DOI: 10.1016/j.tecto.2020.228715
论文题名: Vp/Vs ratios in the Parnaíba Basin from joint active-passive seismic analysis – Implications for continental amalgamation and basin formation
作者: Schiffer C. ; de Lima M.V.A.G. ; Soares J.E.P. ; Stephenson R. ; de Araújo V.C.M. ; Lima F.T. ; Rocha F.A.S. ; Trindade C.R. ; Fuck R.A.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2021
卷: 801 语种: 英语
中文关键词: Composition and structure of the continental crust
; Intracontinental basin
; Seismology
; South America
; Vp/Vs ratios
英文关键词: Buildings
; Metals
; Sedimentology
; Seismic waves
; Seismology
; Structural geology
; Uncertainty analysis
; Common-conversion points
; Crustal composition
; Deep seismic reflections
; Geophysical models
; Geophysical surveys
; Receiver functions
; Tectonic evolution
; Wide-angle reflection
; Sedimentary rocks
; basin evolution
; continental crust
; crustal structure
; P-wave
; S-wave
; sedimentary structure
; seismic velocity
; seismology
; tectonic evolution
; Brazil
; Parnaiba Basin
英文摘要: The Phanerozoic intracontinental Parnaíba Basin in northeast Brazil lies atop crust composed of Archaean to Mesoproterozoic cratonic blocks and Neoproterozoic mobile belts. Recently, active and passive source geophysical surveys characterised the crustal structure beneath the basin. We use information from published active-source seismic and new, coincident receiver function (RF) data to obtain Vp/Vs ratios for sedimentary and crustal structure and make inferences about crustal compositions and tectonic evolution. In our approach, sedimentary and crustal Vp/Vs ratios are adjusted to match common conversion point (CCP) images of RFs and known Moho and basement geometry. We use a P-wave model from published wide-angle reflection/refraction (WARR) seismics, and structural features from a deep seismic reflection (DSR) profile. CCP images of the primary RF conversions were used to model the crust, whilst conversions of multiples were used for the sediment-basement interface. The maximum uncertainties in Vp/Vs are estimated to be 0.15 for the basin and 0.03 for the crust. Vp/Vs ratios in the basin were estimated between 1.7 and 2.2. Lower values correlate with the exposure of older units primarily in the east of the basin, whilst higher values coincide with exposed younger units of the Parnaíba Basin. The obtained crustal Vp/Vs ratios between 1.73 and 1.81 support the previously published segmentation of the crust. In particular, we identified three regions of elevated Vp/Vs ratios, which can be related to proposed Neoproterozoic suture zones underlying the Parnaíba Basin, as well as high velocity lower crust beneath. The high Vp/Vs ratios can be explained by mafic compositions, for example metamorphosed or intruded crust, or fluids and sedimentary rocks entrained into highly deformed crust, typical for modifications related to suture zones. These new deep geophysical models provide important and complementary evidence for crustal amalgamation and the formation of the Parnaíba Basin. © 2021 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170898
Appears in Collections: 气候变化与战略
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作者单位: Department of Earth Sciences, Uppsala University, Uppsala, 752 36, Sweden; Universidade Federal do Pampa, Campus Caçapava do Sul, Avenida Pedro Anunciação, 111, Vila Batista, Caçapava do Sul/RS, CEP: 96.570-000, Brazil; Instituto de Geociências, Universidade de Brasília, Campus Darcy Ribeiro, Asa Norte, Brasília/DF, CEP: 70.910-900, Brazil; School of Geosciences, King's College, University of Aberdeen, Meston Building, Aberdeen, AB24 3EU, United Kingdom; Instituto de Engenharia e Geociências, Universidade Federal do Oeste do Pará, Rua Vera Paz, s/n (Unidade Tapajós), Bairro Salé, CEP 68.180-000, Brazil
Recommended Citation:
Schiffer C.,de Lima M.V.A.G.,Soares J.E.P.,et al. Vp/Vs ratios in the Parnaíba Basin from joint active-passive seismic analysis – Implications for continental amalgamation and basin formation[J]. Tectonophysics,2021-01-01,801