巴西东南海岸晚白垩世碱性岩浆活动:新的古地磁资料和时代约束

IF 1.3 4区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Brazilian Journal of Geology Pub Date : 2023-05-29 DOI:10.1590/2317-4889202320220061

M. Ernesto, M. Raposo

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The Late Cretaceous alkaline magmatism in the SE Brazilian coast: new paleomagnetic data and age constraints

Alkaline dikes from the Santos-Rio de Janeiro coast, SE Brazil, mainly from São Sebastião and Búzios islands, yielded a Late Cretaceous paleomagnetic pole (SR) located at 319.7°E 81.2°S (N = 44, A 95 = 3.0°, k = 44). This pole includes some sites of alkaline stocks from São Sebastião Island of the same age and supersedes the previous pole for this island. To match the available radiometric ages and the prevailing normal polarity remanence of the rocks with the geomagnetic polarity time scale, the SR pole is placed at 84 Myr. Another group of alkaline rocks, dikes located mainly in Rio de Janeiro, was assigned an age of less than 70 Myr. The ages of the Poços de Caldas, Itatiaia, and Passa Qua-tro paleomagnetic poles are also discussed based on available radiometric data. Assuming a rigid plate, the SR pole indicates the southward movement of about 7° with virtually no rotation between 100 and 84 Myr. From approximately 84 to 70 Myr, a clockwise rotation of 8° is postulated, with slight variation in latitude.

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来源期刊

Brazilian Journal of Geology GEOSCIENCES, MULTIDISCIPLINARY-

CiteScore

3.20

自引率

7.10%

发文量

审稿时长

11 weeks

期刊介绍： The Brazilian Journal of Geology (BJG) is a quarterly journal published by the Brazilian Geological Society with an electronic open access version that provides an in-ternacional medium for the publication of original scientific work of broad interest concerned with all aspects of the earth sciences in Brazil, South America, and Antarctica, in-cluding oceanic regions adjacent to these regions. The BJG publishes papers with a regional appeal and more than local significance in the fields of mineralogy, petrology, geochemistry, paleontology, sedimentology, stratigraphy, structural geology, tectonics, neotectonics, geophysics applied to geology, volcanology, metallogeny and mineral deposits, marine geology, glaciology, paleoclimatology, geochronology, biostratigraphy, engineering geology, hydrogeology, geological hazards and remote sensing, providing a niche for interdisciplinary work on regional geology and Earth history. The BJG publishes articles (including review articles), rapid communications, articles with accelerated review processes, editorials, and discussions (brief, objective and concise comments on recent papers published in BJG with replies by authors). Manuscripts must be written in English. Companion papers will not be accepted.