Abstract In fold and thrust belts developing at convergent margins, the migration of the advancing wedge is accompanied by bulging of the downgoing plate, followed by the development of a foredeep basin filled by a thick succession of syn-orogenic sediments. The transition from forebulge to foredeep marks a key moment in the evolution of the orogenic system. In deep water environments, the record of this transition is typically complete and progressive. Conversely, in the shallow-water/continental environment of many collisional systems, the uplift of the forebulge area can imply emersion and erosion, obliterating the stratigraphic record of key steps of the evolution of the orogenic system. The southern Apennines constitute one of these collisional fold and thrust belts where the development of the forebulge has implied emersion and erosion, with the development of a Miocene forebulge erosional unconformity, accompanied by extensional deformation associated with the bending of the lithosphere during the forebulge stage. In this paper, we use strontium isotope stratigraphy to constrain with unprecedented time-resolution the age of the forebulge unconformity in areas presently incorporated in the northern sector of the southern Apennines fold and thrust belt. Integration of our results and those of previous studies indicates, at the regional scale, a younging toward the foreland of the forebulge unconformity across the belt. Our high-resolution ages also reveal a diachronous onset of the flexural subsidence over short distances, associated with the occurrence of horst and graben structures, possibly resulting from inherited paleotopography along with forebulge extension. This work highlights how high-resolution dating is critical to unravel the evolution of foreland basin systems at different scales.

中文翻译：

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通过 Sr 同位素地层学限制亚平宁山脉南部（意大利）中新世前陆弯曲沉降和外围隆起的开始

摘要 在会聚边缘发育的褶皱和冲断带中，前进楔的迁移伴随着下沉板块的隆起，随后发育出一个充满厚层同造山沉积物的前深盆地。从前缘到前缘的转变标志着造山系统演化的关键时刻。在深水环境中，这种转变的记录通常是完整和渐进的。相反，在许多碰撞系统的浅水/大陆环境中，前凸区的隆升可能意味着出水和侵蚀，抹去了造山系统演化关键步骤的地层记录。亚平宁山脉南部构成了这些碰撞褶皱和逆冲带之一，其中前凸起的发展意味着出水和侵蚀，随着中新世前隆起侵蚀不整合面的发展，伴随着与前隆期岩石圈弯曲相关的伸展变形。在本文中，我们使用锶同位素地层学以前所未有的时间分辨率限制了目前被纳入亚平宁山脉南部褶皱和逆冲带北部地区的前凸不整合的年龄。我们的结果与先前研究的结果的整合表明，在区域尺度上，该带上的前隆不整合向前陆年轻化。我们的高分辨率年龄还揭示了短距离内弯曲沉降的历时发生，这与地垒和地堑结构的发生有关，这可能是由于继承的古地形和前缘延伸造成的。