TY - JOUR

T1 - Late to post-Variscan basement segmentation and differential exhumation along the SW Bohemian Massif, central Europe

AU - Eberts, Andreas

AU - Fazlikhani, Hamed

AU - Bauer, Wolfgang

AU - Stollhofen, Harald

AU - De Wall, Helga

AU - Gabriel, Gerald

N1 - Funding Information: Author contributions. AE, HF, WB, and HS designed the study. AE prepared the paper and performed the analysis of the topographic, filtered gravity, granite density, and literature data. HF carried out the filtering of the gravity data and supervised the study. HS and HdW supervised and acquired the financial support for the project leading to this publication. GG provided the gravity data and supported their interpretation. All authors contributed to the reviewing of the paper and the discussion of the results.

PY - 2021/10/12

Y1 - 2021/10/12

N2 - The exposed Variscan basement in central Europe is well-known for its complex structural and lithological architecture resulting from multiple deformation phases. We studied the southwestern margin of the Bohemian Massif, which is characterized by major and long-lived shear zones, such as the Pfahl and Danube shear zones, extending over >ĝ€¯100ĝ€¯km and initiated during Variscan tectonics. We integrated Bouguer gravity anomaly and lidar topographic data analyses and combined our results with available data and observations from low-Temperature thermochronology, metamorphic grades, and the exposed granite inventory to detect patterns of basement block segmentation and differential exhumation. Three NW-SE-striking basement blocks are bordered by the Runding, Pfahl, and Danube shear zones from the northeast to the southwest. Basement block boundaries are indicated by abrupt changes in measured gravity patterns and metamorphic grades. By applying high-pass filters to gravity data in combination with lineament analysis, we identified a new NNW-SSE-striking tectonic structure (Cham Fault), which further segments known basement blocks. Basement blocks that are segmented by the Cham Fault differ in the abundance and spatial distribution of exposed late Variscan granites and are further characterized by variations in apparent thermochronological age data. Based on our observations and analyses, a differential exhumation and tectonic tilt model is proposed to explain the juxtaposition of different crustal levels. Block segmentation along the NW-SE-striking Pfahl and Runding shear zones most likely occurred prior, during, and after late orogenic granite emplacement at ca. 320ĝ€¯±ĝ€¯10ĝ€¯Ma, as some of the granites are cross-cut by the shear zones, while others utilized these structures during magma ascent and emplacement. In contrast, activity and block segmentation along the Cham Fault occurred after granite emplacement as the fault sharply truncates the granite inventory. Our study provides evidence of intense and continuous fault activities during late and post-orogenic times and highlights the importance of tectonic structures in the exhumation and juxtaposition of different crustal levels and the creation of complex lithological patterns in orogenic terrains.

AB - The exposed Variscan basement in central Europe is well-known for its complex structural and lithological architecture resulting from multiple deformation phases. We studied the southwestern margin of the Bohemian Massif, which is characterized by major and long-lived shear zones, such as the Pfahl and Danube shear zones, extending over >ĝ€¯100ĝ€¯km and initiated during Variscan tectonics. We integrated Bouguer gravity anomaly and lidar topographic data analyses and combined our results with available data and observations from low-Temperature thermochronology, metamorphic grades, and the exposed granite inventory to detect patterns of basement block segmentation and differential exhumation. Three NW-SE-striking basement blocks are bordered by the Runding, Pfahl, and Danube shear zones from the northeast to the southwest. Basement block boundaries are indicated by abrupt changes in measured gravity patterns and metamorphic grades. By applying high-pass filters to gravity data in combination with lineament analysis, we identified a new NNW-SSE-striking tectonic structure (Cham Fault), which further segments known basement blocks. Basement blocks that are segmented by the Cham Fault differ in the abundance and spatial distribution of exposed late Variscan granites and are further characterized by variations in apparent thermochronological age data. Based on our observations and analyses, a differential exhumation and tectonic tilt model is proposed to explain the juxtaposition of different crustal levels. Block segmentation along the NW-SE-striking Pfahl and Runding shear zones most likely occurred prior, during, and after late orogenic granite emplacement at ca. 320ĝ€¯±ĝ€¯10ĝ€¯Ma, as some of the granites are cross-cut by the shear zones, while others utilized these structures during magma ascent and emplacement. In contrast, activity and block segmentation along the Cham Fault occurred after granite emplacement as the fault sharply truncates the granite inventory. Our study provides evidence of intense and continuous fault activities during late and post-orogenic times and highlights the importance of tectonic structures in the exhumation and juxtaposition of different crustal levels and the creation of complex lithological patterns in orogenic terrains.

UR - http://www.scopus.com/inward/record.url?scp=85117123035&partnerID=8YFLogxK

U2 - 10.5194/se-12-2277-2021

DO - 10.5194/se-12-2277-2021

M3 - Article

AN - SCOPUS:85117123035

VL - 12

SP - 2277

EP - 2301

JO - SOLID EARTH

JF - SOLID EARTH

SN - 1869-9510

IS - 10

ER -