Abstract The Yaguari and the Buena Vista formations from Uruguay are historically correlated to the Brazilian Rio do Rasto and Sanga do Cabral formations, respectively, as they have some lithostratigraphic similarities, indicating a Permo-Triassic or even Triassic age of the Yaguari-Buena Vista succession. However, they differ in the fossil indexes that characterize the faunistic communities present in both countries. A paleomagnetic work was carried out on some sections of the Buena Vista and the Yaguari formations, as well as on some layers of bentonites, underlying the Buena Vista sediments. The alternating field and thermal demagnetization procedures revealed both normal and reversed magnetization components, but the samples showed evidence of secondary magnetic minerals and possibly remagnetizations. The calculated paleomagnetic pole for the Yaguari-Buena Vista Formation plots near to the poles for the Choiyoi magmatism that is believed to be responsible for the bentonite accumulation, it is also in agreement with other Permian paleomagnetic poles for South America. Based on the paleomagnetic results, the available radiometric data for the bentonites, and the fossiliferous content, a Late Permian (Lopingian) age is assigned to the Yaguari-Buena Vista rocks.

中文翻译：

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乌拉圭古生代 Yaguarí-Buena vista 序列的年龄限制：古地磁和古生物信息

摘要 乌拉圭的 Yaguari 和 Buena Vista 地层在历史上分别与巴西的 Rio do Rasto 和 Sanga do Cabral 地层相关，因为它们在岩石地层学上有一些相似之处，表明 Yaguari-Buena Vista 层序属于二叠纪-三叠纪甚至三叠纪时代. 然而，它们在表征两国存在的动物群落的化石指数方面有所不同。对布埃纳维斯塔和 Yaguari 地层的一些部分以及布埃纳维斯塔沉积物下面的一些膨润土层进行了古地磁工作。交变磁场和热退磁程序显示出正常和反向磁化分量，但样品显示出次生磁性矿物和可能再磁化的证据。Yaguari-Buena Vista 组计算出的古地磁极靠近被认为是膨润土堆积的 Choiyoi 岩浆活动的极地，它也与南美洲其他二叠纪古地磁极一致。根据古地磁结果、可用的膨润土辐射测量数据和化石含量，Yaguari-Buena Vista 岩石属于晚二叠世（Lopingian）时代。