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Gondwanan Inheritance on the Building of the Western Central Andes (Domeyko Range, Chile): Structural and Thermochronological Approach (U‐Pb and 40Ar/39Ar)
Tectonics ( IF 4.2 ) Pub Date : 2021-01-12 , DOI: 10.1029/2020tc006475
M. Espinoza 1, 2 , V. Oliveros 1 , P. Vásquez 3 , L. Giambiagi 4 , L. Morgan 5 , R. González 6 , L. Solari 7 , F. Bechis 8
Affiliation  

Tectonics inheritance controls the evolution of many orogens. To unravel the role of the Gondwanan heritage (late Paleozoic to Triassic) over the building of the Central Andes in northern Chile (Domeyko Range), we performed detrital U‐Pb zircon and 40Ar/39Ar muscovite geochronology along with structural analyses (kinematics and structural balancing). 40Ar/39Ar dating of detrital muscovite reveals contrasting cooling histories for the Paleozoic basement of Triassic rift sub‐basins, indicating that NW‐striking crustal structures segmented the Andean forearc since at least the middle Permian, likely related to an accretional fabric developed along SW Gondwana. These structures can be inferred based on scattered faults, gravimetric data, and basement age disruptions. During the Late Triassic, NS‐striking master faults and secondary NW‐ to NNW‐striking faults configured an oblique rift, primarily driven by subduction dynamics. We suggest that along SW Gondwana, the slab‐pull would have controlled the development of subduction‐related rift basins close to the trench whereas Triassic inland rifts were mainly driven by Pangea‐breakup stresses. Compressional tectonics began in the Late Cretaceous, yet the inversion of the Triassic rift would have started during the Eocene with the inception of the metallogenic‐fertile transpressional Domeyko fault system. Thus, the structural style of this range was determined by the architecture of the Triassic rift, where the inversion of deep‐seated faults accounted for west‐vergent thick‐ and thin‐skinned structures. Pre‐Andean NW‐striking structures also accommodated tectonic rotations during the Incaic orogeny (Eocene‐Oligocene) and may delimit the rupture zone of large earthquakes, suggesting an underestimated role of such ancient discontinuities in Andean neotectonics.

中文翻译:

冈瓦南对安第斯中部西部建筑的继承(智利多梅科山脉):结构和热年代学方法(U-Pb和40Ar / 39Ar)

构造遗传控制着许多造山带的演化。为了揭露冈瓦南遗产(古生代至三叠纪)在智利北部安第斯山脉(Domeyko山脉)上的作用,我们进行了碎屑U-Pb锆石和40 Ar / 39 Ar白云母地质年代学以及结构分析(运动学)和结构平衡)。40氩/ 39碎屑白云母的Ar测年揭示了三叠纪裂陷盆地的古生代基底的冷却历史形成对比,这表明自西北角以来至少在二叠纪以来,西北走向的地壳结构分割了安第斯前臂,这可能与沿着冈瓦纳西南部发育的增生纤维有关。这些结构可以根据分散的断层,重力数据和地下室年龄破坏来推断。在三叠纪晚期,NS冲动的主断层和次生的NW到NNW的冲断断层构造了一条斜裂谷,主要由俯冲动力学驱动。我们认为,在冈瓦纳西南部,平板拉动将控制与海沟相关的俯冲相关裂谷盆地的发展,而三叠纪内陆裂谷主要是由Pangea破裂应力驱动的。压缩构造始于白垩纪晚期,然而,三叠纪裂谷的反转将在始新世始于成矿-肥沃压制性多米科断层系统的开始。因此,该范围的构造样式是由三叠纪裂谷的构造决定的,深部断层的反演是西缘的厚薄皮构造。安第斯前西北碰撞构造在印加造山运动(始新世-渐新世)期间也适应了构造旋转,并可能划定了大地震的破裂带,表明这种古老的不连续性在安第斯新构造学中的作用被低估了。该范围的构造样式是由三叠纪裂谷的构造决定的,深部断层的倒置是西缘的厚薄层构造的原因。安第斯前西北碰撞构造在印加造山运动(始新世-渐新世)期间也适应了构造旋转,并可能划定了大地震的破裂带,表明这种古老的不连续性在安第斯新构造学中的作用被低估了。该范围的构造样式是由三叠纪裂谷的构造决定的,深部断层的倒置是西缘的厚薄层构造的原因。安第斯前西北碰撞构造在印加造山运动(始新世-渐新世)期间也适应了构造旋转,并可能划定了大地震的破裂带,表明这种古老的不连续性在安第斯新构造学中的作用被低估了。
更新日期:2021-03-18
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