Abstract The Paleogene infill of the eastern Golfo San Jorge Basin, Patagonia, Argentina, is composed of marine (Salamanca Formation) and terrestrial (Grupo Rio Chico and lower Sarmiento Formation) deposits. The Rio Chico Group is a fluvial, pedogenically modified succession interlayered with eolian volcaniclastic deposits during the Eocene. Several authors have highlighted the stratigraphic significance and usefulness of strongly developed paleosols in the definition of sequence stratigraphic studies. Even though the area hosts abundant geological and paleopedological data, no large-scale (i.e., basin-scale) stratigraphic architectural correlation including paleosols and relationships within the sequence stratigraphic context had hitherto been carried out. By integrating previously published and unpublished data sets, this paper proposes a sequence stratigraphic framework for the middle Danian–middle Eocene successions of the eastern Golfo San Jorge Basin. Here, spatio-temporal changes in fluvial/alluvial architecture of the Paleogene infill allow us to define four depositional sequences (S), limited by sequence boundaries (SB) that internally presents a low-accommodation system tract (LAST), and a high-accommodation system tract (HAST). Part of these sequences occur as fining-upwards fluvial successions that are pedogenically modified on top by strongly developed paleosols, or are erosively overlain by the coarse-grained base of the following sequence without the development of well-developed paleosols. The sedimentological and paleopedological analysis of the four sequences identified for the early Paleogene infill of the basin indicates that the interplay between subsidence, base level, and climate controlled both fluvial style and landscape evolution, as well as soil development. Volcaniclastic supply also played a significant role, especially during the Eocene.

中文翻译：

---

地层结构和古土壤作为早期古近纪填充物在中南部巴塔哥尼亚、Golfo San Jorge 盆地、阿根廷巴塔哥尼亚的盆地对比工具

摘要 阿根廷巴塔哥尼亚 Golfo San Jorge 盆地东部的古近系填充物由海相（Salamanca 组）和陆相（Grupo Rio Chico 和下部 Sarmiento 组）沉积物组成。Rio Chico 群是始新世期间与风成火山碎屑沉积物夹层的河流、成土改造的层序。几位作者强调了强烈发育的古土壤在层序地层研究定义中的地层意义和有用性。尽管该地区拥有丰富的地质和古土壤学数据，但迄今为止尚未开展包括古土壤和层序地层关系在内的大规模（即盆地尺度）地层建筑对比。通过整合以前发布的和未发布的数据集，本文提出了东Golfo San Jorge盆地中大年-中始新世层序的层序地层框架。在这里，古近系填充物的河流/冲积结构的时空变化允许我们定义四个沉积序列 (S)，受内部呈现低调节系统域 (LAST) 的序列边界 (SB) 和高-住宿系统道（HAST）。这些层序的一部分以向上细化的河流层序形式出现，在上面被强烈发育的古土壤进行土壤改造，或者被以下层序的粗粒基底侵蚀覆盖，而没有发育良好的古土壤。对盆地早期古近纪填充物的四个序列的沉积学和古土壤学分析表明，沉降、基础水平和气候之间的相互作用控制了河流风格和景观演变以及土壤发育。火山碎屑供应也发挥了重要作用，尤其是在始新世期间。