Abstract A paleomagnetic study was carried out in the Ordovician granitoids located in the northeastern North Patagonian Massif (NPM), close to Valcheta town (Rio Negro Province, Argentina), to provide new evidence on the relation between Patagonia and Gondwana during the Early Paleozoic. A paleomagnetic paleopole (VA1) was calculated out of 14 VGPs yielding a mean at 12.7°N, 275.5°E with K = 13.3 and A95 = 11.3°. A second result (VA2-remag), computed on other component found in 12 sites is located at 76.4°S, 84°E, K = 11.8 and A95 = 5°. VA2-remag fits very well with the Lower Jurassic segment of the apparent polar wander path of Gondwana. We interpret that it corresponds to a remagnetization carried mostly by high-coercitive components acquired during the hydrothermal activity associated with the Early Jurassic effusion of the Marifil-Chon Aike volcanic province. VA1 paleopole becomes consistent with the Gondwana apparent polar wander path at ∼450 Ma, after applying a 30–40° CCW rotation of the NPM to restore a V-shaped basin (Sierra Grande sea) opened before Permian-Triassic times. This rotation restores the paleogeographical position of the Ordovician granites of northeast NPM to the south of the Sierras Pampeanas aligning them with the eastern domain of the Famatinian orogenic and magmatic belt. VA1 paleopole suggests that the position of the NPM was close to the South American margin of Gondwana and separated by the Sierra Grande Sea from the Rio de la Plata-Kalahari cratons from, at least, late Ordovician times, which favors a para-autochthonous origin for the NPM. A former hypothesis suggesting a connection of the NPM and the TransAntarctic Mountains is unlikely for the late Ordovician according to our new data, which only allows an allochthonous NPM close to the Kalahari craton.

中文翻译：

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在古生代早期协调巴塔哥尼亚与冈瓦纳古大陆？北巴塔哥尼亚东北部 valcheta 花岗岩的古地磁

摘要 对位于北巴塔哥尼亚地块（NPM）东北部，靠近瓦尔切塔镇（阿根廷里奥内格罗省）的奥陶纪花岗岩进行了古地磁研究，为早古生代巴塔哥尼亚与冈瓦纳大陆的关系提供了新的证据。古地磁古极地 (VA1) 由 14 个 VGP 计算得出，平均值为 12.7°N、275.5°E，K = 13.3 和 A95 = 11.3°。第二个结果 (VA2-remag)，根据在 12 个地点发现的其他分量计算得出，位于 76.4°S、84°E、K = 11.8 和 A95 = 5°。VA2-remag 非常适合冈瓦纳大陆明显的极地漂移路径的下侏罗纪段。我们解释说，它对应于主要由与 Marifil-Chon Aike 火山省的早侏罗世积液相关的热液活动期间获得的高矫顽力成分进行的再磁化。在应用 NPM 逆时针旋转 30-40°以恢复二叠纪-三叠纪之前开放的 V 形盆地（格兰德海）后，VA1 古极与冈瓦纳大陆明显的极地漂移路径在 450 Ma 一致。这种旋转恢复了 NPM 东北部奥陶纪花岗岩的古地理位置，使它们与 Famatinian 造山带和岩浆带的东部区域对齐。VA1 古极地表明 NPM 的位置靠近冈瓦纳大陆的南美边缘，并且被格兰德海与拉普拉塔-卡拉哈里克拉通隔开，至少从奥陶纪晚期开始，这有利于准本土起源对于 NPM。根据我们的新数据，先前提出的 NPM 与跨南极山脉之间存在联系的假设不太可能发生在晚奥陶世，因为它只允许在喀拉哈里克拉通附近有一个外地 NPM。