Abstract The Cambrian Meson Group represents the first infill stages of the NW Argentina Paleozoic basin, given after the major orogenic event represented by the Tilcaric orogenic phase. This unit extends for several hundred kilometers along the Eastern Cordillera in the provinces of Salta and Jujuy, but its age is poorly constrained due to the paucity of fossil evidence and scarce geochronological data. U–Pb LA-ICP-MS geochronological studies were carried out on detrital zircons from the Lizoite, Campanario and Chalhualmayoc formations, that make up the Meson Group, in outcrops in the Santa Victoria sub-basin in northernmost Argentina. Maximum depositional ages of 524.8 ± 4.1, 519.7 ± 2.4 and 508.6 ± 1.7 Ma were obtained for these formations, respectively. These new data, together with previous detrital zircon ages from southernmost outcrops of this Group, points to a possible diachronism in deposition, with younger ages towards the south. In our studied units, a dominant peak of Cambrian to late Ediacaran zircons is characteristic for the three formations, although a somewhat larger contribution from older crystals is observed in the Campanario and Chalhualmayoc formations. This pattern is similar to most other reported detrital zircon age spectra for the Meson Group along the basin. Published paleomagnetic data for the Campanario Formation indicates a very strong reverse magnetic polarity bias, which allows us to infer three more likely intervals for the deposition of this formation (roughly 512–510, 509–505 and 497-493 Ma). These three alternatives are analyzed with respect to either major diachronous or roughly synchronous deposition of the Meson Group sediments across the whole basin. Published magnetic fabric data for the Campanario Formation at three distant localities suggest possible paleocurrent directions from W to E.

中文翻译：

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基于碎屑锆石 U-Pb 年代学和磁极性偏差的寒武纪介子群（阿根廷西北部）的年龄限制

摘要 寒武纪介子群代表了阿根廷西北部古生界盆地的第一次充填阶段，在以提尔卡里造山期为代表的主要造山事件之后给出。该单元沿萨尔塔省和胡胡伊省的东科迪勒拉山脉延伸数百公里，但由于缺乏化石证据和地质年代学数据，它的年龄限制很差。U-Pb LA-ICP-MS 年代学研究是对来自构成介子群的 Lizoite、Campanari 和 Chalhualmayoc 地层的碎屑锆石进行的，这些锆石位于阿根廷最北端的 Santa Victoria 次盆地的露头中。这些地层的最大沉积年龄分别为 524.8±4.1、519.7±2.4 和 508.6±1.7 Ma。这些新数据，与该组最南端露头的先前碎屑锆石年龄一起，表明沉积可能存在历时性，南部年龄较小。在我们研究的单元中，寒武纪到埃迪卡拉纪晚期锆石的主峰是三种地层的特征，尽管在 Campanario 和 Chalhualmayoc 地层中观察到来自较旧晶体的贡献稍大一些。这种模式类似于大多数其他报告的沿盆地介子群的碎屑锆石年龄谱。已发表的 Campanario 地层古地磁数据表明存在非常强的反向磁极偏差，这使我们能够推断出该地层沉积的三个更可能的间隔（大约 512-510、509-505 和 497-493 Ma）。这三个备选方案是根据整个盆地中介子群沉积物的主要历时沉积或大致同步沉积来分析的。在三个遥远地点发布的 Campanario 地层的磁性结构数据表明可能的古海流方向是从 W 到 E。