Tarduno J A, Cottrell R D, Smirnov A V
Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, 14627, USA.
Science. 2001 Mar 2;291(5509):1779-83. doi: 10.1126/science.1057519.
Recent numerical simulations have yielded the most efficient geodynamo, having the largest dipole intensity when reversal frequency is low. Reliable paleointensity data are limited but heretofore have suggested that reversal frequency and paleointensity are decoupled. We report data from 56 Thellier-Thellier experiments on plagioclase crystals separated from basalts of the Rajmahal Traps (113 to 116 million years old) of India that formed during the Cretaceous Normal Polarity Superchron. These data suggest a time-averaged paleomagnetic dipole moment of 12.5 +/- 1.4 x 10(22) amperes per square meter, three times greater than mean Cenozoic and Early Cretaceous-Late Jurassic dipole moments when geomagnetic reversals were frequent. This result supports a correlation between intervals of low reversal frequency and high geomagnetic field strength.
近期的数值模拟已经得出了最有效的地球发电机模型，当反转频率较低时，该模型具有最大的偶极强度。可靠的古强度数据有限，但迄今为止表明反转频率和古强度是解耦的。我们报告了对从印度拉杰马哈尔陷阱玄武岩（形成于白垩纪正极性超期，距今1.13亿至1.16亿年）中分离出的斜长石晶体进行的56次热退磁实验的数据。这些数据表明，时间平均古地磁偶极矩为12.5±1.4×10²²安培每平方米，是地磁反转频繁的新生代及早白垩世—晚侏罗世平均偶极矩的三倍。这一结果支持了低反转频率区间与高地磁场强度之间的相关性。
