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由大陆反射剖面法国际联合组织(COCORP)通过新墨西哥的格兰得河裂谷进行了成功的地震测深以后,一九七七年又在这一地区作了8个磁大地电流点。MT 点位的确定是为了全面研究一个很强的反射地震波.地震波与先前用微地震观测结果所解释的20公里深处的岩浆峒有关。将 Rio Grande 裂谷以内的和过渡到裂谷的这些 MT 点引起的结果与在西伯利亚东部的 Baikol 裂谷、东非裂谷和德国的莱茵河地堑所得类似测深结果进行了对比。对比内容包含实际的 MT 测深数据和几个研究人员发表的地电解释,几个裂谷本身内取得的所有解释有一个共同的特征.那就是在不到30公里深处被模拟有一个低电阻率地带(50 ohm—m).该导电层在邻近地区内没有被观察到。经实验室测量证实,当大量汽孔流体以增高的地热梯度存在时,这样一导电带是能形成的.地热梯度是由结晶基底的局部溶化而引起的。考察到所有因素。包括热液交待的成分,在温度低到500℃的潮湿花岗岩中是可能出现大规模的电阻率减小的。Rio Grande 裂谷测深的一维解释在20公里深处没有显示任何不连续。代之的是到导电层位的深度似乎接近或小于10公里。这样一个电介面仍可能是由深处的高温岩浆(～900℃)引起的;只要有温变低到大约600℃局部溶化的很小连接部分和/或温度也较低(～500℃)的导电含水矿(如闪岩)都可以导致较大幅度的导阻率减小。Rio Grande 裂谷火山岩含有被推测为起源于地表较小深度(可能低于10公里)的捕虏包体,它明显地和闪石相连系。Rio Crande 裂谷成果表明裂谷带以内变化相当大并显露出需要进行三维解释。任一广泛的 MT 研究如果缺乏三维条件都将给计算地壳导电带的电阻率绝对值增加一些疑难.
After successful seismic sounding by the Continental Reflecting Section International Union (COCORP) through the Grand River Rift in New Mexico, eight more magnetic earth current points were made in this area in 1977. The MT site is determined in order to conduct a thorough study of a strong reflected seismic wave, which is related to magma 20 at a depth of 20 km previously explained by microseismic observations. The results from these MT points within the Rio Grande Rift and into the rift are compared with similar sounding results from the Baikol Rift, East African Rift and Germany’s Rhine graben in eastern Siberia. The comparison includes actual MT sounding data and geoelectric interpretation by several researchers, and all of the explanations gained by several rifts themselves have a common characteristic that is simulated at a depth of less than 30 km with a low resistance Rate zone (50 ohm-m). This conductive layer was not observed in the adjacent area. It has been confirmed by laboratory measurements that such a ribbon can be formed when a large amount of vapor is present in an elevated geothermal gradient, which is caused by local dissolution of the crystalline substrate. Examines all the factors. Including the composition of hydrothermal fluids, large-scale resistivity reduction is likely to occur in moist granites as low as 500 ° C. The one-dimensional interpretation of the Rio Grande rift sounding did not show any discontinuities at a depth of 20 km. Instead, the depth to the conductive layer seems close to or less than 10 km. Such a dielectric surface may still be caused by deep, high-temperature magma (~ 900 ° C); as long as there is a small junction where the temperature drops to about 600 ° C and / or the temperature is low (-500 ° C) Conductive hydrous mines, such as amphibolite, can lead to a greater reduction of the resistivity. Rio Grande rift volcanic rocks contain captive inclusions presumed to have originated at a lesser depth (perhaps less than 10 km) above the Earth’s surface and are clearly associated with amphibole. The results of the Rio Crande rift show considerable variation within the rift zone and reveal the need for a three-dimensional interpretation. Any extensive MT study without a three-dimensional condition would give some difficulty in calculating the absolute value of the resistivity of the crustal conductive strip.