DOI: 10.1016/j.epsl.2020.116263
论文题名: Diagnosing an ancient shallow-angle subduction event from Cenozoic depositional and deformational records in the central Andes of southern Peru
作者: Perez N.D. ; Levine K.G.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 541 语种: 英语
中文关键词: central Andes
; flat-slab
; fold-thrust belts
; foreland basins
; tectonics
; thermochronology
英文关键词: Deformation
; Plates (structural components)
; Volcanoes
; Chronostratigraphy
; Crustal thickenings
; Eastern Cordillera
; Mantle lithosphere
; Pluton emplacement
; Sediment accumulation
; Temporal variation
; Thick-skinned deformations
; Subsidence
; Cenozoic
; chronostratigraphy
; paleoenvironment
; structural geology
; subduction
; subduction zone
; tectonic evolution
; tectonic setting
; volcanic arc
; Andes
; Peru
英文摘要: The spectrum of responses exhibited by upper plates to changes in the subduction zone geometry remains poorly constrained. In the Paleogene, the central Andes in southern Peru potentially experienced an episode of flat or shallow-angle subduction. Presented here are new geochronologic, thermochronologic, basin subsidence backstripping analysis, and 2D flexural modeling results. These are synthesized with existing records on the temporal variation of the volcanic arc position, basin fill chronostratigraphy, deformation style and location, and geophysical constraints on lithospheric architecture to investigate how this segment of the Andes developed during a proposed ancient modification to the subduction zone dip. Basin chronostratigraphy confirms persistent contribution from volcanic arc products during the Eocene–Miocene, arguing against complete cessation of arc magmatism. Sediment accumulation was pulsed and generally more rapid during the late Eocene–Oligocene event. The subsidence curve is generally concave-up, atypical for a foreland basin situated within the compressional central Andes. The tectonic subsidence magnitude observed from backstripping analysis is at least 1 km less than the magnitude of subsidence predicted by 2D flexural model results. This suggests a component of basin uplift, potentially as a dynamic response to subduction shallowing, may have opposed flexural subsidence that was driven by crustal thickening and topographic loading. New geo- and thermochronologic results constrain the timing of Late Triassic pluton emplacement, and initial unroofing that predates the proposed timing of flat or shallow-angle subduction. This new timing suggests initial deformation, with mixed thin- and thick-skinned deformation style, in the Eastern Cordillera may be linked to reactivation of inherited structures rather than inboard deformation advance as a response to subduction flattening. The lack of basement-cored uplifts, preservation of mantle lithosphere beneath this segment of the central Andes, and volcanic arc patterns argue against the occurrence of a flat slab event. Instead, these results point to a shallow-angle subduction event and highlight the diverse behaviors of Cordilleran margins affected by variable subduction zone geometry and upper plates with inherited crustal heterogeneities. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165208
Appears in Collections: 气候变化与战略
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作者单位: Department of Geology and Geophysics, College of Geosciences, Texas A&M University, College Station, TX 77843, United States
Recommended Citation:
Perez N.D.,Levine K.G.. Diagnosing an ancient shallow-angle subduction event from Cenozoic depositional and deformational records in the central Andes of southern Peru[J]. Earth and Planetary Science Letters,2020-01-01,541