An integrated palaeomagnetic, palaeointensity and Ar-40/Ar-39 investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands

doi:10.1093/gji/ggu481

	An integrated palaeomagnetic, palaeointensity and Ar-40/Ar-39 investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands
	Caccavari, Ana 1; Calvo-Rathert, Manuel 2; Goguitchaichvili, Avto 1; Soler, Vicente 3; He Huaiyu 4; Vegas, Nestor 5
刊名	GEOPHYSICAL JOURNAL INTERNATIONAL
	2015-03-01
卷号	200 期号:3 页码:1297-1316
关键词	Palaeointensity Palaeomagnetic secular variation Reversals: process time scale magnetostratigraphy Rock and mineral magnetism
ISSN号	0956-540X
DOI	10.1093/gji/ggu481
文献子类	Article
英文摘要	A detailed palaeomagnetic, rock-magnetic and palaeointensity study has been carried out on a Miocene volcanic sequence which consists of 39 consecutive lava flows recording a polarity transition in La Gomera (Canary Islands, Spain). In addition, new Ar-40/Ar-39 ages were obtained in two flows, yielding 9.63 +/- 0.06 Ma in the lower and 9.72 +/- 0.08 Ma in the upper part of the sequence. Palaeomagnetic results allowed determining a ChRM direction in all studied lavas: The 25 lowermost flows of the sequence display normal polarity directions and above, a sequence of 14 flows correspond to a transitional geomagnetic regime. If considered together with palaeomagnetic results from a previous study, which were obtained on the flows immediately overlying the upper part of the sequence analysed in this work, these results indicate that the reversal recorded in the Hermigua sequence corresponds to the normal to reverse C4Ar2n to C4Ar3r polarity transition. The lower-lying 25 normal-polarity flows yield a mean direction D = 359.6 degrees, I = 42.4 degrees (alpha(95) = 5.1 degrees; k = 33) which agrees well with the expected values. Above, a sequence of 14 flows displays a more irregular directional behaviour, including several transitional directions, suggesting the occurrence of a precursor to the transition. The presence of a virtual geomagnetic pole (VGP) cluster in the western Atlantic Ocean observed in this study coincides with previous records of Miocene transitions. Interestingly, this region corresponds to a near-radial flux centre of the present-day non axial dipole field. Angular dispersion of VGPs calculated for the 25 lowermost normal polarity flows of the sequence shows a lower than expected result. Palaeointensity determinations were carried out using a Thellier type double heating method. 27 of the 48 analysed samples measured yielded successful results. Mean VDMs mean values range from 1.1 +/- 0.5 to 8.8 +/- 0.9 x 10(22) Am-2. The intensity values decrease significantly on approaching the directional transitional zone, suggesting an earlier start of the polarity transition in the intensity record, typical of a decreasing axial dipole.
WOS关键词	EARTHS MAGNETIC-FIELD ; GEOMAGNETIC-FIELD ; ABSOLUTE PALEOINTENSITY ; GEOCHEMICAL EVOLUTION ; GRAN-CANARIA ; ROCK MAGNETISM ; REVERSAL ; INTENSITY ; VOLCANISM ; SEDIMENTS
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	OXFORD UNIV PRESS
WOS记录号	WOS:000350042800003
资助机构	Ministerio de Economia y Competitividad, Spain(CGL2012-32149) ; Ministerio de Economia y Competitividad, Spain(CGL2012-32149) ; Ministerio de Ciencia e Innovacion, Spain(CGL2011-23755 ; Ministerio de Ciencia e Innovacion, Spain(CGL2011-23755 ; European Regional Development Fund (ERDF) ; European Regional Development Fund (ERDF) ; CONACYT (Mexico)(257639) ; CONACYT (Mexico)(257639) ; CGL2010-14869) ; CGL2010-14869) ; Ministerio de Economia y Competitividad, Spain(CGL2012-32149) ; Ministerio de Economia y Competitividad, Spain(CGL2012-32149) ; Ministerio de Ciencia e Innovacion, Spain(CGL2011-23755 ; Ministerio de Ciencia e Innovacion, Spain(CGL2011-23755 ; European Regional Development Fund (ERDF) ; European Regional Development Fund (ERDF) ; CONACYT (Mexico)(257639) ; CONACYT (Mexico)(257639) ; CGL2010-14869) ; CGL2010-14869) ; Ministerio de Economia y Competitividad, Spain(CGL2012-32149) ; Ministerio de Economia y Competitividad, Spain(CGL2012-32149) ; Ministerio de Ciencia e Innovacion, Spain(CGL2011-23755 ; Ministerio de Ciencia e Innovacion, Spain(CGL2011-23755 ; European Regional Development Fund (ERDF) ; European Regional Development Fund (ERDF) ; CONACYT (Mexico)(257639) ; CONACYT (Mexico)(257639) ; CGL2010-14869) ; CGL2010-14869) ; Ministerio de Economia y Competitividad, Spain(CGL2012-32149) ; Ministerio de Economia y Competitividad, Spain(CGL2012-32149) ; Ministerio de Ciencia e Innovacion, Spain(CGL2011-23755 ; Ministerio de Ciencia e Innovacion, Spain(CGL2011-23755 ; European Regional Development Fund (ERDF) ; European Regional Development Fund (ERDF) ; CONACYT (Mexico)(257639) ; CONACYT (Mexico)(257639) ; CGL2010-14869) ; CGL2010-14869)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/86794]
专题	中国科学院地质与地球物理研究所
通讯作者	Caccavari, Ana
作者单位	1.Inst Geofis, Lab Interinst Magnetismo Nat, Morelia 58990, Michoacan, Mexico 2.Univ Burgos, EPS, Dept Fis, E-09006 Burgos, Spain 3.CSIC, Estn Volcanol Canarias, E-38206 Tenerife, Spain 4.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China 5.Univ Basque Country, Dept Geodinam, E-48940 Leioa, Bizkaia, Spain
推荐引用方式 GB/T 7714	Caccavari, Ana,Calvo-Rathert, Manuel,Goguitchaichvili, Avto,et al. An integrated palaeomagnetic, palaeointensity and Ar-40/Ar-39 investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands[J]. GEOPHYSICAL JOURNAL INTERNATIONAL,2015,200(3):1297-1316.
APA	Caccavari, Ana,Calvo-Rathert, Manuel,Goguitchaichvili, Avto,Soler, Vicente,He Huaiyu,&Vegas, Nestor.(2015).An integrated palaeomagnetic, palaeointensity and Ar-40/Ar-39 investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands.GEOPHYSICAL JOURNAL INTERNATIONAL,200(3),1297-1316.
MLA	Caccavari, Ana,et al."An integrated palaeomagnetic, palaeointensity and Ar-40/Ar-39 investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands".GEOPHYSICAL JOURNAL INTERNATIONAL 200.3(2015):1297-1316.