构造倾斜角度对盐构造形成的控制模式:以下刚果盆地为例
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摘要
基于下刚果盆地3个工区的地震数据,总结盆地内9种典型的盐相关构造样式,并基于离散元数值模拟方法,以构造倾斜角度为单一控制变量建立模型,对比分析盐岩的运动矢量演化。模拟结果表明,随着构造倾斜角度的增加,盐岩及其上覆岩层的流动速度逐渐增大,后续陆源沉积物的搬运距离也越远,更易形成盐构造;盐岩流动主要有3种控制机制:差异压实作用控制、差异压实作用和重力滑脱作用共同控制以及重力滑脱作用控制,这3种控制作用均受坡度的影响,随着坡度的改变,3种控制作用依次出现,控制着盐构造的形成。在上述分析结果的基础上,建立被动陆缘盆地构造倾斜角度对盐岩流动的控制模式。
Based on the data of three seismic work areas in the Lower Congo Basin, nine typical salt-related tectonic patterns are summarized in the basin and the distribution pattern of salt structures is confirmed. Established with the base tilt angle as a single variable based on the discrete element numerical simulation method, and evolution results of the structure and motion vectors are obtained. With the increase of the basement inclination angle, the flow velocity of salt rock and its overlying sediments gradually increases, and the subsequent terrigenous sediment transport distance is also longer. The basement inclination mainly has three kinds of control effects on the salt rock flow: differential compaction as the master control, differential compaction and gravity gliding combined, gravity gliding as master control. These three control effects are all affected by the basement inclination angle and appear in turn with the change of the angle. Based on the analysis results above, control pattern of basement inclination on salt rock flow in the passive margin basin of the South Atlantic is established.
Based on the data of three seismic work areas in the Lower Congo Basin, nine typical salt-related tectonic patterns are summarized in the basin and the distribution pattern of salt structures is confirmed. Established with the base tilt angle as a single variable based on the discrete element numerical simulation method, and evolution results of the structure and motion vectors are obtained. With the increase of the basement inclination angle, the flow velocity of salt rock and its overlying sediments gradually increases, and the subsequent terrigenous sediment transport distance is also longer. The basement inclination mainly has three kinds of control effects on the salt rock flow: differential compaction as the master control, differential compaction and gravity gliding combined, gravity gliding as master control. These three control effects are all affected by the basement inclination angle and appear in turn with the change of the angle. Based on the analysis results above, control pattern of basement inclination on salt rock flow in the passive margin basin of the South Atlantic is established.
引文
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[8]Kukla P A,Strozyk F,Mohriak W U.South Atlantic salt basins-witnesses of complex passive margin evolution.Gondwana Research,2018,53:41?57
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[18]Cundall P A,Strack O D L.A discrete numerical mode for granular assemblies.Géotechnique,1979,29(1):47?65
[19]Burbidge D R,Braun J.Numerical models of the evolution of accretionary wedges and fold-and-thrust belts using the distinct-element method.Geophysical Journal International,2002,148(3):542-561
[20]Morgan J K,Mcgovern P J.Discrete element simulations of gravitational volcanic deformation:1.Deformation structures and geometries.Journal of Geophysical Research Atmospheres,2005,110(B5):2701?2711
[21]Dean S L,Morgan J K.Influence of mobile shale on thrust faults:Insights from discrete element simulations.AAPG Bulletin,2015,99(3):403?432
[22]Maxwell S A.Deformation styles of allochthonous salt sheets during differential loading conditions:insights from discrete element models[D].Houston:Rice University,2009
[23]Nikolinakou M A,Luo G,Hudec M R,et al.Geomechanical modeling of stresses adjacent to salt bodies:Part 2.Poroelastoplasticity and coupled overpressures.AAPG Bulletin,2012,96(1):65?85
[24]Schultz-Ela D D.Origin of drag folds bordering salt diapirs.AAPG Bulletin,2003,87(5):757?780
[25]Morgan J K.Particle dynamics simulations of rateand state-dependent frictional sliding of granular fault gouge.Birkh?user Basel,2004,161(9/10):1877?1891
[26]Carter N L,Horseman S T,Russell J E,et al.Rheology of rocksalt.Journal of Structural Geology,1993,15(9/10):1257?1271
[2]Mohriak W U,Brown D E,Tari G C.Sedimentary basins in the Central And South Atlantic conjugate margins:deep structures and salt tectonics//Central Atlantic Conjugate Margins Conference.Halifax,2008:1?14
[3]袁圣强,吴时国,马玉波,等.南大西洋深水盆地的构造沉积演化及含油气系统.天然气地球科学,2008,19(2):216?221
[4]何娟,何登发,李顺利,等.南大西洋被动大陆边缘盆地大油气田形成条件与分布规律--以巴西桑托斯盆地为例.中国石油勘探,2011,16(3):57?67
[5]Davison I.Geology and tectonics of the South Atlantic Brazilian salt basins.Geological Society London Special Publications,2007,272(1):345?359
[6]Valle P J,Gjelberg J G,Helland-Hansen W.Tectonostratigraphic development in the eastern Lower Congo Basin,off shore Angola,West Africa.Marine&Petroleum Geology,2001,18:909?927
[7]Hudec M R,Jackson M P A.Terra infirma:understanding salt tectonics.Earth Science Reviews,2007,82(1/2):1?28
[8]Kukla P A,Strozyk F,Mohriak W U.South Atlantic salt basins-witnesses of complex passive margin evolution.Gondwana Research,2018,53:41?57
[9]Marton L G,Tari G C,Lehmann C T.Evolution of the Angolan passive margin,West Africa,with emphasis on postsalt structural styles//Mohriak W U,Talwani M.Atlantic rifts and continental margins.Washington DC:American Geophysical Union,2000,115:129?149
[10]Gamboa D,Alves T M.Bi-modal deformation styles in confined mass-transport deposits:examples from a salt minibasin in SE Brazil.Marine Geology,2016,379:176?193
[11]Quirk D G,Schodt N,Lassen B,et al.Salt tectonics on passive margins:examples from Santos,Campos and Kwanza basins.Geological Society London Special Publications,2012,363(1):207?244
[12]Duval B,Cramez C,Jackson M P A.Raft tectonics in the Kwanza Basin,Angola.Marine&Petroleum Geology,1992,9(4):389?404
[13]Schultz-Ela D D.Origin of drag folds bordering salt diapirs.AAPG Bulletin,2003,87(5):757?780
[14]Barton D C.Mechanics of formation of salt domes with special reference to Gulf Coast salt domes of Texas and Louisiana.AAPG Bulletin,1933,17(9):1025?1083
[15]Cundall P A,Strack O D L.The development of constitutive laws for soil using the distinct element method.Third International Conference on Numerical Methods in Geomechanics,1979,79(1):289?317
[16]Cundall P A,Hart R D.Numerical modelling of discontinua.Analysis&Design Methods,1993,9(2):231?243
[17]Morgan J K,Boettcher M S.Numerical simulations of granular shear zones using the distinct element method:1.Shear zone kinematics and the micromechanics of localization.Journal of Geophysical Research,1999,104(B2):2703?2719
[18]Cundall P A,Strack O D L.A discrete numerical mode for granular assemblies.Géotechnique,1979,29(1):47?65
[19]Burbidge D R,Braun J.Numerical models of the evolution of accretionary wedges and fold-and-thrust belts using the distinct-element method.Geophysical Journal International,2002,148(3):542-561
[20]Morgan J K,Mcgovern P J.Discrete element simulations of gravitational volcanic deformation:1.Deformation structures and geometries.Journal of Geophysical Research Atmospheres,2005,110(B5):2701?2711
[21]Dean S L,Morgan J K.Influence of mobile shale on thrust faults:Insights from discrete element simulations.AAPG Bulletin,2015,99(3):403?432
[22]Maxwell S A.Deformation styles of allochthonous salt sheets during differential loading conditions:insights from discrete element models[D].Houston:Rice University,2009
[23]Nikolinakou M A,Luo G,Hudec M R,et al.Geomechanical modeling of stresses adjacent to salt bodies:Part 2.Poroelastoplasticity and coupled overpressures.AAPG Bulletin,2012,96(1):65?85
[24]Schultz-Ela D D.Origin of drag folds bordering salt diapirs.AAPG Bulletin,2003,87(5):757?780
[25]Morgan J K.Particle dynamics simulations of rateand state-dependent frictional sliding of granular fault gouge.Birkh?user Basel,2004,161(9/10):1877?1891
[26]Carter N L,Horseman S T,Russell J E,et al.Rheology of rocksalt.Journal of Structural Geology,1993,15(9/10):1257?1271