基于三维地震解释资料,对尼日尔三角洲东部M区块AE斜向背斜的形成机制和生长过程及其伴生断裂系统的形成演化过程进行剖析。研究表明,中新世中后期的H4—H6地层沉积时期为初始褶皱逆冲阶段,AE背斜区为斜向伸展断层控制的半地堑,其成因主要是局部的初始差异褶皱逆冲作用下形成的斜向伸展变换构造。该时期的差异滑动也控制了撕裂断层的形成。在中新世晚期到上新世的H1—H4地层沉积时期,大规模褶皱逆冲作用下的收缩变形强度差异导致先存伸展半地堑发生斜向构造反转而形成背斜,背斜在持续生长过程中规模逐渐变大,顶部也逐渐发生迁移。形成的断裂系统有差异逆冲伴生的少量撕裂正断层和由背斜翼部斜坡倾角诱导重力驱动的多米诺正断层。在更新世到全新世的H0—H1地层沉积时期,背斜生长停止,进入后褶皱逆冲演化阶段,局部重力回返垮塌、局部差异滑动与再活动的先存正反转断层耦合控制共轭断层的形成与分布。斜向背斜的反转成因机制及相关断裂系统演化的研究可为揭示其油气富集和油水分布规律提供指导。图10参32
Based on the three-dimensional seismic interpretation data, this paper analyzed the formation mechanism and the growth process of the oblique anticline AE of the M region of the eastern Niger Delta, as well as the evolution process of the associated fault systems. The study results show that the stratigraphic sedimentary period between reflector H4-H6 of the middle and late Miocene was the initial fold-thrust stage, the anticline AE was a half-graben controlled by oblique extensional faults derived from the oblique extensional transfer structure formed by local initial differential fold-thrusting. At the same time the tear faults developed as a result of the differential sliding. During the stratigraphic sedimentary period between reflector H1-H4 of the late Miocene to Pliocene, the large-scale folding and thrusting occurred, differential contractional deformation resulted in the pre-existing extensional half-graben became AE anticline by oblique tectonic inversion, then the anticline grew continually and the crest of the anticline migrated gradually. The newly formed fault systems consist of a small number of associated tear-normal faults caused by differential thrusting and gravity-driven domino normal faults predominantly induced by the slope inclination of the anticline limb. During the stratigraphic sedimentary period between reflector H0-H1 of the Pleistocene to Holocene, as the growth of the anticline ceased, the area entered post-fold thrusting stage. The formation and distribution of conjugated faults were controlled by the local gravity return collapse, local differential sliding and reactivation of pre-existing positive inversion faults jointly. The research results of genetic mechanism of the oblique inversion anticline and evolution of associated faults are helpful to reveal the key factors controlling the accumulation and distribution of oil and gas.
[1] COOPER M A, WILLIAMS G D. Inversion tectonics: A discussion[J]. Geological Society, 1989, 44(1): 335-347.
[2] WILLIAMS G D, POWELL C M, COOPER M A. Geometry and kinematics of inversion tectonics[J]. Geological Society, 1989, 44(1): 3-15.
[3] BUCHANAN J G, BUCHANAN P G. Basin inversion[J]. Geological Society Special Publications, 1995, 88(3): 596.
[4] BURLIGA S, KOYI H A, KRZYWIEC P. Modelling cover deformation and decoupling during inversion, using the Mid-Polish Trough as a case study[J]. Journal of Structural Geology, 2012, 42(2): 62-73.
[5] MANSY J L, MANBY G M, AVERBUCH O, et al. Dynamics and inversion of the Mesozoic Basin of the Weald-Boulonnais area: Role of basement reactivation[J]. Tectonophysics, 2003, 373(1): 161-179.
[6] MCCLAY K R. The geometries and kinematics of inverted fault systems: A review of analogue model studies[J]. Geological Society, London, Special Publications, 1995, 88(1): 97-118.
[7] TURNER J P, WILLIAMS G A. Sedimentary basin inversion and intra-plate shortening[J]. Earth-Science Reviews, 2004, 65(3): 277-304.
[8] BONINI M, SANI F, ANTONIELLI B. Basin inversion and contractional reactivation of inherited normal faults: A review based on previous and new experimental models[J]. Tectonophysics, 2012, 523(3): 55-88.
[9] AMILIBIA A, SABAT F, MCCLAY K R, et al. The role of inherited tectono-sedimentary architecture in the development of the central Andean mountain belt: Insights from the Cordillera de Domeyko[J]. Journal of Structural Geology, 2008, 30(12): 1520-1539.
[10] MAZUR S, SCHECK-WENDEROTH M, KRZYWIEC P. Different modes of the Late Cretaceous-Early Tertiary inversion in the North German and Polish basins[J]. International Journal of Earth Sciences, 2005, 94(5/6): 782-798.
[11] HAYWARD A B, GRAHAM R H. Some geometrical characteristics of inversion[J]. Geological Society, 1989, 44(1): 17-39.
[12] HOOPER R J, FITZSIMMONS R J, GRANT N, et al. The role of deformation in controlling depositional patterns in the south-central Niger Delta, West Africa[J]. Journal of Structural Geology, 2002, 24(4): 847-859.
[13] CORREDOR F, SHAW J H, BILOTTI F. Structural styles in the deep-water fold and thrust belts of the Niger Delta[J]. AAPG Bulletin, 2005, 89(6): 753-780.
[14] BRIGGS S E, DAVIES R J, CARTWRIGHT J A, et al. Multiple detachment levels and their control on fold styles in the compressional domain of the deepwater west Niger Delta[J]. Basin Research, 2006, 18(4): 435-450.
[15] MORLEY C K. Mobile shale related deformation in large deltas developed on passive and active margins[J]. Geological Society, London, Special Publications, 2003, 216(1): 335-357.
[16] ROWAN M G, PEEL F J, VENDEVILLE B C. Gravity-driven fold belts on passive margins[M]. Tulsa: AAPG, 2004: 157-182.
[17] MORLEY C K, KING R, HILLIS R, et al. Deepwater fold and thrust belt classification, tectonics, structure and hydrocarbon prospectivity: A review[J]. Earth-Science Reviews, 2011, 104(1): 41-91.
[18] MAGBAGBEOLA O A, WILLIS B J. Sequence stratigraphy and syndepositional deformation of the Agbada Formation, Robertkiri field, Niger Delta, Nigeria[J]. AAPG Bulletin, 2007, 91(7): 945-958.
[19] CONNORS C D, RADOVICH B, DANFORTH A, et al. The structure of the offshore Niger Delta[J]. Trabajos De Geología, 2009, 29(29): 182-188.
[20] BILOTTI F, SHAW J H. Deep-water Niger Delta fold and thrust belt modeled as a critical-taper wedge: The influence of elevated basal fluid pressure on structural styles[J]. AAPG Bulletin, 2005, 89(11): 1475-1491.
[21] BEGLINGER S E, DOUST H, CLOETINGH S. Relating petroleum system and play development to basin evolution: West African South Atlantic basins[J]. Marine and Petroleum Geology, 2012, 30(1): 1-25.
[22] COHEN H A, MCCLAY K. Sedimentation and shale tectonics of the northwestern Niger Delta front[J]. Marine and Petroleum Geology, 1996, 13(3): 313-328.
[23] ROUBY D, NALPAS T, JERMANNAUD P, et al. Gravity driven deformation controlled by the migration of the delta front: The Plio-Pleistocene of the Eastern Niger Delta[J]. Tectonophysics, 2011, 513(1): 54-67.
[24] AIZEBEOKHAI A P, OLAYINKA I. Structural and stratigraphic mapping of Emi field, offshore Niger Delta[J]. Journal of Geology, 2011, 3(2): 25-38.
[25] JERMANNAUD P, ROUBY D, ROBIN C, et al. Plio-Pleistocene sequence stratigraphic architecture of the eastern Niger Delta: A record of eustasy and aridification of Africa[J]. Marine and Petroleum Geology, 2010, 27(4): 810-821.
[26] RIBOULOT V, CATTANEO A, BERNÉ S, et al. Geometry and chronology of late Quaternary depositional sequences in the Eastern Niger Submarine Delta[J]. Marine Geology, 2012, 319(2): 1-20.
[27] KOLLA V, POSAMENTIER H W, WOOD L J. Deep-water and fluvial sinuous channels: Characteristics, similarities and dissimilarities, and modes of formation[J]. Marine and Petroleum Geology, 2007, 24(6): 388-405.
[28] SYLVESTER Z, PIRMEZ C, CANTELLI A. A model of submarine channel-levee evolution based on channel trajectories: Implications for stratigraphic architecture[J]. Marine and Petroleum Geology, 2011, 28(3): 716-727.
[29] STORTI F, POBLET J. Growth stratal architectures associated to decollement folds and fault-propagation folds. Inferences on fold kinematics[J]. Tectonophysics, 1997, 282(1/2/3/4): 353-373.
[30] MORLEY C K. Development of crestal normal faults associated with deepwater fold growth[J]. Journal of Structural Geology, 2007, 29(7): 1148-1163.
[31] BAUDON C, CARTWRIGHT J. Early stage evolution of growth faults: 3D seismic insights from the Levant Basin, Eastern Mediterranean[J]. Journal of Structural Geology, 2008, 30(7): 888-898.
[32] JIANG F J, PANG X Q, BAI J, et al. Comprehensive assessment of source rocks in the Bohai Sea area, eastern China[J]. AAPG Bulletin, 2016, 100(6): 969-1002.