外文翻譯---應用磁法勘探技術探查南非林波波河地區(qū)的地下情況

1、中文 中文 2546 2546 字附錄 附錄英文原文 英文原文Using the Magnetic Technique to Investigate the Subsurface in the Limpopo Region of South AfricaMitchell L. JohnsonJackson State UniversityAfricaArray 2009AbstractWe employed the magnetic t

2、echnique to take readings of the magnetic field in the Bushveld Complex. The Bushveld Complex is located in Limpopo, South Africa. The Bushveld Complex is known for its richness in natural resources. We are here to image

3、 a previously known dyke. This dyke has already been imaged by aeromagnetic data. Our ground magnetic survey will give one a better image of the dyke. Our survey consisted of 30 east-west lines that were 1000 meters long

4、, oriented perpendicularly to a previously known dyke, as well as 3 north-south lines that ran parallel to this geologic feature. The results do show the previously imaged dyke along with 3 smaller dykes. This data could

5、 be used for future mining exploration in the surveyed area. By knowing what is beneath the subsurface miners will be able to mine in a safe and resourceful way. IntroductionMagnetics is a branch of geophysics that studi

6、es how the properties or effects of magnetic fields change in different places on the Earth. (McCarthy and Rubdige 2005). The Earth’s magnetic field can be thought of as a point on a surface, though it is generated by th

7、e movement of the fluid core, which consists of molten rock called alike and were formed at about the same time. Magma from the Earth’s mantle that came to the surface made the Bushveld Igneous Complex. This continued to

8、 happen over a period of time. As the molten rock cooled over time, crystallization of different minerals at different temperatures lead to the formation layered structures were formed which are called reefs. One importa

9、nt layer is the Upper Group 2 (UG2) reef The UG2 contains has chromite, platinum, and the Merensky Reef. The Merensky Reef has with a width of 30 to 90 cm and the UG2 contains have almost 90% of the worlds known PGE rese

10、rves. Methods Several geophysical methods were employed to investigate the subsurface structure of the Bushveld Complex however, for this study, I will focus on the magnetic method. The magnetic method depends on Coulomb

11、’s Law, which describes the force generated by a magnetic field. 22 1 mr m m F ? ?In this equation, F is the force, m1 and m2 are the strengths of two magnetic poles, m is the magnetic permeability, and r is the distance

12、 between the two poles. (Burger et al., 2006) To collect the magnetic data, an instrument called a magnetometer is used. This instrument measures the strength of the magnetic field at a particular location. The magnetome

13、ter does not measure position, but handheld GPS units can be used to determine the measurement location. The magnetometer will not give a true reading if a reading is taken in the vicinity of metallic objects; therefore,

14、 readings should not be taken near railway lines, cars, houses and electric lines. These places and objects will change the magnetic field in the area. Also, the magnetometer operator should not carry metallic objects be

15、cause these objects will have an influence on the magnetic field. At our fieldsite, data was collected along a grid of GPS coordinates, consisting of 30 lines that were 1000 meters long, striking roughly perpendicular to