Notes on the variation of magnetization within basalt lava flows and dikes
Notes on the variation of magnetization within basalt lava flows and dikes
复制标题
关于玄武岩熔岩流和岩脉内磁化强度变化的注释
DOI：
10.1007/bf00878944
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发表时间：
1976
影响因子：
2
通讯作者：
N. Petersen
中科院分区：
文献类型：
--
作者：
N. Petersen
玄武质岩石的磁性主要由所含的原生Fe-Ti氧化物控制。在固相线温度（约1000°C）下，这些初级氧化物的组成仅限于钛磁铁矿（Fe 3-xTixO 4）和铁镍铁矿（Fe 2-yTiyO 3）。对玄武岩（广义上）中原生铁钛氧化物的269种化学分析的检查得出钛磁铁矿的平均x =0.61（Tc=168°C），血红钛铁矿的平均y =0.89（Tc=−121°C）。如果对拉斑玄武岩、碱性玄武岩和安山岩进行区分，则可观察到x值的明显差异：拉斑玄武岩的平均值x =0.64（Tc=144°C），碱性玄武岩tsx =0.52（Tc=253°C），安山岩x =0.38（Tc=341°C）结晶环境和冷却速率是影响原生Fe-Ti氧化物矿物学随后变化的主要相关因素，从而产生磁性。这已被测试通过研究磁化强度的变化和它的一些参数在三个不同的玄武岩岩石单位：岩脉，180厘米，和两个熔岩流，3米和33米厚，分别。钛磁铁矿的粒度和氧化态控制着玄武岩单元磁化强度的变化。
SummaryThe magnetic properties of basaltic rocks are dominated by the contained primary Fe−Ti oxides. At solidus temperature (∼1000°C) the composition of these primary oxides is restricted to titanomagnetite (Fe3-xTixO4) and hemoilmenites (Fe2-yTiyO3). The examination of 269 chemical analyses of the primary Fe−Ti oxides in basalts (in sensu lato) gives an average ofx=0.61 (Tc=168°C) for the titanomagnetites andy=0.89 (Tc=−121°C) for the hemoilmenites. If distinction is made between tholeiites, alkali basalts and andesites, a clear difference for thex-values is observed: the average for tholeiitesx=0.64 (Tc=144°C), for alkali basaltsx=0.52 (Tc=253°C), for andesitesx=0.38 (Tc=341°C).Environment of crystallization and cooling rate are major interrelated factors influencing subsequent changes in the mineralogy of the primary Fe−Ti oxides and resulting magnetic properties. This has been tested by studying the variation of magnetization and some of its parameters in three different basalt rock units: a dike, 180 cm, and two lava flows, 3 m and 33 m thick, respectively. Grain size and oxidation state of the titanomagnetites control the variation of magnetization in these basalt units.