• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >New paleomagnetic result from the Ethiopian flood basalts in the Abbay (Blue Nile) and Kessem gorges
【24h】

New paleomagnetic result from the Ethiopian flood basalts in the Abbay (Blue Nile) and Kessem gorges

机译：艾比湾（Blue Nile）和凯塞姆峡谷的埃塞俄比亚洪水玄武岩产生了新的古磁结果

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

New paleomagnetic investigations on the Ethiopian trap series have been undertaken at the Abbay and Kessem gorges in an attempt to better constrain the 30 Ma paleomagnetic pole of Africa. We sampled six thick massive basaltic lava flows, totaling 230 m, from Abbay Gorge and 10 lava flows, 180 m in thickness, from Kessem Gorge. Detailed paleomagnetic analyses disclosed that the carriers of the characteristic remanent magnetization (ChRM) are different in different lava flows. These are mostly titanomagnetites, titanomaghemites, and magnetite minerals with a broad range of coercive force and blocking temperatures. The heating and cooling susceptibility vs. temperature curves, many of which are irreversible, may indicate chemical remagnetization, notably low temperature maghemitization. Only one flow (KS04) with a clear 580 ℃ Curie temperature was apparently unaffected by chemical remagnetization occurred, this was shortly after emplacement of the lava flows. All of the flows sampled have normal polarity. However, a reversed component of low to medium coercive force and low to medium unblocking temperature occurs in flow KS01 at Kessem Gorge. The ChRM directions for the 16 sites are D = 3.1°, I = 5.8° (α_(95) = 12.7°). The paleomagnetic pole obtained from these is at λ = 83.0°N, φ = 193.3°E (A_(95) = 9.0°). Comparison with three previous studies of the traps shows remarkable consistency and a number of means are derived and discussed. Two final preferred poles for the traps are at λ = 79.0°, φ = 196.9°E (A_(95) = 2.8°) when all 112 published flows are used, and λ = 78.7°, φ = 209.4°E (A_(95) = 3.48°) when only the 76 flows from the four more recently analyzed sections are included. Both are compatible with the recent reference synthetic pole for Africa of Courtillot and Besse [J. Geophys. Res. (2002) in press]. In that sense, the Ethiopian trap pole is not anomalous and does not require more of a non-dipolar contribution than indicated by analyses of the global paleomagnetic data base covering the last few million years.
机译：为了更好地限制非洲30 Ma的古磁极，在Abbay和Kessem峡谷进行了有关埃塞俄比亚陷阱系列的新古磁研究。我们从阿贝峡谷（Abbay Gorge）采样了六块厚厚的玄武岩熔岩流，总计230 m，从凯西姆峡谷（Kessem Gorge）采样了十层熔岩流，厚度为180 m。详细的古磁分析表明，在不同的熔岩流中，特征剩磁（ChRM）的载流子是不同的。这些主要是钛磁铁矿，钛磁铁矿和磁铁矿，具有宽范围的矫顽力和阻断温度。加热和冷却的磁化率与温度的关系曲线（其中许多是不可逆的）可能指示化学磁化，尤其是低温磁化。熔岩流就位后不久，只有一个清晰的580居里温度的流（KS04）明显不受化学磁化作用的影响。所有采样的流量都具有正常极性。但是，在Kessem Gorge的流KS01中，出现了中低矫顽力和中低解锁温度的反向分量。 16个位点的ChRM方向为D = 3.1°，I = 5.8°（α_（95）= 12.7°）。由此获得的古磁极位于λ= 83.0°N，φ= 193.3°E（A_（95）= 9.0°）。与之前对陷阱的三项研究的比较表明，该方法具有显着的一致性，并推导并讨论了许多方法。当使用所有已发布的112个流量时，陷阱的两个最终首选极点为λ= 79.0°，φ= 196.9°E（A_（95）= 2.8°），以及λ= 78.7°，φ= 209.4°E（A_（ 95）= 3.48°），则仅包括来自最近分析的四个部分的76条流量。两者都与最近的Courtillot和Besse的非洲参考合成杆兼容[J.地理学。 Res。 （2002）。从这个意义上讲，埃塞俄比亚的陷阱极不是异常的，并且不需要比对过去几百万年的全球古地磁数据库进行分析所表明的更多的非偶极贡献。

著录项

相似文献

  • 外文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号