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沉积物厚度、内部结构、平均海拔及布格重力的区域变化,确定了一个邻近中安第斯山的4组分前陆盆地体系。这个盆地的起绐部分位于东 Subandean 带和 Chaco 平原的最西部,此处1～3km 的新生代沉积物覆盖在安第斯造山楔活动褶皱冲断层之上。楔顶沉积物向克拉通方向过渡为前渊沉积带,该沉积带包括一个向 Chaco 平原中—东部宽缓前隆变薄(局部尖灭)的3～4km 厚的沉积柱。前隆下伏于前寒武系—中生界岩石之下,为薄的第四系冲积物所覆盖。前隆以东,Pantanal 湿地之下薄的浅碟状堆积物代表后隆沉积带。在中安第斯山也可以识别这4个沉积带的古代对应物,说明现代的盆地构型是一个复合造山楔和前陆盆地体系自晚白垩世—古新世连续向东迁移的结果。
Sediment thickness, internal structure, mean elevation and Bouguer gravity, a 4-member foreland basin system adjacent to the Central Andes was identified. The basins of this basin are located in the eastern Subandean Belt and the westernmost part of the Chaco plain where 1 ~ 3 km of Cenozoic sediments overlie the active fold-thrust Andean orogenic wedge. The wedge top sediments transition to the craton direction into a foredeep sedimentary belt that includes a 3 to 4 km thick sedimentary column broadly attenuated (locally pinned) toward the middle-eastern part of the Chaco Plain. Precambar underlies Precambrian-Mesozoic rocks and is covered by thin Quaternary alluvial deposits. The thin shallow disc-shaped deposits under the Pantanal wetlands, east of Pre-Lung, represent the post-uplift sediments. The ancient counterparts of the four sedimentary belts can also be identified in the Mid-Andes, indicating that the modern basin configuration is the result of a continuous continuous easterly-foreland basin migration from the Late Cretaceous to the Paleocene.