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Tectonostratigraphic evolution of the Orphan Basin and Flemish Pass region – Part 2: Regional structural development and lateral variations in rifting style
Marine and Petroleum Geology ( IF 4.2 ) Pub Date : 2021-07-10 , DOI: 10.1016/j.marpetgeo.2021.105219
Adam J. Cawood 1 , David A. Ferrill 1 , Alan P. Morris 1 , David Norris 2 , David McCallum 2 , Erin Gillis 2 , Kevin J. Smart 1
Affiliation  

Interpretation of newly acquired modern broadband seismic reflection data and structural restoration of three regional, WNW-ESE oriented cross-sections across the Orphan Basin, Flemish Pass and Flemish Cap provide new insights into rift evolution and structural style in the area. Our results show that regional extension in the Orphan Basin and Flemish Pass area largely occurred between 170 Ma and 135 Ma, and later extension (135 Ma onwards) in the study area was accommodated east of Flemish Cap. Seismic stratigraphic mapping provides evidence for significant thicknesses of Jurassic strata throughout the Orphan Basin and Flemish Pass area, and structural interpretations highlight the importance of crustal-scale extensional detachment faults in controlling the geometry and position of Jurassic sub-basins at a range of scales. Stacked detachment surfaces and coincident extreme crustal attenuation (to ca. 3.1 km) are observed in eastern parts of the Orphan Basin in an area defined in this study as the Orphan Trough. Rifting style in the central, northern, and eastern parts of the Orphan Basin is dominated by low-angle detachment faulting with maximum extension perpendicular to the incipient rift axis. In contrast, structural geometries in the southwestern part of the basin are suggestive of transtensional deformation, and interplay of normal and strike-slip faulting. Results from map-based interpretation show that strike-slip faults within this transtensional zone are associated with displacement transfer between half-grabens of opposing polarity, rather than regional strike-slip displacement. These structures are interpreted as contemporaneous and kinematically linked to displacement along low-angle detachment surfaces elsewhere and are not attributed to distinct episodes of oblique extension.



中文翻译:

孤儿盆地和佛兰芒山口地区的构造地层演化——第 2 部分:区域构造发展和裂谷类型的横向变化

对新获得的现代宽带地震反射数据的解释和横跨孤儿盆地、佛兰芒山口和佛兰芒帽的三个区域性、WNW-ESE 定向横截面的结构恢复,为该地区裂谷演化和构造风格提供了新的见解。我们的研究结果表明,孤儿盆地和弗拉芒山口地区的区域伸展主要发生在 170 Ma 和 135 Ma 之间,后来研究区的伸展(135 Ma 以后)被容纳在 Flemish Cap 以东。地震地层绘图为整个孤儿盆地和佛兰芒山口地区侏罗纪地层的显着厚度提供了证据,并且结构解释突出了地壳尺度伸展拆离断层在控制侏罗纪次盆地几何形状和位置的重要性。在本研究中定义为孤立海槽的孤儿盆地东部地区,观察到堆积的脱离表面和同时发生的极端地壳衰减(至约 3.1 公里)。孤儿盆地中部、北部和东部的裂谷类型以低角度拆离断层为主,最大伸展垂直于初始裂谷轴。相比之下,盆地西南部的构造几何形状暗示了张性变形以及正常断层和走滑断层的相互作用。基于地图的解释结果表明,该张拉带内的走滑断层与相反极性的半地堑之间的位移转移有关,而不是区域走滑位移。

更新日期:2021-09-07
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