Pre-Cretaceous tectonic evolution of the Pacific plate and extension of the geomagnetic polarity reversal time scale with implications for the origin of the Jurassic Quiet Zone
Pre-Cretaceous tectonic evolution of the Pacific plate and extension of the geomagnetic polarity reversal time scale with implications for the origin of the Jurassic Quiet Zone
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DOI：
10.1016/0040-1951(88)90275-2
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发表时间：
1988-12
期刊：
影响因子：
2.9
通讯作者：
D. Handschumacher;W. Sager;T. Hilde;D. R. Bracey
中科院分区：
文献类型：
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作者：
D. Handschumacher;W. Sager;T. Hilde;D. R. Bracey
在西太平洋磁强附近，绘制了海底扩张引起的线状磁异常。新的航磁数据可以更准确地绘制M21至M28的磁场亮度，并能够识别侏罗纪“安静带”的低振幅磁力线。这些线条是由M29之前的磁场反转形成的。建立了一个修正的侏罗纪地磁极性反转时间尺度，其中19次反转的年龄大于M29，编号为M30-M38。这些地磁倒转将地磁极性的记录向后延长了大约8 Ma，并且是对平静带起源的重要限制。特别是，它们暗示侏罗纪不是一个恒定的正常极性时期，这是一些作者提出的解释。此外，他们对这一时期地磁场强度随年龄增加而系统减弱的模型提出了怀疑。北太平洋板块和太平洋-法拉龙-伊扎那吉（P-F-I）三重结的早期历史是通过绘制的磁等时线来追溯的。太平洋板块似乎是从一个小板块进化而来的，这个板块大约在180-188年前形成于凤凰-法拉隆-伊扎那吉三交界处附近，大约在17°N， 160°E（现在的坐标）。直到M21时期，北太平洋板块的演化相对简单，P-F-I三重连接点相对于太平洋向西北偏北移动。
Linear magnetic anomalies resulting from seafloor spreading were mapped in the vicinity of the magnetic bight in the western Pacific Ocean. New aeromagnetic data allowed the magnetic bight to be more accurately mapped from M21 to M28 and enabled the identification of low-amplitude magnetic lineations in the Jurassic “Quiet Zone”. These lineations were formed by magnetic field reversals prior to M29. A revised Jurassic geomagnetic polarity reversal time scale was constructed with nineteen reversals older than M29, numbered M30-M38. These reversals extend the record of geomagnetic polarity back in time by approximately 8 Ma and are important constraints on the origin of the quiet zone. In particular, they imply that the Jurassic was not a period of constant normal polarity, an explanation offered by some authors. Further, they cast doubt on a model of systematically decreasing geomagnetic field strength with increasing age during this period. The early history of the northern Pacific plate and Pacific-Farallon-Izanagi (P-F-I) triple junction was traced by mapped magnetic isochrons. The Pacific plate seems to have evolved from a small plate that formed near the Phoenix-Farallon-Izanagi triple junction about 180–188 m.y. ago at approximately 17°N, 160°E in present coordinates. Until M21 time the evolution of the northern Pacific plate was relatively simple and the P-F-I triple junction migrated north-northwest with respect to the Pacific.