Early Paleozoic accretionary orogens dominated the Western Gondwana margin and were characterized by nearly continuous subduction associated with crustal extension and back-arc basin development. The southwestern margin is represented by Famatinian and Pampean basement realms exposed in South America, both related to the protracted Paleozoic evolution of the Terra Australis Orogen, whereas the northwestern margin is mainly recorded in Cadomian domains of Europe and adjacent regions. However, no clear relationships between these regions were so far established. Based on a compilation and reevaluation of geological, paleomagnetic, petrological, geochronological and isotopic evidence, this contribution focuses on crustal-scale tectonic and geodynamic processes occurring in Western Gondwana accretionary orogens, aiming at disentangling their common Early Paleozoic evolution. Data show that accretionary orogens were dominated by high-temperature/low-pressure metamorphism and relatively high geothermal gradients, resulting from the development of extended/hyperextended margins and bulk transtensional deformation. In this sense, retreating-mode accretionary orogens characterized the Early Paleozoic Gondwana margin, though short-lived pulses of compression/transpression also occurred. The existence of retreating subduction zones favoured mantle-derived magmatism and mixing with relatively young (meta)sedimentary sources in a thin continental crust. Crustal reworking of previous forearc sequences due to trenchward arc migration thus took place through assimilation and anatexis in the arc/back-arc regions. Therefore, retreating-mode accretionary orogens were the locus of Early Paleozoic crustal growth in Western Gondwana, intimately associated with major flare-up events, such as those related to the Cadomian and Famatian arcs. Slab roll back, probably resulting from decreasing convergence rates and plate velocities after Gondwana assembly, was a key factor for orogen-scale geodynamic processes. Coupled with synchronous oblique subduction and crustal-scale dextral deformation, slab roll back might trigger toroidal mantle flow, thus accounting for bulk dextral transtension, back-arc extension/transtension and a large-scale anticlockwise rotation of Gondwana mainland.

早期的古生代增生造山带在冈瓦纳西部边缘占主导地位，其特征是与地壳伸展和弧后盆地发育有关的近乎连续俯冲。西南缘以南美洲暴露的法马汀和庞贝基底层为代表，两者都与大地造山带的古生代演化有关，而西北缘则主要记录在欧洲和邻近地区的卡多米亚地区。但是，到目前为止，这些区域之间尚无明确的关系。根据对地质，古磁，岩石学，地质年代学和同位素证据的汇编和重新评估，该研究成果着重于冈瓦纳西部增生造山带发生的地壳尺度构造和地球动力学过程，目的在于解开它们共同的早期古生代演化。数据表明，增生造山带主要由高温/低压变质作用和相对较高的地热梯度所致，这是由于扩展/超扩展的边缘和大量的超张变形引起的。从这个意义上说，后退模式增生造山带是早期古生代冈瓦纳边缘的特征，尽管还存在短暂的压缩/压迫脉冲。后退俯冲带的存在有利于地幔衍生的岩浆作用，并与较薄的大陆壳中较年轻的（成年）沉积源混合。由于弧向移行，先前的前臂序列进行了地壳改造，因此是通过弧/后弧区域的同化和厌食而发生的。因此，退缩模式增生造山带是冈瓦纳西部古生代早期地壳生长的场所，与主要的爆发事件密切相关，例如与卡多马弧和法马第弧有关的事件。平板回滚，可能是冈瓦纳组装后收敛速度和板速度降低所致，是造山带尺度地球动力学过程的关键因素。与同步斜向俯冲和地壳尺度的右旋变形相结合，板块的回滚可能会触发环形地幔流动，从而解释了冈萨那大陆的总体右旋变形，背向弧伸展/延伸和大规模逆时针旋转。可能是冈瓦纳组装后收敛速度和板速度降低所致，这是造山带尺度地球动力学过程的关键因素。与同步斜向俯冲和地壳尺度的右旋变形相结合，板块的回滚可能会触发环形地幔流动，从而解释了冈萨那大陆的总体右旋变形，背向弧伸展/延伸和大规模逆时针旋转。可能是冈瓦纳组装后收敛速度和板速度降低所致，这是造山带尺度地球动力学过程的关键因素。与同步斜向俯冲作用和地壳尺度的右旋变形相结合，板块的回滚可能触发环形地幔流动，从而解释了冈萨那大陆的总体右旋延伸，背向弧延伸/延伸和大规模逆时针旋转。