The Upper Oligocene Macigno Formation cropping out in the coastal section of SW Tuscany represents the sedimentary fill of a foredeep basin developed during the collisional stages that led to the construction of the Apennine mountain belt of peninsular Italy. The stratigraphic sequence consists of alternating sandstones and siltstones, that are affected by km-scale contractional structures, namely SW-dipping thrusts and related NE-verging folds. An original field survey carried out along a superb coastal exposure, integrated with analysis of mesoscopic fabrics and their overprinting relationships, makes it possible to unravel a complex deformation history. Four main deformation stages are recognized: i) layer-parallel shortening A; ii) top-to-the-foreland shear B; iii) folding C, comprising the fold nucleation sub-stage C1 and the fold amplification sub-stage C2; and iv) thrust propagation D. The sequence of recognized stages indicates a progressive deformation history of the Macigno Formation as it was incorporated within the evolving Apennine orogenic system. The kinematic history inferred from deformation fabrics and their overprinting relationships within Macigno Fm. deposits in SW Tuscany shows remarkable analogies with the structural evolution of foredeep sediments from other fold-and-thrust belts, yet with little deviations mainly consisting of pureshear vs. simple shear fluctuations in the early history of accretion. These provide original information on the modes of accretion of foredeep deposits within evolving collisional belts, thus contributing to an enhanced understanding of orogenic dynamics during mountain building with a classical example whose evolution is unravelled in detail.

托斯卡纳西南海岸的上渐新世麦格尼奥组形成，代表了在碰撞阶段形成的一个前深盆地的沉积物，这导致了意大利半岛的亚平宁山脉地带的建设。地层序列由交替的砂岩和粉砂岩组成，这些砂岩和粉砂岩受到千米尺度的收缩结构的影响，即西南向俯冲冲断和相关的东北向褶皱。沿着极好的沿海地区进行的原始现场调查，结合对介观织物及其叠印关系的分析，可以揭示一个复杂的变形历史。认识到四个主要的变形阶段：i）平行层缩短A；ii）地上剪切B；iii）折叠C，包括倍数成核子阶段C1和倍数扩增子阶段C2；iv）推力传播D.识别的层序表明了Macigno地层的渐进形变历史，因为它被整合到了不断发展的亚平宁造山系统中。运动历史从变形织物及其在Macigno Fm中的套印关系推论得出。托斯卡纳西南部的沉积物与其他褶皱-冲断带的前缘沉积物的结构演化具有明显的相似性，但在增生的早期，几乎没有偏差，主要是纯剪切与简单剪切波动有关。这些信息提供了有关不断发展的碰撞带内前深层沉积物增生模式的原始信息，