EVIDENCE FROM BOREHOLE SAMPLES FOR THE ROLE OF ACCESSORY MINERALS IN LOWER-CRUSTAL CONDUCTIVITY
EVIDENCE FROM BOREHOLE SAMPLES FOR THE ROLE OF ACCESSORY MINERALS IN LOWER-CRUSTAL CONDUCTIVITY
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DOI：
10.1038/367059a0
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发表时间：
1994-01-06
期刊：
影响因子：
64.8
通讯作者：
WILL, G
中科院分区：
文献类型：
--
作者：
DUBA, A;HEIKAMP, S;WILL, G
根据地球物理测量结果推断，下陆壳具有高导电性，这一点无法用简单的解释来解释。孔隙饱和盐水2和相互连接的碳膜3 -5都被认为是导电途径，但它们的相对重要性仍然不确定，并且可能因地而异6。到目前为止，在实验室中解决这个问题的尝试不得不依赖于从地表岩石中收集的变质岩样品7 -10。 虽然这些岩石几乎可以肯定起源于下地壳，但在它们迁移到地表和在地表停留期间的化学蚀变可能影响了它们的导电特性。在这里，我们报告的原始地壳岩石的电导率数据恢复深度达4.6公里的KTB钻孔在德国南部。我们的研究结果表明，如Fe-Ti氧化物和硫化物的副相的导电性可以提高，甚至超过，由盐水流体产生的高导电性。
THE high electrical conductivity of the lower continental crust, as inferred from geophysical measurements1, has defied a simple explanation. Both pore-saturating brines2 and interconnected carbon films3-5 have been proposed as conducting pathways, but their relative importance remains uncertain, and may vary from place to place6. So far, attempts to address this question in the laboratory have had to rely on samples of metamorphic rock collected from surface exposures7-10. Although these rocks almost certainly originated in the lower crust, chemical alteration during their transport to, and residence at, the surface is likely to have affected their conducting properties. Here we report conductivity data for pristine crustal rocks recovered from depths of up to 4.6 km in the KTB boreholes in southern Germany. Our results show that the electrical conductivity of accessory phases such as Fe-Ti oxides and sulphides can enhance, or even surpass, the high conductivity produced by saline fluids.