Palaeomagnetism and geochronology of Oligocene and Miocene volcanic sections from Ethiopia: geomagnetic variability in the Afro-Arabian region over the past 30 Ma
Palaeomagnetism and geochronology of Oligocene and Miocene volcanic sections from Ethiopia: geomagnetic variability in the Afro-Arabian region over the past 30 Ma
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埃塞俄比亚渐新世和中新世火山剖面的古地磁学和地质年代学：过去 30 Ma 非洲-阿拉伯地区的地磁变化
DOI：
10.1093/gji/ggy517
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发表时间：
2019
影响因子：
2.8
通讯作者：
S. A. Gilder
中科院分区：
文献类型：
--
作者：
Lhuillier;S. A. Gilder
本文报道了埃塞俄比亚两个火山序列的古地磁和钾氩年代学结果。Belessa剖面的年代约为29-30 Ma，厚度约为1 km，与渐新世的非洲-阿拉伯圈闭有关，而Debre Sina剖面的厚度约为700 m，位于中新世的10-11和14-15 Ma两个时期。我们在Belessa附近取样了67个主要的玄武岩流，在Debre Sina附近取样了59个流纹岩-粗玄武岩流。从地球动力学的角度来看，Belessa层序的磁地层学证实，埃塞俄比亚圈闭的嵌入速度至少为1米/年，随着时间的推移，火山活动的体积可能会加速。为了深入了解过去30 Myr以来非洲-阿拉伯地区地磁场的演变，我们将我们的结果与以前在同一地区的研究相结合。子午线平面上的定向分布被拉长，与偶极子主导场的场模型相一致。代表古生代变化活力的虚地磁极的频散在10-30 Ma期间比过去5 Myr期间高出约50%。由于早渐新世的倒转频率比上新世-更新世低2倍以上，因此在近赤道地区，沙丘似乎不相关。这种明显的解耦是由于局部异常，还是只是时间上的零星现象，还是代表了地球动力学的一般特征，这仍然是一个悬而未决的问题。
We report palaeomagnetic and K–Ar geochronologic results of two volcanic sequences from Ethiopia. The Belessa section, dated around 29–30 Ma and spanning ∼1 km in thickness, is related to the Oligocene Afro-Arabian traps, whereas the ∼700-m-thick Debre Sina section was emplaced during the Miocene in two periods around 10–11 and 14–15 Ma. We sampled 67 flows of predominantly basaltic rocks near Belessa and 59 rhyolitic to trachybasaltic flows near Debre Sina. From a geodynamic viewpoint, the magnetostratigraphy of the Belessa sequence confirms that the Ethiopian traps were emplaced at a minimum rate of one meter per kyr, with a possible acceleration of the volume of volcanism over time. To provide insight into the evolution of the geomagnetic field in the Afro-Arabian region over the past 30 Myr, we combined our results with previous studies in the same area. Recentred directional distributions were elongated in the meridian plane, in coherence with field models for a dipole-dominated field. The dispersionSof the virtual geomagnetic poles, representative of the vigour of palaeosecular variation, was approximately 50 per cent higher during the 10–30 Ma interval than during the past 5 Myr. As the reversal frequencyfwas more than two times lower during the Early Oligocene than during the Plio-Pleistocene, it appears thatSandfare uncorrelated in this near-equatorial region. It remains an open question whether this apparent decoupling is ascribable to a local anomaly, is only sporadic in time, or represents a general feature of the geodynamo.
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影响因子：
5.3
作者：
Constable, Catherine;Korte, Monika;Panovska, Sanja
通讯作者：
Panovska, Sanja
也门渐新世火山的古地磁和 40Ar / 39Ar 地质年代学：对非洲-阿拉伯圈闭的时间和持续时间以及渐新世古磁场几何形状的影响
DOI：
--
发表时间：
2005
期刊：
影响因子：
--
作者：
P. Riisager;K. Knight;J. Baker;I. Peate;M. Al;Abdulkarim Al;P. Renne
通讯作者：
P. Renne
影响因子：
--
作者：
T. Kidane;V. Courtillot;I. Manighetti;L. Audin;P. Lahitte;X. Quidelleur;P. Gillot;Y. Gallet;J. Carlut;T. Haile
通讯作者：
T. Kidane;V. Courtillot;I. Manighetti;L. Audin;P. Lahitte;X. Quidelleur;P. Gillot;Y. Gallet;J. Carlut;T. Haile
$$^{40}Ar/^{39}Ar$$肯尼亚恩戈罗拉组岩地层和古地磁地层的年龄校准
DOI：
10.1086/629425
发表时间：
1990
期刊：
The Journal of Geology
影响因子：
--
作者：
A. Deino;L. Tauxe;M. Monaghan;R. Drake
通讯作者：
R. Drake
图尔卡纳熔岩的古地磁学
DOI：
--
发表时间：
1966
期刊：
影响因子：
--
作者：
P. Raja;T. Reilly;A. Mussett
通讯作者：
A. Mussett