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New African Lower Carboniferous paleomagnetic pole from intrusive rocks of the Tin Serririne basin (Southern border of the Hoggar, Algeria) 总被引：2，自引：0，他引：2
M.E.M. Derder B. Henry B. Bayou A. Ouabadi H. Bellon H. Djellit A. Khaldi M. Amenna K. Baziz A. Hemmi M.A. Guemache 《Tectonophysics》2006,418(3-4):189-203
A paleomagnetic study has been conducted on intrusive doleritic rocks cropping out within Devonian horizontal tabular formations of the Saharan craton (Tin Serririne basin, South of Hoggar shield). The 40K/40Ar dating of the dolerites gave an age of 347.6 ± 8.1 Ma, i.e. Tournaisian. The paleomagnetic data present three different directions. The first has a paleomagnetic pole close to the previous African poles of Permian age. This direction is therefore interpreted as a Permian remagnetization. The second direction, which is defined by both linear regression and remagnetization circles analysis, is considered as the primary magnetization. It yields a new African Tournaisian paleomagnetic pole (λ = 18.8° S, = 31.2° E, K = 29, A95 = 7.5°) very close to the Ben Zireg Tounaisian pole [Aifa, T., Feinberg, H., Pozzi, J.P., 1990. Devonian/Carboniferous paleopoles for Africa. Consequences for Hercynian geodynamics. Tectonophysics, 179, 288–304]. The third direction has intermediate orientation between those of the first or second directions and that of the Upper Cenozoic field. It is interpreted as related to a composite magnetization. This new Tin Serririne pole improves the APWP of Gondwana, for this key period of the evolution of the Pangea. This APWP confirms the previous paleogeographic reconstruction which shows that the pre-Hercynian ocean between Gondwana and Laurussia is still not close during the beginning of the Carboniferous. 相似文献
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华北蓟县中、上元古界古地磁研究 总被引：12，自引：0，他引：12
本文论述了华北蓟县中、上元古界地层标准剖面古地磁采样及实验室技术,采样地层的磁性特征,多磁成分的分析和测试结果.主要讨论了蓟县中、上元古界地层所代表的古地磁极性、极移路径和古纬度,并与北美大陆及华南(扬子)地块该时期的极移路径进行对比. 相似文献
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The paleomagnetic study of the Namurian of Reouina (28.9°N, 08.0°W) revealed the existence of two magnetization components, either juxtaposed or superimposed, besides a viscous component. The high blocking temperature component, carried by hematite, has a mean direction defined by D = 126.9° and I = 10.8°. It provides a Namurian paleomagnetic pole located at 28.4°S and 56.9°E (K = 642, A
95=1.7°). The second component is carried at least in part, by grains with blocking temperatures lower than 550°C. Though well defined, it consists of two superimposed components, the high unblocking temperature component with a likely Permian overprint. 相似文献
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Jeleńska M. Kądziałko-Hofmokl M. Żelaźniewicz A. 《Studia Geophysica et Geodaetica》2003,47(2):419-434
Studia Geophysica et Geodaetica - The paper presents the Apparent Polar Wander Path (APWP) for the West Sudetes for the period from Devonian to Carboniferous. The data used for construction of the... 相似文献
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A palaeomagnetic study has been carried out at 16 well-dated sites from four areas in central Spain (southeastern Iberian Massif and western Iberian Ranges) in order to constrain the Late Carboniferous to Late Triassic segment of the apparent polar wander path (APWP) of Iberia. 322 samples (218 with useful results) were collected from andesitic rocks at Atienza (287 ± 12 Ma) and from Triassic continental red beds at Molina de Aragón (Anisian-Ladinian), Alcaraz (Ladinian-Carnian), Alcázar de San Juan (Ladinian-Carnian) and Cuevas de Ayllón (Carnian-Norian). Comparison of the palaeomagnetic results from the western Iberian Ranges and from the Iberian Massif indicates that the investigated area of the Iberian Ranges forms part of Stable Iberia. The palaeomagnetic poles obtained in this study and a revision of previous palaeomagnetic data, discarding poles obtained from areas of doubtful stability, show together a gradual and consistent change in latitude and longitude resulting in a coherent segment of the APWP for the Late Carboniferous to Late Triassic time span. 相似文献
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试论前寒武纪变质岩古地磁研究的可行性：以闽北地区的研究为例 总被引：3，自引：1，他引：3
本文从变质作用与岩石矿物获得剩磁的关系和剩磁获得时间与同位素记年的相关性，岩石的形变对磁化方向的影响等方面讨论了前寒武纪变质岩古地磁研究的可行性；并列举部分国外前寒武纪早期岩石的例证；同时重点以闽北地区前寒武纪变质岩的古地磁结果为例，讨论了获得磁性可信性及其在地质构造方面的意义。 相似文献
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《International Geology Review》2012,54(11):1284-1295
Late Cretaceous–early Tertiary granites in the Gyeongsang Basin have distinctly different bulk-rock compositions. Calc-alkaline I-type metaluminous granites display petrographic features implying magma mixing, whereas A-type granites are hypersolvus and peralkaline. I-type plutons mainly consist of enclave-rich granodiorites and enclave-poor porphyritic granites typified by abundant plagioclase phenocrysts; these granitoids contain various mafic clots and magmatic/microgranular enclaves (MMEs). A-type bodies are perthitic alkali-feldspar granites characterized by interstitial annite + riebeckite-arfvedsonite. New SHRIMP-RG zircon U–Pb age dating of an I-type enclave-poor porphyritic granite and an A-type alkali-feldspar granite yielded ages of 65.7 ± 0.7 and 53.9 ± 0.3 million years, respectively. Based on prior geochronologic data and these contrasting ages of granitic magma genesis, SE Korea may have evolved tectonically from latest Cretaceous compression to late Palaeocene extension (i.e. orogenic collapse). The later part of the 66–54 Ma magmatic gap apparently includes the time of tectonic inversion in the SE Korean Peninsula, a far-field effect of the collision of the Indian subcontinent with Eurasia. This process is also reflected in the 69–52 Ma NNE-trending Eurasian apparent polar wandering path. 相似文献
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