MANTLE PLUMES CONTROL MAGNETIC REVERSAL FREQUENCY
MANTLE PLUMES CONTROL MAGNETIC REVERSAL FREQUENCY
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DOI：
10.1016/0012-821x(91)90091-u
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发表时间：
1991-12-01
影响因子：
5.3
通讯作者：
OLSON, P
中科院分区：
文献类型：
--
作者：
LARSON, RL;OLSON, P
磁反转频率与地幔柱活动在过去的150 Ma成反比。以大洋高原、海山链和大陆溢流玄武岩的体积生产率来衡量。这种逆相关性在长的白垩纪磁正常的“超时”，当地幔柱活动处于最大值时，尤其引人注目。我们认为地幔柱通过以下事件序列控制磁反转频率。地幔柱从核/幔边界上方的D”地震层上升，使D”变薄，为地幔柱提供燃料。这通过允许热量更快地穿过地核/地幔边界来增加地核冷却。然后，外核对流活动增加，恢复异常的热损失，导致磁反转频率下降，与α-2和α-ω-发电机的模型预测一致雅阁。当核心对流活动增加到临界水平以上时，就会产生磁超时。造成白垩纪超时的羽流活动脉冲导致核心热损失比现在的水平增加了约1200 GW。这对应于堆芯内焦耳热产生增加约120 GW。
Magnetic reversal frequency correlates inversely with mantle plume activity for the past 150 Ma. as measured by the volume production rate of oceanic plateaus, seamount chains, and continental flood basalts. This inverse correlation is especially striking during the long Cretaceous magnetic normal "superchron", when mantle plume activity was at a maximum. We suggest that mantle plumes control magnetic reversal frequency by the following sequence of events. Mantle plumes rise from the D" seismic layer just above the core/mantle boundary, thinning D" to fuel the plumes. This increases core cooling by allowing heat to be conducted more rapidly across the core/mantle boundary. Outer core convective activity then increases to restore the abnormal heat loss, causing a decrease in magnetic reversal frequency in accord with model predictions for both alpha-2 and alpha-omega-dynamos. When core convective activity increases above a critical level, a magnetic superchron results. The pulse of plume activity that caused the Cretaceous superchron resulted in a minimum increase in core heat loss of about 1200 GW over the present-day level. which corresponds to an increase in Joule heat production of about 120 GW within the core.