百万巴级超高压与2000℃高温的获得及其实验地质意义

六十年代以来,地质科学研究的广度与深度有了明显的进展,其中一个重要方面,是自地表、地壳向地幔、地核扩展研究深度而开拓的深部地质领域。深部地质作用的研究,从方法到内容都具有显著特点,也有重要意义。作为运动着的天体之一的地球,其若干表部现象,与其深部作用有着密切联系。地球各部皆处于一定的温压状态,其本身即为一个复杂的温压系统。对地球从表部—深部—更深部进行系统的整体研究,必须装备和掌握从低压常温—高压高温—超高压高温的设备与技术。

THE SIGNIFICANCE OF THE ULTRA HIGH PRESSURE IN Mb AND THE HIGH TEMPERATURE OF 2000℃ IN EXPERIMENTAL GEOLOGY

The diamond anvil is a kind of new high pressure technology developed in recent years.The diamond cell Model DC-II used in our experiments is constructed and improved by the laboratory and workshop of the Institute of Geology,Academia Sinica,according to the data provided by Dr.H.K.Mao,the researcher of Carnegie Institute,It has a very small volume and the cell is designed after the Bridgman’s principle of opposed-anvil apparatus consisting of two flats parallel pressure faces of gem diamonds.The diamond anvil is mounted on cylindrical holders and piston which are squeezed together by a lever arm actuated by spring-loading mechanism.The sample is compressed into a film between two diamond flats under a high pressure,Pressure calibration is a critical field in high pressure technology.The ruby fluorescence method was developed in the years of the 70’s.The system of ruby fluorescence is composed of He-Cd laser,monochrometer and X-Y recorder.All equipments of our system are China-made.The measurements were made in the system in which the numerous ruby grains are excited to fluorescence with a focussed He-Cd laser beam of 25μ in diameter.By changing wavelength of the monochrometer,the fluorescence can be measured with photoelectric detector and X-Y recorder.We have determined in this way the static pressure up to 1.18 Mb.In the diamond anvil cell the high temperature is gained up to 2000℃ by using YAG laser,and the heating equipments is built up of YAG laser and microscope.According to our experiments under this temperature conditions the forsterite (Mg₂SiO₄) would be melted.The high pressure in million bars obtained in our laboratory is equivalent to the condition of the crust depth of 200 km,drawing near the lower mantle.This kind of pressure in combination with a high temperature of 2000-3000℃,makes us able to study the phases and properties of matter as well as its constitution in the earth interior.It is clear that the high pressure technology is of great significance in geoscience.