Abstract At ~3500 m above sea level in the Eastern Andean Cordillera, Quebrada Honda Basin exposes more than 300 m of middle Miocene sedimentary strata, developed on distal alluvial fan sediments interstratified with volcanoclastic deposits, overlying Paleozoic basement. These deposits are rich in exotic vertebrate fauna adapted to a wetter and warmer climate at lower paleoelevation, as contrasted with the present high-elevation cold and dry Andean conditions. This study provides new magnetostratigraphic and 40Ar/39Ar age control of the Quebrada Honda, Rio Rosario and Huayllajara fossiliferous areas, demonstrating that they are 13.1–12.4 Ma. Part of the succession evidences cyclical deposition of calcretes and reddish mudstones which may be a response to precessional orbital-forcing climatic processes. Paleomagnetic measurements show a significant clockwise tectonic rotation related to postdepositional tectonism, associated with evidence of an important uplift after the deposition of Quebrada Honda sediments. This uplift of the Andean Eastern Cordillera was associated with the formation of the Subandean fold-thrust belt and the development of the Amazon and La Plata drainage basins. Proposed uplift rates of >200 m/Ma are compatible with well-established rates of uplift recorded in contemporaneous alpine sections.

中文翻译：

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来自 Quebrada Honda（玻利维亚）的中新世陆地沉积物和化石脊椎动物的年代学

摘要 在东安第斯山脉海拔约 3500 m 处，Quebrada Honda 盆地暴露了超过 300 m 的中中新世沉积地层，该地层发育在与火山碎屑沉积物夹层的远端冲积扇沉积物上，覆盖在古生代基底上。与目前高海拔寒冷干燥的安第斯山条件形成对比，这些矿床富含外来脊椎动物群，它们适应了较低古海拔的湿润和温暖气候。这项研究提供了 Quebrada Honda、Rio Rosario 和 Huayllajara 化石区的新磁地层学和 40Ar/39Ar 年龄控制，证明它们是 13.1-12.4 Ma。部分序列证明了钙质混凝土和红色泥岩的周期性沉积，这可能是对进动轨道强迫气候过程的反应。古地磁测量显示与沉积后构造作用相关的显着顺时针构造旋转，与 Quebrada Honda 沉积物沉积后重要隆升的证据有关。安第斯东科迪勒拉的这种隆起与 Subandean 褶皱逆冲带的形成以及亚马逊和拉普拉塔流域的发展有关。建议的 >200 m/Ma 的抬升率与同期高山部分记录的公认抬升率相一致。安第斯东科迪勒拉的这种隆起与 Subandean 褶皱逆冲带的形成以及亚马逊和拉普拉塔流域的发展有关。建议的 >200 m/Ma 的抬升率与同期高山部分记录的公认抬升率相一致。安第斯东科迪勒拉的这种隆起与 Subandean 褶皱逆冲带的形成以及亚马逊和拉普拉塔流域的发展有关。建议的 >200 m/Ma 的抬升率与同期高山部分记录的公认抬升率相一致。