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<p>The late Carboniferous—early Permian sedimentary record from the Minas de Henarejos area, located in the SE Iberian Ranges, E Spain, is a key location to study the transition between the Variscan and the Alpine tectonic regimes and the changes between the Carboniferous to Permian flora related to the end of the cold stage of the Late Paleozoic Ice Age in the equatorial zone. The Minas de Henarejos Basin is unique in the Iberian Ranges, as it contains a thick succession of Carboniferous continental sediments rich in macroflora remains and with thick coal beds. The area was subjected to iron and coal mining during different periods of the nineteenth and twentieth centuries and at present it offers magnificent outcrops due to the intense coal extraction work carried out at the beginning of the last decade. The present multidisciplinary study has allowed us to define three new informal lithostratigraphic units based on their lower and upper boundaries, lithological, mineralogical, and sedimentary characteristics, the presence of macroflora, and their degree of deformation. The oldest Minas de Henarejos Unit (1), unconformably overlying Variscan basement, is characterized by dark gray lutites, sandstones, conglomerates, and coal beds deposited in low sinuosity fluvial systems that evolved to lacustrine systems. Based on its macroflora content, this unit has been dated as Stephanian B (late Carboniferous). The overlying Narboneta Unit (2), separated by an erosional unconformity, comprises white breccias and conglomerates of proximal alluvial fans and incipient fluvial systems. These are overlain by the red conglomerates of the Fuente del Compadre Unit (3), again separated by an erosional conformity. All three units underwent compressive deformation linked to the late-stage Variscan compressive regime, which is not noted in the overlying middle Permian Boniches Fm., this latter unit deposited after a long hiatus and comprising red conglomerates of fluvial systems related to large alluvial fans and linked to the extensional Alpine phase. A change in the type of paleosols, from the Histosols of wet climates to Entisols of alternating wet and dry periods, is in agreement with the clay mineral compositions, which suggests humid climate conditions during the Carboniferous and early Permian and a change to more arid conditions during Middle Permian times.</p>

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The late Carboniferous to early Permian continental Minas de Henarejos Basin, SE Iberian Ranges, Spain: a multidisciplinary approach to its climate and Variscan-Alpine tectonic transition

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  • 发表日期：

    2025年7月17日

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  • Raúl De La Horra,
  • Juan Miguel Insua-Arévalo,
  • José López-Gómez,
  • José F. Barrenechea,
  • José B. Diez,
  • Violeta Borruel-Abadía,
  • Ana Belén Galán-Abellán,
  • Maja Marinić,
  • Antonio Hernández-Orúe

摘要

The late Carboniferous—early Permian sedimentary record from the Minas de Henarejos area, located in the SE Iberian Ranges, E Spain, is a key location to study the transition between the Variscan and the Alpine tectonic regimes and the changes between the Carboniferous to Permian flora related to the end of the cold stage of the Late Paleozoic Ice Age in the equatorial zone. The Minas de Henarejos Basin is unique in the Iberian Ranges, as it contains a thick succession of Carboniferous continental sediments rich in macroflora remains and with thick coal beds. The area was subjected to iron and coal mining during different periods of the nineteenth and twentieth centuries and at present it offers magnificent outcrops due to the intense coal extraction work carried out at the beginning of the last decade. The present multidisciplinary study has allowed us to define three new informal lithostratigraphic units based on their lower and upper boundaries, lithological, mineralogical, and sedimentary characteristics, the presence of macroflora, and their degree of deformation. The oldest Minas de Henarejos Unit (1), unconformably overlying Variscan basement, is characterized by dark gray lutites, sandstones, conglomerates, and coal beds deposited in low sinuosity fluvial systems that evolved to lacustrine systems. Based on its macroflora content, this unit has been dated as Stephanian B (late Carboniferous). The overlying Narboneta Unit (2), separated by an erosional unconformity, comprises white breccias and conglomerates of proximal alluvial fans and incipient fluvial systems. These are overlain by the red conglomerates of the Fuente del Compadre Unit (3), again separated by an erosional conformity. All three units underwent compressive deformation linked to the late-stage Variscan compressive regime, which is not noted in the overlying middle Permian Boniches Fm., this latter unit deposited after a long hiatus and comprising red conglomerates of fluvial systems related to large alluvial fans and linked to the extensional Alpine phase. A change in the type of paleosols, from the Histosols of wet climates to Entisols of alternating wet and dry periods, is in agreement with the clay mineral compositions, which suggests humid climate conditions during the Carboniferous and early Permian and a change to more arid conditions during Middle Permian times.