Magnetic evidence of a crustal fault affecting a linear laccolith: The Guadiana Fault and the Monchique Alkaline Complex (SW Iberian Peninsula) |
| |
| Institution: | 1. Key Laboratory of Paleomagnetism and Tectonic Reconstruction of Ministry of Land and Resources, Beijing 100081, China;2. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;3. Tianjin Municipal Water Conservancy Survey and Design Institute, Tianjin 300204, China;1. Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, C/Urgell 187, 08036 Barcelona, Spain;2. Institut de Ciencia i Tecnología Ambientals (ICTA), Universitat Autònoma de Barcelona (UAB). Edifici C, 08193 Bellaterra, Spain;3. Departament de Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona (UAB). Edifici C, 08193 Bellaterra, Spain |
| |
| Abstract: | Magnetic anomalies can help reveal the structure of the upper crust in regions with intermediate or basic igneous rocks, and their continuity is essential to determine the position of crustal faults. The southwestern Iberian Peninsula constitutes the foreland of the Betic Cordillera and is characterized by an elongated E-W dipole extending 200 km toward its external zones. The anomaly is related to the outcropping Monchique Alkaline Complex, characterized by rocks of moderate magnetic susceptibility (0.029 SI) intruding into the metapelitic host rock of the South Portuguese Zone. Analysis of aeromagnetic and field magnetic anomalies serves to constrain the geometry of this laccolith. Toward the east, the magnetic dipole has a 60 km long N-S sharp boundary that coincides with the southern part of the Guadiana River. Field magnetic and gravity anomalies confirm the presence of this structure. It is produced by a sharp step in the elongated anomalous body, with an E downthrown block, interpreted as the offset produced by a deep N-S crustal fault—the Guadiana Fault. Therefore, the Guadiana River has three long linear segments near its mouth, locally coinciding with a N-S trending joint set, that support the presence of this major fault. To date, no evidence of this tectonic discontinuity, coinciding with the Spanish-Portuguese border, has been reported. Magnetic research is essential for understanding the structure of wide regions intruded by intermediate and/or basic igneous rocks. |
| |
| Keywords: | Magnetic anomalies Magnetic susceptibility 2D magnetic models South Portuguese Zone Intermediate igneous rocks Crustal fault |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
