A regional sedimentological and sequence stratigraphic analysis is presented in this paper to provide new insights into the morphological complexity and sedimentary mechanisms of unconformities giving shape to basin margins. Although the development of unconformities entails significant sediment delivery to be considered when analysing ‘source to sink’ systems, as well as large palaeogeographical changes related to basin reconfiguration episodes, the complexity that unconformities can reveal towards basin margins has been scarcely explored. A sedimentological and architectural analysis combining outcrop and subsurface datasets shows five palaeoenvironmental evolutionary stages and four key stratigraphic surfaces in a constrained ca 2 Ma Valanginian interval on the southern margin of the Neuquén back‐arc basin (Argentina). A complex‐type subaerial unconformity was identified, composed in turn of two subaerial unconformities exhibiting both single and composite motifs, different morphologies and facies shifts representative of large palaeogeographical changes. In the studied stratigraphic interval, two erosional stages occur linked to combinations of exclusively non‐marine‐driven processes involved in unconformities developing. The two subaerial unconformities differ in nature and distribution, representing a novel case of complex unconformities and stratigraphic architectures in non‐marine lowstand wedges. The Valanginian complex subaerial unconformity entails a high diachroneity along strike and depositional dip, implying that the hiatus created in landward settings occurred during relative sea‐level fall and rise stages during a period longer than in basinward areas. Disagreeing with classical sequential models, two third‐order sequence components of a complex lowstand wedge are preserved in proximal settings. Subsidence‐controlled accommodation and interplay between second‐order and third‐order cycles were combined, increasing the prospects of sediment storage and preservation potential of composite sequences towards landward areas. This work improves current comprehension about complex subaerial unconformities formation and related lowstand architectures in proximal settings, providing criteria to understand and revaluate lowstand wedge geometries, particularly for more complex examples, such as the case reported in this contribution.

中文翻译：

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非海洋演替中复杂的地下不整合的驱动过程和识别标准：强迫回归过程中盆地边缘整形的含义

本文提出了区域沉积学和层序地层学分析，以提供新的见解，使不整合面的形态复杂性和沉积机理形成盆地边缘。尽管不整合面的发展需要在分析“源到汇”系统以及与盆地重构事件相关的较大古地理变化时考虑大量的泥沙输送，但很少探讨不整合面对盆地边缘的复杂性。甲沉积学和建筑分析相结合露头和地下数据集示出了五个古环境演化阶段和四个关键地层表面在一个受约束的CA2内乌肯后弧盆地南缘（阿根廷）的马瓦兰吉尼纪。确定了复杂类型的地下不整合面，依次由两个展现出单一和复合基序，不同形态和相移的地下不整合面组成，这些变化代表了较大的古地理变化。在研究的地层间隔中，发生了两个侵蚀阶段，这些侵蚀阶段与不整合面发育中涉及的非海洋驱动过程的组合有关。两种陆上不整合面的性质和分布各不相同，这代表了非海洋低台楔块中复杂不整合面和地层构造的新情况。瓦朗哥尼亚复杂的航下不整合性导致沿走动和沉积倾角的高铁通性，这意味着在陆上环境中产生的裂隙发生在相对海平面的下降和上升阶段，而该阶段的时间要比盆地地区更长。与经典序列模型不同，复杂的低位楔块的两个三阶序列分量保留在近端设置中。将沉降控制和二阶和三阶循环之间的相互作用结合起来，增加了沉积物的沉积和复合序列向陆地区域的保存潜力。这项工作改善了当前对近端环境中复杂的空中不整合形成和相关低位构造的理解，为理解和重新评估低位楔形几何结构提供了标准，尤其是对于更复杂的示例，例如本贡献中报道的案例。