization behavior of basaltic melts.

构造了带搅拌装置的气控加热炉。加热器为Siliconit DSP-26（螺旋SiC加热器），半径56mm，长度300mm。该炉的特点是样品内部温度梯度小（30ml铂熔胶，上直径36mm）。炉内气氛由H2和CO2混合气体控制，温度由采用Pt-PtRh热电偶的自动晶闸管炉控制器控制。炉内温度控制在2ºC以内，样品现场氧逸度精度在0.5 log单位棒以内。搅拌Pt管直径为11mm，连接在陶瓷棒上，以5- 57rpm的速度旋转。从炉顶观察和取样可熔料中的熔体。样品是用陶瓷棒手工制作的，并在空气中淬火。我们用的是1778A。日本伊豆大岛的熔岩，作为起始材料。以前用静态线环法研究了结晶行为和元素分配关系。先在1250℃（高于液温约50℃）下不搅拌熔融10小时，然后在搅拌下恒速冷却。过热的基性熔体延迟斜长石成核已经有很好的记录（例如Gibb， 1974 Min）。杂志)。在本实验中，当旋转速率为57 rpm，冷却速率为10‰/小时时，斜长石的成核需要约35‰的过冷。在1150℃的样品中，不搅拌时斜长石的密度为4*10^4cm^<-3>，转速为57rpm时斜长石的密度为7*10^5cm^<-3>，表明搅拌对基性熔体中斜长石的成核有影响。

An atmosphere-controlled furnace with stirring device was constructed. The heater is a Siliconit DSP-26 (spiral SiC heater) with radius of 56mm and length of 300mm. The furnace is characterized by small temperature gradient within the sample (30ml platinum crusible, with upper diameter of 36mm). The furnace atmosphere is controlled by mixed gas of H2 and CO2, and the temperature is controlled by an automatic thyristor furnace controller using a Pt-PtRh thermocouple. The furnace temperature is controlled within 2ﾟC and oxygen fugacity is accurate within 0.5 log unit of bars at the sample site. The stirring Pt pipe is 11mm in diameter and is attached to ceramic rod, which is rotated at a rate of 5-57 rpm. The melt in the crusible is observed and sampled from the top of the furnace. The sampling was made manually by a ceramic rod, and quenched in air.We used a 1778A. D. lava of Izu-Oshima, Japan, as a starting material. The crystallization behavior and element partition relation was investigated by static wire-loop method previously. The sample is first melted at 1250ﾟC (about 50ﾟC above the liquidus temperature) for 10 hours without stirring, and then cooled at constant rate with stirring. Delay of plagioclase nucleation from overheated basaitic melts has been well documented (e. g. Gibb, 1974 Min. Mag.). In the present experiment, ca. 35ﾟC undercooling was requirred for plagioclase nucleation for rotation rate of 57 rpm at a cooling rate of 10ﾟC/hr. Plagioclase population density at 1150ﾟC sample is 4*10^4cm^<-3> for a run without stirring, and 7*10^5cm^<-3> for a run with rotation rate of 57rpm, indicating an effect of stirring on the nucleation of plagioclase in a basaitic melt.