Abstract The continental succession of the Cretaceous Chubut Group (Aptian-Maastrichtian) in the Golfo San Jorge Basin (GSJB), central extra-Andean Patagonia (Argentina) contains a high proportion of volcaniclastic input derived from explosive volcanism at the Andes Cordillera. Cutting records obtained from regionally distributed oil-wells distanced by hundreds of kilometers show a significant west-to-east decreasing in the proportion of tuffaceous components. These regional lithologic changes currently difficult the recognition of lithostratigraphic units both in the western Rio Mayo sub-basin (high tuffaceous content) and in the eastern basin center-offshore (low tuffaceous content). We use seismic sections and cutting records for: a) to study a basement intra-basin paleo-high in the Northern Flank (Rio Chico High) and b) to analyze the marginal basin substrate in offshore areas of the Northern Flank. The sedimentary record adjacent to the igneous-metamorphic Rio Chico High contains variable amounts of quartz and detrital muscovite, identified in marine, pre-rift sequences of Lower Jurassic age and within the continental units of the Chubut Group. Basement influence in the infill composition decreases both upward and away from the Rio Chico High, regarding the gradual burial of the paleo-high. Our data reveal that the igneous-metamorphic basement remained as a positive paleorelief compartmentalizing the basin and providing siliciclastic sediments at least during 100 millions of years, from early Jurassic to late Cretaceous, even before the beginning of the extensional phase that originated the basin in the uppermost Jurassic. Thus, the GSJB displays a spatially variable volcaniclastic record derived from the Andes, distorted by the presence of inherited morpho-structures that supply siliciclastic sediments provided from cratonic sources.

中文翻译：

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中生代沉积记录的时空变化，Golfo San Jorge 盆地（阿根廷巴塔哥尼亚）：安第斯与克拉通来源

摘要 位于安第斯山脉外巴塔哥尼亚中部（阿根廷）的 Golfo San Jorge 盆地 (GSJB) 白垩纪丘布特群 (Aptian-Maastrichtian) 的大陆序列包含来自安第斯山脉爆发性火山作用的高比例火山碎屑输入。从相距数百公里的区域分布油井获得的切割记录显示凝灰质组分的比例从西向东显着下降。这些区域岩性变化目前难以识别 Rio Mayo 次盆地西部（高凝灰质含量）和东部盆地中心-近海（低凝灰质含量）的岩石地层单元。我们将地震剖面和切割记录用于：a) 研究北翼 (Rio Chico High) 的基底盆地内古高地和 b) 分析北翼近海区域的边缘盆地基底。与火成岩变质的 Rio Chico High 相邻的沉积记录包含不同数量的石英和碎屑白云母，在下侏罗纪时代的海洋、裂谷前序列和丘布特群的大陆单元内发现。关于古高地的逐渐掩埋，地下室对填充成分的影响向上和远离里约奇科高地都降低。我们的数据显示，至少在从侏罗纪早期到白垩纪晚期的 1 亿年内，火成岩变质基底仍然是一个正古地貌，将盆地分隔开来并提供硅质碎屑沉积物，甚至在起源于侏罗纪最上层盆地的伸展阶段开始之前。因此，GSJB 显示了源自安第斯山脉的空间可变火山碎屑记录，由于存在提供克拉通来源提供的硅质碎屑沉积物的继承形态结构而扭曲。