Tectonic Evolution and Sedimentary Filling of the Andean Foreland Basin in South America

According to the characteristics of the Pacific plate subduction plate boundary, the geometric variations of the Andes arc and back-arc foreland basin system, the Andean foreland basin system is generally divided into three tectonic domains. Based on the analysis of the tectonic-sedimentary evolution of typical sedimentary basins in the eastern piedmont of the Andes in South America, the tectonic evolution process of basins in different tectonic domains and the sedimentary filling characteristics of tectono-stratigraphy are summarized. The northern basins focus on the analysis of the Oriente Basin in Ecuador, which is composed of three tectono-sequences upwards, namely, the rift tectono-sequence, the continental margin tectono-sequence, and the retroarc foreland tectono-sequence. The foreland tectono-sequence has only one depozone characterized by the foredeep. The central basins focus on the analysis of the Ucayali Basin in Peru, which developed three types of prototype basins, namely rift basin, craton marginal basin and back-arc foreland basin. The tectonic compression at the end of the Cretaceous led to the activation and inversion of early normal faults. The shallow structural reservoirs in the basin are mostly related to the deep fault inversion at the foreland stage. This type of foreland basin is divided into four depozones in the east-west direction, namely, wedge-top, foredeep, forebulge and backbulge. The southern basins focus on the analysis of the Neuquén Basin in Argentina. The structural deformation style is basement-involved type, which has undergone tectonic evolution of rift, post-rift and foreland. The foreland basin of this type can be divided into five tectono-sedimentary units in the east-west direction: wedge-top, foredeep, forelimb, basement-involved uplift and backlimb. According to the comparative analysis of the tectonic styles and sedimentary filling characteristics of the Andean foreland system in South America, the sedimentary filling patterns of the Andean foreland basin can be divided into three types, namely, the foreland basin with a single foredeep, the classical foreland basin and the broken foreland basin. The above analysis of Andean foreland basin will be helpful to the evaluation of oil & gas exploration and the optimization of new overseas exploration projects in this area.