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Evolution of the South-Iberian paleomargin: From hyperextension to continental subduction
Journal of Structural Geology ( IF 2.6 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.jsg.2020.104122
Antonio Pedrera , Ana Ruiz-Constán , Jesús García-Senz , Antonio Azor , Carlos Marín-Lechado , Conxi Ayala , José Alberto Díaz de Neira , Luis Roberto Rodríguez-Fernández

Abstract Three crustal-scale sequentially restored cross-sections along the Central External Betic Cordillera enable us to pinpoint the role of extreme crustal thinning, tectonic inheritance and salt tectonics during the evolution of the South-Iberian paleomargin from Mesozoic rifting to Cenozoic continental subduction. This interpretation puts forward the existence of a former highly extended Mesozoic rift system, namely the Subbetic Basin. The basin comprises three main domains that coincide with the classical zoning of the External Betics: (i) The Intermediate units in the northern basin margin represent primary thick minibasins separated by salt walls; (ii) the External Subbetic units attest an inflated salt body in a central trough; and (iii) the Median and Internal Subbetic units in the southern basin margin are analogous to a group of primary minibasins with intercalations of submarine volcanic rocks overlying hyperextended crust. Shortening led to the extrusion of a salt canopy and the development of secondary minibasins. Furthermore, the tectonic inversion of the Subbetic Basin created two major thrusts sheets detached at the Upper Triassic evaporites, accommodating a shortening of ≈100–145 km at early Eocene-middle Miocene time. Compression reshaped the hyperextended domain into a subduction trench, and the former transfer faults into tear faults. Ongoing shortening led to the subduction of the South-Iberian paleomargin beneath the Alboran Domain lithosphere. Our results provide a new perspective on the inversion of segmented rift basins partly floored by mantle rocks and call for a major reconsideration on the tectonic architecture and evolution of the Betic-Rif Cordillera.

中文翻译:

南伊比利亚古边缘的演化:从超伸展到大陆俯冲

摘要 沿着中外贝蒂克山脉的三个地壳尺度顺序恢复的横截面使我们能够确定极端地壳减薄、构造继承和盐构造在南伊比利亚古边缘从中生代裂谷到新生代大陆俯冲演化过程中的作用。这种解释提出了以前高度延伸的中生代裂谷系统的存在,即亚贝蒂盆地。该盆地包括三个主要区域,与外部 Betics 的经典分区相吻合: (i) 盆地北部边缘的中间单元代表被盐壁隔开的原生厚小盆地;(ii) 外部亚贝特单位证明中央槽中有膨胀的盐体;(iii) 盆地南部边缘的中部和内部亚贝蒂单元类似于一组原生小型盆地,其中海底火山岩夹层覆盖在超伸展的地壳上。缩短导致盐冠的挤压和次级小盆地的发展。此外,亚贝蒂盆地的构造反转在上三叠统蒸发岩上产生了两个主要的逆冲断层,适应了早始新世-中中新世时间约 100-145 公里的缩短。压缩将超伸展区域重塑为俯冲沟,而前者将断层转变为撕裂断层。持续的缩短导致阿尔博兰域岩石圈下方的伊比利亚南部古边缘俯冲。
更新日期:2020-09-01
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